Thiophene bridged Ni-V units in bimetallic hydroxides electrodes to improve the cycling stability of supercapacitor

Layered double hydroxides (LDHs) are promising electrode materials for supercapacitors, owing to their high theoretical capacitance and excellent redox activity arising from their unique layered structure and the synergistic effects of bimetallic elements. Among them, NiV-LDHs stand out as a promising candidate for high-performance capacitors, since the + 2/+ 3 valence states of nickel and the multi-valence states of vanadium (+3/+4/+5) synergistically facilitate rapid and reversible pseudocapacitive reactions, significantly enhancing specific capacitance. However, the high-coordination structure of V 5 + tends to collapse during charge-discharge cycles, leading to reduced cycling stability. To address these issues, this study proposes a dynamic electronic balancing strategy to regulate electron transfer from Ni to V, thereby suppressing the formation of unstable high-coordination V 5+ and improving the structural stability of NiV-LDH. Through the electrochemical polymerization and intercalation of thiophene-3-carboxylic acid (3TCA) into the LDH layers, the resulting poly(thiophene-3-carboxylic acid) (P3TCA) acts as a conductive bridge to dynamically adjust the electron distribution between Ni and V. This redistribution enhances the activity of Ni while stabilizing the structure of V. The optimized NiV-LDH/NF/P3TCA electrode demonstrates exceptional cycling stability and charge transfer kinetics. Remarkably, it achieves an ultra-high specific capacitance of 2040 F g −1 at 1 A g −1 and maintains 78.72 % of its initial capacity after 5000 cycles, underscoring its potential for high-performance supercapacitor applications.