Sulfuration of NiV-layered double hydroxide towards novel supercapacitor electrode with enhanced performance

NiV-LDH as a novel electrode material has rarely been investigated in the energy storage field. Herein, novel ultrathin NiV-LDH was designed and synthesized, which displays high specific capacitance but poor stability. To further improve the stability, NiV-LDH was transformed to the sulfide named NiV-S through an ion exchange reaction (S2- replaces OH-). The obtained NiV-S maintains the ultrathin (5 nm in thickness) and porous structure, and displays higher specific capacitance (2270.4 F g(-1) at 2 A g(-1)), compared to NiV-LDH (1502 F g(-1) at 2 A g(-1)). What is more improtant is that the cycling stability of NiV-S is much higher than NiV-LDH, (91.9% retention after 10,000 cycles for NiV-S vs only 63% retention after 5000 cycles for NiV-LDH). The asymmetric supercapacitor assembled using ultrathin porous NiV-S as the positive electrode and activated carbon (AC) as the negative electrode was found to deliver a maximum energy density of 51 Wh kg(-1) at a power density of 1600 W kg(-1) and 12 kW kg(-1) M 23.7 W h kg(-1). In addition, 98.5% of the initial capacitance retains after 10,000 continuous cycling.