Ti 2 O 3 (H 2 PO 4 ) 2 ·2H 2 O as a Novel Intercalated Anode for Ultralong Lifespan “Rocking‐Chair” Aqueous Zinc‐Ion Batteries

The application of aqueous zinc-ion batteries (AZIBs) with Zn metal anode is hindered by severe dendritic growth, corrosion, and inefficient Zn utilization. "Rocking-chair" type AZIBs are considered a viable approach toward practical applications due to the success of commercial lithium-ion batteries employing intercalated graphite anodes. Herein, a new type of layered titanium phosphate Ti₂O₃(H₂PO₄)₂·2H₂O is proposed for the first time as the intercalated anodes for AZIBs, exhibiting a capacity of 108 mAh g^-1 at 50 mA g^-1, with a low discharge potential of 0.17 V (vs. Zn²⁺/Zn). The ion insertion process is thoroughly investigated, and a micro-dendrite growth-corrosion mode is proposed to explain the capacity degradation mechanism. Corresponding countermeasures are designed, resulting in a significant improvement in cycle life. When coupled with a zinc hexacyanoferrate (KZnHCF) cathode, the "rocking-chair" full battery exhibits an ultralong lifespan of 50000 cycles (111 days) at 2000 mA g^-1 with 94% capacity retention. This work presents a novel perspective for the development of practical AZIBs.