Ultrafine ZnSe/CoSe nanodots encapsulated in core–shell MOF-derived hierarchically porous N-doped carbon nanotubes for superior lithium/sodium storage

Abstract

Rational design and development of hierarchical composite structures are of great significance for high-performance lithium-ion and sodium-ion batteries. In this work, core–shell ZIF-8@ZIF-67 nanotubes and polydopamine-derived hierarchically porous N-doped carbon composites with uniformly encapsulated ZnSe/CoSe nanodots (ZnSe@CoSe@CN) were constructed for enhanced lithium/sodium storage. Benefiting from the heterogeneous phase interface of ultrafine ZnSe/CoSe nanodots that can enhance Li⁺/Na⁺ diffusion and storage and the assembled hierarchically porous structured N-doped carbon nanotubes with high electronic conductivity and structural integrity, the bifunctional ZnSe@CoSe@CN anode delivers improved pseudo-capacitive contribution for both lithium and sodium storage, providing excellent rate capabilities (650.8 and 331 mA h g⁻¹ at 5 A g⁻¹ for lithium and sodium storage, respectively) and long-term cycling stability (a high reversible capacity of 1500 and 622.3 mA h g⁻¹ after 100 cycles at 100 mA g⁻¹ and 600 and 397.3 mA h g⁻¹ after 1000 cycles at 5 A g⁻¹ for lithium and sodium storage, respectively). This work provides an efficient design perspective to construct high-performance electrodes for energy storage devices.