Lithium-ion batteries applied for example in electric driven vehicles aim towards increased energy density at high active mass loading per unit area. Therefore, calendering processes are used to densify the electrodes. However, a low porosity, especially in top layer of the material compound, leads in general to a low rate (dis-) charging capability due to hindered lithium-ion diffusion. This work proposes a laser surface treatment method of highly densified cathodes to reduce the apparent process limitation of ion diffusion. The surface treatment is done with a short pulsed infrared laser in the nanosecond regime. Depending on the provided energy density in the laser spot the electrochemical inactive matrix of the cathode can be ablated partially and most of the pores below the top layer get reopened. Cathodes with different high densities after calendering are laser treated and electrochemically analyzed. Highly densified cathodes with a porosity of 20% exhibit a distinct improvement of rate capability at C-rates higher than 2C in relation to cathodes without laser treatment. Explicitly, at high current rates of 5C the electrodes of 20% porosity show an improved capacity of more than 20%. In addition, at low current rates the results show no negative impact of the laser treatment. The results lead to the interpretation, that selective laser ablation enables an improved access of Li-ions into the active mass of the cathode. Keywords: Li-ion battery, cathodes, selective laser ablation, rate
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