Ammonium ion pre‐intercalated manganese dioxide with hydrogen bond for high‐rate and stable zinc‐ion batteries

The low‐cost and high‐safety zinc‐ion batteries (ZIBs) are expected to be promising alternatives of lithium‐ion batteries (LIBs). Nevertheless, sluggish kinetics and unstable structure of cathode lead to the low‐rate capability and poor cycling stability of ZIBs, which severely hinder their commercial application. Herein, a (NH4)xMnO2 cathode with ammonium ions (NH4+) pre‐intercalation is reported. The NH4+ ions with small molar mass expand the layer spacing, accelerating ion diffusion and act as “structural pillars”, preventing structural collapse. Moreover, hydrogen bond between NH4+ and MnO2 promotes the charge transfer and further stabilize the layered structure. Therefore, the (NH4)xMnO2 cathode delivers a high specific capacity (228.7 mAh g−1 at 0.3 A g−1), a superior high‐rate performance (122.5 mAh g−1 at 3.0 A g−1), and an outstanding long‐term cycling stability without obvious capacity fading after 1500 cycles at 2.0 A g−1. This work provides a new perspective for future development of high‐performance ZIBs. (NH4)xMnO2 is prepared by pre‐intercalating NH4+ ions into the layered structure of MnO2. NH4+ with small molar mass and hydrogen bond between NH4+ and MnO2 accelerate the charge transfer and ion diffusion, promoting fast kinetics and structural stability. Therefore, the (NH4)xMnO2 cathode with Zn2+/H+ co‐insertion/extraction energy storage mechanism delivers a high reversible capacity, superior rate performance, and ultralong cycling stability.