Ksp-Regulated Electrochemically Etching Strategy: BaSO4-Decorated NiCo-LDH with Strong Built-in Electric Field for High-Performance Aqueous Alkaline Zinc Batteries

Abstract

Although layered double hydroxides (LDHs) provide structural advantages for alkaline zinc-ion battery (AZIB) cathodes via their inherent layered architecture, their intrinsic low electrical conductivity and anisotropic ion transport limits charge transfer kinetics. A Ksp-regulated electrochemical etching strategy is first proposed to solve this challenge by exploiting the dramatic solubility difference between BaSO₄ and Co/NiSO₄. The thermodynamic selectivity enables the precise construction of BaSO₄ nanodot-anchored NiCo-LDH heterostructures (BS@CN-LDH) within a rapid minute-scale process, achieving atomic-level control over heterointerface architecture. Density functional theory (DFT) calculations coupled with UPS analysis reveal a strong built-in electric field (BEF) at the heterointerface (ΔΦ = 0.70 eV), driving interfacial charge redistribution of 0.013 e from NiCo-LDH to BaSO₄. The optimized BS@CN-LDH electrode material exhibits a high specific capacity of 450.5 mAh g⁻¹ at a current density of 2 mA cm⁻², maintaining 83.3% excellent cycling stability after 10 000 cycles. Moreover, the as-fabricated BS@CN-LDH//rGO-Zn AAZB cell achieves a record energy density of 747.9 Wh kg⁻¹ at a power density of 0.27 kW kg⁻¹, surpassing most reported zinc-based energy storage devices. This Ksp-regulated etching strategy provides critical insights into electric field engineering of heterostructured materials to resolve the persistent electron/ions transfer kinetics for dramatically increased energy storage performance.