High-performance Zn battery with transition metal ions co-regulated electrolytic MnO₂

Electrolytic MnO₂/Zn batteries have attracted extensive attention for use in large-scale energy storage applications due to their low cost, high output voltage, safety, and environmental friendliness. However, the poor electrical conductivity of MnO₂ limits its deposition and dissolution at large capacities, which leads to sluggish reaction kinetics and drastic capacity decay. Here, we report a theory-guided design principle for an electrolytic MnO₂/Zn battery co-regulated with transition metal ions that has improved electrochemical performance in terms of deposition and stripping chemistries. We start with first-principles calculations to predict the electrolytic effects of regulating transition metal ions in the deposition/stripping chemistry of the MnO₂ cathode. The results indicate that with the simultaneous incorporation of strongly electronegative Co and Ni, the MnO₂ cathode tends to possess more active electron states, faster charge-transfer kinetics, and better electrical conductivity than either MnO₂ regulated with Co or Ni on their own, or pristine MnO₂; hence, this co-regulation is beneficial for the cathode solid/liquid MnO₂/Mn²⁺ reactions. We then fabricate and demonstrate a novel Co²⁺ and Ni²⁺ co-regulated MnO₂/Zn (Co–Ni–MnO₂/Zn) battery that yields significantly better electrochemical performance, finding that the synergistic regulation of Co and Ni on MnO₂ can significantly increase its intrinsic conductivity and achieve high rates and Coulombic efficiencies at large capacities. The aqueous Co–Ni–MnO₂/Zn battery exhibits a high rate (10C, 100 ​mA ​cm^–2), high Coulombic efficiency (91.89%), and excellent cycling stability (600 cycles without decay) at a large areal capacity of 10 mAh cm^–2. Our proposed strategy of co-regulation with transition metal ions offers a versatile approach for improving the electrochemical performance of aqueous electrolytic MnO₂/Zn batteries in large-scale energy storage applications.