Research status and prospects of cathode materials for aqueous zinc ion batteries

The energy consumption of production in modern society is increasing gradually. With the implementation of policies like “carbon neutrality”,the development and utilization of new energy has become a new direction. The instability of new energy sources such as wind energy and solar energy limits their application,thus how to reasonably store and distribute energy has become a widely concerned issue. The current large scale energy storage is mainly achieved by the potential energy of water such as energy storage hydropower stations,and it has strict geographical restrictions,large floor space and low energy conversion rate,and is not suitable for large scale promotion and application. The high energy conversion rate,and region free of battery make it a suitable energy storage method,but the high cost and the safety issue limit its application. However,the cost of batteries is too high and the safety is poor. Aqueous zinc ion batteries(AZIBs) are composed of cathode materials,aqueous electrolytes,and zinc metal anodes.Due to the high safety and low cost,the AZIBs have become a potential way of power station level energy storage in the future. However,the insufficient capacity of the cathode material and cycle instability are still obstacles. This paper first introduces the current energy storage mechanism of cathode materials of AZIBs, and then summarizes and reviews the problems, solutions and current research progress of common positive electrode materials (MnO2, V2O5 and VO2, etc.), analyzes the performance changes of cathode materials under different conditions, and finally, on the basis of comparation of the electrochemical performance, a variety of possible optimization strategies including exploration of the mechanism, improving the conductivity, preparation of new positive electrode materials, defect engineering and electrolyte modification are proposed,which provide some references for future cathode optimization strategies.