Stability of Li2CO3 in cathode of lithium ion battery and its influence on electrochemical performance

Abstract

Lithium carbonate is an unavoidable impurity at the cathode side. It can react with LiPF6-based electrolyte and LiPF6 powder to produce LiF and CO2, although it presents excellent electrochemical inertness. Samples of Li2CO3-coated and LiF-coated LiNi0.8Co0.1Mn0.1O2 were prepared to compare their influence on a cathode's behavior. After 200 cycles at 1C, in contrast to 37.1% of capacity retention for the Li2CO3-coated material, the LiF-coated LiNi0.8Co0.1Mn0.1O2 retained 91.9% of its initial capacity, which is similar to the fresh sample. This demonstrates that decomposition of Li2CO3 can seriously deteriorate cyclic stability if this occurs during working.