Progressive “Layer to Hybrid Spinel/Layer” Phase Evolution with Proton and Zn2+ Co-intercalation to Enable High Performance of MnO2-Based Aqueous Batteries

Manganese oxides are promising host materials in rechargeable aqueous batteries due to their low cost and high capacity; however, their practical applications have long been restricted by their sluggish reaction kinetics and poor cycling stability. Herein, the layered K 0.36 H 0.26 MnO 2 ·0.28H 2 O (K36) with a proton and Zn 2+ cointercalation mechanism leads to a progressive phase evolution from layer-type K36 to hybrid layer-type K x H y Zn z MnO 2 · n H 2 O and spinel-type ZnMn 2 O 4 nanocrystal after a long-term cycle. Accordingly, K36 shows a high specific capacity (∼329.8 mAh g –1 at 0.1C), a superior rate performance (∼100.1 mAh g –1 at 10C), and a remarkable cycling stability (capacity retention of ∼93.4% over 3000 cycles at 4C). This work provides a new viewpoint of enhancing electrode performance via generating hybrid phases under electrochemical driving and will be a benefit to developing the next-generation aqueous batteries.