Vanadium nitride quantum dots@carbon skeleton anode material synthesized via in situ oxidation initiation strategy

Vanadium nitride (VN) has received significant attention as a potential negative electrode material due to its remarkable theoretical and physical properties. However, the electrochemical performance needs to be improved due to its low specific surface area and the issue of being easily dissolved in electrolyte. Researches have shown that the composite structure of carbon-coated nanoscale VN particles could significantly increase the specific surface area of VN, and more importantly, and the carbon matrix can effectively restrain the dissolution of VN particles in the electrolyte, thereby improving its chemical and electrochemical performance, including specific capacity and cycling stability. Herein, VN quantum dots are synthesized and protected by uniformly coating the carbon skeleton on its surface via an in situ strategy of oxidation initiation, which initiates dopamine polymerization, forming a crystalline complex of polydopamine and vanadium. After heat treatment, the product is a composite material with VN quantum dots embedded in the amorphous carbon skeleton. The resulting small-sized and crosslinked carbon particles formed a graded pore structure, more reasonable channels provided for electrolyte ions transport quickly. When the composite material was used as the negative electrode material for supercapacitors, it exhibits the specific capacity of 391.9 F·g −1 at a current density of 0.5 A·g −1 and excellent capacity retention rate of 83.6% after 5000 cycles. The synthesis method of this quantum dot could be applied to other metal compounds and has potential applications in catalysis, environmental protection, and other fields.