Biphasic silicon oxide nanocomposites as high-performance lithium storage materials

Abstract

Silicon oxides (SiO_x) have been widely explored as high-capacity lithium storage materials for lithium ion batteries (LIBs) due to the enhanced stability of their cycling performance compared to other Si-based materials. However, these materials suffer from insufficient electrochemical performance and reliability for commercial use in LIBs. Since the electrochemical performance of SiO_x relies on microstructures and chemical compositions, we propose a material layout design of a biphasic SiO_x composite that can achieve synergy between two different types of SiO_x materials to improve electrochemical performance. Taking advantage of the properties of each component, a biphasic SiO_x composite composed of silicon monoxide (SiO) and Si nanocrystals embedded in SiO_x (Si/SiO_x) exhibits notably improved electrochemical performance and suppressed volume expansion during cycling. The proposed biphasic material exhibits a high reversible capacity of 966 mA h g⁻¹ with excellent long-term cycle performance for up to 350 cycles. With a core–shell structure, the biphasic Si/SiO_x–SiO composite also has excellent dimensional stability. This approach presents a promising way to produce highly reliable high-capacity anode materials with a low production cost for mass production.