Improving the initial coulombic efficiency (CE) of lithium-ion batteries (LIBs), especially anodes with the low initial capacity loss (ICL), is actively pursued by researchers to reduce the ratio of anode to cathode (N/P ratio) and thus enhance the energy density of cells. Here, we fabricated a graphite electrode through a facile approach with a hybrid binder of polyvinylidene fluoride (PVDF) and a water-soluble polymer. Acting as the anode of LIBs, the graphite electrode with the hybrid binder demonstrated an unprecedently low ICL, promising rate capability and cycle life. The significantly improved CE during the initial cycle is associated the distribution of hybrid binder in the graphite electrode. The analysis from Fourier-transform infrared spectroscopy (FTIR) showed new bonds formed between PVDF and the water-soluble polymer in the hybrid binder. Characterizations from nitrogen adsorption demonstrated that the surface area of pristine electrodes with the hybrid binder is lower than those with PVDF binder. The small surface could significantly alleviate the side reactions occurred between graphite particles and the electrolyte. This was corroborated by characterizations on cycled electrodes. Observations from electron microscope revealed that the cycled electrodes with hybrid binder have thinner solid electrolyte interface (SEI) films formed at the surface, compared with those with PVDF binder. In addition, electrochemical characterization showed lower resistance in cells with the hybrid binders.

Key words: hybrid binder, lithium-ion battery, coulombic efficiency, graphite