Capacity Fade of Li[sub 1+x]Mn[sub 2−x]O[sub 4]-Based Lithium-Ion Cells

Mesocarbon microbeads (MCMB), soft carbon coated nature graphite (GDR), and soft carbon were investigated as the negative electrodes for spinel/carbon cells with the aim to understand the capacity loss mechanism of carbon/spinel cells at elevated temperatures. The high-temperature cycling performance of MCMB/spinel cell and GDR/spinel cell was improved by formatting the cells at . In this case, a stable solid electrolyte interphase (SEI) was believed to form at and hence protected the carbon electrodes from attack by the solvents and . Particularly, the cycling performance of the cells was dramatically improved by limiting the upper cutoff voltage of the cells to . The poor performance of the cells cycled to was believed to be related to the extra electrochemical reactions of lithium removal from the lithium-rich manganese oxide spinel that occurs at about vs Li. The relationship between the accelerated capacity fade and extra electrochemical reaction of lithium-rich spinel is also discussed in this manuscript.