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Spray pyrolysis is a scalable process to fabricate functional particles as cathode/anode materials in rechargeable batteries from precursor solutions. However, one prerequisite of spray pyrolysis to achieve uniform particle-to-particle composition and structure is a stable precursor solution, restricting its usage to highly soluble salts. Otherwise, extremely acidic precursors are necessary to ease the uncontrollable hydrolysis of the salts and the subsequent precipitation. Moreover, strong reducing agents such as H2 are also needed for complete solid-state reactions, introducing potential safety concerns. Herein, for the first time, we develop a novel process, colloidal spray pyrolysis (CSP), which can eliminate all the prerequisites simultaneously. Our process can generate particles directly from a multiphase precursor in mild processing conditions through in-situ solid-state reactions. The product structure and composition can be precisely designed based on aerosol dynamics and reaction kinetics. By applying CSP, Sn@C particles with three distinct interior nanostructures have been synthesized and evaluated as anodes for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The best performing Sn@C anode delivers 627.9 mAh/g at 2 C with capacity retention of 88.5% after 1500 cycles in LIBs and demonstrates superior rate capability for SIBs. This novel CSP process is promising in preparing electrode materials in LIBs and SIBs for future practical applications.

A cost-effective, environmentally friendly and industrialized method of using low-grade sources to prepare high-performance anode material for lithium ion batteries (LIBs) with high energy density and long cycle life is both appealing and challenging. Herein, we present a low-cost, scalable and controllable approach for preparing unique sub-micrometer core-shell structure nanocrystal-FeSi-embedded Si/SiOx (FSO) anode material directly from a low-grade Fe-Si alloy. The sub-micrometer FSO anode materials are controlled by in-situ reaction of the Fe-Si-O in the Fe-Si alloy according to the phase diagram. The XRD and Rietveld refinement results indicate that when the treatment temperature increase, (i) FeSi phase appears together with Si and FeSi2, and then (ii) Fe3Si phase appears together with Si and FeSi. Most importantly, benefited from the formation of the amorphous SiOx as buffer layer and self-conductive nanocrystal-FeSi as a robust skeleton to mechanically support the large volume change of Si during cycling, the sub-micrometer core-shell structure FSO anode exhibits a high capacity (931.3 mA h g−1) at 50 mA g−1 and a prolonged cycle performance with 86% capacity retention over 1000 cycles at 1 A g−1. The full cell with prelithiated FSO as the anode and commercial LiCoO2 as the cathode delivers a high energy density of 467.5 W h kg−1 at the 0.05 C. This work provides a promising route for commercial production of high-performance Si/SiOx-based anode materials in LIBs.