Oxygen Vacancy-Driven Embedded Electric Fields in TiO2–x/SiOx Anodes for Superior Lithium-Ion Battery Performance

Silicon-based anodes, with a theoretical capacity of ∼4200 mAh/g, are promising candidates for lithium-ion batteries. However, significant volume expansion during cycling leads to electrode fragmentation and poor cycling stability. This study presents a novel approach leveraging metal oxide coatings to simultaneously enhance the mechanical stability and the electronic and ionic diffusion capabilities of silicon-based anodes. TiO2–x/SiOx nanocomposites with a Maudan-like structure were synthesized via hydrolysis and subjected to high-temperature reduction in a H2/Ar atmosphere. The unique heterogeneous structure of these composites features oxygen vacancies in TiO2–x, which induce localized electronic states and generate embedded electric fields at the interface with TiOx. The oxygen vacancies provide additional pathways for electron transport and ion storage, while the embedded electric fields further optimize the electronic and ionic transport properties of the material. This synergistic effect significantly enhances the diffusion of electrons and lithium ions at the interface, effectively mitigating volumetric strain during electrochemical cycling. At a current density of 1 C, the TiO2–x/SiOx composite electrode maintains a capacity of 608.4 mAh/g after 1000 cycles. The synergistic effects of oxygen vacancies and embedded electric fields in TiO2–x/SiOx provide new avenues for silicon-based anode materials, particularly in electric vehicles and energy storage systems.