锂源对双草酸硼酸锂合成的影响

Influence of lithium source on synthesis of LiBOB

用改进的固相合成方法及精馏提纯方法,获得一种含有螯合硼酸根离子的电解质锂盐—双草酸硼酸锂(LiBOB)。分别选取4种含锂化合物作为锂源,采用红外光谱、X线衍射方法和化学定量分析方法,比较不同锂源对合成LiBOB的产物纯度、电化学性能的影响。研究结果表明:由LiOH.H2O合成的粗产品1次纯化纯度为99.4%,2次纯化纯度为99.8%;由Li2C2O4合成的LiBOB杂相较多;由CH3COOLi.2H2O合成的LiBOB含水分较多。用不同锂源合成的LiBOB配制成0.7 mol/L LiBOB/(EC/PC/DMC=1:1:3,质量比)电解液,组装成LiM2O4/Li电池进行电池循环性能的测试。LiOH.H2O和Li2CO3作为锂源合成的LiBOB具有良好的电化学性能,Li2C2O4和CH3COOLi.2H2O作为锂源合成的LiBOB电化学性能较差。

A new lithium salt（LiBOB） based on a chelated borate anion, BOB [Bis （oxalate） borate] was synthesized by an improved solid-state method and purified by rectification. Four different lithium-containing compounds were selected as lithium sources. The synthesized LiBOB was identified by infrared spectrum, X-ray diffraction（XRD） and quantitative chemical analysis. The effects of lithium sources on the purity and electrochemical performance of LiBOB products were investigated. The results show that the purity of LiBOB synthesized from LiOH.H20 is larger than 99.4% after one time of purification and larger than 99.8% after two times of purification. The LiBOB synthesized from Li2C204 has impurity phases and that from CHaCOOLi＇2H20 has high water content. The lithium manganese dioxide button cell was assembled with 0.7 mol/L LiBOB/（EC：PC：DMC =1：1＂3, mass ratio） as electrolyte and the cycle performance of the cell was tested. LiBOB with LiOH＇H20 or Li2CO3 as lithium sources shows better electrochemical performance while that with LiEC204 or CH3COOLi＇2H20 as lithium sources shows poor electrochemical performance.