Biomass-derived hard carbon host with added commercial silicon for high-capacity lithium-ion battery anodes

Abstract

Silicon–carbon composites were prepared by introducing commercial silicon powder into a barley husk (BH)-derived SiO₂/C hard-carbon host, producing Si–SiO₂–C hybrid anodes with controlled Si loadings (20–50 wt%). Structural integration of Si within the porous BH matrix enabled mixed Li-storage behaviour, combining hard-carbon adsorption/pore filling with silicon alloying/dealloying. Increasing Si content raised reversible capacity but increased polarisation and accelerated capacity fade, indicating a trade-off between active Si utilisation and mechanical/electrochemical stability. At C/5 (defined relative to each anode's theoretical capacity), BH50–Si20, BH35–Si35 and BH20–Si50 delivered approximately ∼670, ∼880 and ∼1180 mAh g⁻¹ after 50 cycles, respectively, compared with ∼380 mAh g⁻¹ for BH and ∼350 mAh g⁻¹ for graphite under the same protocol. Among the hybrids, BH35–Si35 provided the most balanced behaviour, combining high initial coulombic efficiency (∼87%) with stable voltage/dQ/dV signatures indicative of moderated silicon-driven degradation. A BH20–Si50//NMC622 full cell delivered 165 mAh g⁻¹ (cathode basis) with 98.3% initial coulombic efficiency and retained 89% capacity after 100 cycles at C/5, demonstrating compatibility with a high-voltage layered cathode and practical energy-density potential.