锂镧锆钽氧改性对固态锂离子电池的性能影响

Modification of Li6.75La3Zr1.75Ta0.25O12 and its effect on performance of solid state lithium ion

利用无水乙醇离心洗涤法对LLZTO进行预处理,对LLZTO与PVDF溶液凝胶变色的原因进行了研究,通过XRD,FTIR,ICP测试手段对LLZTO中碱性杂质的成分进行了研究,对洗涤前后的LLZTO的离子电导率、固态电解质膜的离子电导率和SEM照片进行了对比,并对分别使用洗涤前后的LLZTO的固态锂离子电池的电化学性能进行了对比测试。结果表明,使得LLZTO与PVDF溶液凝胶变色的原因为LLZTO中的碱性杂质,其主要成分为LiOH。通过无水乙醇离心洗涤能对碱性杂质做到良好的去除,可以将LLZTO的离子电导率提高约1.668×10-4S·cm-1,固态电解质膜的离子电导率提高约1×10^-4S·cm^-1。去除碱性杂质的固态电解质膜成膜性更好,并且其电池的循环稳定性更好,循环200圈过后比使用未洗涤的LLZTO的电池容量高约50mAh·g^-1。

The LLZTO was pretreated by anhydrous ethanol centrifugal washing method. The causes of gel discoloration in LLZTO and PVDF solutions were studied. The alkaline impurities in LLZTO were analyzed by XRD, FTIR and ICP. After washing, the ionic conductivity of LLZTO and solid electrolyte membranes was compared with the original sample. The film formation of LLZTO solid electrolyte membranes were studied by SEM, and the electrochemical performances of solid-state lithium ion batteries were also compared. The results show that the cause of gel discoloration is the alkaline impurities in LLZTO, of which the main componentisLiOH. The ionic conductivity of LLZTO is improved by about 1.668×10^-4S·cm^-1,the ionic conductivity of the solid electrolyte membrane is improved by about 1×10^-4 S cm^-1. Meanwhile, the solid electrolyte membrane has better film formation. The cycle stability of the battery is better, and the capacity of the battery after 200 cycles is higher than that of the unwashed LLZTO by about 50 mAh g^-1.