| Abstract: | All-solid-state lithium batteries (ASSLB) are promising candidates for next-generation energy storage devices.Nevertheless,the large-scale commercial application of high energy density ASSLB with the polymer electrolyte still faces challenges.In this study,a thin solid polymer composite electrolyte (SPCE) is prepared through a facile and cost-effective strategy with an infiltration of thermoplastic polyurethane (TPU),lithium salt (LiTFSI or LiFSI),and halloysite nanotubes (HNTs) in a porous framework of polyethylene separator (PE) (TPU-HNTs-LiTFSI-PE or TPU-HNTs-LiFSI-PE).The composition,electrochemical performance,and especially the effect of anions (TFSI-and FSI-) on cycling performance are investigated.The results reveal that the flexible TPU-HNTs-LiTFSI-PE and TPU-HNTs-LiFSI-PE with a thickness of 34 μm exhibit wide electrochemical windows of 4.9 and 5.1 V (vs.Li+/Li) at 60 ℃,respectively.Reduction in FSI-tends to form more LiF and sulfur compounds at the interface between TPU-HNTs-LiFSI-PE and Li metal anode,thus enhancing the interfacial stability.As a result,cell composed of TPU-HNTs-LiFSI-PE exhibits a smaller increase in interfacial resistance of solid electrolyte interphase (SEI) with a distinct decrease in charge-transfer resistance during cycling.Li|Li symmetric cell with TPU-HNTs-LiFSI-PE could keep its stable overpotential profile for nearly 1300 h with a low hysteresis of approximately 39 mV at a current density of 0.1 mA cm-2,while a sudden voltage rise with internal cell impedance-surge signals was observed within 600 h for cell composed of TPU-HNTs-LiTFSI-PE.The initial capacities of NCM|TPU-HNTs-LiTFSI-PE|Li and NCM|TPU-HNTs-LiFSI-PE|Li cells were 149 and 114 mAh g-1,with capacity retention rates of 83.52％ and 89.99％ after 300 cycles at 0.5 C,respectively.This study provides a valuable guideline for designing flexible SPCE,which shows great application prospect in the practice of ASSLB. |
