Interfacial Ohmic contact engineering in MoSe2/Ti3C2 Heterostructures for high-performance sodium-ion capacitors

The development of sodium-ion capacitors (SICs) is hindered by the kinetic mismatch between sluggish ion diffusion in battery-type anodes and rapid surface reactions in capacitive cathodes. Herein, a MoSe2/Ti3C2 heterostructure with ohmic contact interfaces is synthesized via a facile solvothermal method, which simultaneously improve charge transfer kinetics and structural stability. Density functional theory (DFT) calculations reveal that the MoSe2/Ti3C2 interface reduces Na+ diffusion energy barriers while providing efficient electron transport pathways. Notably, the MoSe2/Ti3C2 heterostructure as a sodium-ion battery (SIB) anode delivers a high reversible capacity of 506.2 mAh g-1 at 0.1 A g-1 and retains a capacity of 314.2 mAh g-1 at 10.0 A g-1, demonstrating exceptional rate capability. When coupled with a commercial activated carbon (AC) cathode, the SIC device achieves energy densities of 101.3 Wh kg-1 at 297.8 W kg-1, retaining 26.1 Wh kg-1 even at 11.2 kW kg-1. Additionally, the device exhibits outstanding cycling stability with 97.5 % capacity retention after 5500 cycles. These results highlight the critical role of ohmic contact engineering in optimizing hybrid electrode design and provide a pathway for advancing high-performance SICs.