Gas-Phase Synthesis of Silicon-Rich Silicon Nitride Nanoparticles for High Performance Lithium-Ion Batteries

The practical application of silicon-based anodes is severely hindered by continuous capacity fade during cycling. A very promising way to stabilize silicon in lithium-ion battery (LIB) anodes is the utilization of nanostructured silicon-rich silicon nitride (SiNx), a conversion-type anode material. Here, SiNx with structure sizes in the sub-micrometer range have been synthesized in a hot-wall reactor by pyrolysis of monosilane and ammonia. This work focusses on understanding process parameter-particle property correlations. Further, a model for the growth of SiNx nanoparticles in this hot-wall-reactor design is proposed. This synthesis concept is of specific interest regarding simplicity, flexibility, and scalability: A way utilizing any mixtures of precursor gases to build multi-functional nanoparticles that can be directly used for LIBs instead of focusing on modification of nanostructures after they have been formed. Lab-scale production rates as high as 30 g h(-1) can be easily achieved and further scaled. SiN0.7 nanoparticles provide a first cycle coulombic efficiency of 54%, a specific discharge capacity of 1367 mAh g(-1), and a capacity retention over 80% after 300 cycles at 0.5 C (j = 0.68 mA cm(-2)). These results imply that silicon-rich silicon nitrides are promising candidates for high-performance LIBs with very high durability.