In-situ N-doped MnCO3 anode material via one-step solvothermal synthesis: Doping mechanisms and enhanced electrochemical performances

摘要

In-situ N-doped MnCO3 microcrystal was prepared by a mild one-step solvothermal process for the first time. The influences of N-doping on microstructures and electrochemical performances of MnCO3 microcrystal have been investigated systematically. A plausible mechanism for the in-situ N-doping in MnCO3 also has been proposed. It is found that nitrogen was successfully doped into the MnCO3 by the substitution of lattice oxygen, generating a specific defect structure with oxygen vacancies and narrowing the band gap of MnCO3 effectively from 5.021 to 3.885 eV. When used as anode material, the as-obtained N-doped MnCO3 exhibits outstanding electrochemical performances: it delivers a large capacity of 685 mAh g(-1) after 600 cycles at 1 C; exhibits a superior high-rate performance and long-term stability with a high capacity of 437 mAh g(-1) even after 1000 cycles at a very large current rate of 5 C. Compared with the pristine MnCO3, such the outstanding electrochemical performances of N-doped MnCO3 should be attributed to the specific defect structure provided by N-doping, which can not only create more active sites for lithium storage, but also improve the poor electronic conductivity of MnCO3. This work can offer an effective and facile strategy to realize in-situ N-doping by wet chemical synthesis route, as well as enhance the electrochemical performances of transition metal carbonates.