(中南大學 材料科學與工程學院，長沙 410083)
摘 要: 用乙炔碳作為碳源，采用機械活化輔助碳熱還原兩步法合成xLi3V2(PO4)3·LiVPO4F/C復合正極材料。采用XRD、SEM、TEM等技術(shù)對樣品的晶體結(jié)構(gòu)和微觀形貌進行了表征，采用循環(huán)伏安法和恒流充放電等測試方法對合成樣品的電化學性能進行分析研究。結(jié)果表明：xLi3V2(PO4)3·LiVPO4F/C復合正極材料兼?zhèn)淞薒i3V2(PO4)3的循環(huán)穩(wěn)定性好、倍率性能佳的優(yōu)點和LiVPO4F能量密度高的優(yōu)勢，此外還彌補了Li3V2(PO4)3在3~4.7 V電壓范圍充放電時放電電壓平臺缺失的缺陷。該材料在3~4.7 V之間的循環(huán)穩(wěn)定性較好，在1C倍率下最高放電比容量為119.7 mA？h/g，循環(huán)300圈后為97.5 mA？h/g。其倍率性能較好，在0.1C倍率下充放電可獲得高達152 mA？h/g的放電比容量，倍率升高到8C時仍能保持100 mA？h/g的放電比容量。
關(guān)鍵字: 鋰離子電池；正極材料；碳熱還原法；xLi3V2(PO4)3·LiVPO4F/C
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:A two-step mechanical activation and carbon thermal reduction method was used to synthesize xLi3V2(PO4)3·LiVPO4F/C composite cathode material, using actylene black as carbon source. The crystal structure and morphology were characterized by using XRD, SEM, and TEM techniques. In addition, the electrochemical performances of the prepared materials were characterized by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. The results show that xLi3V2(PO4)3LiVPO4F/C composite cathode material has the advantages of good cyclic stability of Li3V2(PO4)3 and the high energy density of LiVPO4F. Meanwhile, it makes up for the shortcoming of the disappeared voltage platform of Li3V2(PO4)3 cathode within 3-4.7 V. The cyclic stability of the composite is good. The maximum value of discharge specific capacity is 119.7 mA？h/g under the rate of 1C which can retain 97.5 mA？h/g after 300 cycles. The rate performance is excellent. The composite electrode delivers a high capacity of 152 mA？h/g at 0.1C. When the current density increases to 8C, the electrode can still deliver a specific discharge capacity of 100 mA？h/g.
Key words: lithium-ion battery; cathode material; carbothermal reduction method; xLi3V2(PO4)3·LiVPO4F/C
