Electrode/Electrolyte Interface Reactivity in High-Voltage Spinel LiMn1.6Ni0.4O4/Li4Ti5O12 Lithium-Ion Battery

High-voltage spinel oxides combined with Li4Ti5O12 result in 3 V lithium-ion batteries with a high power capability; however, the electrochemical performances are limited by electrode/electrolyte interfacial reactivity at high potential. We have investigated electrode/electrolyte interfaces in LiMn1.6Ni0.4O4/Li4Ti5O12 cells by X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectrocopy (EIS). EIS has shown that both electroadsorption and film-formation mechanisms occur at the positive electrode. XPS has revealed that very low amounts of lithiated species are deposited at the surface of the positive electrode, despite the high potential, but that great amounts of organic species are deposited. Interesting results were obtained for the Li4Ti5O12 electrode. Whereas Li4Ti5O12 is usually considered as a passivation-free electrode material, large amounts of organic and inorganic species were deposited at the surface of this electrode. The question of a possible interaction between both electrodes in the formation mechanisms of surface films is discussed.