Doping Effects on Na3V2(PO4)2F3 Cathode Materials for Sodium-Ion Batteries

• Main Authors: Shu-Han Zhuang, 莊舒涵
• Other Authors: Wei-Ren Liu
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/564zsz

碩士 === 中原大學 === 化學工程研究所 === 107 === The demand of green energy has rapidly increased in these years, particularly for the on-going massive demand for electric and plug-in hybrid vehicles. The main limiting factor of lithium-ion battery arises from the limited resource of lithium metal availability in the world. During recent decades, sodium-ion batteries (SIBs) have been regarded as a promising alternative to lithium-ion batteries as a result of their advantages, such as abundancy, low cost, safety and high-power energy storage. In this regard, present investigation focused on the synthesis and development of Na3V2(PO4)2F3 as a cathode material for sodium-ion battery application. Na3V2(PO4)3 (NVP) and Na3V2(PO4)2F3 (NVPF) are known as two appealing NASICON-type materials capable of motivating intercalation chemistry for sodium ions. This research provides a step-by-step improvement for NASICON-type Na3V2(PO4)2F3 sodium-ion battery cathode materials. It involves finding the optimal concentration suitable for the sol-gel method and evaluating the best dopant for NVPF. The electrochemical tests revealed that C-rate performance was enhanced when an excess of sodium fluoride (NaF) was used. The batteries obtained capacities of 72.8 and 98.7 mAh/g for standard and excess NaF content, respectively when cycled back to 0.1C. In addition, ionic conductivity and diffusion of NVPF was improved by doing it with chromium and aluminum. X-ray diffraction and transmission electron microscopy confirm that high purity doped NVPF samples were obtained. Furthermore, electronic conductivity was augmented through amorphous carbon coating. The results indicate that NVCrPF-0.03 and NVAlPF-0.07 provided.