An interface-enhanced continuous 2D-carbon network enabling high-performance Si anodes for Li-ion batteries

Abstract

Silicon (Si) has been regarded as a promising anode material for next-generation Li-ion batteries by virtue of its high theoretical capacity and low working potential. Although various strategies have been proposed to solve the problems of Si anodes (e.g., poor electrical conductivity and volume effects), there is still a lack of efficient ways to simultaneously realize the high capacity, good rate capability and stability of Si anodes. Herein, an interface-enhanced 2-D carbon network is introduced into the Si anode by a simple templating method using gelatin as a carbon precursor. Electrochemical measurement, in situ Raman spectroscopy, and theoretical simulation results suggest that the unique gelatin-derived carbon nanosheet (GCNS) structure not only promotes the Li-ion diffusion and electron transport within the Si anode, but also stabilizes the Si structure. The Si anode having the interface-enhanced GCNS network (Si@GCNS) exhibits high charge capacity (2975 mA h g⁻¹ at 0.2 A g⁻¹), good rate capability (1892 mA h g⁻¹ at 5 A g⁻¹), and long lifetime (with a capacity retention of 83.4% after 400 cycles), superior to the Si-based anodes modified by 3-D or 2-D carbons. Moreover, a pouch cell based on the Si@GCNS anode and a commercial LiFePO₄ cathode shows a high energy density of ∼460 W h kg⁻¹ and good cycling performance.