Hybrid Plasma Spray Synthesis of Spherical Si_0.8Ge_0.2 Alloy Nanoparticles for Lithium-Ion Battery Anodes

Despite its ultrahigh theoretical capacity, silicon anodes for lithium-ion batteries suffer from severe capacity decay caused by over 300% volume changes during cycling. While Si-Ge alloying and spherical nanostructuring have been demonstrated to improve ionic/electronic transport and mechanical resilience, scalable synthesis of homogeneous, sub-150 nm SiGe nanospheres from low-cost precursors remains challenging. Here, we report a hybrid plasma-spraying physical vapor deposition (PS-PVD) process that directly converts metallurgical-grade Si and Ge powders into phase-pure Si_0.8Ge_0.2 nanospheres (<100 nm) at a continuous rate of 1 g min^-1. The co-condensation mechanism during formation was elucidated through molecular dynamics (MD) simulations, which revealed a process initiated by inhomogeneous nucleation and followed by uniform cluster growth and spheroidization. Multiscale characterization confirmed the spherical morphology, compositional uniformity, and crystalline structure of the produced Si_0.8Ge_0.2 nanoparticles. The resulting anodes exhibited a stable capacity of ~1500 mAh g^-1 at 0.1C over 100 cycles (>80% retention) and a Coulombic efficiency of ~98%. This approach bridges the gap between high-performance design and industrial manufacturability, offering a practical route to next-generation anodes for electric vehicles.