The invention provides a sandwich structure MCMB-Si-C
silicon-carbon negative
electrode material and a preparation method and application thereof.The preparation method comprises the steps that 1,
pitch serves as a
raw material to prepare mesocarbon microbeads, by means of
solid-
liquid interface pushing force in the mesocarbon microbead growth process, uniform attachment of nanometer
silicon to the surfaces of the mesocarbon microbeads is achieved through a one-step self-
assembly method, and the mesocarbon microbeads are formed; the MCMB (at) Si
silicon-carbon negative
electrode material taking the mesocarbon microbeads as the core is obtained. And (2)
coating the surface of the silicon-carbon negative
electrode material with a layer of carbon material to construct the MCMB-Si-C silicon-carbon negative
electrode material with a sandwich structure, and forming a compact
carbon layer on the outermost layer after high-temperature
carbonization treatment by using a liquid-phase
coating process, so that the double functions of a buffer layer and a conductive layer can be achieved. The
composite material is composed of mesocarbon microbeads as a core,
nano silicon as an intermediate layer and a compact
carbon layer as an outermost layer. The
sandwich type buffer structure effectively improves the
volume change of the negative electrode in the
lithium intercalation /
lithium removal process, endows the silicon-carbon negative
electrode material with the sandwich structure with excellent cycle stability and rate capability, and is beneficial to formation of a more stable
solid electrolyte membrane.