Preparation Of Two-dimensional Layered Titanium-based Metal Oxide/carbon Composite Electrode With High Mass Loadings

High conductivity and mass transfer channels of electrode materials with high mass loadings are the fundamental requirements for achieving high-rate performance and high-volume energy density,as well as one of the future design priorities for batteries.However,there are still significant challenges in preparing miniature batteries with high-mass loading electrodes due to the limitations of size processing and the difficulty of charge transmission in high-mass loading electrodes.This paper explores the preparation method of high-mass loading electrodes and their application in lithium metal batteries from three aspects:the selection of active electrode materials,the design of mass transfer porous structures,and the construction of a conductive network.The specific research contents are as follows:（1）Based on the regular layered structure of titanium-based two-dimensional metal oxide(K_0.8Ni_0.4Ti_1.6O₄),introducing carbon source between layers by intercalation of organic amine and use p-phenylenediamine as a binder and conductive agent to construct carbon skeleton of the porous network,and realize“welding”between graphene and carbon skeleton in layers during oxidative polymerization and carbonization.Oxalic acid is used as a pore-forming agent,and the mass transfer channel of liquid electrolyte is provided through the pores formed by oxalic acid pyrolysis.The existence of porous conductive networks not only provides electrolyte mass transfer channels and convenient charge transfer paths but also maintains the mechanical strength of the electrode and limits its volume expansion.It is verified that the prepared pellet electrode shows a Young’s modulus of 511 MPa at a porosity of 44%,and has good rate performance at mass loadings of 37.7 mg cm^-2.After 200 cycles at a current density of 2.83 m A cm^-2,the cycle stability of is significantly improved compared with the electrodes without porous conductive network.The volume expansion after cycling is only 8.04%,which is generally lower than the layered composite electrode prepared by slurry method（～40%）.In addition,the charge conduction network can be extended to electrodes with higher mass loadings and maintain good rate performance in a certain range.（2）Based on the good intrinsic ionic conductivity and excellent thermal stability of La/Ti-based two-dimensional layered metal oxide(Li₂La₂Ti₃O₁₀),preparing a two-dimensional lanthanum titanate/graphene composite with high conductivity by inserting a carbon source between its layers.Based on previous exploration,built a porous conductive network inside the pellet electrode by adding oxalic acid and p-phenylenediamine and constantly optimized the addition amount of the two to maximize the transmission characteristics of ions and electrons.It is verified that the electrode can show excellent rate performance in liquid lithium metal batteries.Under the mass load of 73.4 mg cm^-2 and the current density of 2.83 m A cm^-2,the capacity retention rate of the battery is 86%after 500 cycles,which further shows that the electrode has great application potential in all-solid-state batteries.