Efficient Chemical Prelithiation with Modificatory Li⁺ Solvation Structure Enabling Spatially Homogeneous SEI toward High Performance SiO_x Anode^†

Chemical prelithiation is widely proven to be an effective strategy to address the low initial coulombic efficiency (ICE) of promising SiO_x anode. Though the reagent composition has been widely explored, the Li⁺ solvation structure, which practically plays the cornerstone role in the prelithiation ability, rate, uniformility, has rarely been explored. A novel environmentally-friendly reagent with weak solvent cyclopentyl methyl ether (CPME) is proposed that enables both improved ICE and spatial homogeneous solid electrolyte interphase (SEI). And the prelithiation behavior and mechanism were explored focused on the Li⁺ solvation structure. Both theoretical investigation and spectroscopic results suggest that weak solvent feature of CPME reduces the solvent coordination number and decreases the Li⁺ desolvation energy. The optimized Li⁺ solvation structure enables high-efficiency prelithiation that ensures the horizontal homogenization and mechanical properties of SEI. Moreover, the accompanied CPME molecules preferentially occupy positions in initial SEI, reducing the likelihood of LiPF₆ decomposition and promoting longitudinal homogenization of SEI. Consequently, the efficient and homogenous prelithiation enables impressive ICE of 109.52% and improved cycling performance with 80.77% retained after 300 cycles via just 5 min soaking. Furthermore, the full cells with LiNi_0.83Co_0.12Mn_0.05O₂ (NCM831205) cathode display an enhancement in the energy density of 179.74% and up to 648.35 Wh·kg^–1.