Novel insights into higher capacity from the Li-ion battery cathode material Li2FeSiO4
2017 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 223, 109-114 p.Article in journal (Refereed) Published
A highly reactive composite cathode material incorporating nano-particles of the popular Li-ion battery cathode material Li2FeSiO4 (LFS) is here studied to probe the activation of the controversial Fe3+/Fe4+ redox couple in exploiting the second Li-ion in the formula unit - for use in rechargeable Li-ion batteries. A novel form of in situ Mossbauer spectroscopy is used to monitor the oxidation state of the Fe-ions in symmetric LFS LFS cells. This is based on mapping the poorly resolvable Mossbauer spectra from the expected Fe3+/Fe4+ redox couple in the working electrode onto the highly resolvable Fe2+/Fe3+ spectra from the counter electrode. Comparison of such data from half-delithiated Li(1)Fe3+SiO4 parallel to Li(1)Fe3+SiO4 and almost lithium-free "Li(0)Fe4+SiO4 parallel to Li(0)Fe4+SiO4" symmetric cells is demonstrated - to distinguish the electrode reactions from the those involving the electrolyte. Lithium is shown to cycle reversibly in the symmetric cells. However, a large proportion of the cycled lithium (similar to 70%) does not derive from the bulk of the electrodes, but is rather a result of high-V electrolyte degradation, where charge balance is maintained by leaching lithium from the electrolyte and inserting it into the electrodes.
Place, publisher, year, edition, pages
2017. Vol. 223, 109-114 p.
Lithium-ion batteries, positive electrode, Li2FeSiO4, in situ Mossbauer spectroscopy, Fe4+
IdentifiersURN: urn:nbn:se:uu:diva-316422DOI: 10.1016/j.electacta.2016.12.008ISI: 000392773100012OAI: oai:DiVA.org:uu-316422DiVA: diva2:1077943