Experimental Considerations of the Chemical Prelithiation Process via Lithium Arene Complex Solutions on the Example of Si-Based Anodes for Lithium-Ion Batteries

Losses of Li inventory in lithium-ion batteries lead to losses in capacity and can be compensated by electrode prelithiation before cell assembly or before cell formation. The approach of chemical prelithiation, for example, via Li arene complex (LAC)-based solutions is technically an apparently simple and promising approach. Nevertheless, as shown herein on the example of Si-based anodes and LAC solutions based on 4,4 '-dimethylbiphenyl (4,4 '-DMBP), several practical challenges need to be considered. Given their reactivity, the LAC solution can not only decompose itself within a range of a few hours, as seen by discoloration and confirmed via mass spectrometry, but can also decompose its solvent and binder of added composite electrodes. Effective prelithiation requires an excess in capacity of the LAC solution (relative to anode capacity) and optimized system characteristic conditions (time, temperature, etc.) as exemplarily shown by comparing Si-based nanoparticles with nanowires. It is worth noting that the prelithiation degree alone does not determine the boost in cycle life, but relevantly depends on previously applied prelithiation conditions (e.g., temperature), as well. Prelithiation is a promising approach to compensate active lithium (= capacity) losses, in particular relevant for "high-energy" anode materials like Si. The chemical approach, that is, contact of anode with a lithium arene complex (LAC) solution, is technically apparently simple but reveals practical challenges. The experimental hurdles and influence of relevant parameter on prelithiation degree and performance are highlighted.image (c) 2023 WILEY-VCH GmbH