A novel aqueous sodium–manganese battery system for energy storage

Abstract

Rechargeable aqueous sodium-ion batteries have become promising candidates for electrochemical grid-scale energy storage systems because of the rich natural abundance of sodium and the favourable safety of aqueous electrolytes. However, the electrochemical stability window of water limits the selection of electrode materials, and the poor performance of electrode materials hinders the comprehensive performance of the full batteries. In this work, a novel cost-effective and eco-friendly aqueous sodium–manganese hybrid battery system using a graphite felt cathode, activated carbon anode, and hybrid electrolyte (1 M Na₂SO₄ + 1 M MnSO₄ + 0.1 M H₂SO₄) is proposed. The battery exhibits a discharge voltage of 1.2 V, a high coulombic efficiency (∼99.2%) and a lifetime of more than 7000 cycles. The hybrid system displays long cycling stability and high rate capability, demonstrating its feasibility for energy storage. It also provides a reference for the design of a new battery system that can be applied to develop high-performance aqueous sodium ion batteries for large-scale energy storage.