Metallurgically lithiated SiOx anode with high capacity and ambient air compatibility

Abstract

A common issue plaguing battery anodes is the large consumption of lithium in the initial cycle as a result of the formation of a solid electrolyte interphase followed by gradual loss in subsequent cycles. It presents a need for prelithiation to compensate for the loss. However, anode prelithiation faces the challenge of high chemical reactivity because of the low anode potential. Previous efforts have produced prelithiated Si nanoparticles with dry air stability, which cannot be stabilized under ambient air. Here, we developed a one-pot metallurgical process to synthesize Lix Si/Li2 O composites by using low-cost SiO or SiO2 as the starting material. The resulting composites consist of homogeneously dispersed Lix Si nanodomains embedded in a highly crystalline Li2 O matrix, providing the composite excellent stability even in ambient air with 40% relative humidity. The composites are readily mixed with various anode materials to achieve high first cycle Coulombic efficiency (CE) of >100% or serve as an excellent anode material by itself with stable cyclability and consistently high CEs (99.81% at the seventh cycle and ∼99.87% for subsequent cycles). Therefore, Lix Si/Li2 O composites achieved balanced reactivity and stability, promising a significant boost to lithium ion batteries.