Embedding ZnSe nanodots in nitrogen-doped hollow carbon architectures for superior lithium storage

Abstract

Transition metal chalcogenides represent a class of the most promising alternative electrode materials for high-performance lithium-ion batteries (LIBs) owing to their high theoretical capacities. However, they suffer from large volume expansion, particle agglomeration, and low conductivity during charge/discharge processes, leading to unsatisfactory energy storage performance. In order to address these issues, we rationally designed three-dimensional (3D) hybrid composites consisting of ZnSe nanodots uniformly confined within a N-doped porous carbon network (ZnSe ND@N-PC) obtained via a convenient pyrolysis process. When used as anodes for LIBs, the composites exhibited outstanding electrochemical performance, with a high reversible capacity (1,134 mA·h·g−1 at a current density of 600 mA·g−1 after 500 cycles) and excellent rate capability (696 and 474 mA·h·g−1 at current densities of 6.4 and 12.8 A·g−1, respectively). The significantly improved lithium storage performance can be attributed to the 3D architecture of the hybrid composites, which not only mitigated the internal mechanical stress induced by the volume change and formed a 3D conductive network during cycling, but also provided a large reactive area and reduced the lithium diffusion distance. The strategy reported here may open a new avenue for the design of other multifunctional composites towards high-performance energy storage devices.