Dual-functional and polydopamine-coated vanadium disulfide for "fast-charging" lithium-ion batteries

As a typical representative of vanadium-based sulfides, vanadium disulfide has attracted the attention of researchers ascribed to its high theoretical capacity and unique crystal structure. However, overcoming its structural collapse while achieving dual functionalization that serves as both active material and binder remains challenging. This study designs a dopamine-coating vanadium disulfide core-shell structure through the synergistic effect of V-O bonds and hydrogen bonds between vanadium disulfide and dopamine, which is further employed as a dual-function electrode material. The polydopamine-coated vanadium disulfide without binder exhibits specific capacity of 682.03 mAh g-1, and the Coulombic efficiency of 99.78% at a current density of 200 mA g-1 after 400 cycles. More importantly, at a larger current density of 1000 mA g-1, the specific capacity is 385.44 mAh g-1 after 1500 cycles. After 3150 cycles, the specific capacity is 200.32 mAh g-1 at 2000 mA g-1. Electrochemical kinetics analysis displays that the polydopamine-coated vanadium disulfide without binder exhibits fast ion-diffusion kinetics, with the order of magnitude of ion-diffusion coefficients ranging from 10-11 to 10-12. This kind of material has the potential to be a significantly promising electrode material for "fast-charging" lithium-ion batteries. 1) A polydopamine-coated vanadium disulfide (VS2@PDA) core-shell structure is designed through the combined action of hydrogen bonding and covalent bonding. 2) The VS2@PDA acts as a binder, which not only stabilizes the structure but also successfully buffers the volume effect of vanadium disulfide. 3) Compared with vanadium disulfide, polydopamine units store more lithium ions, which is more conducive to Li+ storage. 4) The VS2@PDAN demonstrated excellent electrochemical performance (a specific capacity of 385.44 mAh g-1 at 1000 mA g-1 for 1500 cycles). image A polydopamine-coated vanadium disulfide (VS2@PDA) core-shell structure is designed through the combined action of hydrogen bonding and covalent bonding. The VS2@PDA acts as a binder, which not only stabilizes the structure but also successfully buffers the volume effect of vanadium disulfide. Compared with vanadium disulfide, polydopamine units store more lithium ions, which is more conducive to Li+ storage. The VS2@PDAN demonstrated excellent electrochemical performance (a specific capacity of 385.44 mAh g-1 at 1000 mA g-1 for 1500 cycles).