A Near 0 V and Low-Strain Intercalative Anode for Aqueous Zinc-Ion Batteries

Metallic Zn anodes exhibit uncontrollable dendrites, impractically low Zn utilization, hydrogen evolution, and unexpected byproducts, limiting the practical process of aqueous zinc-ion batteries (AZIBs); thus, exploring alternative insertion anodes has become a reasonable strategy, exemplified by the successful application of graphite anodes in lithium-ion batteries. However, the current intercalative anodes are still plagued by high Zn2+ insertion potential and inadequate cycle life, and the alternative choice is quite limited. Here, we report a polyanionic insertion anode (Ti2O(PO4)2·2H2O) that shows an extremely low insertion potential of 0.07 V with a reversible capacity of 124.6 mAh g–1. This anode possesses a robust and spacious framework, demonstrating high reversibility with low strain during cycling. Coupled with a KZnHCF cathode, a 1.6 V "rocking-chair" full battery is achieved with an ultralong life of 5000 cycles, surpassing the reported congeneric batteries. This work shares a new vision for the development of practical AZIBs.