(1. 中南大學(xué) 冶金與環(huán)境學(xué)院，長(zhǎng)沙 410083；
2. 中南大學(xué) 先進(jìn)電池材料教育部工程研究中心，長(zhǎng)沙 410083)
摘 要: 研究了低溫(-20 ℃)下磷酸鐵鋰正極材料與電解液的相容性。采用不同溶劑組成的電解液與磷酸鐵鋰正極組裝成LiFePO4/Li半電池，進(jìn)行電化學(xué)測(cè)試。結(jié)果表明：低溫下電池界面阻抗是影響磷酸鐵鋰電池性能的關(guān)鍵因素；隨著界面阻抗的增大，LiFePO4/Li半電池的放電容量顯著下降，同時(shí)極化加重，放電平臺(tái)降低，并且其界面阻抗的變化直接與電解液中線性酯和環(huán)狀酯溶劑的比例相關(guān)。在-20 ℃下，環(huán)狀酯類溶劑含量(體積分?jǐn)?shù))為33%的電解液界面阻抗最小，其組裝的LiFePO4/Li半電池0.1C倍率下放電容量為113.9 mA·h/g，是常溫放電容量的75%。
關(guān)鍵字: 低溫電解液；磷酸鐵鋰；相容性；電化學(xué)性能
（1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Research Center of Advanced Battery Materials Engineering, Ministry of Education,
Central South University, Changsha 410083, China）
Abstract:The compatibility of LiFePO4 cathode with electrolyte at low temperature (-20 ℃) was studied. Electrochemical analysis was employed to investigate a series of electrolytes with different compositions for the LiFePO4/Li half cells. The results show that the interface impendence at low temperature is the key factor affecting the performance of LiFePO4 batteries. The discharging capacity of the LiFePO4/Li cells significantly decreases, and the polarization and resistance increase due to an increase in the interface impedance between the electrode and electrolyte. In addition, the interface impedance change is directly related to the ratio of the linear and cyclic carbonate solvents. At -20 ℃, the electrolyte with 33% (volume fraction) cyclic carbonate has the lowest interface impedance. The discharging capacity of the corresponding LiFePO4/Li half cells is 113.9 mA·h/g and about 75% as that of the room temperature one.
Key words: low temperature electrolyte; LiFePO4 cathode; compatibility; electrochemical performance
