Proportionate Influence of Anode and Cathode Structuring on Electrode Characteristics and Cell Performance

Summary:

Lithium-ion batteries (LIBs) are currently the dominating energy storage solution for most consumer electronics and electromobility applications. For an increased market penetration, further enhancements of the cell performance of LIBs are needed. Microscopic diffusion channels in the coatings of battery electrodes are a promising approach to improve the (dis)charge performance and increase the lifetime of LIBs. The microscopic drillings can be introduced with high precision and reproducibility with the help of short-pulsed laser radiation.
In this study, the proportionate impact of laser structuring on the cell performance of LIBs was investigated if applied on the anode or cathode side, respectively. To this aim coin cells comprising graphite anodes and NMC622 cathodes in pristine and structured conditions, respectively, were manufactured. In discharge rate tests, particularly cells containing laser-structured anodes showed a significant increase in their capacity retention in comparison to cells with pristine anodes. Symmetric cells were manufactured and examined with the help of electrochemical impedance spectroscopy. Fitting an equivalent circuit model to the impedance spectra revealed a reduction of the ionic resistances by approx. 45 % for the anodes and approx. 21 % for the cathodes through laser structuring. In conclusion, laser structuring offers a particular potential to overcome the diffusion-limiting characteristics of the graphite anodes. The insights into the proportionate impact of anode or cathode structuring are of high value for the design and manufacturing of future LIBs.