RSE’s research on sodium-ion batteries (NIB) focuses on studying the active materials of the electrodes, both cathode and anode, to develop a complete battery.

This work specifically describes the optimization of the synthesis process for the cathode material Na0.44MnO2 (NMO).

Previous studies focused on the synthesis methods to obtain a pure phase of the active material. However, initial electrochemical characterizations, especially when scaling up the quantity of synthesized material, revealed that the morphology of the final product significantly impacted electrochemical performance.

This report outlines the analysis of various synthesis steps to achieve the correct morphology. A morphology composed of prismatic, bar-like structures limited to a few microns in length was identified. Various synthesis parameters were then optimized, particularly during the high-temperature treatment phase, including heating rate, isothermal conditions, and cooling speed. Process reproducibility tests showed that manual grinding between calcination and thermal treatment affected the final morphology. As a result, this step was automated using a mill, and grinding parameters such as material-to-ball ratio, speed, and rotation times were optimized.

Lastly, long-term cycling tests on a sample with the correct morphology confirmed that this material is not stable over extended periods. Future efforts will focus on synthesizing second-generation materials by doping NMO with other elements to stabilize its structure and potentially increase its working potential.