Yaxiong Tian,Gongshu Wang,Lin Zhu,Huaxia Chen,Ting Sun
The morphology and structural engineering of V 2 O 3 anode of lithium-ion batteries plays a significant role in improving the energy storage performance since V 2 O 3 material suffers from tremendous volume changes, self-aggregation and intrinsic poor conductivity. In this work, we devise a novel 3D self-supporting N, C doped-V 2 O 3 (NC@V 2 O 3 ) composite, which consist of nanoparticles by adding urea to obtain 3D flower-like V 2 O 3 microspheres precursor during the annealing process. The V 2 O 3 microspheres self-assembled with nanosheets is fabricated by one-step solvothermal route. A possible morphological evolution mechanism of fabrication of granular NC@V 2 O 3 is explored by SEM and TEM. As anode in Li + batteries, NC@V 2 O 3 material exhibits outstanding rate performance of 227 mAh g −1 at the current density of 2 A g −1 and a reversible capacity of 272 mAh g −1 at 0.1 A g −1 after 200 cycles. Such great performance is attributed to granulated NC@V 2 O 3 architecture, which increasing the contact area of electrode-electrolyte and shortening Li + diffusion pathway. In addition, the doped N and C atoms can create more defects, providing electrochemical active sites and electronic conduction. The achievements of this study may provide new insight into design novel architecture of V 2 O 3 anode.
Lithium-sulfur (Li-S) batteries receive considerable attention for their high energy density, but their slow reaction kinetics and poor shuttle effects raise concerns. Here, synthesized V 2 O 3 spheres were used as substrate templates, and ZIF-67 particles were grown on the surface of V 2 O 3 by in-situ growth method. ZIF-67 was calcined at high temperature to form N-doped porous carbon attached to the surface of V 2 O 3 spheres (Co-NC@V 2 O 3 -sp). The hollow structure of V 2 O 3 spheres provided abundant buffer space for sulfur volume expansion and enhanced the stability of the battery cycle. In addition, the great pore volume and specific surface area resulted in abundant active physical and chemical sites, the strong chemical adsorption of V 4+ effectively trapped polysulfides , and the cobalt nanoparticles on the surface effectively consolidated the active sites. The rapid transformation between shuttle effect and polysulfides were limited by physical coordination and chemisorption, respectively. Owing to this double synergistic effect, the prepared composites had an initial discharge capacity of 1483 mAh g −1 (0.1 C). The initial specific capacity reached 1002 mAh g −1 (0.5 C), and it achieved 645 mAh g −1 after 500 cycles. These results showed that Co-NC@V 2 O 3 -sp has high electrochemical function in Li-S batteries.
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