Scalable micron-sized amorphous silicon nitride for Li-ion battery anode
Asbjørn Ulvestad
Department for Battery Technology, Institute for Energy Technology
Silicon anodes for Li-ion batteries exhibit very high capacity but suffers from significant swelling and capacity fade during cycling. Nanoparticles of amorphous and substoichiometric silicon nitride (a-SiNx) have previously been demonstrated to exhibit both high reversible capacity and cycling stability. In this work we demonstrate the scalable synthesis of micron-sized particles of a-SiNx and show that such particles not only exhibit the same high capacity and similar stability as their nanoparticulate counterparts, but also higher first cycle Coulombic efficiency than has previously been reported for such materials (>80%). TEM and FIB/SEM analyses reveal that the materials are structurally stable during lithiation and delithiation. Dilatometry experiments also determine that electrodes containing a-SiNx exhibit lower swelling than those containing pure Si, both with regards to reversible expansion/contraction during lithiation/delithiation, and irreversible swelling during cycling.