Preparation Of High Ternary Cathode And LiNi_0.8Co_0.1Mn_0.1O₂ Artificial Solid Electrolyte Interface For Li-ions Batteries

Among the lithium-ion battery materials,ternary materials have received increasing attention as one of the most promising and widely used cathode materials.However,in practical applications,ternary materials have problems such as faster capacity decay and poor high temperature stability.In order to overcome these shortcomings,this paper optimizes the ternary synthesis process,taps the electrochemical potential of the ternary material,and prepares the ternary material into a cathode film to carry out relevant research on the ternary material.Using different methods,LiNi_0.5Co_0.2Mn_0.3O₂ and LiNi_0.8Co_0.1Mn_0.1O₂ micron-sized spherical particles were successfully prepared.1)In the process of synthesizing(Ni_0.5Co_0.2Mn_0.3)CO₃ by hydrothermal method-high temperature solid phase method,the micron-scale LiNi_0.5Co_0.2Mn_0.3O₂ spherical precursor with good morphology was obtained by adjusting the hydrothermal time by adjusting the calcination temperature,LiNi_0.5Co_0.2Mn_0.3O₂ spherical particles were obtained.When the calcination temperature is 850?,the material has the best electrochemical performance.When the voltage is set to 2.7-4.2V and the current density is 0.5C After 100 charge-discharge cycles,the capacity retention rate was 77.79%.2)Micro-spherical LiNi_0.8Co_0.1Mn_0.1O₂material was synthesized by co-precipitation method-high temperature solid phase method,and proved to be an?-NaFeO₂ phase structure by XRD and other characterization methods.For LiNi_0.8Co_0.1Mn_0.1O₂ material,the electrochemical analysis shows that it has a higher specific discharge capacity in the first week(199.7mAh·g^-1).In order to improve the electrochemical performance of LiNi_0.8Co_0.1Mn_0.1O₂,the inorganic and organic solid electrolyte interface layer.1)When the LiF inorganic solid electrolyte layer is coated in situ through the liquid phase,the reason for the improvement of the electrochemical performance of the LiNi_0.8Co_0.1Mn_0.1O₂ material by the LiF coating layer is analyzed:on the one hand,the LiF coating layer reduces the electrolyte and the direct contact between the electrode materials avoids the corrosion of HF and other acids in the electrolyte;on the other hand,the LiF coating layer can maintain the integrity of the LiNi_0.8Co_0.1Mn_0.1O₂ secondary particles during cycling,making its microscopic structure not easily destroyed.In addition,LiF has high Li⁺conductivity,which facilitates lithium ions transport and diffusion between the electrode material and the electrolyte.2)When the interface layer of sulfite-rich organic solid electrolyte was generated in situ by the electrolyte additive,we studied its electrochemical performance in 2%DTD,1%MMDS and 2%DTD+1%MMDS composite additive electrolyte At a high temperature of 60°C,the capacity retention rate after a 90-week cycle was 51.4%.EIS test shows that 2%DTD+1%MMDS composite additive can significantly reduce the dynamic impedance of LiNi_0.8Co_0.1Mn_0.1O₂.Today's thin-film batteries are faced with the problem of small cathode capacity per unit area.We have tried to prepare LiNi_1/3Co_1/3Mn_1/3O₂ thin-film cathodes by radio-frequency magnetron sputtering.The magnetron sputtering process and its effect on the electrochemical performance of thin films were studied.The results show that LiNi_1/3Co_1/3Mn_1/3O₂ thin film materials and LiNi_1/3Co_1/3Mn_1/3O₂ powder materials have obvious changes in structure and performance,and various sputtering parameters have a great influence on the film preparation process.When the ratio of oxygen to argon is1:3 and the sputtering power is 90W,the prepared LiNi_1/3Co_1/3Mn_1/3O₂ thin film material has excellent electrochemical performance,and its specific discharge capacity at the first week was 149.14 mAh·g^-1 at a current density of 0.1C,the discharge specific capacity after 50 cycles was 103.47 mAh·g^-1,and the capacity retention rate was 69.4%.