Influence of Atmospheric Composition on the Performance of Prelithiated C/SiOx Anodes – from Lab to Mass Production

Summary:

Silicon is a promising candidate as a high capacity anode active material and is already used in small quantities in state of the art products. One of the main hindrances for increasing the share of silicon within the anode is the high irreversible lithium loss that is characteristic for most silicon materials. Prelithiation offers a solution to this problem by introducing additional quantities of lithium into the cell. Accordingly, the interest in prelithiation technologies increased exponentially over the last years [1].
The concept of prelithiation covers a variety of different techniques. Some well-known approaches are the addition of lithium rich additives or the electrochemical prelithiation. In both cases, the stability and reactivity of the (pre)lithiated additives/electrodes under ambient humidity is a major concern. If only small amounts of lithium shall be introduced, the addition of air-stable positive electrode additives can be a good option. This approach is already actively investigated by industry players like e.g. Tesla [2]. However, if maximum energy density is targeted, the electrochemical prelithiation is likely the best choice [3] but the reactivity of the prelithiated electrodes towards even trace amounts of water remains a critical issue.
In the presented study C/SiOx anodes were electrochemically prelithiated to a prelithiation degree of 30% and are subsequently subjected to atmospheres with varying levels of humidity. The electrodes are then assembled into 3-electrode half-cell and tested for their remaining electrochemical performance. The results indicate, that handling of prelithiated electrodes under dry room atmosphere is possible, but can result in a decrease of prelithiation degree. The preserved prelithiation capacity depends on dry room quality and utilization.
[1] Jin et al. (2021) Pre‐Lithiation Strategies for Next‐Generation Practical Lithium‐Ion Batteries. Advanced Science, 2005031.
[2] Gowda et al., U.S. Patent 2020136142A1, 2020
[3] Holtstiege et al. (2018). Pre-lithiation strategies for rechargeable energy storage technologies: Concepts, promises and challenges. Batteries, 4(1), 4.