Evaluation of Deformation Behavior and Fast Elastic Recovery of Lithium‐Ion Battery Cathodes via Direct Roll‐Gap Detection During Calendering

Abstract

Calendering is the state‐of‐the‐art process for electrode compaction in lithium‐ion battery manufacturing through which the final electrode structure is defined. As the electrode structure determines the electrical und electrochemical transport properties, it is essential to develop a deep understanding of the interdependence between the calendering process and the deformation behavior of the electrodes. Therefore, a novel method for the investigation of the deformation behavior of electrodes, especially the springback (SB) effect, through direct‐gap detection within the calendering machine, is developed. With this installation, it is possible to directly access the maximum compression of the electrodes during calendering. With this approach, two different variations of cathodes, a variation of mass loading and a variation of binder weight content, based on lithium nickel manganese cobalt oxide (NMC622), are manufactured and investigated. Moreover, an empirical model is introduced, allowing the estimation of the SB for NMC622 cathodes considering different mass loadings and cathode compositions. Due to more space for particle rearrangement, cathodes with higher mass loading show a lower SB effect. Adding binder leads to higher plastic deformation and thus lowers also the SB effect of the electrodes.

Simulation of the Calendering Process of NMC‐622 Cathodes for Lithium‐Ion Batteries

“…Thus, the percentage values of the springback are in good agreement with the values of the springback for NMC-622 cathodes of 4-37% in literature for comparable compaction rates. [14] In general, the mean thickness deviation of the electrodes after calendering is AE2.88 μm comparing the electrode thickness of the simulation and the experiment. The porosity of the particle bed of the simulation before calendering was set to 43%, whereas the porosity of the electrode coated in the laboratory ranged from 42.17% to 43.93%.…”

“…Cathodes with higher binder content lead to higher plastic deformation resulting in a lower springback. [14] Experiments with different roll diameters and roll temperatures show that both parameters influence the adhesion strength of electrodes. [15,16] An increase in roll temperature from 23 to 40 °C decreases the required line load.…”

The Impact of Calendering Process Variables on the Impedance and Capacity Fade of Lithium‐Ion Cells: An Explainable Machine Learning Approach

“…33 Mn 0 . 33 O 2 (NCM) in other studies, [ 13,14 ] and for LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) in ref. [15] electrodes.…”

Data Specifications for Battery Manufacturing Digitalization: Current Status, Challenges, and Opportunities

“…The spring-back increases linearly with the applied line load and decreases with higher mass loadings and higher binder weight contents, which induce higher plasticity. [133] Discrete models can explicitly consider MPs such as gap, pressure, speed, and temperature. In contrast, the accuracy and capability of the models to represent structure parameters can vary.…”

“…Additionally, roll displacement enables the determination of the electrode spring‐back, which describes the recovery of the electrode thickness directly after the compaction process. The spring‐back increases linearly with the applied line load and decreases with higher mass loadings and higher binder weight contents, which induce higher plasticity [133] …”