Modification based on primary particle level to improve the electrochemical performance of SiOx-based anode materials

Abstract

A two-phase mixture of SiOx-TiO2 encapsulated by reduced graphene oxide (SiOx-TiO2@RGO, 0 < x < 2) is fabricated for novel composite anode of lithium ion batteries. The dual-phase SiOx-TiO2 distributes uniformly at primary particle level is synthesized by liquid phase co-deposition before high energy ball milling. The liquid phase co-deposition method ensures dual-phase mixture of SiOx-TiO2 with uniform distribution at the particle level, while the high energy ball milling prompts conversion of the SiO2 component without lithium intercalation activity into SiOx anode with partial reduction and oxygen loss. The incorporation of TiO2 nanocrystal plays the roles of lithium ions and electron conduction (LixTiO2) promoter during the electrochemical reaction and prevents the agglomeration of active material particles. The graphene bubble film can decrease irreversible Li+ consumption and film resistance after lithiation, as well as enhance the electronic conductivity. As a consequence, the SiOx-TiO2@RGO composite exhibits excellent rate property (420 mAh g−1 at 5 A g−1) and exceptional long-term cycling performance (730 mAh g−1 after 200 cycles at 100 mA g−1). The extraordinary electrochemical property combined with the facile synthesis process shows attractive prospect of the modification strategy at the primary particle level.