In recent years, with the continuous development of high-voltage cathode materials for lithium-ion (Li + ) batteries, the LiMn 1-X Fe X PO 4 solid solution obtained by using Mn element to replace part of Fe on the basis of LiFePO 4 (LFP) has received extensive attention. It shows significantly improved voltage and capacity than LFP, which is currently regarded as a leading update for the traditional LFP cathode. At present, preparation of high-performance LiMn 1-X Fe X PO 4 using common high-temperature solid-state method is still challenging and the basic intricate coupling of the Mn-Fe ratio and ball milling time parameters on its electrochemical performance is still need to be fully studied due to the parametric complexity. Herein, the carbon wrapped LiMn 1-X Fe X PO 4 /C material was prepared by high-temperature solid-phase method, and paper-based LiMn 1-X Fe X PO 4 /C electrodes were also fabricated to fully study the synergistic effects of ball milling times (0.5 h, 1 h, 2 h) and Mn-Fe ratios (5:5, 6:4, 7:3, 8:2) on their electrochemical performance. It was found that there happened to be optimized ball milling time for each Mn-Fe ratio based LiMn 1-X Fe X PO 4 /C materials. The higher Mn-Fe ratio, the longer ball milling time that is needed to achieve high electrochemical performance of paper-based LiMn 1-X Fe X PO 4 /C cathodes. Through detailed analysis of cyclic voltammetry (CV) curves, cycling and rate performance, it was found that LiMn 1-X Fe X PO 4 /C cathode prepared by ball milling for 1 h and Mn-Fe ratio of 7:3 has the best optimized voltage, cycling and rate performance.
Yan Gao,Tao Luan,Mingyang Zhang,Wenke Zhang,Wenchen Feng
A series of Mn−Fe−Ce−Ox/γ-Al2O3nanocatalysts were synthesized with different Mn/Fe ratios for the catalytic oxidation of NO into NO2and the catalytic elimination of NOxvia fast selective catalytic reduction (SCR) reaction. The effects of Mn/Fe ratio on the physicochemical properties of the samples were analyzed by means of various techniques including N2adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H2-temperature-programmed reduction (TPR), NH3-temperature-programmed desorption (TPD) and NO-TPD, meanwhile, their catalytic performance was also evaluated and compared. Multiple characterizations revealed that the catalytic performance was highly dependent on the phase composition. The Mn15Fe15−Ce/Al sample with the Mn/Fe molar ratio of 1.0 presented the optimal structure characteristic among all tested samples, with the largest surface area, increased active components distributions, the reduced crystallinity and diminished particle sizes. In the meantime, the ratios of Mn4+/Mnn+, Fe2+/Fen+and Ce3+/Cen+in Mn15Fe15−Ce/Al samples were improved, which could enhance the redox capacity and increase the quantity of chemisorbed oxygen and oxygen vacancy, thus facilitating NO oxidation into NO2and eventually promoting the fast SCR reaction. In accord with the structure results, the Mn15Fe15−Ce/Al sample exhibited the highest NO oxidation rate of 64.2% at 350 °C and the broadest temperature window of 75–350 °C with the NOxconversion >90%. Based on the structure–activity relationship discussion, the catalytic mechanism over the Mn−Fe−Ce ternary components supported byγ-Al2O3were proposed. Overall, it was believed that the optimization of Mn/Fe ratio in Mn−Fe−Ce/Al nanocatalyst was an extremely effective method to improve the structure–activity relationships for NO pre-oxidation and the fast SCR reaction.
危险品化学品经营许可证（带存储）