A self-supporting Co(OH)F nanosquares with ion and electron conductive structure for high performance electrochemical energy storage

The integration of Cobalt hydroxide fluoride Co(OH)F-based materials is expected to significantly enhance the electrochemical performance of supercapacitor electrodes. In this work, Co(OH)F with various morphologies was synthesized using a simple hydrothermal method and evaluated as an electrode material for supercapacitors. The porous nano square-like morphology exhibited excellent durability in electrochemical reactions, providing abundant active sites. Furthermore, the highly electronegative fluorine atom contributes to fast ion diffusion to electrode surface and reduces intrinsic resistance during the reaction, leading to remarkable electrochemical performance. Remarkably, the optimized Co(OH)F₄₅₀ exhibited an ultrahigh specific capacitance of 558 F g⁻¹ at a current density of 1 A g⁻¹, which is greater than that of Co(OH)F₃₀₀, and Co(OH)F₁₅₀ electrodes. Furthermore, the device delivered outstanding cyclic performance, maintaining 80 % capacitance retention after 10,000 charge-discharge cycles. Finally, the Co(OH)F₄₅₀ electrode demonstrates a promising energy density of 27 Wh kg⁻¹ at a power density of 2571 W kg⁻¹. Above results suggest that Co(OH)F₄₅₀ electrode could pave way for the development of high-performance electrodes in the field of energy storage.