First-principles design of cation-doped H-Nb2O5 negative electrode material and its electrochemical performance investigation
Niobium-based oxide negative electrode materials have attracted much attention because of their excellent lithium-ion diffusion rate,but their poor electrical conductivity severely limits their large-scale application.In this study,the effects of different cationic doping on the bandgap of H-Nb2O5 state density were calculated by using the VASP software package and Hubbard modified generalized gradient approximation(GGA+U).The results show that Ni,Co and Ag can improve the electronic structure of H-Nb2O5 and reduce the band gap compared to pure phase H-Nb2O5 from 0.35 eV to 0,0.13 and 0.17 eV,respectively.On this basis,H-Nb2O5 doped with Ni,Co and Ag was prepared using the solid phase method,and its structure and electrochemical lithium storage mechanism were studied,respectively.The experimental results show that Ni-doped H-Nb2O5 exhibits the best electrochemical performance among the doped H-Nb2O5 anodes.The specific discharge capacity reaches 203 mAh/g at 2.5 C.The capacity remains at 89 mAh/g at 50 C.The capacity loss rate per 3000 cycles is only 0.002 1%under the 25 C condition.The calculation results show that the migration barrier of Ni-doped H-Nb2O5 is 0.674 eV,much lower than 0.847 eV of pure H-Nb2O5.
lithium-ion batterycationic dopingniobium oxidefirst principlesnegative electrode material
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