固态电解质Li_(10)Ge_(0.75)Si_(0.25)P_2S_(12)的制备与电化学性能研究

Preparation and electrochemical performance of solid electrolyte Li_(10)Ge_(0.75)Si_(0.25)P_2S_(12) for lithium-ion batteries

采用固相反应法制备了固体电解质Li_(10)Ge_(0.75)Si_(0.25)P_2S_(12)(LSiGPS),用X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)、交流阻抗技术(EIS)、用恒电流间歇滴定技术(GITT)和恒电流恒电压测试分析了LSiGPS的物相、形貌、离子导电性和锂离子的扩散系数及相对应电池的充放电特性等进行了表征,结果表明,LSiGPS具有四方结构;在-40、25、50℃等较宽广的温度范围内,固态电解质的离子导电性(7.13×10^(-4)、6.57×10-3、2.21×10^(-2) S·cm^(-1))和液态电解液的离子导电性(8.03×10^(-4)、6.72×10-3、2.55×10-2S·cm^(-1))很接近;在3.60、3.95、4.18 V时,固态电解质锂离子扩散系数(4.65×10^(-10)、0.38×10^(-10)、0.53×10^(-10) cm^2·s^(-1))和液态电解液组成的锂离子电池的离子扩散系数(5.80×10^(-10)、0.57×10^(-10)、0.70×10^(-10)cm^2·s^(-1))基本处于一个数量级;LSiGPS固态电解质有很优异的耐高温安全性,在150℃收缩率接近于零。

Li10Ge0.75Si0.25P2S12 （LSiGPS）as the electrolyte for Li-ion batteries was prepared by means of solid reaction method. The samples were characterized by X-ray cliff raction （XRD） and scanning electron microscopy （SEM）. The electrochemical properties of the LSiGPS were studied by charge-discharge testing, EIS and Gll-r. The results show that the LSiGPS solid electrolyte has an ion conductivity Of 7.13× 104, 6.57 × 10-3, 2.21 ×10-2 S-cm-1 at -40, 25, 50 ℃ respectively and the Li ion diffusion coefficient 4.65 ×10-10, 0.38×10-10, 0.53×10-10at 3.60, 3.95, 4.18 V respectively, good high temperature stability and safety. Key words： solid electrolyte; diffusion coefficient; ion conductivity; electrochemical performance