Development of Laser Strategies for Improved Rate Capability and Reduced Lithium Plating

Over the past few years, laser structuring of electrodes has been shown as a powerful tool to significantly improve the rate capability and cycling ability of lithium-ion batteries. However, the impact of anode/cathode pattern combinations on electrochemical performance in full-cell configurations remains poorly understood. This work investigated for the first time the influence of laser structuring strategies and pattern combinations on the laser processing rate as well as the electrochemical performance of full cells containing NMC 811 cathodes and graphite anodes. Meanwhile, the mass losses due to laser ablation with different strategies were kept similar for cathodes and anodes. The line-patterning process exhibited a processing rate that was an order of magnitude higher than that for blind hole drilling. Moreover, line patterning of graphite anodes with an average laser power of 5.0 W showed a two to five times higher laser processing rate than with 2.5 W. Subsequently, the structured electrodes were cross-combined and assembled into full cells. All cells with laser-structured electrodes exhibited improved rate performance, reduced ionic resistance, and a shift in the onset of lithium plating to higher C-rates in comparison to the reference cells with unstructured electrodes. In particular, the cells with “Line 5 W” electrodes demonstrated excellent rate performance, delivering an increase of 72 mAh g−1 in discharge capacity compared to the reference cells at 5C and achieving 80% state of charge in 18 min. The results indicated that line patterns enhance rate performance more effectively than hole patterns. Furthermore, wider grooves in the electrodes were produced using higher average laser power, which may provide larger electrolyte reservoirs. This could support the rewetting processes of the electrolyte in the electrodes during electrochemical cycling and thus significantly improve rate performance and cell lifetime.