Crystal Water Boosted Zn²⁺ Transfer Kinetics in Artificial Solid Electrolyte Interphase for High-Rate and Durable Zn Anodes

The commercialization of aqueous zinc ion batteries (ZIBs) is seriously hindered by the inferior stability of the Zn anode, which principally originates from water-induced side reactions and dendrite issues. Interfacial engineering has been considered as a cost-effective way to tackle these bottlenecks. However, most artificial solid electrolyte interphase (SEI) suffers from sluggish Zn2+ migration and thus compromises the kinetic merits of aqueous ZIBs especially at ultrahigh rates. Herein, we present a unique H2O molecules-rich zinc phytate (PAZn) interphase for the optimization of Zn anodes. The critical role of crystal water on the Zn2+ transport process is demonstrated. Benefiting from the shielding effect, the Zn2+ diffusion coefficient increases by orders of magnitude in the presence of crystal water. Accordingly, the Zn anode modified by PAZn interphase delivers an impressive lifespan of 1200 h and dramatically reduced voltage hysteresis even under an ultrahigh current density of 10 mA cm–2, and it remains stable even at a higher Zn utilization exceeding 50%. Moreover, the V2O5//PAZn@Zn full cell exhibits remarkable performance with a high capacity retention of 89.3% after 600 cycles. This work provides an effective strategy for rationally designing highly Zn2+-conductive artificial SEI for durable Zn anodes and high-performance commercially available ZIBs.