Electrical Properties Of LLTO Nanofiber Array And All-solid-state Li-ion Batteries Based On LLZO

Though lithium-ion battery is one of the most widely used chemical energy storage technologies,it still possesses many shortcomings to be improved.All-solid-state lithium-ion battery is the ultimate solution to the safety issue of current lithium-ion battery technology.However,a lower ionic conductivity than that of liquid electrolytes,and the huge resistance of the interface between electrolyte and electrode have to be solved for all-solid-state lithium-ion battery.In this work,oriented Li_3xLa_2/3-x?_1/3-2xTiO₃?LLTO?nanofiber arrays were assembled by means of electrostatic spinning.The nanometer scale effects on lithium-ion conductivity was investigated.In addition,the doping influence of Al and Ga on Li_7-xLa₃Zr_2-xTa_xO₁₂?LLZTO?were inverstigated.Li_6.25Ga_0.25La₃Zr₂O₁₂2 solid electrolytes with cubic garnet structure were fabricated by hot pressing sintering,and the all-solid-state lithium-ion batteries based on LLZO were fabricated.By electric properties examination,it is found that there is no half arc in the impedance spectrum of the LLTO nanofibers,which represents the resistance of the grain boundary.The electronic conductivity of the nanofibers is only 1%of the total conductivity.The ionic conductivity of the LLTO nanofibers at 20?is 0.743 mS/cm and the activation energy is 0.37 eV.The Al and Ga have been domenstrated to be supervalent dopants stabilizing cubic garnet and sintering aid compositions increasing the overall conductivity of LLZTO electrolytes.The overall conductivities of Ga-LLZTO electrolytes were higher than that of the Al-LLZTO electrolytes with almost the same nominal Li-content.Finally,the highest overall conductivity of 0.87 mS/cm with a low activation energy of 0.33 eV was achieved for the Li_6.4Ga_0.1La₃Zr_1.7Ta_0.3O₁₂2 sample.Li_6.25Ga_0.25La₃Zr₂O₁₂2 solid electrolyte fabricated by hot pressing has a garnet structure and its conductivity at 25?is 1.31 mS/cm.Adding Li₃BO₃ into anode material as fluxing and binding agent and ITO as electrically conductive material,all-solid-state lithium-ion batteries were assembled after a high temperature calcining.EIS was adopted to make an electric property test.A charge-discharge test was made of the battery testing system.When the LiCoO₂-LBO-ITO/LLZO-Ga/Li all-solid-state lithium-ion battery was charged and discharged at 50?A·cm^-22 at 100?,its first charging capacity reached 83.3 mAh/g and 293.5?Ah/cm²,and a good cycling performance was kept.