Mechanics and deformation behavior of lithium-ion battery electrode during calendering process

The calendering process in lithium-ion battery electrode manufacturing is pivotal and significantly affects battery performance and longevity. However, current research on the mechanical and deformation characteristics of lithium-ion battery electrodes during calendering is limited, and a systematic theoretical foundation for informing practical production is lacking. This study investigated the mechanics and deformation behavior of lithium-ion battery electrodes during calendering through experimental methods. Data on the calendering pressure for electrodes at varying compression rates were gathered, revealing a correlation between the calendering pressure and compression rate that aligns well with the Kawakita equation commonly used in powder forming. Furthermore, the study examined the effects of the roller diameter and roller surface temperature on the calendering pressure. Within the typical compression rate range, a linear relationship was observed between the compression rate and the percentage elongation of the battery electrode. The study also explored how the roller diameter, roller surface temperature, and number of calendering passes influence the percentage of elongation. A quantitative formula linking the roller diameter to the percentage elongation of the battery electrode was proposed considering the effect of the roller diameter. Additionally, through electrode cleaning experiments, the study identified the coordination relationship between the extension of the electrode coating and the current collector. Mercury intrusion porosimetry (MIP) tests were conducted to elucidate the influence of calendering on the porosity, pore size distribution and specific surface area of the electrode coating. This research offers valuable insights and a theoretical basis for optimizing the calendering process in lithium-ion battery electrode production.