Optimisation Of Ion Transport Kinetics In All-solid-state Batteries

With the continuous development of science and technology,social production of lithium-ion battery energy storage system requirements is higher and more stringent.Traditional liquid lithium-ion batteries still have problems such as low safety and low energy density,which cannot meet the development of future energy technology.Allsolid-state batteries have the advantages of high safety and high specific energy,and are expected to meet the future needs of society for energy storage technology.However,the contact between the solid-phase and solid-phase interface is not as tight as the contact between the solid-phase and liquid-phase,which leads to the obstruction of the interfacial ion transport between the solid electrolyte and the solid-phase electrode material,which becomes a key problem that restricts the performance of all-solid-state batteries.In order to prepare all-solid-state lithium-ion batteries with both high safety and high energy density,electrode materials with high ion transport capability and surface modification of the electrode material-solid electrolyte interface are required to enhance the ion transport efficiency in all-solid-state batteries.This is of great importance for the improvement of energy density and power density of all-solid-state batteries.To address the problems of low ion transport efficiency inside the all-solid-state battery,and the many factors affecting the ion transport kinetics,the experimental process is more complicated.In this paper,based on the Nernst-Planck equation and ButlerVolmer equation,a mathematical model of a one-dimensional all-solid-state battery containing an interfacial modification layer is established with the electrode overpotential as the link.The model can describe more realistically the effects of interface modification material and electrode material parameter changes on the ion transport kinetics of allsolid-state batteries,and point out the direction for how to effectively improve the ion transport efficiency of all-solid-state batteries.The model is used to perform calculations in finite element by setting up effective boundary conditions.In this paper,we simulated the distribution of lithium-ion concentration and the first turn capacity play rate under different modification layer thickness,different modification layer ion diffusion coefficient,different electrode material thickness,and different electrode material ion diffusion coefficient.The effects of changing the parameters of electrode material and modification material on the electrochemical performance of the battery were obtained.In order to verify the accuracy of the pre-simulation results,we conducted corresponding experiments for validation.The simulation results show that with the increase of the thickness of the modification layer,the first turn capacity of the battery plays the first increase and then decreases.The ion diffusion coefficient of the modification layer and the ion diffusion coefficient of the electrode material show a positive relationship on the electrochemical performance of the battery.When the thickness of the electrode material increases,the capacity performance increases first and then decreases.The experimental results show that the Ti-doped and LLTO-modified samples have better cycle performance,multiplicity performance and ion transport efficiency compared with the intrinsic LCO material.The charge transfer impedance of the LLTO-modified and Ti-doped films is greatly reduced compared to that of the intrinsic LCO films.The results presented in the experiments are consistent with the simulation calculations,demonstrating the reliability of the simulation model and the accuracy of the simulation results.This points to the direction for the subsequent research on the optimization of ion transport dynamics in all-solid-state batteries.