Ultrafast laser structuring of Li(Ni$_{0.6}$Mn$_{0.2}$Co$_{0.2}$)O₂ cathodes for high energy and high power lithium-ion batteries

Since firstly introduced, lithium-ion batteries have dominated the market for years. Recently, due to rising concern about environmental protection and more restrict regulation in CO2 emission, automobile industries are turning to develop E-mobility, such as hybrid electric vehicle and battery electric vehicle. In order to compete conventional vehicles, a battery with high power, high energy, good rate capability, and cycling stability is of great importance. There are several ways to achieve high energy batteries, such as increasing the active material ratio and the film thickness. The mass loading can be increased by employing thick film electrodes, which on the other hand reduces the amount of inactive components in batteries, such as current collector and separator. This leads to an overall cost reduction in battery manufacturing. However, the capacity loss of cells with thick film electrodes at high charge / discharge rate is more severe due to the limited lithium-ion diffusion kinetics inside the electrolyte filled porous composite electrodes. With ultrafast laser ablation, 3D patterns can be generated from the electrode surface down to the current collector, which enlarges the electrode surface area which is in direct contact with the free electrolyte, leading to additional lithium-ion diffusion pathways and finally to a higher capacity retention at high charge /discharge rates. ... mehrIn this work, Li(Ni0.6Mn0.2Co0.2)O2 cathodes were manufactured with different mass loading and were laser structured with 200 µm pitch distance. The cathodes were afterwards assembled versus lithium using coin cell design. Rate capability tests showed that cells with structured cathode provide a higher discharge capacity for medium and high electrical currents, namely for C-rates of C/2 to 2C. Finally, in order to shorten the processing time, a high power laser with parallel laser beam processing was applied.