Cation Vacancy Strategy Activated Layered Double Hydroxides: Enhanced Electrochemical Performance and Longevity

The defect design strategy has been extensively employed to enhance the reaction kinetics of layered double hydroxide (LDH) electrode materials. Furthermore, it is anticipated to improve the cyclic stability of LDHs through this approach, serving a dual purpose. However, the potential mechanisms of cation vacancies' impact on the electrochemical performance of electrodes at the atomic scale still need further clarification. In this study, a typical aluminum-vacancy LDH material via a simple alkaline etching method was demonstrated. Electrochemical in situ Raman spectroscopy, ex situ X-ray diffraction (XRD), and first-principles calculations were utilized to elucidate the mechanism of Faradaic reactions. The findings indicate that this cation vacancy strategy not only enhances the electrochemical reaction kinetics of the electrodes but also effectively reduces the energy barrier for the α to γ phase transition of LDHs during the charge-discharge processes, thereby enhancing its longevity. To further validate the practical application of this defect design, an asymmetric solid-state supercapacitor was formed, which maintains 93.9% capacity after 20 000 charge-discharge cycles. This research offers technical guidance for the development of a new generation of high-performance and long-life LDH electrode materials based on a cation vacancy strategy.