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  • 1.
    Chien, Yu-Chuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Justus Liebig Univ Giessen, Phys Chem Inst, D-35392 Giessen, Germany.
    Lee, Ming-Tao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lacey, Matthew
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Scania CV AB, S-15187 Sodertalje, Sweden.
    Cellulose Separators With Integrated Carbon Nanotube Interlayers for Lithium-Sulfur Batteries: An Investigation into the Complex Interplay between Cell Components2019In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 14, p. A3235-A3241Article in journal (Refereed)
    Abstract [en]

    This work aims to address two major roadblocks in the development of lithium-sulfur (Li-S) batteries: the inefficient deposition of Li on the metallic Li electrode and the parasitic "polysulfide redox shuttle". These roadblocks are here approached, respectively, by the combination of a cellulose separator with a cathode-facing conductive porous carbon interlayer, based on their previously reported individual benefits. Both approaches result in significant improvements in cycle life in test cells with positive electrodes with practically relevant specifications. Despite the substantially prolonged cycle life, the combination of the interlayer and cellulose separator generates an increase in polysulfide shuttle current, leading to greatly reduced Coulombic efficiency. Based on XPS analyses, the latter is ascribed to a change in the composition of the solid electrolyte interphase (SEI) on the Li electrode. At the same time, the rate of electrolyte decomposition is found to be lower in cells with cellulose-based separators, which corroborates the observation of longer cycle life. These seemingly contradictory and counterintuitive observations demonstrate the complicated interactions between the cell components in the Li-S system and how strategies aiming to mitigate one unwanted process may exacerbate another. This study demonstrates the value of a holistic approach to the development of Li-S chemistry.

  • 2.
    Chien, Yu-Chuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lacey, Matthew
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrochemical Analysis of Modified Separators for Li-S Batteries2018Conference paper (Other academic)
    Abstract [en]

    The lithium-sulfur system is one of the potential energy storage technologies of the next generation due to the high theoretical specific capacity (1672 mAh/g), abundance and nontoxicity of sulfur [1]. However, there are still challenges yet to be overcome, one of which is the ‘polysulfide shuttle’ [1]. In order to address this issue, several modifications of the separators have been proposed. For example, longer cycle life, higher Coulombic efficiency and higher specific capacities have been reported with metal oxide coatings [2] and conductive interlayers [3,4] on the separators. Performance improvements in one or more of these properties have been ascribed to a suppression of polysulfide transport across the separator, even though this has not always been correlated with the difference in electrochemistry.

     

    In this work, the Intermittent Current Interruption (ICI) method [5] is applied to monitor the evolution of internal resistance of Li-S cells with different separators during repeated charge and discharge. Cells with different separators exhibit significant differences in resistance as a function of state-of-charge in the initial cycles, as shown in the figure.  Complemented by self-discharge tests and impedance spectroscopy at selected states of charge, the roles of the interlayers in the system can be further interpreted electrochemically. This work aims to associate the electrochemical properties of the interlayers to their corresponding microstructural counterparts, which can in turn facilitate further development of the interlayer materials.

     

    Figure: Internal resistance of cells vs specific charge for Li-S cells with different separators (Zero charge indicates the fully charged state.) for the 2nd, 5th and 10th cycles at C/10 rate.

     

    References:

    [1]         S. Urbonaite, T. Poux, P. Novák, Adv. Energy Mater. 5 (2015) 1–20.

    [2]         Z. Zhang, Y. Lai, Z. Zhang, K. Zhang, J. Li, Electrochim. Acta 129 (2014) 55–61.

    [3]         H. Yao, K. Yan, W. Li, G. Zheng, D. Kong, Z.W. Seh, V.K. Narasimhan, Z. Liang, Y. Cui, Energy Environ. Sci. 7 (2014) 3381–3390.

    [4]         J. Balach, T. Jaumann, M. Klose, S. Oswald, J. Eckert, L. Giebeler, Adv. Funct. Mater. 25 (2015) 5285–5291.

    [5]         M.J. Lacey, K. Edström, D. Brandell, Chem. Commun. 51 (2015) 16502–16505.

  • 3.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wang, Zhaouhui
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Separators As a Tool for Enhanced Battery Performance2019In: International Battery Association 2019: Batteries and Energy Storage / [ed] The electrochemical Society, La Jolla, 2019, article id 117872Conference paper (Refereed)
  • 4.
    Lindgren, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Rehnlund, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Karlsruhe Inst Technol, Dept Appl Biol, Inst Appl Biosci, Kaiserstr 12, D-76131 Karlsruhe, Germany.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    On the Capacity Losses Seen for Optimized Nano-Si Composite Electrodes in Li-Metal Half-Cells2019In: Advanced Energy Materials, ISSN 1614-6832, Vol. 9, no 33, article id 1901608Article in journal (Refereed)
    Abstract [en]

    While the use of silicon‐based electrodes can increase the capacity of Li‐ion batteries considerably, their application is associated with significant capacity losses. In this work, the influences of solid electrolyte interphase (SEI) formation, volume expansion, and lithium trapping are evaluated for two different electrochemical cycling schemes using lithium‐metal half‐cells containing silicon nanoparticle–based composite electrodes. Lithium trapping, caused by incomplete delithiation, is demonstrated to be the main reason for the capacity loss while SEI formation and dissolution affect the accumulated capacity loss due to a decreased coulombic efficiency. The capacity losses can be explained by the increasing lithium concentration in the electrode causing a decreasing lithiation potential and the lithiation cut‐off limit being reached faster. A lithium‐to‐silicon atomic ratio of 3.28 is found for a silicon electrode after 650 cycles using 1200 mAhg−1 capacity limited cycling. The results further show that the lithiation step is the capacity‐limiting step and that the capacity losses can be minimized by increasing the efficiency of the delithiation step via the inclusion of constant voltage delithiation steps. Lithium trapping due to incomplete delithiation consequently constitutes a very important capacity loss phenomenon for silicon composite electrodes.

  • 5.
    Liu, Chenjuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Carboni, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhu, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Insights into the Stability of Discharge Products in Na-O2 BatteriesManuscript (preprint) (Other academic)
  • 6.
    Liu, Chenjuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Carboni, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Hedman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    On the Stability of NaO2 in Na–O2 Batteries2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 16, p. 13534-13541Article in journal (Refereed)
    Abstract [en]

    Na–O2 batteries are regarded as promising candidates for energy storage. They have higher energy efficiency, rate capability, and chemical reversibility than Li–O2 batteries; in addition, sodium is cheaper and more abundant compared to lithium. However, inconsistent observations and instability of discharge products have inhibited the understanding of the working mechanism of this technology. In this work, we have investigated a number of factors that influence the stability of the discharge products. By means of in operando powder X-ray diffraction study, the influence of oxygen, sodium anode, salt, solvent, and carbon cathode were investigated. The Na metal anode and an ether-based solvent are the main factors that lead to the instability and decomposition of NaO2 in the cell environment. This fundamental insight brings new information on the working mechanism of Na–O2 batteries.

  • 7.
    Liu, Chenjuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Carboni, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Insights into the Stability of Discharge Products in Na-O2 Batteries2017Other (Other academic)
  • 8.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Cladophora Cellulose-based Separators for Lithium Batteries2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development of lithium-ion batteries (LIBs) has been focused on exploring and improving the electrode materials and electrolytes in the past decades. An indispensable component, the separator, is however not studied as extensively. In general, a separator has two functions, i.e. preventing the direct contact between the cathode and anode and providing the ionic transport pathways. Commercial separators for LIBs are usually made of polyolefin materials, which often have low thermal stabilities and poor electrolyte wettabilities.

    In this thesis, a new type of material, i.e. Cladophora cellulose, is used to manufacture separators for LIBs and lithium-metal batteries (LMBs). The separators, made with Cladophora cellulose fibers via a straightforward paper making method, possess several advantages compared to conventional polyolefin separators regarding, e.g. ionic conductivity, thermal stability, electrolyte wettability and pore distribution, providing promising alternatives for battery separators.

    Apart from studying the two basic functions mentioned above, two types of advanced separator functionalities have been studied, i.e. redox-activity and the attainment of a homogeneous current distribution, in conjunction with proposals for new separator designs.

    Two types of redox-active separators have been devised for the first time in the separator field, based on the use of a redox-active conducting polymer, polypyrrole (PPy) and a natural polymer, polydopamine (PDA). Based on their redox-active potentials, the PPy-based redox-active separator was designed to contribute capacity to the cathode of a LIB, while the PDA-based redox-active separator was proposed to be used on the anode side.

    It is known that a homogeneous current distribution is beneficial for the battery performance. Therefore, two new types of separators with homogenous pore distributions have been manufactured to study the influence of the pore distribution on the Li deposition/stripping behavior and composite cathode utilization in LMBs. With the knowledge obtained from the study, a stable, long lifetime paper-based LMB was designed.

    List of papers
    1. Mesoporous Cladophora cellulose separators for lithium-ion batteries
    Open this publication in new window or tab >>Mesoporous Cladophora cellulose separators for lithium-ion batteries
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    2016 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 321, p. 185-192Article in journal (Refereed) Published
    Abstract [en]

    Much effort is currently made to develop inexpensive and renewable materials which can replace the polyolefin microporous separators conventionally used in contemporary lithium-ion batteries. In the present work, it is demonstrated that mesoporous Cladophora cellulose (CC) separators constitute very promising alternatives based on their high crystallinity, good thermal stability and straightforward manufacturing. The CC separators, which are fabricated using an undemanding paper-making like process involving vacuum filtration, have a typical thickness of about 35 mu m, an average pore size of about 20 nm, a Young's modulus of 5.9 GPa and also exhibit an ionic conductivity of 0.4 mS cm(-1) after soaking with 1 M LiPF6 EC: DEC (1/1, v/v) electrolyte. The CC separators are demonstrated to be thermally stable at 150 degrees C and electrochemically inert in the potential range between 0 and 5 V vs. Li+/Li. A LiFePO4/Li cell containing a CC separator showed good cycling stability with 99.5% discharge capacity retention after 50 cycles at a rate of 0.2 C. These results indicate that the renewable CC separators are well-suited for use in high-performance lithium-ion batteries.

    Keywords
    Separator, Cellulose, Crystallinity, Paper-making, Lithium-ion battery, Cladophora
    National Category
    Inorganic Chemistry Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-299548 (URN)10.1016/j.jpowsour.2016.04.115 (DOI)000377729200020 ()
    Funder
    Swedish Energy AgencyStandUpStiftelsen Olle Engkvist Byggmästare
    Available from: 2016-07-25 Created: 2016-07-22 Last updated: 2019-03-25
    2. Redox-Active Separators for Lithium-Ion Batteries
    Open this publication in new window or tab >>Redox-Active Separators for Lithium-Ion Batteries
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    2018 (English)In: ADVANCED SCIENCE, ISSN 2198-3844, Vol. 5, no 3, article id 1700663Article in journal (Refereed) Published
    Abstract [en]

    A bilayered cellulose-based separator design is presented that can enhance the electrochemical performance of lithium-ion batteries (LIBs) via the inclusion of a porous redox-active layer. The proposed flexible redox-active separator consists of a mesoporous, insulating nanocellulose fiber layer that provides the necessary insulation between the electrodes and a porous, conductive, and redox-active polypyrrole-nanocellulose layer. The latter layer provides mechanical support to the nanocellulose layer and adds extra capacity to the LIBs. The redox-active separator is mechanically flexible, and no internal short circuits are observed during the operation of the LIBs, even when the redox-active layer is in direct contact with both electrodes in a symmetric lithium-lithium cell. By replacing a conventional polyethylene separator with a redox-active separator, the capacity of the proof-of-concept LIB battery containing a LiFePO4 cathode and a Li metal anode can be increased from 0.16 to 0.276 mA h due to the capacity contribution from the redox-active separator. As the presented redox-active separator concept can be used to increase the capacities of electrochemical energy storage systems, this approach may pave the way for new types of functional separators.

    Place, publisher, year, edition, pages
    WILEY, 2018
    Keywords
    capacity, cellulose, conducting polymers, lithium-ion batteries, redox-active separators
    National Category
    Materials Chemistry Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-354519 (URN)10.1002/advs.201700663 (DOI)000428310500012 ()29593967 (PubMedID)
    Funder
    Swedish Foundation for Strategic Research , RMA-110012]Swedish Energy AgencyStandUpCarl Tryggers foundation
    Available from: 2018-07-20 Created: 2018-07-20 Last updated: 2018-12-10Bibliographically approved
    3. Polydopamine-based redox-active separator for lithium-ion batteries
    Open this publication in new window or tab >>Polydopamine-based redox-active separator for lithium-ion batteries
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    (English)In: Article in journal (Refereed) Submitted
    Abstract [en]

    The performance of lithium-ion batteries (LIBs) can be effectively increased with functionalized separators. Herein, it is demonstrated that polydopamine-based redox-active (PRA) separators can provide additional capacity to that of typical anode materials, increase the volumetric capacity of the cell, as well as, decrease the cell resistance to yield an improved performance at higher cycling rates. The PRA separators, which are composed of a 2 µm thick electrically insulating nanocellulose fiber (NCF) layer and an 18 µm thick polydopamine (PDA) and carbon nanotube (CNT) containing redox-active layer, are readily produced using a facile paper-making process. The PRA separators are also easily wettable by commonly employed electrolytes (e.g. LP40) and exhibit a high dimensional stability even at elevated temperatures (e.g. 150 ºC). In addition, the pore structure endows the PRA separator with a high ionic conductivity (i.e. 1.06 mS cm-1 after soaking with LP40 electrolyte) that increases the rate performance of the cells. Due to the presence of the redox-active layer, Li4Ti5O12 (LTO) half-cells containing PRA separator were found to exhibit significantly higher capacities than the corresponding cells containing commercial separators. These results clearly show that the implementation of this type of redox-active separators constitutes a straightforward and effective way to increase the energy and power densities of LIBs.

    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-368958 (URN)
    Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2018-12-10
    4. Nanocellulose Modified Polyethylene Separators for Lithium Metal Batteries
    Open this publication in new window or tab >>Nanocellulose Modified Polyethylene Separators for Lithium Metal Batteries
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    2018 (English)In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 14, no 21, article id 1704371Article in journal (Refereed) Published
    Abstract [en]

    Abstract Poor cycling stability and safety concerns regarding lithium (Li) metal anodes are two major issues preventing the commercialization of high‐energy density Li metal‐based batteries. Herein, a novel tri‐layer separator design that significantly enhances the cycling stability and safety of Li metal‐based batteries is presented. A thin, thermally stable, flexible, and hydrophilic cellulose nanofiber layer, produced using a straightforward paper‐making process, is directly laminated on each side of a plasma‐treated polyethylene (PE) separator. The 2.5 µm thick, mesoporous (≈20 nm average pore size) cellulose nanofiber layer stabilizes the Li metal anodes by generating a uniform Li+ flux toward the electrode through its homogenous nanochannels, leading to improved cycling stability. As the tri‐layer separator maintains its dimensional stability even at 200 °C when the internal PE layer is melted and blocks the ion transport through the separator, the separator also provides an effective thermal shutdown function. The present nanocellulose‐based tri‐layer separator design thus significantly facilitates the realization of high‐energy density Li metal‐based batteries.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2018
    Keywords
    cellulose, current distribution, lithium dendrites, lithium metal batteries, separators
    National Category
    Materials Chemistry Engineering and Technology
    Research subject
    Engineering Science with specialization in Nanotechnology and Functional Materials
    Identifiers
    urn:nbn:se:uu:diva-349143 (URN)10.1002/smll.201704371 (DOI)000434173300006 ()29675952 (PubMedID)
    Funder
    Swedish Foundation for Strategic Research , RMA-110012Swedish Energy AgencyStandUp
    Available from: 2018-04-22 Created: 2018-04-22 Last updated: 2018-12-10Bibliographically approved
    5. Sandwich-structured nano/micro fiber-based separators for lithium metal batteries
    Open this publication in new window or tab >>Sandwich-structured nano/micro fiber-based separators for lithium metal batteries
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    2019 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 55, p. 316-326Article in journal (Refereed) Published
    Abstract [en]

    Although the increased need for high-energy/power-density energy storage systems has revived the research on lithium metal batteries (LMBs), the influence of the separator on the performance of LMBs is still generally neglected. In the present study, a sandwich-structured separator (referred to as the CGC separator below) composed of two 2.5µm thick cellulose nanofiber (CNF) surface layers and an intermediate 15µm thick glass microfiber (GMF) and CNF composite layer is described. While the CNF surface layers of the CGC separator feature a homogeneous distribution of nano-sized pores favoring the attainment of a homogeneous current distribution at both electrodes, the intermediate GMF/CNF layer contains macropores facilitating the ionic transport through the separator. The CGC separator exhibited a much better electrolyte wettability and thermal stability compared to a Celgard separator, due to the use of the hydrophilic and thermally stable CNFs and GMFs. It is also shown that the combination of nano-sized and micro-sized fibers used in the CGC separator yields a higher ionic conductivity than that for the commercial separator (1.14 vs. 0.49 mS cm−1). Moreover, the influence of the separator pore structure (e.g. the porosity and pore distribution) on the performance of LMBs is studied for both Li anodes and LiFePO4 composite cathodes. The results demonstrate that the use of separators with high porosities and homogeneous surface pore distributions can improve the performances (e.g. capacities and stabilities) of LMBs considerably, and also highlights the importance of proper separator/electrode interactions. The present approach constitutes a practical engineering strategy for the production of separators with nano/micro fibers and a promising route for the development of LMBs with improved safety and enhanced electrochemical performances.

    Keywords
    Cellulose, separator, sandwich structure, lithium metal battery, current distribution, three-electrode
    National Category
    Nano Technology Materials Chemistry
    Research subject
    Engineering Science with specialization in Nanotechnology and Functional Materials
    Identifiers
    urn:nbn:se:uu:diva-364826 (URN)10.1016/j.nanoen.2018.11.005 (DOI)000454636200029 ()
    Funder
    StandUpSwedish Energy Agency
    Available from: 2018-11-04 Created: 2018-11-04 Last updated: 2019-06-12Bibliographically approved
    6. Nanocellulose Structured Paper-Based Lithium Metal Batteries
    Open this publication in new window or tab >>Nanocellulose Structured Paper-Based Lithium Metal Batteries
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    2018 (English)In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 8, p. 4341-4350Article in journal (Refereed) Published
    Abstract [en]

    We report for the first time, a lithium metal battery (LMB) design based on low-cost, renewable, and mechanically flexible nanocellulose fibers (NCFs) as the separator as well as substrate materials for both the positive and negative electrodes. Combined with carbon nanofibers, the NCFs yield 3D porous conducting cellulose paper (CCP) current collectors with large surface areas, enabling a low effective current density. The porous structure yields a dendrite-free deposition of lithium (Li), faciliates the mass transport within the electrodes, and also compensates for the volume changes during the cycling. Stable Li electrodes are obtained by electrodepositing Li on CCP substrates while positive electrodes are realized by embedding LiFePO4 (LFP) particles within the flexible CCP matrix. The mesoporous NCF separator features a homogeneous pore distribution which provides uniform current distributions at the electrodes. This effect, which yields a more homogeneous Li deposition on the negative electrode as well as improves the safety, lifespan, and sustainability of the LMB. As a result, the present all-nanocellulose-based LMB demonstrates excellent cycling stability for a Li metal battery obtained to date, with 91% capacity retention after 800 cycles and 85% capacity retention after 1000 cycles at a rate of 2 C (i.e., 1.27 mA cm–2).

    National Category
    Inorganic Chemistry Materials Chemistry Engineering and Technology
    Research subject
    Engineering Science with specialization in Nanotechnology and Functional Materials
    Identifiers
    urn:nbn:se:uu:diva-358031 (URN)10.1021/acsaem.8b00961 (DOI)000458706400094 ()
    Funder
    Swedish Energy AgencyStandUpSwedish Foundation for Strategic Research , RMA-110012Carl Tryggers foundation
    Available from: 2018-08-23 Created: 2018-08-23 Last updated: 2019-03-07Bibliographically approved
  • 9.
    Pan, Ruijun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Cheung, Ocean
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Tammela, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Huo, Jinxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mesoporous Cladophora cellulose separators for lithium-ion batteries2016In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 321, p. 185-192Article in journal (Refereed)
    Abstract [en]

    Much effort is currently made to develop inexpensive and renewable materials which can replace the polyolefin microporous separators conventionally used in contemporary lithium-ion batteries. In the present work, it is demonstrated that mesoporous Cladophora cellulose (CC) separators constitute very promising alternatives based on their high crystallinity, good thermal stability and straightforward manufacturing. The CC separators, which are fabricated using an undemanding paper-making like process involving vacuum filtration, have a typical thickness of about 35 mu m, an average pore size of about 20 nm, a Young's modulus of 5.9 GPa and also exhibit an ionic conductivity of 0.4 mS cm(-1) after soaking with 1 M LiPF6 EC: DEC (1/1, v/v) electrolyte. The CC separators are demonstrated to be thermally stable at 150 degrees C and electrochemically inert in the potential range between 0 and 5 V vs. Li+/Li. A LiFePO4/Li cell containing a CC separator showed good cycling stability with 99.5% discharge capacity retention after 50 cycles at a rate of 0.2 C. These results indicate that the renewable CC separators are well-suited for use in high-performance lithium-ion batteries.

  • 10.
    Pan, Ruijun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Double-sided conductive separators for lithium-metal batteries2019In: Energy Storage Materials, ISSN 2405-8297, Vol. 21, p. 464-473Article in journal (Refereed)
    Abstract [en]

    A novel double-sided conductive (DSC) separator consisting of two 5 μm-thick carbon nanotube (CNT)/cellulose nanofiber (CNF) composite layers coated on each side of a 20 μm-thick glass-fiber (GF)/CNF composite membrane is described. In a lithium-metal battery (LMB), the DSC separator exhibits a high ionic conductivity (i.e. 1.7 mS cm−1 using an LP40 electrolyte) due to the high porosity (i.e. 66%) of the GF/CNF membrane. More stable Li anodes can also be realized by depositing Li within the porous electronically conducting CNT/CNF matrix at the DSC separator anode side due to the decreased current density. The CNT/CNF layer of the DSC separator facing the cathode, which is in direct electric contact with the current collector, decreases the overpotential for the cathode and consequently improves its capacity and rate performance significantly. A Li/Li cell containing a DSC separator showed an improved cycling stability compared to an analogous cell equipped with a commercial Celgard separator at current densities up to 5 mA cm−2 for Li deposition and stripping capacities up to 5 mAh cm−2. A proof-of-concept LMB containing a lithium iron phosphate (LFP) composite cathode and a DSC separator showed a significantly improved rate capability, yielding capacities of about 110 mAh g−1 at 5 C and 80 mAh g−1 at 10 C. The LMB cell containing a DSC separator also exhibited a capacity retention of 80% after 200 cycles at a rate of 6 C indicating that the two-sided conductive separator design has significant potential in facilitating the development of well-functioning LMBs.

  • 11.
    Pan, Ruijun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sandwich-structured nano/micro fiber-based separators for lithium metal batteries2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 55, p. 316-326Article in journal (Refereed)
    Abstract [en]

    Although the increased need for high-energy/power-density energy storage systems has revived the research on lithium metal batteries (LMBs), the influence of the separator on the performance of LMBs is still generally neglected. In the present study, a sandwich-structured separator (referred to as the CGC separator below) composed of two 2.5µm thick cellulose nanofiber (CNF) surface layers and an intermediate 15µm thick glass microfiber (GMF) and CNF composite layer is described. While the CNF surface layers of the CGC separator feature a homogeneous distribution of nano-sized pores favoring the attainment of a homogeneous current distribution at both electrodes, the intermediate GMF/CNF layer contains macropores facilitating the ionic transport through the separator. The CGC separator exhibited a much better electrolyte wettability and thermal stability compared to a Celgard separator, due to the use of the hydrophilic and thermally stable CNFs and GMFs. It is also shown that the combination of nano-sized and micro-sized fibers used in the CGC separator yields a higher ionic conductivity than that for the commercial separator (1.14 vs. 0.49 mS cm−1). Moreover, the influence of the separator pore structure (e.g. the porosity and pore distribution) on the performance of LMBs is studied for both Li anodes and LiFePO4 composite cathodes. The results demonstrate that the use of separators with high porosities and homogeneous surface pore distributions can improve the performances (e.g. capacities and stabilities) of LMBs considerably, and also highlights the importance of proper separator/electrode interactions. The present approach constitutes a practical engineering strategy for the production of separators with nano/micro fibers and a promising route for the development of LMBs with improved safety and enhanced electrochemical performances.

  • 12.
    Pan, Ruijun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Polydopamine-based redox-active separators for lithium-ion batteries2019In: Journal of Materiomics, ISSN 2352-8478, p. 204-213Article in journal (Refereed)
    Abstract [en]

    The performance of lithium-ion batteries (LIBs) can be effectively increased with functionalized separators. Herein, it is demonstrated that polydopamine-based redox-active (PRA) separators can provide additional capacity to that of typical anode materials, increase the volumetric capacity of the cell, as well as, decrease the cell resistance to yield an improved performance at higher cycling rates. The PRA separators, which are composed of a 2 μm thick electrically insulating nanocellulose fiber (NCF) layer and an 18 μm thick polydopamine (PDA) and carbon nanotube (CNT) containing redox-active layer, are readily produced using a facile paper-making process. The PRA separators are also easily wettable by commonly employed electrolytes (e.g. LP40) and exhibit a high dimensional stability. In addition, the pore structure endows the PRA separator with a high ionic conductivity (i.e. 1.06 mS cm−1) that increases the rate performance of the cells. Due to the presence of the redox-active layer, Li4Ti5O12 (LTO) half-cells containing PRA separator were found to exhibit significantly higher capacities than the corresponding cells containing commercial separators. These results clearly show that the implementation of this type of redox-active separators constitutes a straightforward and effective way to increase the energy and power densities of LIBs.

  • 13.
    Pan, Ruijun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Thickness difference induced pore structure variations in cellulosic separators for lithium-ion batteries2017In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 24, no 7, p. 2903-2911Article in journal (Refereed)
    Abstract [en]

    The pore structure of the separator is crucial to the performance of a lithium-battery as it affects the cell resistance. Herein, a straightforward approach to vary the pore structure of Cladophora cellulose (CC) separators is presented. It is demonstrated that the pore size and porosity of the CC separator can be increased merely by decreasing the thickness of the CC separator by using less CC in the manufacturing of the separator. As the pore size and porosity of the CC separator are increased, the mass transport through the separator is increased which decreases the electrolyte resistance in the pores of the separator. This enhances the battery performance, particularly at higher cycling rates, as is demonstrated for LiFePO4/Li half-cells. A specific capacity of around 100 mAh g-1 was hence obtained at a cycling rate of 2 C with a 10 μm thick CC separator while specific capacities of 40 and close to 0 mAh g-1 were obtained for separators with thicknesses of 20 and 40 μm, respectively. As the results also showed that a higher ionic conductivity was obtained for the 10 μm thick CC separator than for the 20 and 40 μm thick CC separators, it is clear that the different pore structure of the separators was an important factor affecting the battery performance in addition to the separator thickness. The present straightforward, yet efficient, strategy for altering the pore structure hence holds significant promise for the manufacturing of separators with improved performance, as well as for fundamental studies of the influence of the properties of the separator on the performance of lithium-ion cells.

  • 14.
    Pan, Ruijun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Xingxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nanocellulose Modified Polyethylene Separators for Lithium Metal Batteries2018In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 14, no 21, article id 1704371Article in journal (Refereed)
    Abstract [en]

    Abstract Poor cycling stability and safety concerns regarding lithium (Li) metal anodes are two major issues preventing the commercialization of high‐energy density Li metal‐based batteries. Herein, a novel tri‐layer separator design that significantly enhances the cycling stability and safety of Li metal‐based batteries is presented. A thin, thermally stable, flexible, and hydrophilic cellulose nanofiber layer, produced using a straightforward paper‐making process, is directly laminated on each side of a plasma‐treated polyethylene (PE) separator. The 2.5 µm thick, mesoporous (≈20 nm average pore size) cellulose nanofiber layer stabilizes the Li metal anodes by generating a uniform Li+ flux toward the electrode through its homogenous nanochannels, leading to improved cycling stability. As the tri‐layer separator maintains its dimensional stability even at 200 °C when the internal PE layer is melted and blocks the ion transport through the separator, the separator also provides an effective thermal shutdown function. The present nanocellulose‐based tri‐layer separator design thus significantly facilitates the realization of high‐energy density Li metal‐based batteries.

  • 15.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ruan, Changqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Redox-Active Separators for Lithium-Ion Batteries2018In: ADVANCED SCIENCE, ISSN 2198-3844, Vol. 5, no 3, article id 1700663Article in journal (Refereed)
    Abstract [en]

    A bilayered cellulose-based separator design is presented that can enhance the electrochemical performance of lithium-ion batteries (LIBs) via the inclusion of a porous redox-active layer. The proposed flexible redox-active separator consists of a mesoporous, insulating nanocellulose fiber layer that provides the necessary insulation between the electrodes and a porous, conductive, and redox-active polypyrrole-nanocellulose layer. The latter layer provides mechanical support to the nanocellulose layer and adds extra capacity to the LIBs. The redox-active separator is mechanically flexible, and no internal short circuits are observed during the operation of the LIBs, even when the redox-active layer is in direct contact with both electrodes in a symmetric lithium-lithium cell. By replacing a conventional polyethylene separator with a redox-active separator, the capacity of the proof-of-concept LIB battery containing a LiFePO4 cathode and a Li metal anode can be increased from 0.16 to 0.276 mA h due to the capacity contribution from the redox-active separator. As the presented redox-active separator concept can be used to increase the capacities of electrochemical energy storage systems, this approach may pave the way for new types of functional separators.

  • 16.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nanocellulose Structured Paper-Based Lithium Metal Batteries2018In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 8, p. 4341-4350Article in journal (Refereed)
    Abstract [en]

    We report for the first time, a lithium metal battery (LMB) design based on low-cost, renewable, and mechanically flexible nanocellulose fibers (NCFs) as the separator as well as substrate materials for both the positive and negative electrodes. Combined with carbon nanofibers, the NCFs yield 3D porous conducting cellulose paper (CCP) current collectors with large surface areas, enabling a low effective current density. The porous structure yields a dendrite-free deposition of lithium (Li), faciliates the mass transport within the electrodes, and also compensates for the volume changes during the cycling. Stable Li electrodes are obtained by electrodepositing Li on CCP substrates while positive electrodes are realized by embedding LiFePO4 (LFP) particles within the flexible CCP matrix. The mesoporous NCF separator features a homogeneous pore distribution which provides uniform current distributions at the electrodes. This effect, which yields a more homogeneous Li deposition on the negative electrode as well as improves the safety, lifespan, and sustainability of the LMB. As a result, the present all-nanocellulose-based LMB demonstrates excellent cycling stability for a Li metal battery obtained to date, with 91% capacity retention after 800 cycles and 85% capacity retention after 1000 cycles at a rate of 2 C (i.e., 1.27 mA cm–2).

  • 17.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ruan, Changqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Conducting polymer paper-derived separators for lithium metal batteries2018In: Energy Storage Materials, ISSN 2405-8297, Vol. 13, p. 283-292Article in journal (Refereed)
    Abstract [en]

    Overoxidised polypyrrole (PPy) paper has been employed as a mesoporous separator for lithium metal batteries (LMBs) based on its narrow pore size distribution, good thermal stability, high ionic conductivity (1.1 mS cm−1 with a LP40 electrolyte) and high electrolyte wettability. The overoxidised PPy paper was produced from a PPy/cellulose composite using a combined base and heat-treatment process, yielding a highly interrupted pyrrole molecular structure including N-containing polar groups maintaining the readily adaptable mesoporous structure of the pristine PPy paper. This well-defined pore structure gave rise to a homogeneous current distribution which significantly increased the performance of a LiFePO4|Li cell. With the overoxidised PPy separator, a symmetric Li|Li cell could be cycled reversibly for more than 600 h without any short-circuits in a LP40 electrolyte. This approach facilitates the manufacturing of well-defined separators for fundamental investigations of the influence of the separator structure on the performance of LMBs.

  • 18. Wang, Zhaouhui
    et al.
    Tammela, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Flexible Nanocellulose based Energy Storage Devices2019In: MRS Spring Meeting 2019 / [ed] MRS, Phoenix, 2019, article id ES03.06.01ES03.06.01Conference paper (Refereed)
    Abstract [en]

    The strong need for the development of inexpensive, flexible, light-weight and environmentally friendly energy storage devices has resulted in large interest in new cellulose-based electrode materials that can be used in batteries and supercapacitors [1-3]. In this presentation it will be shown that flexible nanocellulose and polypyrrole composites, manufactured by chemical polymerization of e.g. pyrrole on a nanocellulose substrate, can be used as electrodes in charge storage devices containing either water or organic solvent based electrolytes. The aqueous flexible paper-based devices exhibit high charge storage capacities (e.g. 9 Wh/kg) as well as excellent power capabilities (e.g. 3.5 kW/kg) due to the large surface area (up to 250 m2/g) of the nanocellulose and the thin (i.e. 50 nm) layer of polypyrrole present on the nanocellulose fibers. The straightforward (papermaking) composite synthesis approach and the electrochemical properties of the resulting composites will be discussed. It will also be shown that high active mass paper electrodes [4-8] with mass loadings of up to 20 mg/cm2 can be employed at high current densities without significant loss of electrochemical performance as a result of the advantageous structure of the electrodes. Devices with unprecedented areal and volumetric cell capacitances (e.g. 5.7 F/cm2 and 240 F/cm3) that can cycle for thousands of cycles in aqueous electrolytes can likewise be realized. As the cellulose composites also can be used in lithium-ion batteries [9,10], functional (e.g. redox-active) separators [11] for lithium based batteries and in the realization of all-cellulose energy storage devices [12], the present materials provide new exciting possibilities for the development of green and foldable devices for a range of new applications, many of which are incompatible with conventional batteries and supercapacitors.

  • 19.
    Zhao, Jie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Wen, Chenyu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhang, Shi-Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wu, Biao
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    High-Conductivity Reduced-Graphene-Oxide/Copper Aerogel for Energy Storage2019In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, p. 760-767Article in journal (Refereed)
    Abstract [en]

    This work reports a room-temperature, solution-phase and one-pot method for macro-assembly of a three-dimensional (3D) reduced-graphene-oxide/copper hybrid hydrogel. The hydrogel is subsequently transformed into a highly conductive aerogel via freeze-drying. The aerogel, featuring reduced graphene oxide (rGO) networks decorated with Cu and CuxO nanoparticles (Cu/CuxO@rGO), exhibits a specific surface area of 48 m(2)/g and an apparent electrical conductivity of similar to 33 and similar to 430 S/m prior to and after mechanical compression, respectively. The compressed Cu/CuxO@rGO aerogel delivers a specific capacity of similar to 453 mAh g(-1) at a current density of 1 A/g and similar to 184 mAh g(-1) at 50 A/g in a 3 M KOH aqueous electrolyte evidenced by electrochemical measurements. Galvanostatic cycling tests at 5 A/g demonstrates that the Cu/CuxO@rGO aerogel retains 38% (similar to 129 mAh g(-1)) of the initial capacity (similar to 339 mAh g(-1)) after 500 cycles. The straightforward manufacturing process and the promising electrochemical performances make the Cu/CuxO@rGO aerogel an attractive electrode candidate in energy storage applications.

1 - 19 of 19
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