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Emulsion-templated graphitic carbon foams with optimum porosity for 3D Li-ion microbatteries
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. (Structural Chemistry)ORCID-id: 0000-0001-5861-4281
Stockholm University. (Materials and Environmental Chemistry- Arrhenius laboratory)
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Oorganisk kemi. (Oorganisk kemi, Elektrokemi och korrosion)
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi. (Strukturkemi)ORCID-id: 0000-0003-4440-2952
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
Emneord [en]
carbon, foam, graphitic, anode, three-dimensional, microbattery, lithium
HSV kategori
Identifikatorer
URN: urn:nbn:se:uu:diva-312893OAI: oai:DiVA.org:uu-312893DiVA, id: diva2:1065286
Forskningsfinansiär
Swedish Research Council, 2012–4681StandUpTilgjengelig fra: 2017-01-14 Laget: 2017-01-14 Sist oppdatert: 2017-12-30
Inngår i avhandling
1. Multifunctional Carbon Foams by Emulsion Templating: Synthesis, Microstructure, and 3D Li-ion Microbatteries
Åpne denne publikasjonen i ny fane eller vindu >>Multifunctional Carbon Foams by Emulsion Templating: Synthesis, Microstructure, and 3D Li-ion Microbatteries
2017 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Carbon foams are among the existing electrode designs proposed for use in 3D Li-ion microbatteries. For such electrodes to find applications in practical microbatteries, however, their void sizes, specific surface areas and pore volumes need be optimized. This thesis concerns the synthesis of highly porous carbon foams and their multifunctional applications in 3D microbatteries. The carbon foams are derived from polymers that are obtained by polymerizing high internal phase water-in-oil emulsions (HIPEs).

In general, the carbonization of the sulfonated polymers yielded hierarchically porous structures with void sizes ranging from 2 to 35 µm and a BET specific surface area as high as 630 m2 g-1. Thermogravimetric and spectroscopic evidence indicated that the sulfonic acid groups, introduced during sulfonation, transformed above 250 oC to thioether (-C-S-) crosslinks which were responsible for the thermal stability and charring tendency of the polymer precursors. Depending on the preparation of the HIPEs, the specific surface areas and void-size distributions were observed to vary considerably. In addition, the pyrolysis temperature could also affect the microstructures, the degree of graphitization, and the surface chemistry of the carbon foams.

Various potential applications were explored for the bespoke carbon foams. First, their use as freestanding active materials in 3D microbatteries was studied. The carbon foams obtained at 700 to 1500 oC suffered from significant irreversible capacity loss during the initial discharge. In an effort to alleviate this drawback, the pyrolysis temperature was raised to 2200 oC. The resulting carbon foams were observed to deliver high, stable areal capacities over several cycles. Secondly, the possibility of using these structures as 3D current collectors for various active materials was investigated in-depth. As a proof-of-concept demonstration, positive active materials like polyaniline and LiFePO4 were deposited on the 3D architectures by means of electrodeposition and sol-gel approach, respectively. In both cases, the composite electrodes exhibited reasonably high cyclability and rate performance at different current densities. The syntheses of niobium and molybdenum oxides and their potential application as electrodes in microbatteries were also studied. In such applications, the carbon foams served dual purposes as 3D scaffolds and as reducing reactants in the carbothermal reduction process. Finally, a facile method of coating carbon substrates with oxide nanosheets was developed. The approach involved the exfoliation of crystalline VO2 to prepare dispersions of hydrated V2O5, which were subsequently cast onto CNT paper to form oxide films of different thicknesses.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2017. s. 139
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1469
Emneord
Battery, Carbon, Electrochemical, Electrodeposition, Emulsion, Energy, Exfoliation, Foam, Lithium, Microbattery, Multifunctional, Nanoparticles, Polyaniline, Polymer, Power, Sol-gel, Storage, Structured, Three-dimensional
HSV kategori
Forskningsprogram
Kemi med inriktning mot materialkemi
Identifikatorer
urn:nbn:se:uu:diva-312897 (URN)978-91-554-9799-6 (ISBN)
Disputas
2017-03-03, Polhemsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 09:15 (engelsk)
Opponent
Veileder
Forskningsfinansiär
Swedish Research Council, 2012–4681Swedish Energy Agency
Tilgjengelig fra: 2017-02-08 Laget: 2017-01-14 Sist oppdatert: 2017-02-15

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