A ?Reinforced Concrete? Structure of Silicon Embedded into an In Situ Grown Carbon Nanotube Scaffold as a High-Performance Anode for Sulfide-Based All-Solid-State Batteries

Replacing lithium with a Si anode is a very promising route for the development of all-solid-state batteries (ASSBs) to eliminate the uncontrolled growth of Li dendrites. However, the Si anode still undergoes low electric conductivity and severe volume changes during cycling leading to poor interfacial stability against solid electrolytes. Herein, we report an integrated anode of silicon/ carbon-nanotubes/carbon (Si/CNTs/C) for the stable operation of sulfide-based ASSBs. The in situ synthesized Si/CNTs/C from Mg2Si reacting with CaCO3 in the presence of a ferrocene catalyst for CNT growth exhibits a similar '' reinforced concrete '' structure, where CNTs provide a mechanical stable scaffold for Si particle embedding. In this composite, CNTs act as a '' reinforcing bar '' fixing Si active particles tightly, which not only maintain good interfacial contact between Si and Li6PS5Cl components but also alleviate the volume expansion of Si and prevent the lithium-ion channel of Li6PS5Cl from being destroyed. As the anode for ASSBs, the reversible capacity of Si/CNTs/C was 1226 mA h g-1 after 50 cycles at 50 mA g-1. This study provides an idea for the application of Si-based materials in ASSBs.