NASICON-Type NaV2(PO4)3 as High-Voltage and Stable Cathode Materials for Manganese Metal Batteries

Manganese-based batteries (MBs) have emerged as a compelling class of aqueous energy storage systems, owing to their intrinsic safety, low cost, and high energy density. In this study, we report a high-voltage aqueous MB employing NASICON-type NaV₂(PO₄)₃ (NVP) as a structurally robust cathode and metallic manganese as the anode. The cell delivers a discharge capacity of 41.1 mAh g⁻¹ at 0.4 A g⁻¹ and retains 79.4% of its initial capacity after 1000 cycles, underscoring excellent long-term cycling stability. Combined spectroscopic and structural characterizations reveal that Na⁺ ions are extracted from the NVP framework during charging, while Mn²⁺ ions from the electrolyte are reversibly inserted into the vacant interstitial sites upon discharge. The cation diffusion analyses further confirm the viability of Mn²⁺ transport within the NASICON lattice. Compared to conventional Zn-based aqueous batteries, the Mn-based system achieves a higher operating voltage (∼0.34 V), attributed to the lower redox potential of Mn. Although challenges such as Mn dissolution and interfacial resistance remain, this work establishes NVP-based MBs as a promising platform for next-generation aqueous rechargeable batteries with improved voltage output and cycling stability.