Biphasic silicon oxide nanocomposites as high-performance lithium storage materials

Abstract

Silicon oxides (SiOx) 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 SiOx relies on microstructures and chemical compositions, we propose a material layout design of a biphasic SiOx composite that can achieve synergy between two different types of SiOx materials to improve electrochemical performance. Taking advantage of the properties of each component, a biphasic SiOx composite composed of silicon monoxide (SiO) and Si nanocrystals embedded in SiOx (Si/SiOx) 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/SiOx–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.