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.