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To improve the electrochemical performance of positive electrode materials, constructing graded nanostructures is a worthwhile approach. This study successfully synthesized nitrogen-doped graphene quantum dots (NGQD) modified (Ni 0.5 Co 0.5 ) 3 V 2 O 8 on a carbon nanotube (CNT) substrate to construct self-supporting electrodes for high-performance supercapacitors. The (Ni 0.5 Co 0.5 ) 3 V 2 O 8 nanosheets were successfully wrapped onto the CNT surface through a solution impregnation process, which increased the specific surface area and interlayer spacing of the material. Furthermore, the electrochemical properties of the electrode material underwent significant enhancement due to the synergistic interplay between metal ions and the numerous redox centers. The embedding of the NGQD enriched the materials with active sites and further improved its specific capacity without compromising the structure intergrity of the layer configuration. Using CNT as the substrate ensured the self-supporting nature of the electrode. Consequently, the (Ni 0.5 Co 0.5 ) 3 V 2 O 8 /NGQD@CNT composite exhibits an ultra-high specific capacitance of 3018.2 F g -1 at 1 A g -1 and 2332 F g -1 at 10 A g -1 . The asymmetric supercapacitor constructed with (Ni 0.5 Co 0.5 ) 3 V 2 O 8 /NGQD@CNT and activated carbon (AC) presented an impressive energy density of 160.2 Wh kg -1 at a power density of 800 W kg -1 . After 8000 charge-discharge cycles, the capacity retention rate was 78.5 %, with a Coulo mbic efficiency consistently above 98 %., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)