Three-dimensional porous carbon nanosheet networks anchored with Cu6Sn5@carbon as a high-performance anode material for lithium ion batteries

Abstract

The poor cycling stability resulting from large volume change is the major obstacle to the application of tin-based anode materials. In this paper, three-dimensional porous carbon nanosheet networks anchored with Cu₆Sn₅@carbon nanoparticles (10–35 nm) as a high-performance anode for lithium ion batteries are synthesized via a self-assembly NaCl template-assisted in situ chemical vapor deposition strategy. The composite exhibits superior rate capability (523, 443, 395, 327, 281, and 203 mA h g⁻¹ at 0.2, 0.5, 1, 2, 5, and 10 A g⁻¹, respectively) and excellent cycling stability (396.8 mA h g⁻¹ at 1 A g⁻¹ for the first cycle and maintains 92.3% after 200 cycles). The superior performance is attributed to the unique architecture: inactive metal copper serves as a “buffer matrix” and relaxes the large volume change of the tin; a uniform distribution of nano-sized Cu₆Sn₅ makes the inevitable stress/strain small, meanwhile it provides a short path for lithium ion diffusion; onion-like carbon shells not only prevent the Cu₆Sn₅ nanoparticles from agglomerating and growing but also offer mechanical support to accommodate the stress associated with the volume change of tin upon cycling, thus alleviating pulverization; 3D porous carbon nanosheet networks ensure the mechanical integrity and facilitate lithium ion diffusion as well as electron transportation.