Enhancing electrochemical properties of graphite anode by using poly(methylmethacrylate)–poly(vinylidene fluoride) composite binder

Poly(methylmethacrylate)–poly(vinylidene fluoride) (PVDF–PMMA) composite binder is adopted for preparation of graphite electrode laminate in lithium-ion batteries. Compared to that using the traditional PVDF binder, the electrode with composite binder exhibits significantly enhanced electrochemical performance in terms of rate capability, specific capacity and cycling behavior. At a very high discharge rate of 50 C, the electrode with PVDF–PMMA binder still retains more than 80% of its capacity while the electrode based on PVDF binder only delivers 16.2% of its capacity. The significant improvement of the rate capability is due to the improvement of Li ion diffusion within the graphite anode. Electrochemical impedance spectroscopy study shows that Li ion diffusion coefficient in the graphite anode is increased by an order of magnitude. After 200 charge–discharge cycles, capacity retention of the electrode is also considerably higher than with single PVDF binder. This is due to the good stability of the solid electrolyte interphase formed on the graphite electrode.