Self‐Adapting Lattice Respiration Enabled by Crystal Design and d‐p Orbital Hybridization towards 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 three‐dimensional (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.