High-Electronegativity Dopant Optimizing the Electrochemical Kinetics and Stability of Manganese Oxide Cathodes for Zinc-Ion Batteries

Manganese oxides with high theoretical capacity and natural abundance are promising cathode materials for aqueous zinc-ion batteries (ZIBs), yet their intrinsic Jahn–Teller distortion and the strong Zn2+–cathode electrostatic interactions tend to trigger rapid capacity degradation and inferior rate performance. Herein, we propose a high-electronegativity substitution doping strategy to enhance the electrochemical kinetics and stability of manganese oxide cathodes. Manganese oxide materials doped by a trace amount of high-electronegativity Ru atoms are synthesized, for which the Ru dopant substituting Mn atoms not only improves the electronic conductivity of manganese oxides but also induces the compression of [MnO6] octahedra to strengthen the Mn–O bonds, effectively improving ion diffusion capability and mitigating Jahn–Teller distortion-associated lattice expansion during the Zn2+ storage process to improve the electrochemical kinetics and stability of the high-electronegativity Ru-doped manganese oxides. As a result, the synthesized Ru-doped MnO2 cathode possessing a high specific capacity of 230 mAh/g presents good rate performance and attractive cycling stability with a stable average output voltage of 1.34 V and an energy efficiency of over 84%, notably superior to those of currently reported manganese oxide cathode materials. This work provides new insights for designing stable Zn2+ storage cathode materials and is believed to promote the development of ZIBs.