A Novel Lithium Salt with a Chelate Compound of Phosphorus for Lithium Battery Electrolytes

Abstract We have synthesized a novel Li salt with a chelate compound of phosphorus, lithium tris[4-methyl-1,2-benzenediolato(2–)-O,O′]phosphate (4-MLTBP). The thermal stability and electrolytic properties of 4-MLTBP, and the charge–discharge characteristics of a lithium electrode are investigated. The thermal decomposition temperature of 4-MLTBB is higher than those of a common lithium salt with phosphorus, LiPF6, and lithium tris[1,2-benzenediolato(2–)-O,O′]phosphate, which we previously synthesized. The specific conductivities and the cycling efficiencies become higher in an ethylene carbonate– and a propylene carbonate–dimethyl carbonate equimolar binary solutions containing a mixture of 4-MLTPB with LiPF6.