Yttrium-preintercalated layered manganese oxide as a durable cathode for aqueous zinc-ion batteries.

Rechargeable aqueous zinc-ion batteries (RAZIBs) are regarded as competitive alternatives for large-scale energy storage on account of cost-effectiveness and inherent safety. In particular, rechargeable Zn-MnO batteries have drawn increasing attention due to high manufacturing readiness level. However, obtaining MnO with high electrochemical activity and high cyclic stability toward Zn/H storage still remains challenging. Herein, we reveal that incorporating yttrium ions (Y) into layered MnO can regulate the electronic structure of the MnO cathode by narrowing its band gap (from 3.25 to 2.50 eV), thus boosting the electrochemical performance in RAZIBs. Taking advantage of this feature, the optimized Y-MnO (YMO) sample exhibits greater capacity (212 152 mA h g at 0.5 A g), better rate capability (94 61 mA h g at 8 A g), reduced charge-transfer resistance (79 148 Ω), and promoted mass transfer kinetics (3.13 × 10 2.37 × 10 cm s) in comparison with Y-free MnO (MO). More importantly, compared to MO, YMO-0.1 exhibits enhanced energy storage capability by nearly 40% (309 222 W h kg) and stable cycle performance (94 52 mA h g after 3000 cycles). Raman microscopy further reveals that the presence of Y endows MnO with remarkable electrochemical reversibility during charge/discharge processes. This work highlights the importance of the Y preintercalation strategy, which can be further developed to obtain better cathode materials for aqueous batteries.