Constructing a Yolk–Shell\nStructure SiO_<i>x</i>/C@C Composite for Long-Life\nLithium-Ion\nBatteries

Abstract

Silicon oxide is one of the most representative anode\nmaterials\nfor lithium-ion storage. However, the poor conductivity of silicon\noxide and the large volume expansion during the repeated lithium alloying/dealloying\nreaction have a huge impact on the cycle stability of the electrode.\nHere, we propose a design strategy for constructing a yolk–shell\nstructure to enhance the electrochemical performance of the silicon\noxide-based anode. Using a silane coupling agent as the raw material,\norganosilicon nanoparticles are prepared by hydrolysis and a self-condensation\nreaction. Combining with polydiallyldimethylammonium chloride modification\nand polymethyl methacrylate coating, the SiO_<i>x</i>/C@C composite with a yolk–shell structure (YS-SiO_<i>x</i>/C@C) was obtained by one-step carbonization.\nThe modification of polydiallyldimethylammonium chloride ensures the\nformation of a stable cavity during the pyrolysis process, which can\neffectively relieve the volume variation of the silicon oxide electrode,\nand the carbon shell can enhance the overall conductivity. As the\nanode of lithium-ion batteries, the YS-SiO_<i>x</i>/C@C electrode showed outstanding electrochemical stability with\na high specific capacity of 770 mAh g^–1 and a Coulombic\nefficiency of 99% after 500 cycles (0.5 A g^–1).\nThis research provides a direction for the preparation of yolk–shell\nelectrode materials and promotes further development of high-performance\nsilicon oxide-based anodes.