Synthesis and electrochemical performance of Li_(1+x)V _3O_8 as cathode material prepared by citric acid and tartaric acid assisted sol-gel processes

摘要

Lithium-ion battery cathode material Li_(1+x)V _3O_8 is synthesized by a citric acid/tartaric acid assisted sol-gel method and sintered at 350 °C, 450 °C and 550 °C for 3 h for the formation of Li_(1+x)V_3O_8 phase. The synthesized samples were fully characterized by FTIR, TG/DTA, XRD, SEM, EIS and charge-discharge tests. Li_(1+x)V _3O_8 material synthesized by tartaric acid assisted route and sintered at 450 °C for 3 h shows best electro-chemical performance. It shows a high initial capacity of 249 mAh g-1 and still reserves a discharge capacity of 260 mAh g-1 after 50 cycles. Moreover, in the case of tartaric assisted products, no capacity decadence is observed in 50 cycles. XRD together with TG/DTA measurements reveal that compared with citric acid assisted products, the adoption of tartaric acid as chelating agent effectively lowers the crystallization temperature of amorphous Li _(1+x)V_3O_8. Therefore, precursors obtained by tartaric acid route calcinated at 450 °C for 3 h exhibit lower crystallinity and smaller grain size, which contributes to the better electrochemical performance of the cathode electrodes. From EIS measurements, the bulk resistance is reduced, which favors the intercalation and de-intercalation of lithium ions while cycling.