Degradation Mechanism and Enhanced Stability of Organolithium for Chemical Lithiation

Abstract

Organolithium solutions, especially Li-arene solutions (LASs) with high reactivity and controllable redox potentials, have gained significant attention because of their wide applications in chemical lithiation, liquid anodes, and battery recycling. However, the sudden loss of reactivity when stored or applied at room temperature is still puzzling and inhibits the application of LASs. In this work, the degradation mechanism of LASs is fully investigated and revealed by combining various experimental characterization and computational simulations. A hierarchical reaction mechanism for lithium biphenyl/2-methyl tetrahydrofuran (Li-Bp-2MT), a lithiation solution used for most anodes, explains degradation and side product formation. Specifically, the dimerization of the active component Li₁Bp[2MT]₁ forms an inactive dimer that is irreversibly reduced in the presence of locally accumulated highly reductive Li⁰. This reaction mechanism reveals the atomic origins of lithiation solution deactivation and accounts for all solid and gaseous byproducts. LiH is identified as the dominating solid byproduct, indicating irreversible destruction of the active components and facilitating side reactions producing H₂ and CH_4. Based on reaction mechanism insights, modifying molecular interactions and reaction kinetics are experimentally shown to inhibit Li⁰ aggregation kinetics, enhancing long-term prelithiation performance. This research provides comprehensive guidelines for practical applications of LASs.