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

Abstract 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 (SiN x ), a conversion‐type anode material. Here, SiN x 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 SiN x 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. SiN 0.7 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.