Electron Delocalization-Driven Dual-Electron Redox Chemistry in NiCo-LDH for High-Capacity Aqueous Ni-Zn Batteries

As a cathode material for alkaline Zn batteries, Ni(OH)₂ shows limited capacity and efficiency due to its single-electron transfer per redox site and the side reaction of oxygen evolution during charge-discharge processes. Here, we report an electrode material featuring an ultrathin NiCo-LDH layer coated on hollow carbon shell (NC@HCS). Incorporating Co into the lattice affects the conformation and band structure of adjacent Ni sites via CoO₆ octahedral distortion, leading to the formation of charge-transfer orbitals through electron delocalization near the Fermi level, which significantly reduces the oxidation potential of Ni(OH)₂. The ultrathin NC@HCS architecture weakens interlayer hydrogen bonding during the dehydrogenation process (charging), lowering the dehydrogenation energy barrier. This structural feature facilitates the formation of high-valence states and enables efficient two-electron transfer. As an efficient cathode material for Zn batteries, the ultrathin NC@HCS cathode exhibits a remarkable capacity of 528 mAh g^-1 at 5 A g^-1 (0.63 mAh cm^-2). This strategy provides a pathway for developing high-performance and durable cathode materials for Ni-Zn batteries.