Research Projects

The development of high-voltage cathode materials is necessary to enhance the energy density in sodium-ion battery cells. The proposed works aim to substitute Fe for V in NASICON-type Na3+xV2-xFex(PO4)3 and activate the V4+/V5+ redox reaction at high potential (~ 4 V vs. Na+/Na). The extra sodium (x) in the formula unit will be extracted because of this reaction during the charging process, which will result in a capacity enhancement in NVP. Besides, replacing V with earth-abundant Fe will make the NVP cathode cheaper and less toxic. The work will also involve constructing a porous electrode architecture through ex-situ carbon modification using various carbonaceous materials. Nano-sized particles synthesized using the hydrothermal method will be embedded in these structures, having a fast electron-conducting network. This will be beneficial in achieving ultra-high rate performance as NASICON-type materials exhibit inherently poor electronic conductivity (~ 10-6 S.cm-1). Nevertheless, using such high-potential cathodes requires battery cells to be in solid-state cell configuration using solid electrolytes for safe operation. This proposed study will look into the fabrication and electrochemical testing of solid-state cells using the developed Fe-doped NVP cathode and Mg-doped NZSP electrolyte. The full solid-state cells will be assembled and tested using Na-metal and hard carbon as an anode. This work aims to achieve at least 300 Wh/Kg energy density at a C/10 discharge rate.