A High‐Nickel Layered Double Hydroxides Cathode Boosting the Rate Capability for Chloride Ion Batteries with Ultralong Cycling Life

Abstract Chloride‐ion batteries (CIBs) have drawn growing attention in large‐scale energy storage applications owing to their comprehensive merits of high theoretical energy density, dendrite‐free characteristic, and abundance of chloride‐containing materials. Nonetheless, cathodes for CIBs are plagued by distinct volume effect and sluggish Cl⁻ diffusion kinetics, leading to inferior rate capability and short cycling life. Herein, an unconventional Ni₅Ti‐Cl LDH is reported with a high nickel ratio as a cathode material for CIB. The reversible capacity of Ni₅Ti‐Cl LDH retains 127.9 mAh g⁻¹ over 1000 cycles at a large current density of 1000 mA g⁻¹, which exceeds that of ever reported CIBs, with extraordinary low volume change of 1.006% during a whole charge/discharge process. Such superior Cl‐storage performance is attributed to synergetic contributions consisting of high redox activity from Ni²⁺/Ni³⁺ and pinning Ti that restrains local structural distortion of LDH host layers and enhances adsorption intensity of chloride atoms during the reversible Cl⁻ intercalation/de‐intercalation in LDH gallery, which are revealed by a comprehensive study including X‐ray photoelectron spectroscopy, kinetic investigations, and DFT calculations. This work provides an effective strategy to design low‐cost LDHs materials for high‐performance CIBs, which are also applicable to other types of halide‐ion batteries (e.g., fluoride‐ion and bromide‐ion batteries).