Unlocking Layered Double Hydroxide as a High‐Performance Cathode Material for Aqueous Zinc‐Ion Batteries

Advanced cathode materials play an important role in promoting aqueous battery technology for safe energy storage. Transition metal double hydroxides are usually elusive as a stable cathode for aqueous zinc-ion batteries (AZIBs) due to their unstable crystal structure, sluggish ion transportation, and insufficient active sites for zinc-ion storage. Here, a trinary layered double hydroxide (LDH) with hydrogen vacancies (Ni₃ Mn_0.7 Fe_0.3 -LDH) is reported as a new cathode material for AZIBs. A reversible high capacity up to 328 mAh g^-1 can be obtained and cycle stably over 500 cycles with a capacity retention of 85%. Experimental and theoretical studies reveal that the hydrogen vacancies in LDH can expose lattice oxygen atoms as active sites for zinc-ion storage and accelerate ion diffusion by reducing the electrostatic interactions between zinc ions and the host structure. In addition, the synergy of the trinary transitional metal cations can suppress the Jahn-Teller distortion of manganese (III) oxide octahedron and enable long cycle stability. This work provides not only a series of high-performance cathode materials for AZIBs but also a novel materials design strategy that can be extended to other multi-valence metal-ion batteries.