双丙二酸硼酸锂及其衍生物的合成与电解质性能

Synthesis and properties of the Lithium salts bis(malonato) borate(LiBMB)and its derivatives

合成电解质锂盐双丙二酸硼酸锂(LiBMB)及3种基于LiBMB的有机阴离子锂盐:双-2-乙基丙二酸硼酸锂(LiBMB-A)、双-2-丁基丙二酸硼酸锂(LiBMB-B)、双-2-辛基丙二酸硼酸锂(LiBMB-C),并与电解质锂盐双草酸硼酸锂(LiBOB)进行对比,用核磁共振(NMR)以及红外光谱(IR)对其进行结构表征.考察不同长度的烷基链(乙基,正丁基,正辛基)对电解质理化性质的影响,研究不同的锂盐阴离子结构以及溶剂组成对电解液性能的影响.结果表明:当采用碳酸乙烯酯(EC)+碳酸丙烯酯(PC)+碳酸二甲酯(DMC)(vol.3∶3∶4)三元混合溶剂体系时电解液综合性质最好.锂盐LiBMB-A配制的电解液常温下电导率可达4×10-3 S/cm以上,电化学稳定窗口也在4.4V以上,并且3种新型电解质锂盐的分解温度均在180℃以上,疏水性能良好.

The lithium salts lithium bis （malonato） borate （LiBMB） and its three derivatives bis （2-alkyl-malonato） borate （LiBMB-A）,bis（2-butyl-malonato） borate （LiBMB-B）,and bis（2-octyl-malonato） borate （LiBMB-C） were prepared and characterized by IR and NMR spectroscopies.As a comparison,the lithium salts bis（oxalate）borate （LiBOB） was prepared as well.The effect of different alkyl chain （n-ethyl,n-butyl,n-octyl） on the physical and chemical properties of electrolyte were investigated.The effect of different lithium ion structure and solvent composition on electrolyte performance were studied.The results showed that the comprehensive properties of electrolyte were the best when the ethlene carbonate （EC） ＋ propylene carbonate （PC）＋dimethyl carbonate （DMC） （vol.3 ∶ 3 ∶ 4） ternary mixture were used.The conductivity and electrochemical stability window of electrolyte of LiBMB-A were more than 4 × 10-3 S/cm and 4.4 V at room temperature respectively and the decomposition temperature was more than 180 ℃ for the three new lithium salts.