In-situ Built Interphase with High Interface Energy and Fast Kinetics for High Performance Zn Metal Anodes
In-situ constructing multifunctional solid electrolyte interphase (SEI) for Zn anode is promising to address the dendrite growth and side reactions (corrosion and hydrogen evolution) in aqueous Zn-ion batteries. However, there is a lack of constructive methods for choosing suitable SEI compounds and feasible implementation routes. Here, inspired by SEI-design for Li-metal batteries, we identified that Zn3(PO4)2 with high interface energy could suppress Zn dendrite growth effectively and ZnF2 could accelerate the kinetics of Zn2+ transference and deposition, thus constructing a Zn3(PO4)2-ZnF2 composite SEI (ZCS) is likely to improve interface deposition and electrode kinetics comprehensively. However, the high redox potential of Zn/Zn2+ make it difficult to develop an in-situ SEI for Zn anode in aqueous electrolytes via traditional electrochemical route. Considering this dilemma, we take advantage of the instability of KPF6 in aqueous environment and build in-situ ZCS on Zn anode through PF6- anion-induced chemical strategy. Surprisingly, the ZCS protencted Zn exhibits enhanced reversibility with smooth and compact structure during long-term cycling. Both cumulative capacity (2020 mA h cm-2) and the product of largest current density and areal capacity (10 mA cm-2 × 20 mA h cm-2) reach the highest levels compared with recent reports under mildly acidic condition. This work paves a new way for designing desirable SEI on Zn anode and may also enlighten other systems to overcome intrinsic defects in constructing favorable interphases.