Improving electrochemical performance through particle size engineering in NaCu0.2Fe0.8-xMnxO2 cathodes for sodium-ion battery

For sodium-ion batteries, layered sodium transition metal oxides NaxMO2, where M is a combination of copper (Cu), iron (Fe), and manganese (Mn), show promise as cathode materials. Furthermore, a number of studies demonstrate that particle size has an impact on battery performance.
From this perspective, this study focuses on the investigation of the effect of the particle size on the electrochemical properties of NaCu0.2Fe0.8-xMnxO2 (x= 0.4; 0.5; 0.6; 0.7) materials. These samples were synthesized by conventional solid state method. Then, the ball milling
process was used to reduce the particle sizes. Through the structural characterization, it was proved that these samples crystallize in hexagonal system (R-3m space group). The crystalline structures O3 and P3 types were founded for x= 0.4; 0.5 and x=0.6; 0.7 respectively. However, after ball milling process x= 0.4; 0.5 kept their O3 type crystalline structures, whereas, x= 0.6 and 0.7 change their structure to O3 and P2 structures types respectively. Furthermore, the particles size evolution was measured using laser granulometry during the ball milling and the morphological study reveal the effectiveness of the ball milling process in destroying the particles agglomerations. Electrochemical analyses proved the enhancement of the specific capacity of NaCu0.2Fe0.8-xMnxO2 (x= 0.4; 0.5; 0.6; 0.7) materials after the ball milling process, essentially at fast C-rates.