Preparation of Silicon/Carboxymethylcellulose-Polydopamine/Carbon Nanotube Composite Material and Its Electrochemical Performance as Anode of Lithium-Ion Batteries

Abstract Silicon (Si) is a universally acknowledged alternative for next-generation anode material of lithium-ion batteries due to its extremely high theoretical capacity of 4200 mAh/g. However, its practical applications were limited due to relatively lower electrical conductivity and larger volume expansion/contraction. Therein, the silicon/carboxymethylcellulose-polydopamine/carbon nanotube ternary silicon-based composite electrode materials (Si@CMC-PDA@CNT) were successfully prepared by the in situ method. The successful construction of this structure not only enhanced the electronic conductivity but also stabilized the composite electrode material, thereby endowing the electrode material with excellent mechanical properties and electrochemical stability. By optimizing the added carbon nanotubes, the ternary composite material containing 0.025 g of carbon nanotube (Si@CMC-PDA@CNT-2) exhibited optimal performances. It demonstrated a discharge specific capacity of 1540.8 mAh/g in the initial cycle and 1232.6 mAh/g after the 100 cycles under the current density of 0.2 A/g, with an 81.6% of the first coulombic efficiency. Additionally, it displayed the enhanced rate performances, and under current densities of 0.1, 0.2, 0.4, 0.8, and 1 A/g, its discharge specific capacities were 1861.7, 1700.9, 1453.6, 1133.7, and 1009.0 mAh/g, respectively. The charge storage process indicated that the electrochemical process was a diffusion and capacitive co-controlled process.