Rational synthesis of sea urchin-like NiCo-LDH/tannin carbon microsphere composites using microwave hydrothermal technique for high-performance asymmetric supercapacitor

Abstract

In this study, tannin-derived porous carbon (TAC) with different microstructures was prepared via a microwave hydrothermal method, followed by KOH activation. Subsequently, the sea urchin–like NiCo-LDH/Tannin-derived carbon-based microsphere composite materials were rationally synthesized through a single-step microwave hydrothermal co-assembly process. The physicochemical characteristics and supercapacitive performance were systematically analyzed. TAC with a microspherical structure promoted and controlled the growth of LDHs, resulting in a more regular sea urchin–like structure, improved dispersibility, reduced resistance, and increased active sites. NiCo-LDH@TAC600-0 (without KOH activation) as an electrode material delivered a specific capacitance (Cs) of 1250 F g⁻¹ at 1 A g⁻¹ and 1035 F g⁻¹ at 10 A g⁻¹, with a rate performance of 82.8%. The asymmetric supercapacitor device using NiCo-LDH@TAC600-0 and TAC provided an energy density of 30.8 Wh kg⁻¹ at 800 W kg⁻¹ and a capacitance retention rate of 72.5% after 5000 cycles. This study offers a novel approach to enhancing NiCo-LDH properties for efficient energy storage.