Inductive drying of lithium ion NMC622 cathodes

To match the steadily increasing demand of lithium-ion batteries all battery production steps have to be enhanced in terms of quality and performance. In this regard, the drying process of electrodes holds great potential for improvement. The main challenge of state-of-the-art convective drying methods is the high energy consumption within the drying step.

This study focuses on the development and prototypical implementation of a new method for drying electrodes based on inductive heating. By placing recently coated electrodes in an alternating electromagnetic field the metallic current collector is immediately heated due to the induced eddy currents inside the material. Since the heat is generated within the metallic material of the current collector, the inductive heating process allows for the efficient drying of the coating starting from the interface between the coating and the current collector. This in turn, could lead to a significant reduction of heating time and energy losses compared to conventional convective drying methods, respectively.

However, the negative impact of high drying rates on electrode properties is well known as a reduction in cycle stability due to binder and carbon black segregation may occur. As a result, the drying rate of conventional convective drying processes is limited. This may also be the case, when the novel induction-based heating method is applied.

Within this study, stationary inductive drying experiments are carried out at NMC622&nbsp“;“cathodes on a laboratory scale at different drying intensities and drying times. An infrared camera was used to determine the coatings local heat distribution as well at the temporal temperature development during the drying process. In addition, the drying rates were determined as a function of the drying intensity and time. Finally, the inductive dried cathodes were further examined to investigate the influence of the drying process on their electrical and mechanical properties. Based on the results, the transferability of the already know impact of the convection heating process on the electrical and mechanical properties of the electrodes to the inductive heating process is evaluated.

The results so far indicate that the inductive drying methods is a promising alternative to the conventional convective drying process.