An Aqueous Manganese‐Ion Battery with NaV₆O₁₅/C Microrods as a Stable Mn²⁺ Storage Host

Abstract Manganese‐ion batteries (MIBs) involving aqueous electrolytes are regarded as next‐generation energy‐storage systems for utilization in safe and non‐flammable, grid‐scale energy‐storing appliances. For practical application, it is very important to establish a stable cathode with a high capacity and stable cycle life. In this respect, vanadium‐based layered oxides have been well demonstrated as suitable cathodes for aqueous‐electrolyte‐based batteries due to their high theoretical capacity and adequate working voltage. However, the dissolution of vanadium in the aqueous electrolyte directly affects the cycle life of the vanadium‐based layered oxides. In the present study, a carbon‐coating approach is established to boost the rate capability and cycling stability of the NaV 6 O 15 (NVO) cathode. When employed as a cathode for MIBs, the carbon‐coated NaV 6 O 15 (NVO/C) supplies a stable recoverable capacity of 149 mAh g −1 at 0.4 A g −1 after the 1600 consecutive cycles with 88 % capacity retention, along with a rapid Mn 2+ storage ability of 6000 cycles at 3.0 A g −1 with 74 % capacity retention.