SnSe2/CoSe2@N-C composites with high energy storage performance for lithium ion batteries

Abstract

Tin-based selenide is regarded as one of the promising anode materials for the advanced lithium ion batteries (LIBs) due to its high theoretical capacity and environmental friendliness. However, the huge volume change during cycling has severely hampered their practical application. Herein, core–shell nanostructured SnSe₂/CoSe₂@N-C composites are prepared by in-situ selenization of carbon-encapsulated Co-imidazole-based ZIF-67 grown on prefabricated SnO₂ nanoparticles. The composite exhibits good structural stability and improved electrical conductivity when used as anode, since the N-doped carbon skeleton originated from ZIF-67 can act as an elastic protecting and electronically conductive layer to alleviate the volume expansion. In addition, the CoSe₂ derived from ZIF-67 plays an important role in the enhancement of the specific capacity. As anode for LIBs, the SnSe₂/CoSe₂@N-C shows excellent cycle stability with a capacity of 1111.8 mA h g⁻¹ after 200 cycles at the current density of 200 mA g⁻¹. Even at a high rate of 1000 mA g⁻¹, the specific capacity of 597.3 mA h g⁻¹ can be achieved after 450 cycles.