High Voltage Lithium Cobalt Oxide Electrode based on Aqueous Binder

The formation of the active H1-3 metastable phase is the main cause of the poor cycle life of 4.6V high-voltage lithium cobalt oxide (LiCo02) electrodes for lithium-ion batteries. Based on the trace multi-component doping and surface coating methods to prepare LiCo02, this project proposes a new strategy to stabilize 4.6V LiCo02 by using hydrosoluble functionalized glucan instead of traditional PVDF binder. Trace multielement doping will be used to stabilize the layered structure and surface coating will be employed to inhibit electrolyte decomposition. Molecular engineering will be used toregulate the functional groups of hydrosoluble glucan. This will adjust its interaction with LiCo02 and optimize the surface charge distribution and chemical bond energy of LiCo02. The functionalized glucan will stabilize the H1-3 phase and inhibit the oxygen release and surface side reactions of LiCo02 during the redox processes. The viscoelasticity of the binder will be tailored by adjusting the molecular weight and degree of branching of the functionalized glucan. Functionalized glucan will be employed as a binder to coat a conductive carbon layer on the surface of the aluminum foil to solve the corrosion problem of the aluminum foil in aqueous solution, and simultaneously improve the electronic and ion conductivity of the current collector. The structural phase transition and surface morphology evolution mechanism of LiCo02 under high voltage will be studied through theoretical simulation and in-situ electrochemistry tests including neutron diffraction, Raman spectroscopy, and cryo-electron microscopy. We will establish therelationship among the composition, structure and electrochemical performance of LiCo02 electrode based on functionalized dextran binder. This project will provide new methods for stabilizing high-voltage lithium cobalt oxide electrode at 4.6V and above.