Laser patterning and electrochemical characterization of thick-film cathodes for lithium-ion batteries

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Lithium-ion batteries (LIBs) are currently dominating the electrochemical storage sector due to their excellent properties such as high energy density, high power density, and long cycle lifetime. For automotive applications, current research focuses on the merger of two concepts: (i) the “thick film concept” which enables a high energy density due to a reduced amount of inactive materials, and (ii) the “three-dimensional (3D) battery concept”, which provides a high power density with improved interfacial kinetics at mass loadings ≥ 35 mg/cm². Latter could be realized by applying ultrafast laser patterning of electrodes, which in turn includes an advanced 3D electrode design. Briefly, a rapid and homogeneous electrode wetting with liquid electrolyte can be induced, and besides a high capacity retention during long-term cyclability. Recently, various electrode designs such as line, grid, and hole structures have been reported for cathodes and anodes. However, the mass loss of those electrodes needs to be considered, since the cathode represents about 50 % of the total material costs of LIBs. Thus, the use of electrode structures with a high aspect ratio as well as a significantly reduced material removal is of great importance. In this work, 150 μm thick-film Li(Ni_0.6Mn^0.2Co_0.2)O₂ electrodes were manufactured by roll-to-roll tape-casting and subsequently structured with different pattern types using ultrafast laser radiation. Additionally, different designs were applied for laser patterning and the mass loss was minimized down to 7%. Finally, the cathodes were assembled in half-cells for studying the impact of different laser patterning designs on electrochemical performance.