Ultrafast Laser Materials Processing of Electrodes for Next Generation Li-Ion Batteries (NextGen-3DBat)

To contribute to a turnaround in energy policy, lithium(Li)-ion cells with significantly increased power and energy density are required. Therefore, high energy materials such as nickel-enriched lithium nickel manganese cobalt oxide (NMC 622) and silicon/graphite (Si/G) composite electrodes with a high areal capacity (>>4 mAh/cm2) and respective film thickness (>> 100 µm), and a 3D electrode structure for high rate capability will be developed. Batteries with NMC 622 show in comparison to those with NMC 111 a higher capacity, and a better capacity retention and cell lifetime in comparison to cells with NMC 811. The manufactured slurries are either NMP- or water-based. The usage of water-based instead of NMP-based systems will lead to a better environmental sustainability while making the recovery of the organic solvent redundant. To further increase the energy density on cell level, Si/G composite anodes are being used, as Si provides one order of magnitude higher theoretical capacity than graphite. To make this advantage practicable, the utilisation of Si-nanoparticles as well as the introduction of free-standing structures in the anode via laser structuring to compensate the volume changes of Si during alloying with Li are necessary. ... mehrTo match the increased capacity of the Si/G anodes, cathodes with a high film thickness with adapted high areal mass loading are being prepared for reaching a cell balancing of 1.2-1.3. To increase the active surface area of the electrodes, microstructures are generated with ultrashort pulsed laser radiation. These 3D structures accelerate the de-/intercalation of Li while cycling and improve the electrolyte wettability, which leads to a decrease in storage and formation time as well as an increased process reliability and an enhanced cell lifetime. To accelerate the laser structuring, a roll-to-roll process is implemented, the process is parallelised with the utilisation special designed optics, and the laser energy and fluence are being increased by using a new generation of industrial reliable laser sources.