Preparation Of LiCoO₂ Cathode Thin Film For LATP Electrolyte By Magnetron Sputtering And Study Of All-Solid-State Battery

With the increasing demand for new energy sources,large capacity,high security,miniaturization,flexibility has become the new development goals for lithium-ion battery.Large capacity,high security,miniaturization,flexibility has become the new development goals for lithium-ion battery.All-so lid-state thin-film batteries has the characteristics of small size,high safety performance,capacity density,size can be controlled.By controlling the orientation of the growth of lithium cobalt oxide film can reduce the impedance between the electrode and electrolyte to improve lithium-ion transport efficiency.The research of depositing LCO film directly on the solid electrolyte by magnetron sputtering is relatively less.In this study,the LCO thin film was deposited directly on the substrate LATP electrolyte.The optimum orientation and surface morphology of LiCoO2 thin Films was obtained by ameliorate the power,substrate temperature,Ar/O ratio,and annealing temperature during the sputtering process.Construct the LCO/LATP/Li all-solid-state battery.The main results are as follows:(1)The preferred orientations of LiCoO2 thin films prepared by magnetron sputtering deposition on the surface of the LATP electrolyte is(1 01),(104)and(11 0).Improving the RF power can improve the crystallinity of the deposited LiCoO2 thin films and enhance the diffraction peak intensity.Substrate temperature mainly affects the migration speed of atoms on the film surface,and the thermal stress between the substrate and film.The higher Ar/O ratio leads to the larger lithium cobalt oxide particles deposited,the roughness of the film increases,the main diffractive diffraction peak of LiCoO2 decreases,and the crystallinity decreases.The post-annealing obviously improved the crystallinity of the films,which is favorable for the uniform deposition of thin films and the enhancement of the optimal orientation.(2)The optimal preparation conditions of LiCoO2 thin film deposited on LATP substrate were as follows:sputtering power 180W,substrate temperature 90℃,argon/oxygen ratio 3:1 and subsequent annealing temperature 500℃.The film prepared by magnetron sputtering has good adhesion to the substrate and high surface smoothness,and it can reach 0.8μm in 70 min.(3)The first discharge capacity of the LCO/LATP/Li all-solid-state cell is 66mAh·g-1,the coulomb efficiency is 21.4%,the maximum discharge capacity is 80mAh·g-1 and the coulomb efficiency is 39.1%.The reversibility of the all-solid-state battery is poor.The impedance after the electrochemical cycle increases 4000Ω.(4)The interfacial diffusion of P.Ti and Al occurs at the interface between the LATP electrolyte and LiCoO2,and the interfacial impedance is increased.After the cycle,the structure of the L ATP electrolyte was loose and the surface of the cathode film was voided.The(104)orientation of the lithium cobalt oxide which is favored the lithium ion migration disappeared,and the diffraction peak intensities of the(110)and(101)orientation were weakened.These may be the reasons for the battery performance not meet expectations.