Confined interfacial assembly of controlled Li2Ti3O7 building blocks and Si nanoparticles in Lithium-ion batteries

Abstract Most studies combine high-capacity silicon (Si) with high-conductivity carbon materials to overcome the poor electrical connectivity of Si, but the pathway for the Li+ rapid transmission to Si is often ignored. Lithium titanate (LixTiyOz) as a protective additive to improve the transmission speed of Si-based anodes has attracted extensive scientific interest. However, highly reactive titanium precursor imparts great difficulties in precisely controlling the growth of LixTiyOz on the Si surface, resulting in poor secondary particle formation, and severely weakening the advantage of LixTiyOz at the Si-based electrode level. Herein, we propose a confined interfacial assembly method to combine the controlled Li2Ti3O7 building blocks and the Si nanoparticles through the electrostatic interaction and Ostwald-ripening. This facile and reproducible method relies on the surface charge change effect of CTAB, the solvent-confinement effect of glycerol and the crystalline dimension control of ammonia. The Li2Ti3O7 building blocks has a height-adjustable shape (2D-layered, 3D-spherical), size, and controlled coating surface. As a result, the selected hierarchical microcluster has the advantages of rapid 3D interpenetrating electron/Li+ pathways, buffer space and electrolyte barrier, which achieves superior rate capability (1261 mAh g−1 at 5 A g−1) and high stable cycle performance (1080 mAh g−1 after 1000 cycles at 2 A g−1).