Reinforced bonding of Mo-doped MnO 2 with ammonium-ion as cathodes for durable aqueous MnO 2 –Zn batteries

Aqueous rechargeable Zn//MnO 2 batteries have attracted extensive research interest owing to their low cost and high energy density. However, the slow reaction kinetics, the disproportionation of the MnO 2 cathode, and the irreversible phase transition mechanism considerably restrict their development. Here, we chose Mo-doped α-MnO 2 (Mo–MnO 2 ) as the cathode material and proposed a stable N–H⋯O bond-reinforced interaction formed via NH 4 + intercalation to stabilize the 2 × 2 tunnel structure of Mo–MnO 2 . Theoretical and experimental studies were conducted to demonstrate the performance of the cathode. Mn 3+ dissolution was effectively inhibited, and lattice distortion did not occur during the proton insertion/removal process, which further improved the cyclic stability of the cathode. Specifically, at a current density of 100 mA g −1 , the Mo–MnO 2 cathode exhibited a specific capacity of 265.2 mA h g −1 , the energy density was 364.3 W h kg −1 , and the cathode exhibited excellent cyclic stability. At a current density of 2.0 A g −1 , the specific capacity was 95.2% after 1000 cycles. This work provides further insight into the bond interaction between nonmetallic cations in the main materials of electrodes and contributes to the construction of aqueous-based zinc-ion batteries with high energy density and long-term cycling capability.