Carbon Nanotube-Reinforced Binder-Free Sn/SnO ₂ /Cu ₃ Sn Composite Materials for High-Capacity Lithium-Ion Battery Anodes

Tin (Sn)-based anodes have been extensively studied because of the abundant reserves, low cost of Sn, high theoretical capacity and ideal working voltages. However, the Li + insertion/deinsertion process induces huge volume changes, leading to pulverization of the active particles, limiting their commercial application. Therefore, in this work, an Sn/SnO 2 /Cu 3 Sn/CNTs composite anode material with a three-dimensional (3D) conductive network structure was synthesized by electrodeposition on a copper (Cu) collector. The results showed that when used as an anode in a lithium-ion battery (LIB), the Sn/SnO 2 /Cu 3 Sn/CNTs sample retained a reversible specific capacity of 779 mAh/g after 200 cycles, whereas a Sn/SnO 2/ Cu 3 Sn sample retained only 367 mAh/g after 100 cycles. Moreover, the Sn/SnO 2 /Cu 3 Sn/CNTs sample retained a capacity of 553 mAh/g even after 500 cycles at 1C. The Li + diffusion coefficient of the Sn/SnO 2 /Cu 3 Sn/CNTs sample was calculated as 2.82 × 10 –12 cm 2 s –1, almost four times higher than that of the Sn/SnO 2 /Cu 3 Sn sample (7.45 × 10 –13 cm 2 s –1 ). The is because the CNTs conductive network is effective in mitigating the stress changes caused by volume expansion of the composite during Li + insertion/deinsertion, which improves electronic conductivity and reduces Li + diffusion resistance. This work provides a viable approach for designing anodes with high power density.