Engineering Micro-Structured Lithium-Ion Battery Electrodes for Enhanced Performance Using High-Throughput Ultrafast Laser Ablation

Abstract

As the demand for electric vehicles continues to grow, secondary batteries with larger storage capacities, faster charging times, and lower manufacturing costs are desired. Current U.S. Advanced Battery Consortium cell-level targets for low-cost and fast charge lithium-ion batteries (LiBs) for electric vehicles include energy densities of >275 Wh/kg, cost less than $100/Wh, and charge to more than 80% capacity within 15 minutes.1 One way to increase capacity is to increase the thicknesses of the electrodes so that there is more active lithium-ion storage material in the cell; however, increasing electrode thickness is usually limited to less than approximately 150 µm due to problems with through-plane Li-ion diffusion. Too-thick electrodes exhibit poor rate performance and with Li plating problems that accelerate cell degradation at charging rates > 1C. Recently, we have demonstrated that laser-ablated micro-structures, such as pores or channels, in thick battery electrodes improves the performance of LiBs.2 Using advanced predictive modelling, we have explored the limitations of planar electrodes for fast charge performance and the importance of microscale features for improving ion-transport.3,4 The cell’s energy density and capacity retention is significantly improved by engineering the appropriate micro-structure geometry. Here, we will present some of the technical challenges of accomplishing the ultrafast laser ablation and provide examples of advanced characterization of the patterned electrodes to understand their effects on electrode performance. We will also describe methods to scale-up the laser processing to enable high-throughput roll-to-roll fabrication of micro-structured thick battery electrodes which requires fast and accurate steering of the emitted laser light. Our results provide an overview for translating the technology from the lab scale to industry-relevant manufacturing.