Effects of functional binders on electrochemical performance of graphite anode in potassium-ion batteries

Electrochemical properties of the graphite electrode in potassium-ion batteries (KIBs) depend on the selection of the proper binder. The results in our experiment show that compared with the conventional binders of poly(vinylidene fluoride) (PVDF) and carboxymethylcellulose sodium (CMCNa), the polyacrylate sodium (PAANa) binder can greatly improve the electrochemical performance during the potassiation and depotassiation. Specifically, the initial discharge and charge capacity of the graphite-PAANa electrode are 415.4 and 238.5 mAh g−1, respectively. Even after 50 cycles, it still has a high charge capacity retention of 96.9%. Considering the good swelling property of the PAANa binder, the adhesive and mechanical strength of composite electrodes are obviously enhanced. In addition, the graphite-PAANa electrode can also decrease the electrolyte decomposition on the graphite particle surface and restrain the capacity fading resulted from the repeatedly volume expansion.