Construction and verification of simulation model for multi-roll rolling of dry electrode composite powder

With the rapid expansion of electrochemical energy storage industry and the popularity of electric vehicles, the demand for high-performance lithium batteries is increasing. The performance of the anode material in a lithium battery greatly impacts the overall battery performance. Therefore, developing better negative electrode processing technology is crucial for improving lithium battery performance. In this paper, a new negative electrode processing technology - dry electrode process, the particle evolution of the negative composite powder during processing was studied. Through simulation analysis and experimental research, we identified methods to optimize the process parameters and verified these optimized parameters experimentally. First, we analyzed the characteristics of powder particles through experimental research, and then explored the evolution mechanism of composite particles during processing. Using the dry multi-roll calendering process for the main components of silicon oxide (SiO) and polytetrafluoroethylene (PTFE) negative composite powder, we examined the characteristics of SiO and PTFE particles through cohesive zone theory (CZM) and particle viscoelastic theory, respectively. Based on the multi-particle finite element analysis (MPFEM) and the particle characteristics of the composite powder, we measured key particle parameters such as the particle plane fracture stress and the relaxation curve under high temperature, providing a basis for establishing the roller compression model. Next, we determined the particle simulation model according to the key machining parameters and quantitatively verified its accuracy. We established a simulation model with different initial porosities to simulate the damage and fracture evolution of SiO particles and the mechanism of particle rearrangement when the composite powder was rolled into film multiple times. We also examined the degree of fibrosis and diffusion of PTFE resin particles. The reliability of the model was verified through quantitative experiments, such as dressing layer resistivity measurement and electrode surface profile measurement.