Operando Tailoring of Defects and Strains in Corrugated β‐Ni(OH)₂ Nanosheets for Stable and High‐Rate Energy Storage

Abstract Nickel hydroxide represents a technologically important material for energy storage, such as hybrid supercapacitors. It has two different crystallographic polymorphs, α‐ and β‐Ni(OH)₂, showing advantages in either theoretical capacity or cycling/rate performance, manifesting a trade‐off trend that needs to be optimized for practical applications. Here, the synergistic superiorities in both activity and stability of corrugated β‐Ni(OH)₂ nanosheets are demonstrated through an electrochemical abuse approach. With ≈91% capacity retention after 10 000 cycles, the corrugated β‐Ni(OH)₂ nanosheets can deliver a gravimetric capacity of 457 C g⁻¹ at a high current density of 30 A g⁻¹, which is nearly two and four times that of the regular α‐ and β‐Ni(OH)₂, respectively. Operando spectroscopy and finite element analysis reveal that greatly enhanced chemical activity and structural robustness can be attributed to the in situ tailored lattice defects and the strain‐induced highly curved micromorphology. This work demonstrates a multi‐scale defect‐and‐strain co‐design strategy, which is helpful for rational design and tuned fabrication of next‐generation electrode materials for stable and high‐rate energy storage.