Sub-micron silicon/pyrolyzed carbon@natural graphite self-assembly composite anode material for lithium-ion batteries

Si/C@NGs composite containing flake-shaped sub-micron sized silicon (Si) enwrapped by pyrolyzed carbon and natural graphite (NG) was successfully prepared by spray-drying-assisted self-assembly method and was systematically studied as an anode material for lithium-ion batteries. The as-prepared Si/C@NGs composite material has a loading amount of sub-micron sized silicon as low as 6.7 wt%. The Si/C@NGs composite has a hierarchical structure with Si/C embedded into natural graphite which further assembles into larger secondary particles of ∼20–50 μm. Compared with pure silicon, the as-synthesized Si/C@NGs composite has multi-layer carbon coating as well as voids to alleviate the structural changes of Si during charging/discharging, exhibits an initial efficiency of 82.8% and a capacity retention of 428.1 mA h g⁻¹(1524.0 mA h g⁻¹vs. Si) after 100 cycles at 0.1 A g⁻¹. The remarkable cycling performances, high initial cycle efficiency together with low-cost manufacturing process make Si/C@NGs composite appealing for commercial applications.