The Emerging Layered Hydroxide Plates with Record Thickness for Enhanced High‐Mass‐Loading Energy Storage

Abstract The past decade has witnessed the development of layered‐hydroxide‐based self‐supporting electrodes, but the low active mass ratio impedes its all‐around energy‐storage applications. Herein, the intrinsic limit of layered hydroxides is broken by engineering F‐substituted β‐Ni(OH) 2 (Ni–F–OH) plates with a sub‐micrometer thickness (over 700 nm), producing a superhigh mass loading of 29.8 mg cm −2 on the carbon substrate. Theoretical calculation and X‐ray absorption spectroscopy analysis demonstrate that Ni–F–OH shares the β‐Ni(OH) 2 ‐like structure with slightly tuned lattice parameters. More interestingly, the synergy modulation of NH 4 + and F − is found to serve as the key enabler to tailor these sub‐micrometer‐thickness 2D plates thanks to the modification effects on the (001) plane surface energy and local OH − concentration. Guided by this mechanism, the superstructures of bimetallic hydroxides and their derivatives are further developed, revealing they are a versatile family with great promise. The tailored ultrathick phosphide superstructure achieves a superhigh specific capacity of 7144 mC cm −2 and a superior rate capability (79% at 50 mA cm −2 ). This work highlights a multiscale understanding of how exceptional structure modulation happens in low‐dimensional layered materials. The as‐built unique methodology and mechanisms will boost the development of advanced materials to better meet future energy demands.