Preparation Of Garnet-type Solid Electrolyte And Modification Of Electrolyte Interface

Solid-state electrolytes are the focus of solid-state lithium expected batteries research.With high lithium ion conductivity(¹0^-3 S/cm)and its icoexistence with lithium metal,garnet-type solid electrolytes are expected to become a substitute of organic electrolyte.However,its high production difficulty and interfacial resistance which limit its development.Considering the afore-mentioned defects of LLZO solid-state batteries,this paper has accomplished the following research:?1?The LLZO electrolytes Li_6.4La₃Zr_1.4Ta_0.6O₁₂ and Li_6.4La₃Zr_1.4Nb_0.6O₁₂?LLZTO,LLZNO?,which were replaced by Ta and Nb,were prepared by high-temperature solid-phase method,The results showed that the best sintering temperature of LLZTO was about 900?.The use of MgO crucible instead of Al₂O₃ crucible prepared high sintering density,less porosity,low particle rate,crystal The dense LLZTO and LLZNO electrolyte sheets,the prepared LLZTO and LLZNO electrolyte ion conductivity probes are 5.58×10^-4 S/cm,1.97×10^-4 S/cm,and the highest density is94%.?2?In the composite cathode with LLZNO powder added to LiNi_0.5Co_0.2Mn_0.3O₂?NCM523?cathode material,adding 5wt%LLZNO electrolyte powder can significantly improve the specific capacity,cycle and rate performance of NCM523 cathode material.The impedance of the battery is 54%lower than that of the non-added battery,and it shows a high discharge specific capacity?183.3 mAh/g?and the best rate performance.The capacity is still 100 cycles after 1 C at room temperature.Maintained around 162.3 mAh/g,the retention rate was 94.4%.The addition of ion conductive material not only enhances the diffusion rate of Li⁺in the cathode material,but also can be combined with an electronic conductive agent to form an excellent electron-ion transmission channel,so that the irreversible loss of battery cycle is reduced,thereby reducing the electrode impedance and Improve the overall performance of the battery.?3?On the basis of adding LLZNO powder to LiNi_0.8Co_0.1Mn_0.1O₂?NCM811?,further adding flexible carbon nanotubes?CNT?to form a composite cathode,using LLZNO as an electrolyte sheet,the assembled solid-state battery explored its performance.In order to reduce the interface impedance,a carbon interface buffer layer and flexible carbon nanotube films?CNMs?were introduced as a current collector modification through the interface.The first discharge specific capacity of the assembled solid-state battery was increased from 71.8 mAh/g to 158.5 mAh/g from unmodified,and the efficiency was increased from 54%to 93%,indicating that the contact performance between the modified cathode and the electrolyte was well improved.and the stability of the interface between the composite cathode and the LLZNO solid electrolyte has also been significantly enhanced.