Binder-Free Lightweight Silicon-Carbon-Bucky Paper Electrodes

Silicon (Si)-based electrodes are promising candidates for next-generation lithium-ion batteries due to their high theoretical capacity. However, their commercialization is hindered by challenges such as severe volume expansion, low electrical conductivity, and reliance on binders and metallic current collectors, which reduce energy density and increase manufacturing costs. To address these limitations, we developed a binder-free Si-based electrode (Si@CC@BP) by impregnating a silicon-carbon composite (Si@CC) into a freestanding carbon nanotube (CNT)-based paper called Bucky Paper (BP) during its synthesis. This approach leverages BP's high porosity, high conductivity, mechanical strength, and lightweight nature to enhance electrode performance while eliminating the need for binders and relatively heavy metallic current collectors. The Si@CC@BP porous electrode retained ∼74% of its initial capacity after 180 cycles, outperforming the conventional slurry-coated Si/Cu electrode. Compared to the Si/Cu electrode, the Si@CC@BP electrode achieved a ∼75% higher areal capacity (1.84 mAh cm^-2) and ∼107% higher electrode-level gravimetric capacity (207.14 mAh g_elec^-1) after 180 cycles at 0.42 A cm^-2. Furthermore, the binder-free approach reduced electrode weight by at least 15%, improving gravimetric capacity while lowering manufacturing complexity and environmental impact. Full cells with Si@CC@BP anode and NMC622 cathode demonstrated stable cycling up to 100 cycles at 0.3C. This work provides a scalable and sustainable strategy for developing lightweight, high-performance Si-based anodes toward practical implementation in lithium-ion batteries.