In situ construction of NiCo-layered double hydroxide nanobranches with adjustable layer spacing on micro-sized...

Binary layered double hydroxides (LDHs) are an emerging class of materials for supercapacitors owing to their tunable topological structure and excellent theoretical energy storage capacity. However, aggregation and restacking cause a decrease in the interlayer distance of LDHs, resulting in a considerable drop in real specific capacitance. To address this, large-sized anions are intercalated into the interlayer space. Herein, we constructed 3D top-tangled NiCo-LDH nanobranches in situ on a biomass micro-sized carbon plate (CP). By varying the amount of benzene-1,4-dicarboxylic acid (BDC), we prepared a BDC-intercalated CP/NiCo-LDH composite material with adjustable interlayer spacing. Remarkably, the CP/NiCo-LDH-BDC(0.03) composite exhibited excellent electrochemical properties (1530 F g^-1/212.5 mAh/g at 1 A/g). It retained 88.36 % capacity after 5000 charge-discharge cycles. The constructed CP/NiCo-LDH-BDC(0.03)//CP asymmetric supercapacitor showed excellent gravimetric capacitance (123 F g^-1/54.7 mAh/g at 1 A/g) and energy density (43.7 Wh kg^-1 at 800 W kg^-1). Furthermore, two asymmetric capacitors connected in series powered a small lightbulb for 2 min, even in a bent state. These findings show that the fabricated CP and CP/NiCo-LDH-BDC(0.03) electrode materials can be applied in flexible and wearable energy storage systems.