Fabricating a high-performance anode by coating a carbon layer on a yolk–shell bimetallic selenide microsphere for enhanced lithium storage†

Abstract

The rational synthesis of an electrode material with a highly active and stable architecture is very critical to achieving high-performance electrochemical energy storage. Herein, N-doped carbon restricting yolk–shell CoSe₂/Ni₃Se₄ (CoSe₂/Ni₃Se₄@NC) flower-like microspheres were successfully synthesized from solid CoNi-glycerate microspheres using a coating technology as an anode material for lithium-ion batteries (LIBs). The unique yolk–shell CoSe₂/Ni₃Se₄@NC microspheres with hierarchical pores can increase the contact area with the electrolyte and provide enough transfer channels for the diffusion of Li⁺. The carbon layer on the surface of CoSe₂/Ni₃Se₄@NC can not only improve the conductivity of the electrode but also provide the protective effect of active nanosheets during the process of synthesis, avoiding the overall structure collapse during the charge/discharge process of LIBs. Benefiting from the high conductivity, hollow structure, and elastic NC shell bestowed by the unique architecture, the yolk–shell CoSe₂/Ni₃Se₄@NC anode shows excellent lithium storage performances, such as an excellent reversible specific capacity of 319 mA h g⁻¹ at a current density of 1000 mA g⁻¹ after 500 cycles and excellent cycling stability. This synthesis strategy provides a new way to optimize the lithium storage performance of transition metal compound electrode materials, which is helpful to the design of the next generation of high-performance LIBs.