Dehydrogenation-driven Li metal-free prelithiation for high initial efficiency SiO-based lithium storage materials

Highlights: • Simple but safe prelithiation was developed for improving initial efficiency of SiO. • 3D-networked Li_xSiO_y -Si nanocomposites were obtained by prelithiation of SiO. • Initial Coulombic efficiency of SiO was improved up to 90.5% through prelithiation. • Atom probe tomography revealed 3D-network structure of prelithiated SiO materials. • Prelithiated SiO showed enhanced energy density of full cell by 50% compared to SiO. Silicon monoxide (SiO) based materials are the most widely used high-capacity anode materials for commercialized lithium-ion batteries. However, their low initial Coulombic efficiency (ICE) hinders their full potential as anode materials for lithium-ion batteries. Here, we demonstrate that Li metal-free dehydrogenation-driven prelithiation employing lithium hydride (LiH) could improve the ICE of SiO up to 90.5%. Lithium liberated from LiH served as a source for preemptive formation of lithium silicate phases that are the main reason for the poor ICE of SiO, leading to three-dimensionally networked Si/lithium silicate nanocomposites, which were visualized by laser-assisted atom probe tomography (LA-APT) and scanning transmission electron microscopy (STEM). The prelithiated SiO delivered a capacity of 1203 mAh g⁻¹ with an ICE of 90.5% without any degradation in other electrochemical performance. The improved ICE of prelithiated SiO made possible to enhance the energy density of full cell (37 mAh) by 50% compared to that adopting pristine SiO with an excellent cycle performance over 800 cycles.