Constructing a Yolk–Shell Structure SiO_x/C@C Composite for Long-Life Lithium-Ion Batteries

Abstract

Silicon oxide is one of the most representative anode materials for lithium-ion storage. However, the poor conductivity of silicon oxide and the large volume expansion during the repeated lithium alloying/dealloying reaction have a huge impact on the cycle stability of the electrode. Here, we propose a design strategy for constructing a yolk–shell structure to enhance the electrochemical performance of the silicon oxide-based anode. Using a silane coupling agent as the raw material, organosilicon nanoparticles are prepared by hydrolysis and a self-condensation reaction. Combining with polydiallyldimethylammonium chloride modification and polymethyl methacrylate coating, the SiOx/C@C composite with a yolk–shell structure (YS-SiOx/C@C) was obtained by one-step carbonization. The modification of polydiallyldimethylammonium chloride ensures the formation of a stable cavity during the pyrolysis process, which can effectively relieve the volume variation of the silicon oxide electrode, and the carbon shell can enhance the overall conductivity. As the anode of lithium-ion batteries, the YS-SiOx/C@C electrode showed outstanding electrochemical stability with a high specific capacity of 770 mAh g–1 and a Coulombic efficiency of 99% after 500 cycles (0.5 A g–1). This research provides a direction for the preparation of yolk–shell electrode materials and promotes further development of high-performance silicon oxide-based anodes.