Direct Contact Prelithiation of Multi-Layered Lithium-Ion Battery Pouch Cells Using a Scalable Prelithiation Process

Prelithiation is known to enhance the performance of lithium-ion batteries and is becoming increasingly popular. To date, different approaches and concepts for prelithiation processes have only been implemented on a laboratory scale, which is due to the complex upscaling of the process approaches. Moreover, investigations of prelithiation approaches are mostly limited to small-format laboratory cells, and concepts for implementation on an industrial scale are scarce. The present study introduces a scalable, roll-to-roll capable process for direct contact prelithiation of anodes for large-format and multi-layered pouch cells. The process is based on calendering for applying lithium foils to anodes. The feasibility of scaling the approach from single-layer to multi-layer pouch cells was further investigated. The prelithiated cells with silicon-graphite composite anodes showed an improved first-cycle coulombic efficiency of up to 8% and increased coulombic efficiencies during cyclization compared to non-prelithiated cells. By improving capacity retention, cycle life could be increased by up to 170% compared to non-prelithiated cells. Post-mortem analyses conducted after 4000 cycles show that the direct contact prelithiation method used does not cause profound lithium plating. Summarizing, the employed direct contact prelithiation process is suitable for a scalable, industry-capable prelithiation of lithium-ion batteries.