The Influence of Solvents and Salts on the Properties of High-Voltage Cathode Materials

Abstract

Lithium - ion batteries play an increasingly important role in the battery industry and they have become the dominant source of energy in the recent years, especially for portable electronic devices due to their high gravimetric energy density. This article examines the influence of mixtures of solvents with different combinations of lithium salts on the stability of two types of high-voltage cathode materials: LiNi0.5Mn1.5O4 and LiCr0.1Ni0.4Mn1.5O4 produced by a solid phase reaction. These materials were combined with several different electrolytes, cycled at various loads and higher temperature. Various combinations of solvents ethylene carbonate (EC), dimethyl carbonate (DMC) and Tetrahydrothiophene 1.1-dioxide (Sulfolane) were used for these measurements. Salts LiPF6, LiNO3 and LiTFSI were used. The influence of solvents and salts on the properties of high-voltage cathode materials was tested by cycling at different current loads and by cycling at high temperature. It was found out, by LSV analysis, that the addition of Sulfolane increases the stability of electrolyte. The addition of chromium to the cathode material LiNi0.5Mn1.5O4 causes increasing of capacity and stability at high temperature. The combination of the cathode material LiCr0.1Ni0.4Mn1.5O4 with the electrolyte 1.5 M LiPF6 EC:DMC:Sulfolane 1:2:1 w/w/w leads to increased stability in comparison with other electrolytes.