Hongwei Tian

Nickel hydroxyfluoride (Ni ₄ OHF ₇ ) has attracted increasing attention due to its high theoretical capacitance, yet its rate capability and cycling stability remain to be substantially improved. Here, we achieve dual optimization through elemental doping and support interaction, doping with Fe and Cr to enhance the rate capability, and compositing with reduced graphene oxide (rGO) to improve cycling stability. Experimental results show that the introduction of Cr, with lower electronegativity, further elevates the electronic state of the host element, while rGO facilitates the uniform distribution of active materials. The comprehensively optimized electrode material, denoted NFCHF/G, delivers a specific capacitance of 2852 F g ⁻¹ at a current density of 1 A g ⁻¹ , and retains 80% of its initial specific capacitance after 10,000 cycles. An asymmetric supercapacitor (ASC) based on NFCHF/G//AC achieves a maximum energy density of 71.9 Wh kg ⁻¹ at a power density of 750 W kg ⁻¹ , demonstrating promising application prospects. This work provides a reliable strategy for the development of hydroxyfluoride‐based electrode materials and is expected to better meet future energy demands.

In recent years, renewable energy sources, which aim to replace rapidly depleting fossil fuels, face challenges due to limited energy storage and conversion technologies. To enhance energy storage and conversion efficiency, extensive research has been conducted in the academic community on numerous potential materials. Among these materials, metal fluorides have attracted significant attention due to their ionic metal–fluorine bonds and tunable electronic structures, attributed to the highest electronegativity of fluorine in their chemical composition. This makes them promising candidates for future electrochemical applications in various fields. However, metal fluorides encounter various challenges in different application directions. Therefore, we comprehensively review the applications of metal fluorides in the field of energy storage and conversion, aiming to deepen our understanding of their exhibited characteristics in different electrochemical processes. In this paper, we summarize the difficulties and improvement methods encountered in different types of battery applications and several typical electrode optimization strategies in the field of supercapacitors. In the field of water electrolysis, we focus on surface reconstruction and the critical role of fluorine, demonstrating the catalytic performance of metal fluorides from the perspectives of reconstruction mechanism and process analysis. Finally, we provide a summary and outlook for this field, aiming to offer guidance for future breakthroughs in the energy storage and conversion applications of metal fluorides.