Controllable vacancy strategy mediated by organic ligands of nickel fluoride alkoxides for high-performance aqueous energy storage

Abstract

Vacancy engineering plays a significant role in the rational design of electrochemical energy conversion and storage. However, limited by traditional strategies, controllably introducing abundant vacancies remains challenging. Herein, a new strategy for controllable modulation of vacancy content by regulating the number of hydrogen bonds based on nickel fluoride alkoxide precursors (denoted as F–Ni–O_x–R_y) is proposed. The hydrogen bonds are formed by micro-design of the carbon chain structure to stabilize F ions on the surface during the synthesis process. Afterward, their breakage during electrochemical reconstruction processes leads to the overall release of F ions to generate vacancies. The adjustment of the carbon chain length can effectively control the number of hydrogen bonds, further microregulating the number of vacancies. The unique microstructural design yields a reconstructed nickel fluoride alkoxide (F–Ni–O₂–R₂) electrode with an ultra-high specific capacitance of 2975 F g⁻¹ at a current density of 1 A g⁻¹. This work not only provides a new strategy for the controllable modulation of vacancy engineering, but also a new perspective for the construction of novel energy storage electrodes by incorporating organic ligands into inorganic systems.