Improvement of Electrode/Electrolyte Interfaces in High-Voltage Spinel Lithium-Ion Batteries by Using Glutaric Anhydride as Electrolyte Additive

摘要

High-voltage spinel oxides combined with Li4Ti5O_(12) result in 3 V Li-ion batteries with a high power capability, but electrochemical performances are limited by electrode/electrolyte interfacial reactivity at high potential. We have investigated glutaric anhydride (GA) as an electrolyte additive to improve the performances of LiNi_(0.4)Mn_(1.6)O4/ Li4Ti5O_(12) cells. We showed that GA efficiently reduces both the capacity fading upon cycling and the self-discharge. From X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), and electrochemical impedance spectroscopy (EIS) measurements, we showed that GA reduces salt (LiPF6) degradation. Addition of 2% GA in the electrolyte results in a passivation film at the surface of both electrodes, which is mainly composed of organic compounds resulting from degradation of GA. The film is much thicker but less resistive due to a better ionic conductivity, and behaves like a polymer electrolyte interface.