Controllable synthesis of CoAl LDH@Ni(OH)2 nanosheet arrays as binder-free electrode for supercapacitor applications

• Smartly designed 3D CoAl LDH@Ni(OH)2 NSAs have been successfully synthesized.
• This hierarchical electrode represents enhanced supercapacitive performance.
• The synergy and structural features account for the enhanced capacitive properties.

Electrodes with novel hierarchical nanoarchitectures can offer many opportunities for achieving the enhanced performance in energy storage. Herein, we have designed and synthesized 3D hierarchical structures of CoAl LDH@Ni(OH)2 nanosheet arrays (NSAs) by a facile two-step route. Compared with the pristine CoAl LDH NSAs, the hierarchical CoAl LDH@Ni(OH)2 NSAs represents much better capacitive behaviors. Specifically, under the same test conditions, CoAl LDH@Ni(OH)2 electrode exhibits the maximum specific capacitance of 1528 F g−1 (by galvanostatic discharge at the current density of 5 mA cm−2 in 2 M KOH, based on the total mass; that for CoAl LDH NSAs is only 738 F g−1) and excellent cycling performance (retaining 92% of its original capacitance after 1300 times of cycling). Such enhanced supercapacitor performances can be attributed to the novel 3D architectures, which can benefit the full contact of the Ni(OH)2 layer with OH− in the electrolyte.