Multi-step electrodeposited Ni–Co–P@LDH nanocomposites for high-performance interdigital asymmetric micro-supercapacitors

Abstract

The development of high-performance electrode materials and the rational design of asymmetric structures are the two main keys to fabricating micro-supercapacitors (MSCs) with high energy density. Transition metal compounds, especially nickel–cobalt phosphides and hydroxides, are promising electrode materials with excellent pseudo-capacitance. However, they are rarely used in fabricating asymmetric MSCs (AMSCs) due to the limitations of the preparation method. In this work, we constructed hierarchical Ni–Co–P@LDH nanocomposites with outstanding mass specific capacitance (1980 F g⁻¹ at 1 A g⁻¹) via a multi-step electrodeposition method, which is employed with FeOOH to fabricate an interdigital AMSC device (Ni–Co–P@LDHs//PVA–KOH//FeOOH). The as-prepared device exhibits a high working voltage (1.4 V), a large specific capacitance (24.0 mF cm⁻² at 0.14 mA cm⁻²), a high energy density (6.54 μW h cm⁻² at a power density of 100 μW cm⁻²) and good cycling stability (86.5% of capacitance retention after 5000 cycles). This work may provide novel methods for the synthesis of high-performance nickel–cobalt composite materials and their potential applications in interdigital AMSC devices.