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

Abstract

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 (∼80%) to that of NiCoLDH@NiCoSe₂ (∼49%) after 5000 cycles. Then, the corresponding fiber-shaped supercapacitors provide an energy density of 45.00 μW h cm⁻² at a power density of 800.00 μW 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.