摘要
Silicon suboxide(SiOx)is considered to be one of the most promising materials for next-generation anode due to its high energy density.For its preparation,the wet-chemistry method is a cost-effective and readily scalable route,while the so-derived SiOx usually shows lower capacity compared with that prepared by high temperature-vacuum evaporation route.Herein,we present an elaborate particle structure design to realize the wet-chemistry preparation of a high-performance SiOx/C nanocomposite.Dandelion-like highly porous SiOx particle coated with conformal carbon layer is designed and prepared.The highly-porous SiOx skeleton provides plenty specific surface for intimate contact with carbon layer to allow a deep reduction of SiOx to a low O/Si ratio at relatively low temperature(700℃),enabling a high specific capacity.The abundant mesoscale voids effectively accommodate the volume variation of SiOx skeleton,ensuring the high structural stability of SiOx@C during lithiation/delithiation process.Meanwhile,the three-dimensional(3D)conformal carbon layer provides a fast electron/ion transportation,allowing an enhanced electrodereaction kinetics.Owing to the optimized O/Si ratio and well-engineered structure,the prepared SiOx@C electrode delivers an ultra-high capacity(1,115.8 mAh·g^-1 at 0.1 A·g^-1 after 200 cycles)and ultra-long lifespan(635 mAh·g^-1 at 2 A·g^-l after 1,000 cycles).To the best of our knowledge,the achieved combination of ultra-high specific capacity and ultra-long cycling life is unprecedented.
基金
This work was financially supported by the National Natural Science Foundation of China(Nos.U1637202 and 51634003)
the National Key R&D Program of China(No.2018YFB0905600)
Beijing Municipal Education Commission-Natural Science Foundation Joint Key Project(No.KZ201910005003).
