Multiple‐Scale Probing of Intrinsic Active Sites and Reaction Kinetics in Processable Cation‐Inserted Nickel Hydroxide Films

Abstract Nanoplate‐shaped Ni(OH) 2 with numerous exposed active sites hold much promise for high‐performance energy storage devices. However, restricted by the wide band gap, which leads to a low concentration of charge carrier, the energy barrier of electron mobility in lattice plane is high, further inhibiting the electron transfer and their practical application. Here, several unique processable nickel‐based hydroxide films are constructed via the cation‐inserted strategy to probe the intrinsic relationship between component and electronic micro‐structure. Benefiting from the component‐driven effects, the concentration of charge carrier at the lattice plane can be accumulated after injecting heterogeneous cations, and the fastened dynamics process can be realized and confirmed by multiple real‐time operando techniques. Meanwhile, the more well‐matched Co core rather than Mn core in Ni(OH) 2 is also certified. Finally, the CoNi(OH) 2 electrode achieves 623 C g –1 @1 A g –1 without any conductivity additives and binders, which is nearly threefold that of pristine Ni(OH) 2 . This work clarifies the critical role of inserted cations, and corresponding electron and electrolyte ion transfer across the matrix, thus enabling a better guideline for Ni(OH) 2 ‐based energy storage/conversion systems.