Infrared-drying for Li-Ion battery production: Effects on the electrode´s characteristics

Infrared-drying is an innovative technology in the Li-Ion battery manufacturing [1]. Since drying is the most energy intensive process step [2], new technologies have to be discovered in order to reduce costs and material sources. One solution is the addition of an IR-module. The aim of this study is the analysis on the electrode properties that arise from the combination of a convection dryer with an IR-module. The potential of a combination of both technologies was confirmed by earlier scientific studies [3]. Infrared-drying offers different advantages for the operation technology. First comparable results to the convection drying can be achieved through the high IR-radiation energy density and the local energy transfer to the coating [3]. Then a much smaller space is required. In addition to shorter switching and lead times, high flexibility and modularity in the integration and use of the IR-module are reached. In this way results are achieved faster and with lower demand on material resources.

In this study tests are driven with the IR-module as Stand-alone and in combination with the convection dryer. The IR-module is located between the slot nozzle of the coating line and the oven. The principle is as follows: The solvent content is heated up fast and with high energy density by the IR-module. Afterwards the convection dryer allows uniform drying [3]. The IR-module´s power is varied to achieve a residual moisture of 3 %. Adhesive train tests have proven the highest adhesion by this value of residual moisture. The electrode´s quality has to be maintained in terms of residual moisture and adhesion. For the results with the desired residual moisture the adhesion is measured and presented in diagrams. These samples underwent the calandering process and the results are compared with those of the previous step. In the most of cases the samples not yet submitted to the calandering process show higher adhesion.

Another important result concerns the reduction of process times: with the addition of the IR-module the tape speed is doubled with comparative good results.

In conclusion, the three main factors for the introduction of IR-drying in the Li-Ion battery production are: energy savings, lower space needed and shorter switching and lead times. However the IR-module´s power should not to be too high, in order to produce high quality electrodes. Further tests would validate the energy saving and the infrared-drying on the cell level.

Literature:

[1] Dr. S. Michaelis, E. Rahimzei, Prof. Dr. A. Kampker et al. VDMA Roadmap Batterie-Produktionsmittel 2030

[2] E. Emilsson, L. Dahllöf, Lithium-Ion Vehicle Battery Production Status 2019 on Energy Use, CO₂ Emissions, Use of Metals, Products Environmental Footprint, and Recycling

[3] W. Xianfeng, L. Xujia, B. Xinzhi. Experiments on Hot-Air and Infrared Drying Characteristics of LiCoO₂ Cathode Coating for Lithium-Ion Battery