Scalable synthesis of interconnected hollow Si/C nanospheres enabled by carbon dioxide in magnesiothermic reduction for high-performance lithium energy storage

Silicon (Si) anode has great potential for use in practical Li-ion batteries due to large specific capacity beyond that of conventional graphite. The main challenges for Si are large volume changes (similar to 400%) during (de)alloying with lithium caused material cracking and pulverization, instability of solid electrolyte interphase (SEI) layer and electric contact loss. Herein, we demonstrate a novel interconnected hollow Si/C nanospheres with thin shells consisting of Si crystals and highly wrinkled amorphous carbon layers synthesized by introducing carbon dioxide (CO2) as a green carbon source in magnesiotherimic reduction to accelerate the commercialized application of Sibased anodes. Interconnected carbon networks in the Si intervals and MgO as cores generate simultaneously via the reaction between CO2 and excess Mg vapor. Additionally, hollow structure can be realized after the removal of in-situ generated MgO templates by acid etching. Unique interconnected Si/C hybrid delivers a high capacity, impressive cycling performance and good Coulombic efficiency, benefiting from the improved Li+ ions transportation and electron transfer kinetics and the volume butter effects of hollow architecture. In particular, such new synthetic route is low-cost and easily scaled up, which probably facilitates the commercial application of Si/C hybrids for high energy Li-ion batteries.

Automated summary

The study demonstrates a novel interconnected hollow Si/C nanospheres with thin shells consisting of Si crystals and highly wrinkled amorphous carbon layers, synthesized by introducing CO2 as a green carbon source in magnesiotherimic reduction to accelerate commercial application. The interconnected carbon networks and MgO cores are simultaneously generated via the reaction between CO2 and excess Mg vapor, with the hollow structure realized after removing in-situ generated MgO templates through acid etching. The unique interconnected Si/C hybrid delivers high capacity, impressive cycling performance, and good Coulombic efficiency, benefiting from improved Li+ ion transportation and electron transfer kinetics, as well as the volume buffering effects of the hollow architecture.