NiCo layered double hydroxide anchored on MXene/tannin carbon cryogel composite with 3D hierarchical sea urchin-like structure for asymmetric supercapacitors

Layered bimetallic hydroxides have attracted considerable attention as electrode materials for supercapacitors, with various modification strategies being explored to enhance their practical electrochemical performance. In this study, we present a simple and robust bottom-up synthesis method for fabricating a 3D hierarchical interwoven NiCo-LDH@MT-based electrode through a microwave-assisted hydrothermal co-assembly process, using MXene, NiCo-LDH, and tannin-based cryogel. The resulting NiCo-LDH@MT electrode exhibited an exceptional specific capacitance of 1210.55F g- 1 at a current density of 1 A g-1, along with an impressive rate capability of 80.05 %, compared to 53.3 % for the pure NiCo-LDH electrode. Asymmetric supercapacitor devices assembled using NiCo-LDH@MT as the positive electrode and MXene-TPUF as the negative electrode demonstrated a high energy density of 48.22 Wh kg- 1 at a power density of 946.5 W kg-1. Furthermore, the devices achieved a remarkable capacity retention of 93.2 % and a Coulombic efficiency of 100 % after 10,000 cycles at 10 A g- 1. The outstanding specific capacitance, long-term stability, and excellent energy and power density of the NiCoLDH@MT-based asymmetric supercapacitor underscore its significant potential for energy storage applications.