In Situ Defect‐Free Vertically Aligned Layered Double Hydroxide Composite Membrane for High Areal Capacity and Long‐Cycle Zinc‐Based Flow Battery

Abstract Rechargeable aqueous zinc‐based flow batteries (ZFBs) are promising candidates for large scale energy storage devices. However, the challenges from zinc dendrites and limited areal capacity considerably impede their wide application. Here, an in situ vertical growth of layered double hydroxide membrane (LDH‐G) is constructed to enable long‐life ZFBs. Owing to the high hydroxide ion conductivity and ion selectivity nature of LDH nanosheets, specifically, the precise control of directional ion transport in vertical arrangement LDHs, a superior battery performance can be realized. Moreover, the defect‐free LDHs layer serves as a buffer layer to enable a uniform Zn deposition, which effectively enhances the areal capacity of the battery. As a result, the designed membrane endows an alkaline zinc‐iron flow battery with excellent rate performance and cycling stability, maintaining an energy efficiency of 80% at 260 mA cm −2 for 800 cycles, which is the highest performance ever reported. Most importantly, the LDHs layer enables the battery for 1200 h long‐cycle stability with a uniform Zn deposition and high areal capacity of 240 mAh cm −2 . This work realizes an in situ growth of 3D LDHs arrays on the polymer substrate, which provides a strategy toward high areal capacity and dendrite‐free Zn deposition for ZFBs.