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

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.