Effect of Binding Affinity of Crystal Water on the Electrochemical Performance of Layered Double Hydroxides

The ever-increasing demand for safe batteries has driven research efforts to develop aqueous rechargeable batteries. In this regard, Ni-based layered double hydroxides (LDHs) have received marked attention owing to their adequate operating potential, high specific capacity, and decent cycling performance. Nevertheless, the effect of immobile intercalants (e. g., crystal water and anions) that are inherently present in the interlayer galleries is barely understood. In this paper, we report that the electrochemical performance of LDH largely depends on the extent to which the crystallinity is affected by the binding strength of crystal water to the transition metal slabs. A series of infrared spectroscopy and in-situ X-ray absorption analyses reveal that the lattice disordering in LDHs is beneficial for accommodating the stress during the (de)intercalation of carrier ions, which serves as the origin of their superior specific capacities and cycle life. This study presents a useful structure-property relationship of the way in which the binding affinity of crystal water affects the key electrochemical properties of the host electrode materials.