Plasma-tailored ZnNi-layered double hydroxides with ultrashort processing for supercapacitors

Designing effective strategies for developing nanoarchitectures with high energy storage capabilities remains a significant challenge in advanced supercapacitors. Among the emerging electrode materials for supercapacitors, layered double hydroxides (LDHs) are particularly promising due to their tunable structures. However, their low conductivity and delayed ion transport make them challenging to use as a non-compound electrode for widespread applications. Herein, we demonstrate a fast surface engineering process of LDH to improve its energy storage capabilities using environmentally friendly plasma techniques to overcome these limitations. The effect of sulfur and hydrogen plasma-based surface engineering on improving electrochemical reactions was systematically investigated. The surface and structural analysis of the materials revealed that fast plasma processing improves structural quality, creates structural defects and defines structures, all of which will enhance ion transport and electronic conductivity. By introducing surface activation functional groups on the ZnNi-LDH anosheet-like structures, the charge-storage capacity of LDH was significantly improved without using hazardous chemicals or time-consuming processes. As an electrode for a supercapacitor, the plasma-tailored ZnNi-LDH electrode delivers a high specific capacitance of 856 F g −1 at 1 A g −1 (385C g −1 at 1 A g −1 ) with improved rate capability and cycling stability. An S-LDH//AC asymmetric cell prototype is fabricated to assess practical application and exhibits an energy density of 16 Wh kg −1 and a power density of 572 W kg −1 , with outstanding capacitance retention after 5000 cycles. Such a sustainable plasma surface tailoring approach offers a potential path towards using LDH-based stand-alone electrodes for next-generation supercapacitors. • A rapid (<20s) plasma-surface engineering for fine-tuning ZnNi-LDH surface. • Plasma surface engineering improves the structural quality and morphology of LDH. • A sixfold capacitance increase achieved by sulfur plasma-treated LDH (385C/g at 1 A/g).