Open this publication in new window or tab >>2017 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 223, p. 109-114Article in journal (Refereed) Published
Abstract [en]
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.
Keywords
Lithium-ion batteries, positive electrode, Li2FeSiO4, in situ Mossbauer spectroscopy, Fe4+
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-316422 (URN)10.1016/j.electacta.2016.12.008 (DOI)000392773100012 ()
2017-03-012017-03-012017-11-29Bibliographically approved