Multi-core yolk-shell like mesoporous double carbon-coated silicon nanoparticles as anode materials for lithium-ion batteries

Various techniques have been developed to mitigate the volume expansion of silicon-based materials and improve their conductivity in lithium ion batteries (LIBs). Here, we have synthesized a novel cobalt and nitrogen co-doped double carbon coated silicon/carbon/metal-organic framework (MOF) multi-core yolk-shell like mesoporous materials through sol-gel and MOF self-template methods. The structure and morphology of the sample was characterized by X-ray diffraction and electron microscopy. The results show that the prepared composite is made up of multiple phenolic resin-based carbon-coated silicon embedded in MOF-derived carbon framework. The composite exhibits excellent lithium storage performance with a reversible capacity of 1107 mA h g(-1) at 0.5 A g(-1) after 100 cycles and cycling stability capacity of 852 mA h g(-1) at a current density of 1 A g(-1) over 300 cycles. The improved electrochemical performance could be attributed to double carbon coated multi-core yolk-shell mesoporous structure in conjunction with cobalt and nitrogen co-doping, which can improve electrical conductivity and the cycle performance of silicon. Moreover, as the electrolyte blocking layer, the double-layer carbon coating is beneficial to the formation of stable solid electrolyte interphase films, and empty space inside the MOF-derived carbon multi-core yolk-shell structure can effectively mitigate the volume change of silicon during the lithiation/delithiation process.