Bi-Doped Low-Cost P2 Layered Sodium Ion Battery Cathode with Improved Cycling Stability

Sodium-ion batteries, free from material scarcity concerns, offer potential for versatile applications across various industries. However, the development of an optimal cathode material for sodium ion batteries remains a challenge in part due to long term stability issues. Among the various cathode chemistries explored for sodium-ion battery applications, those based on layered transition metal oxides have displayed promise, primarily due to their high energy density and scalability. Our work demonstrated a novel modified P2 layered sodium ion cathode material created via the introduction of bismuth into a manganese and iron-based layered transition metal oxide material, specifically Na_0.8Mn_0.75Fe_0.2Al_0.05. Our research has demonstrated that even a small amount of bismuth doping can have a profound impact on the cycling stability of this cathode material, both in half cells and also in hard carbon anode full cells. Furthermore, ambient environment storage of the Bi-doped materials (even in humid environments) does not reduce performance and in some cases seems to improve it. This finding holds promise for enhanced feasibility and reliability in sodium-ion batteries and could be beneficial for advancing the application of sodium-ion batteries in large-scale applications.