Researching the electrochemical performance by Mn2+ substituted Na3+xV2-xMnx(PO4)3/rGO cathode materials for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are gaining rising popularity as potential energy storage solutions for large-scale renewable energy, attributed to their affordable pricing and inherent safety features. The reversible capacity of AZIBs, which is crucial for their cycle performance, is significantly influenced by the choice of cathode material, with Na₃V₂(PO₄)₃ standing out as promising candidates for their large 3D transport channels and rapid kinetics. However, they suffer from rapid degradation caused by low structural stability during the charge-discharge process. In this work, we researched the electrochemical performance of cathode materials by employing a sol-gel preparation for Mn-doped Na_3-xV_2-xMn_x(PO₄)₃/rGO (x = 0, 0.05, 0.1), in which graphene oxides (rGO) were introduced as carbon sources. It is identified that the Mn doping exerts a beneficial influence to enhance stability of the structure. The Mn0.05-NVP/rGO material, optimized for performance, exhibits a specific capacity of 106.3 mAh·g⁻¹ with a discharge plateau at 1.3 V at a current density of 100 mA·g⁻¹, which corresponds to an energy density of 134.7 Wh·kg⁻¹. Particularly, the addition of Mn enhances cycling performance, leading to a remarkable capacity retention rate of 75.3 % even after 100 cycles. This work confirms the feasibility using NASICON-type cathodes and offers valuable perceptions into the advancement of cathode materials in AZIBs.