Ultrafine ZnSe/CoSe Nanodots Encapsulated in Core-shell MOFs-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 composite 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 the 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 mAh 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 mAh g -1 after 100 cycles at 100 mA g -1 , and 600 and 397.3 mAh 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.