Si@Nitrogen-Doped Carbon Nanoparticles for Lithium-Ion Battery Anodes

The formation of a core–shell structure by coating silicon (Si) nanoparticles with a carbon layer is considered a promising method to address the poor conductivity of a Si-based anode and volume expansion of silicon particles during the charging/discharging process. However, Si/C composite anodes usually perform below expectations with a single layer of carbon utilized as the coating layer, while introducing multilayer carbon coating results in the additional complexity and cost. To overcome this challenge, in this work, waterborne polyurethane (WPU) had been simply mixed with the Si nanoparticles to form the Si/WPU composite via the hydrogen bonds, and the core–shell structure with the single carbon layer containing N atoms (Si@NC) was obtained after the pyrolysis of the composite. The carbon layer not only significantly alleviated the breakage of the anode caused by the volume expansion of Si nanoparticles but also optimized the rate performance of the anode. At a current density of 0.5 A g–1, the discharge specific capacity of the Si@NC anode is still as high as 945.63 mAh g–1 after 300 cycles, surpassing various single-layer carbon and multilayer carbon-coated Si-based anodes. This work provides a convenient and feasible method for preparing economical Si/C composite anode materials.