High crystalline VSe2@PANI collaborating with ether electrolyte to construct efficient sodium-ion storage interface

VSe 2 is a promising anode material for sodium-ion batteries due to its exceptional electrical conductivity, large layer-spacing, and high-capacity conversion energy storage mechanism. However, inherent defects and unsatisfactory electrical conductivity of VSe 2 hinder its practical applications as anode, resulting in low capacity and unstable cycling performance. To address these issues, we synthesized a VSe 2 @PANI (polyaniline) composite through hydrothermal and in-situ polymerization steps to reduce inherent defects and improve crystallinity of VSe 2 for preventing its volume expansion and improving electrical conductivity. Meanwhile, simulation results reveal that the binding energy (E b ) between NaCF 3 SO 3 and VSe 2 @PANI is lower in dimethoxyethane (DME) compared to that in Diglyme, facilitating kinetics for Na + intercalation/deintercalation reactions. Consequently, collaborating with DME electrolyte, the VSe 2 @PANI anode exhibits a high reversible capacity (572 mA h g −1 at 0.5 A g −1 ), exceptional rate capability (303 mA h g −1 at 5 A g −1 ), and excellent cycling stability (244 mA h g −1 after 1000 cycles at 5 A g −1 ). Finally, a sodium-ion capacitor based on the VSe 2 @PANI anode achieved an ultra-high energy density of 243 W h kg −1 , and demonstrated unexpectedly stable performance over 5000 cycles as well. This study highlights the importance of co-regulation of the electrode/electrolyte interface in enhancing electrochemical performance. • The VSe 2 @PANI was optimized by PANI to reduce internal defects and enhance crystallinity, enabling efficient Na + storage. • The weak Na + –DME binding energy enables a compact solvation structure, enhancing ion transport and desolvation kinetics. • Collaborating with DME electrolyte, the VSe 2 @PANI anode exhibits a high reversible capacity of 572 mA h g −1 at 0.5 A g −1 . • The SICs device based on VSe 2 @PANI anode exhibited an ultra-high energy density and excellent cycling stability.