Unraveling the electrochemical charge storage dynamics of defective Oxides-Based cathodes toward High-Performance aqueous Zinc-Ion batteries

Aqueous Zinc ion batteries (AZIBs) show tremendous potential for large-scale energy storage infrastructure owing to high affordability and high safety but are plagued by the undesired rate capability and inevitable capacity deterioration of the used cathodes. Defect engineering has been recognized as one of the most effective strategies for the electrochemical performance enhancement of cathodes. However, its underlying electrochemical kinetics and performance-enhancing mechanism are still immature. Herein, we performed comprehensive studies on the charge storage dynamics with the prototypical of defective manganese oxides (d-ZMO) by combining the three-dimensional (3D) Bode map and theoretical calculations. Bode analysis reveals that the d-ZMO exhibits the most significant values of real capacitance and the largest phase angle compared to that of the pristine MnO2 (MO) electrode, demonstrating the validity of defects on the electrochemical kinetic enhancement. Further theoretical results indicate the lowest zinc ions diffusion energy barrier (0.52 eV) of d-ZMO (1.23 eV of MO) with significantly enhanced ion kinetics, corroborating well with the Bode analysis. As expected, the configured AZIBs with d-ZMO cathode deliver an appreciable specific capacity of 419.7 mAh·g−1 (at 0.1 A·g−1) and exceptional cycle stability with capacity retention of 81.76 % (at 3 A·g−1) after 1000 cycles.