锂盐对LAGP-PEO复合固体电解质及全固态LFP锂离子电池性能的影响

Effect of lithium salt on electrochemical properties of LAGP-PEO solid composite electrolyte and solid state LiFePO_4 lithium-ion battery

将Li_(1.5)Al_(0.5)Ge_(1.5)(PO_4)_3(LAGP)与少量PEO(LiX)复合,采用溶液浇注法制备了以LAGP为主相的固体复合电解质,研究了LiClO_4、LiTFSI、LiBOB 3种锂盐对固体复合电解质离子电导率、电化学稳定窗口、与锂负极界面的化学稳定性和电化学稳定性的影响以及锂盐种类对LFP固态电池循环及倍率性能的影响。研究结果表明,采用LiClO_4、LiTFSI、LiBOB_3种锂盐制备的固体复合电解质分解电压均超过5 V,具有较好的电化学稳定性。LAGP-PEO(LiTSFI)固体复合电解质的离子电导率以及室温对锂界面的稳定性相对更高。LAGP-PEO(LiBOB)与锂的界面在60℃时相对更稳定。与之对应,采用LAGP-PEO(LiTSFI)和LAGP-PEO(LiBOB)固体复合电解质的LFP全固态电池,分别在25℃和60℃具有最高的比容量和最好的循环稳定性。

LAGP-PEO（LiX） solid composite electrolyte were prepared with Li（1.5）Al（0.5）Ge（1.5）（PO4）3, LiX as conductive components and poly（ethylene oxide） as the binder using solution casting method. Effect of lithum salt, such as LiClO4, LiTFSI and LiBOB, on the ionic conductivity and electrochemical window of solid composite electrolyte were studied. At the same time, chemical and electrochemical cycling stability of interface between solid composite electrolyte and lithium were also studied. The results show that the decomposition voltage of LAGP-PEO（LiX） was higher than 5 V, the ionic conductivity of LAGP-PEO（LiTSFI） is the highest and it is stable at room temperature, but LAGP-PEO（LiBOB） is more stable at 60 ℃. In addition, the rate capability and the cycling performance of solid state LFP lithium ion battery with LAGP-PEO（LiX） were studied. The best properties was present at room temperature when LAGP-PEO（LiTSFI） composite electrolyte was used in battery, while LAGP-PEO（LiBOB） shows its best performances at 60 ℃.