Li_(7)La_(3)Zr_(2)O_(12)-聚氧化乙烯/聚偏氟乙烯固态复合电解质的制备及全固态电池性能

Preparation of Li_(7)La_(3)Zr_(2)O_(12)-Polyethylene Oxide/Polyethylene Partial Fluoride Solid Composite Polymer Electrolyte and Performance of All Solid State Batteries

以固态电解质构建的全固态锂离子电池具有极高的安全性及可靠性,是目前锂离子电池领域的研究热点,其中研发无机物-高分子复合固体电解质用于全固态锂离子电池具有重要意义。通过溶胶-凝胶法及球磨细化制备了纳米级Li_(7)La_(3)Zr_(2)O_(12)(LLZO)粉末,进而采用溶液浇注法制备出以LLZO为活性填料,聚氧化乙烯(PEO)和聚偏氟乙烯(PVDF)共混的固态复合聚合物电解质。通过场发射扫描电子显微镜以及X射线衍射仪对材料的形貌、物相及电化学性能表征表明:添加质量分数为10%LLZO的LLZO/PEO/PVDF固态复合聚合物电解质具有高离子电导率(8.93×10^(-5)S/cm)以及稳定的电化学窗口(4.9 V)。添加LLZO之后的LiFePO_(4)/Li全固态电池的倍率性能以及循环性能均得到提高,在60℃高温下,容量恢复率为99.4%,0.2 C循环100圈后容量保持率为84.1%。

All-solid-state lithium-ion batteries constructed with solid-state electrolytes have extremely high safety and reliability,which are an existing research hotspot in lithium-ion batteries.It is thus a great significance to develop inorganic-polymer composite solid electrolytes.In this paper,Li_(7)La_(3)Zr_(2)O_(12)(LLZO)nano-powders were prepared by a sol-gel and ball milling method.Also,a solid-state composite polymer electrolyte with LLZO as an active filling material and polyethylene oxide(PEO)blended with polyethylene partial fluoride(PVDF)was prepared by a solution pouring method.The samples were characterized by field emission scanning electron microscopy and X-ray diffraction.The results show that LLZO/PEO/PVDF solid-state composite polymer electrolyte(SCE)membrane with 10%(in mass fraction)LLZO has a high ionic conductivity(8.93×10^(-5) S/cm)and a stable electrochemical window(4.9 V).The rate capabilities and cycle performance of LiFePO_(4)/Li all-solid-state lithium battery with 10%LLZO both are improved.At 60 C,the capacity recovery rate is 99.4%,and the capacity retention rate after 100 cycles is 84.1%at 0.2C.