Hydrogen Bond Network Anchoring and Oxygen Vacancy Synergistic Regulation for High-Performance Aqueous Zinc−Ion Batteries

Abstract α-MnO2 possesses a unique 2 × 2 tunneling crystal structure and offers outstanding advantages such as high specific capacity and high operating voltage, making it a hot topic in research on cathode materials for aqueous zinc−ion batteries. However, its poor structural stability and intrinsic conductivity severely limit its electrochemical performance. Based on this, this study innovatively incorporated lightweight NH4+ into α-MnO2 to prepare NMO-x materials with different NH4+ doping levels. The results indicate that the N─H bonds in NH4+ form a hydrogen-bond network (N─H···O) with the framework oxygen atoms, effectively anchoring NH4+ and shielding the electrostatic repulsion between Zn2+ and O. Simultaneously, this induces the formation of oxygen vacancies, which suppress the Jahn−Teller distortion of Mn3+ and Mn dissolution, thereby significantly enhancing structural stability and ionic migration kinetics. Consequently, the optimized NMO-2 cathode material maintains excellent rate performance of 150 mAh g−1 even at a high current density of 5.0 A g−1, and retains a high capacity retention of 87% after 1000 cycles at a current density of 1.0 A g−1. This work has advanced research on the modification of MnO2 cathode materials and provided new insights for the design of high-performance aqueous zinc−ion battery cathode materials.