Analysis of the self-discharge process in LiCoPO4 electrodes: bulks. (10th October 2015)

• Record Type: Journal Article
• Authors: Manzi, J.; Vitucci, F.M.; Paolone, A.; Trequattrini, F.; Di Lecce, D.; Panero, S.; Brutti, S.
• Is Part Of: Electrochimica acta. Volume 179(2015)
• Page Start: 604
• Page End: 610
• Publication Date: 2015-10-10
• Subjects: LiCoPO4 -- self-discharge -- high voltage cathode -- Synchrotron XRD -- Synchrotron FT-IR; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2015.03.071
• Languages: English
• ISSNs: 0013-4686

Abstract

Graphical abstract: Highlights: Electrochemically de-lithiated LiCoPO4 electrodes spontaneously self-discharge in open circuit conditions. Ex-situ synchrotron XRD and FTIR of self-discharged de-lithiated LiCoPO4 electrodes highlight the spontaneous reincorporation of lithium in the CoPO4 lattice to give back LiCoPO4 . Upon the spontaneous self-discharge in lithium cells, charged LiCoPO4 electrodes oxidize the organic carbonates in the electrolyte leading to the release of gaseous CO2 . Abstract: LiCoPO4 (LCP) is a promising high voltage cathode for next-generation high energy Li-ion batteries. However, once electrochemically de-lithiated, it suffers from a spontaneous self-discharge process in open circuit conditions. Here we present our systematic study about the phase composition and structural changes of LCP electrodes upon charging and self-discharging processes by ex situ synchrotron X-ray diffraction and Fast-Fourier Transform Infrared Spectroscopy (FT-IR) analyses. Various initial charging states and different current rates have been studied. Our investigation highlights large structural alterations of the de-lithiated CoPO4 phase upon self-discharge. However, after 160 hours with open circuit the pristine LCP structure is recovered. The electrochemically de-lithiated phase reincorporates lithium by a spontaneous reduction reaction releasing gaseous CO2 and likely degrading the electrolyte molecules.