Gaining a New Technological Readiness Level for Laser-Structured Electrodes in High-Capacity Lithium-Ion Pouch Cells

Abstract

For the first time, the laser structuring of large-footprint electrodes with a loading of 4 mAh cm−2 has been validated in a relevant environment, including subsequent multi-layer stack cell assembly and electrochemical characterization of the resulting high-capacity lithium-ion pouch cell prototypes, i.e., a technological readiness level of 6 has been achieved for the 3D battery concept. The structuring was performed using a high-power ultrashort-pulsed laser, resulting in well-defined line structures in electrodes without damaging the current collector, and without melting or altering the battery active materials. For cells containing structured electrodes, higher charge and discharge capacities were measured for C-rates >1C compared to reference cells based on unstructured electrodes. In addition, cells with structured electrodes showed a three-fold increase in cycle lifetime at a C-rate of 1C compared to those with reference electrodes.

Benefits of Femtosecond Laser 40 MHz Burst Mode for Li-Ion Battery Electrode Structuring

“…Nevertheless, laser-based processes stand out based on their precision and their agnosticism to material and slurry. Additional benefits, such as lifespan extension [7,8], a reduction in lithium plating risk [9,10] and acceleration of the electrode wetting were demonstrated [9,11]. However, laser-based approaches suffer from the loss of matter and their relatively low throughput.…”

“…In the second part, we show how to tailor the hole width in the NMC and reduce the process time by varying the length of a 40 MHz burst. As the benefits of laser structuring on electrochemical performances have already been abundantly reported [7][8][9][10][11]27], electrochemical characterizations will not be presented here. For example, by drilling graphite electrodes in a hexagonal way, Chen et al could improve the capacity retention [7].…”

“…For example, by drilling graphite electrodes in a hexagonal way, Chen et al could improve the capacity retention [7]. Meyer et al, through the line structuring of both electrodes, could increase the discharge capacity and the lifetime by a factor 3 [8]. Dunlap et al, through line structuring NMC and graphite electrodes, showed an improvement in charge cycling performance and a reduction in the Li-plating risk [9].…”

Optimizing Structural Patterns for 3D Electrodes in Lithium-Ion Batteries for Enhanced Fast-Charging Capability and Reduced Lithium Plating

“…However, to integrate the process into industrial cell production, the laser structuring process must keep pace with the belt speed in production. The upscaling of the structuring process is therefore the current subject of research, and the concept was recently transferred to large-format pouch cells demonstrating a technology readiness level (TRL) of 5 to 6 [28,29]. Several pattern types have been investigated and used in research and development, including a hexagonal arrangement of holes, parallel oriented lines, and grid patterns or combinations and variations of the above [30][31][32][33][34][35][36][37][38][39].…”