Three-dimensional spherical NiCoOX@NiCo layered double hydroxides nanosheets for high-performance all-solid-state supercapacitors
Jibiao Wang, Dan Wang, Yuan Chu, Sujuan Zha, Minxian Wu, Changhai Liu, Wenchang Wang, Naotoshi Mitsuzaki, Shuyong Jia, Zhidong Chen
Abstract
The low conductivity of cobalt-based oxides greatly limits its application in supercapacitors (SCs). Recently, construction of heterogeneous structural materials has emerged as an effective way to solve this problem. Herein, nickel‑cobalt oxide @ nickel‑cobalt layered double hydroxides (NiCoO X @NiCo LDH) heterostructure is synthesized by an electrodeposition-annealing-electrodeposition step, in which the inner nickel‑cobalt oxide (NiCoO X ) layer is firstly deposited on the carbon cloth with a subsequent annealing process, and the outer nickel‑cobalt layered double hydroxides (NiCo LDH) layer is electrodeposited on the prepared NiCoO X layer. Benefiting from the multi-channel structure and extensive specific surface area produced by the heterogeneous structure material , as same as its synergistic effect, at 1 A g −1 , NiCoO X @NiCo LDH exhibits an extremely advanced specific capacitance (2451 F g −1 ). It is much better than pure NiCoO X and pure NiCo LDH. Meanwhile, its specific capacitance retention rate still keeps 62.8 % even at 20 A g −1 , indicating its excellent rate property. Furthermore, the assembled all-solid-state asymmetric SCs with NiCoO X @NiCo LDH//Active carbon (AC) exhibits a high energy density of 34.9 Wh kg −1 when the power density is 800 W kg −1 . Meanwhile, it has a high capacitance retention of 81.79 % (10 A g −1 ) after 10,000 cycles, which indicates a remarkable cycle life.