Self-supported core-shell heterostructure MnO₂/NiCo-LDH composite for flexible high-performance supercapacitor

Nickel cobalt layered double hydroxides (NiCo-LDHs) nanosheets (NSs) were synthesized on a flexible carbon cloth (CC) substrate by a simple hydrothermal method. Then the manganese dioxide (MnO₂) NSs were directly deposited on the NiCo-LDH/CC to form three-dimensional (3D) self-supported core-shell MnO₂/NiCo-LDH/CC flexible electrodes. The MnO₂ NSs with three different loading amount on NiCo-LDH/CC substrate, named MnO₂-1/NiCo-LDH/CC, MnO₂-2/NiCo-LDH/CC and MnO₂-3/NiCo-LDH/CC, were hydrothermally synthesized in 0.01 M, 0.02 M and 0.03 M potassium permanganate (KMnO₄) solution, respectively. The morphology and electrochemical performance of these obtained composite electrodes were observed and analyzed. The MnO₂-2/NiCo-LDH/CC electrode exhibits a capacitive performance of 312 F g⁻¹ at 0.2 A g⁻¹ (937 mF cm⁻² at 1 mV s⁻¹) and maintains 97% of the original capacitance after 5000 charge-discharge cycles. The good mechanical stability and excellent cycle performance of MnO₂-2/NiCo-LDH/CC electrode is benefit from the numerous channels for rapid electron transport provided by the large specific surface area and self-supported of NiCo-LDH nanoflakes. Therefore, the MnO₂-2/NiCo-LDH/CC composite electrode is a potential candidate in wearable energy storage device.