Controllable Synthesis of Heterogeneous ZnS/SnS2 Encapsulated in Hollow Nitrogen-Doped Carbon Microcubes as Anode for High-Performance Li-ion Capacitors

Abstract

Li-ion capacitors (LICs) integrate the desirable features of lithium-ion batteries (LIBs) and supercapacitors (SCs), but the kinetic imbalance between the both electrodes leads to inferior electrochemical performance. Thus, constructing an advanced anode with outstanding rate capability and terrific redox kinetics is crucial to LICs. Herein, heterostructured ZnS/SnS₂ nanosheets encapsulated into N-doped carbon microcubes (ZnS/SnS₂@NC) are successfully fabricated. The sufficient ZnS/SnS₂ heterostructure possesses abundant active sites, and the built-in electric field formed at the heterojunction interface can facilitate electron/ion migration. The interconnected hollow carbon layers could reduce the electron transfer resistance effectively and accommodate the volume change of SnS₂, thereby maintaining the structural stability. Due to the synergy between multi-components, the ZnS/SnS₂@NC anode demonstrates impressive Li storage performance with an excellent cyclic durablity (690 mAh g⁻¹ at 0.5 A g⁻¹ after 600 cycles) and considerable rate capability. Moreover, when matched with active carbon, the ZnS/SnS₂@NC based LIC device delivers an admirable energy density of 134.1 Wh kg⁻¹ and a high power output of 11,250 W kg⁻¹, as well as remarkable capacity retention of 73.2 % after 6,000 cycles at 1.0 A g⁻¹. The experimental results demonstrate the significance of optimized heterointerface engineering toward construction of electrode materials with high-performance for Li storage.