Bimetal-organic framework derived Co9S8/ZnS@NC heterostructures for superior lithium ion storage.

Heterostructure engineering of electrode materials, which is expected to accelerate the ion/electron transport rates driven by a built-in internal electric field at the heterointerface, offers unprecedented promise in improving their cycling stability and rate performance. Herein, carbon nanotubes with Co9S8/ZnS heterostructures embedded in a N-doped carbon framework (Co9S8/ZnS@NC) have been rationally designed via an in-situ vapor chemical transformation strategy with the aid of thiophene, which not only acted as carbon source for the growth of carbon nanotubes but also as sulfur source for the sulfurization of metal Zn and Co. Density functional theory (DFT) calculation shows an about 3.24 eV electrostatic potential difference between ZnS and Co9S8, which results in a strong electrostatic field across the interface that makes electrons transfer from Co9S8 to the ZnS side. As expected, a stable cycling performance with reversible capacity of 411.2 mAh g(-1) at 1000 mA g(-1) after 300 cycles, excellent rate capability (324 mAh g(-1) at 2000 A g(-1)) and a high percentage of pseudocapacitance contribution (87.5% at 2.2 mv/s) for lithium-ion batteries (LIBs) are achieved. This work provides a possible strategy for designing multicomponent heterostructural materials for application in energy storage and conversion fields.