Alternately electrodeposited mesoporous NiCoSe₂@MnO₂ nanocomposite-anchored Ni-Co layered double hydroxide nanoneedles for hybrid supercapacitors

A rational strategy for preparing effective electrode materials is crucial for high-performance electrochemical energy storage devices. Herein, a facile route to construct hierarchical composite electrodes (NiCoLDH@NiCoSe2@MnO2) consisting of hydrothermally synthesized NiCo-layered double hydroxide (NiCoLDH) nanoneedle arrays decorated with alternately electrodeposited NiCoSe2 and MnO2 nanocrystals on carbon fibers was developed. The NiCoLDH nanoneedles are designed to facilitate the one-step electrodeposited growth of NiCoSe2 nanoparticles for 60 s and also strengthen the interfacial contact between the NiCoSe2 film and the conductive fiber substrate. While the secondary electrodeposition of MnO2 layers for 40 s further enhances the electrochemical performance and cycling stability of composite electrodes, such composite electrodes display a high area specific capacitance of 1051.3 mF cm(-2) at 1 mA cm(-2), with obviously superior capacitance retention (similar to 80%) to that of NiCoLDH@NiCoSe2 (similar to 49%) after 5000 cycles. Then, the corresponding fiber-shaped supercapacitors provide an energy density of 45.00 mu W h cm(-2) at a power density of 800.00 mu W cm(-2) while having good stability. Notably, this fabrication strategy is also available for other conductive substrates (e.g., metal fibers/wires). This work presents a low cost, simple operation and efficient way for the in situ preparation of high-performance electrode materials for electrochemical energy storage applications.