Stabilization of P2 layered oxide electrodes in sodium-ion batteries through sodium evaporation

Sodium-ion batteries are well positioned to become, in the near future, the energy storage system for stationary applications and light electromobility. However, two main drawbacks feed their underperformance, namely the irreversible sodium consumption during solid electrolyte interphase formation and the low sodiation degree of one of the most promising cathode materials: the P2-type layered oxides. Here, we show a scalable and low-cost sodiation process based on sodium thermal evaporation. This method tackles the poor sodiation degree of P2-type sodium layered oxides, thus overcoming the first irreversible capacity as demonstrated by manufacturing and testing all solid-state Na doped-Na~$_1$Mn$_{0.8}$Fe$_{0.1}$Ti$_{0.1}$O$_2$ ǀǀ PEO-based polymer electrolyte ǀǀ Na full cells. The proposed sodium physical vapor deposition method opens the door for an easily scalable and low-cost strategy to incorporate any metal deficiency in the battery materials, further pushing the battery development.