Constructing Sub 10 nm Scale Interfused TiO2/SiOx Bicontinuous Hybrid with Mutual-Stabilizing Effect for Lithium Storage

Abstract

TiO2 has been considered as a promising intercalation lithium-ion-battery (LIB) anode material owing to its robust cyclability. However, it suffers from low capacity. Herein, we construct a sub 10 nm scale interfused TiO2/SiOx hybrid with a bicontinuous structure, in which bridged TiO2 nanoparticles (over 80 wt %) are densely packed within a wormlike SiOx network, through the simple oxidation of MAX Ti3SiC2 ceramic. State-of-the-art in situ microscopy characterization unravels a "mutual-stabilizing" effect from the interfused TiO2/SiOx hybrid upon lithiation. That is to say, the two interpenetrated active components restrain the volume expansion of each other with the stress being relieved through abundant interfaces. Meanwhile, the stress generated from one phase functioned as the compressive force on the other phase and vice versa, offsetting the overall volume effect and synergistically reinforcing the structure integrity. Benefiting from the "mutual-stabilizing" effect, the TiO2/SiOx composite manifests a high and stable specific capacity (∼671 mAh g-1 after 580 cycles at 0.1 A g-1) with a low volume expansion of ∼14% even in an extended potential window of 0.01-3.0 V (vs Li+/Li). The concept of mutual-stabilizing effect, in principle, applies to a wide class of interfused bicontinuous hybrids, providing insight into the design of LIB anode materials with high capacity and longevity.