Spinel lithium manganese oxide in LiBOB electrolyte for high power li-ion battery application

Lithium ion batteries using stabilized and unstabilize lithium manganese oxide spinel were investigated in a new electrolyte that contained lithium bisoxalatoborate, LiB(C ₂O ₄) ₂ (acronym LiBOB) salt. It was confirmed by high temperature storage tests that Mn-dissolution from the spinel was greatly reduced in the LiBOB electrolyte than in the case of LiPF ₆ electrolyte Electrochemical tests show that the capacity fading in spinel/graphite cells is improved by using LiBOB electrolyte at elevated temperature, for the reason that no HF can be generated in this electrolyte. The results of this work clearly indicate that at elevated temperatures, the spinel based Li-ion cell performance characteristics are limited by the impedance rise in the graphite electrode, and that this rise is associated with the presence of dissolved manganese in the electrolyte. The Li-ion cells using a stabilized lithium manganese oxide spinel, LiBOB electrolyte, and graphite as cathode, electrolyte and anode, respectively, had much lower levels of Mn dissolved in the electrolyte, improved high temperature cycle life and excellent power capabilities for hybrid electric vehicle applications.