Self-Adapting Lattice Respiration Enabled by Crystal Design and d-p Orbital Hybridization Toward Highly Stable Rechargeable Aluminum Batteries

Rechargeable aluminum batteries (RABs) are promising for large-scale energy storage due to the appealing three-electron transfer feature, low cost, and high safety. However, the strong electrostatic interaction between Al³⁺ and host lattice induces severe lattice distortion and structural collapse, leading to poor cycle stability in RABs. Herein, we develop a new-type FeWO₄ cathode with a comprehensive consideration of the crystal structure and electronic structure. The 3D open framework and strong W─O covalent network of the FeWO₄ greatly improve the storage of high charge density Al³⁺. Moreover, the d-p orbital hybridization between the transition metal and oxygen facilitates electron delocalization, which effectively weakens the interaction with the trivalent cation (Al³⁺). Importantly, combining in situ characterizations and theoretical calculations, it is demonstrated that as-prepared cathode exhibits a “self-adapting lattice respiration” (SALR) effect. Specifically, the reversible W–O bond elongation/compression (Δd ≈ 0.05 Å) during cycling reduces lattice strain and confines volume expansion to less than 3%. As results, the FeWO₄ cathode delivers a high capacity of 192 mAh g⁻¹ at 500 mA g⁻¹ and long cycle life of over 2300 cycles with quiet low capacity decay of 0.01% per cycle in RABs.