Sodium Dual‐Ion Batteries with Concentrated Electrolytes

Abstract Na‐based dual‐ion batteries (DIBs) are a class of post‐lithium technology with advantages including extremely fast charging, cost‐effectiveness, and high natural abundance of raw materials. Operating up to high voltages (≈5.0 V), the decomposition of classic carbonate‐based electrolyte formulations and the subsequent fade of capacity continues to be a major drawback in the development of these systems. Here, the performance of a Na‐DIB was investigated in different commonly employed electrolyte system, and a highly concentrated (3 m NaPF 6 ) and fluorine‐rich carbonate‐based formulation was optimized to achieve a good performance when compared with literature (based on energy and power density, calculated at coin cell and only using the active mass of active materials).