Currently, coal, natural gas, or other carbon-based fuels are used to produce the majority of the world's electricity, which produces greenhouse gases. For a sustainable future, we need to focus on renewable energy like solar and wind, but these are intermittent in nature. For the utilization of these renewable energy resources, energy storage devices like batteries are an important component.

There are different types of chemistries available, each with its advantages and disadvantages. However, zinc-based aqueous chemistry with high volumetric capacity has been recognized as a potentially useful technique for stationary energy storage.

In this report, we are exploring the utilization of MnO2 polymorphs as cathode material in zinc-ion batteries. Since all polymorphic structures have different discrete translation symmetry, they are expected to show different performance as electrode materials. We have synthesized the different polymorphic structures of MnO2 via hydrothermal methods, and the electrochemical performance was tested with 1M ZnSO4·7H2O + 0.1M MnSO4·H2O as an aqueous electrolyte. We have discussed the role of crystal structure in the zinc storage mechanism and further presented general design strategies to improve electrode performance.