Prelithiation Mechanism of Silicon Anodes through the Interfacial Destabilization of Lithium Hydride

Abstract

Prelithiation is an effective strategy to compensate for irreversible capacity loss caused by solid-electrolyte interphase (SEI) formation during initial cycling of silicon-based anodes. However, the mechanism is complicated due to dynamic phase evolution of metastable alloys based on thermodynamic variables. Prelithiation mechanisms between lithium hydride (LiH) and silicon (Si) anodes were studied. LiH can be easily controlled as a reactant due to its slow reactivity. The interfacial destabilization and reaction kinetics of prelithiation mechanisms are investigated. Interfacial chemical reactions play a critical role in the prelithiation mechanism, involving the release of hydrogen gas. These reactions enable a sacrificial lithium source to penetrate the Si structure, leading to formation of LixSi phases contributing to the prelithiation process efficiency. Additionally, LixSi phase compositions depend on LiH concentrations that are designed to compensate for active lithium loss. An optimized LiH concentration demonstrated more than a 54.9% capacity retention improvement after 100 cycles. LixSi materials can offset the irreversible capacity loss during the first cycle, thereby improving the initially low Coulombic efficiency (ICE), while enhancing the battery cycling stability. This research provides insights into interfacial destabilization and reaction kinetics of the prelithiation method and significantly improves the electrochemical performance of lithium-ion batteries.