Ultralong Cycle Life and High Rate of Zn?I₂ Battery Enabled by MBene-Hosted I₂ Cathode

High rate tolerance and long cycle life represent the critical demand of the market for energy storage devices, known as one of major challenges for the development of rechargeable aqueous batteries. Herein, a layered Mo4/3B2T2 (where "T" denotes -O, -OH, and -F terminations) MBene (a transition metal boride) with in-plane ordered metal vacancies is first proposed as an iodine species host of an aqueous Zn||I-2 battery, delivering a discharge capacity of 106.8 mAh g(-1) at 25 A g(-1) after 230 000 cycles and 80 mAh g(-1) at 100 A g(-1), far exceeding those of all Zn||I-2 batteries ever reported. The high performance is attributed to the strong affinity with iodine species and accelerated the redox kinetics by the conductive MBene with metal vacancies, as evidenced by the one-step conversion of I-/I-0 without the generation of I3- ions. This work unlocks a new route for the construction of other halide or sulfur electrode batteries with superior durability and kinetics.