In Situ Growth of Hierarchical Ni‐Mn‐O Solid Solution on a Flexible and Porous Ni Electrode for High‐Performance All‐Solid‐State Asymmetric Supercapacitors.

Yu, Huan; Li, Xiaofeng; Yang, Jing; Deng, Zhiming; Yu, Zhong‐Zhen

To endow all‐solid‐state asymmetric supercapacitors with high energy density, cycling stability, and flexibility, we design a binder‐free supercapacitor electrode by in situ growth of well‐distributed broccoli‐like Ni0.75Mn0.25O/C solid solution arrays on a flexible and three‐dimensional Ni current collector (3D‐Ni). The electrode consists of a bottom layer of compressed but still porous Ni foam with excellent flexibility and high electrical conductivity, an intermediate layer of interconnected Ni nanoparticles providing a large specific surface area for loading of active substances, and a top layer of vertically aligned mesoporous nanosheets of a Ni0.75Mn0.25O/C solid solution. The resultant 3D‐Ni/Ni0.75Mn0.25O/C cathode exhibits a specific capacitance of 1657.6 mF cm−2 at 1 mA cm−2 and shows no degradation of the capacitance after 10 000 cycles at 3 mA cm−2. The assembled 3D‐Ni/Ni0.75Mn0.25O/C//activated carbon asymmetric supercapacitor has a high specific capacitance of 797.7 mF cm−2 at 2 mA cm−2 and an excellent cycling stability with 85.3 % of capacitance retention after 10 000 cycles at a current density of 3 mA cm−2. The energy density and power density of the asymmetric supercapacitor are up to 6.6 mW h cm−3 and 40.8 mW cm−3, respectively, indicating a fairly promising future of the flexible 3D‐Ni/Ni0.75Mn0.25O/C electrode for efficient energy storage applications.

SUPERCAPACITOR electrodes; SUPERCAPACITORS; POROUS electrodes; SOLID solutions; ENERGY density; ENERGY storage; POWER density

Chemistry - A European Journal, 2019, Vol 25, Issue 66, p15131

0947-6539

Academic Journal

10.1002/chem.201903244