Intercalating anion and hydrogen-bond network in layered double hydroxide to breakthrough the diffusion limit for unsealing theoretical capacity

Although the intrinsic layer structure of layered double hydroxide (LDH) is beneficial for more accessible active centers and faster electrolyte ions diffusion rate than closed-packed atom arrangement for achieving higher capacitance, the narrow interlaminar spacing results in inevitable “death volume” during the rapid charging-discharging process. Herein, an electrochemical assistant MOF etching strategy is developed to construct hierarchical porous LDH with pre-embed OH − ions and filled H 2 O molecule in inter-layer space (E-MOF-0.5 V) for unsealing theoretical capacity. According to the valence equilibrium theory, the increased valence of the metal center during electrochemical polarization can accelerate the filling of OH − ions and H 2 O molecules in the LDH inter-layer space. The involved OH − and water molecules can achieve rapid mass transfer processes through ‘‘Newton’s Cradle’’ and the rich pore and ultra-thin layer structure may make sure the active centers are almost completely accessible. Therefore, the optimized E-MOF-0.5 V delivers an outstanding specific capacity of 8547.2 mF cm −2 (2670.9 F g −1 ) at 4 mA cm −2 and maintains an excellent cycling performance of 88 % after 7200 cycles at 20 mA cm −2 . Besides, an E-MOF-0.5 V//rGO-Zn hybrid supercapacitor device is assembled, which presents an energy density of 7.97 mWh cm −2 and a power density of 6.63 mW cm −2 .