Comparative Analysis of Silicon-Carbon Composite, Graphite, and Microscale Silicon Anodes for Next-Gen Lithium-Ion Batteries

While silicon can significantly enhance the energy density of lithium-ion battery (LiB) anodes, its volume expansion of +280% in the fully lithiated Li 15 Si 4 state and the resulting poor cycle life have limited its use in commercial applications. This study investigates a novel silicon-carbon (Si/C) composite anode material, composed of a carbon host structure infiltrated by silicon. The Si/C performance characteristics is compared with those of state-of-the-art graphite (Gra) and silicon-dominant (Si) anodes in full-cells with an NCA cathode. Full-cell charge and discharge rate tests show the same rate capability for the Si/C and Si anodes, which outperform the Gra anode. For a capacity retention of 80%, the cycle life of the full-cells with the Si/C anode of ∼650 cycles far exceeds the ∼200 cycles obtained with the Si anode but is still short of the ∼1000 cycles obtained with the graphite anode. The projected stack-level gravimetric/volumetric energy densities assuming commercial separator and current collector properties are ∼7%/∼16% higher for the Si/C compared to the graphite anode, approaching the ∼15%/∼20% energy density gains of the Si anodes. Consequently, this Si/C composite is a promising anode active material for LiBs, offering a combination of high energy density, rate capability, and lifetime.