Deeply Discharged, Quiescently Stable, and Long‐Life Zn Anode by Spontaneous SEI Formation

Abstract Zn ion batteries (ZIBs) are a promising candidate in safe and low‐cost large‐scale energy storage applications. However, significantly deteriorated cycling stability of Zn anode in high depth of charge or after long‐term quiescence impedes the practical application of ZIBs. Aiming at the above issue, a spontaneous solid electrolyte interphase (SEI) formation of Zn 4 (OH) 6 SO 4 ·xH 2 O (ZHS) on Zn powder is achieved in pure ZnSO 4 electrolyte by facile and rational interface design. The stable and ultrathin ZHS SEI plays a crucial part in insulating water molecules and conducting Zn 2+ ions, intrinsically suppressing the severe hydrogen evolution and dendrite formation on the Zn powder anode. The ZHS‐Zn anode delivers a stable cycling at a high DOD of 50% for over 500 h, as well as a lifespan of over 200 h after 40‐days of resting at a DOD of 25%. Benefiting from the high utilization of Zn anode, the energy density of the Zn‐Mn x V 2 O 5 full cell is up to 118 Wh Kg −1 . This facile method can fabricate the ZHS‐Zn anode as long as 1 m, revealing its feasibility in large‐scale production and commercialization.