Orthorhomic LixMnO2 was synthesized by rheological phase reaction method. The thermal decomposition of the precursor was characterized by thermogravimetry analysis (TG). The product was characterized by X-Ray diffract...Orthorhomic LixMnO2 was synthesized by rheological phase reaction method. The thermal decomposition of the precursor was characterized by thermogravimetry analysis (TG). The product was characterized by X-Ray diffraction (XRD). Scan Electron Microscope (SEM), and electrochemical measurements. The electrodes of Li1.05MnO2 and Li1.10MnO2 showed a discharge capacity of 114.7 mAh·g-1, and 118.5 mAh·g-1, respectively after 40 cycles.展开更多
Using Mn(OH)2 as precursor, LiOH as lithiat- ing agent and (NH4)2S2O8 as oxidant, layered o-LiMnO2 was obtained by a novel method——in situ oxidation-intercalation under mild conditions (80℃). The product was charac...Using Mn(OH)2 as precursor, LiOH as lithiat- ing agent and (NH4)2S2O8 as oxidant, layered o-LiMnO2 was obtained by a novel method——in situ oxidation-intercalation under mild conditions (80℃). The product was characterized by XRD, ICP, TEM and Li-NMR. The results reveal that 7 orthorhombic LiMnO2 with high purity and good crystallin- ity can be obtained by this method. During electrochemical tests, a LiMnO2/Li cell shows an initial reversible capacity of 208 mAh·g?1 and a reversible capacity of 180 mAh·g?1 after 30 cycles at room temperature.展开更多
Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel struct...Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel structure LiMn2O4 and rock-salt structure Li2MnO3, whereas in argon single-phase orthorhombic LiMnO2 could obtain at the range of 750℃ to 920℃. The substitution of Mn by Zn2+ or Co3+ in LiMnO2 led to the structure of LiMnO2 transiting to Qα-LiFeO2. The results of electrochemical cycles indicated that the discharged capacity of orthorhombic-LiMnO2 was smaller at the initial stages, then gradually increased with the increasing of cycle number, finally the capacity stabilized to certain value after about 10th cycles. This phenomenon reveals that there is an activation process for orthorhombic LiMnO2 cathode materials during electrochemical cycles, which is a phase transition process from orthorhombic LiMnO2 to tetragonal spinel Li2Mn2O4. The capacity of orthorhombic LiMnO2 synthesized at lower temperature is larger than that synthesized at high temperature.展开更多
Nanosized orthorhombic LiMnO2 was successfully synthesized using Mn2O3 and LiOH.H2O as starting materials.Not only the reaction temperature was lower, but the reaction time for synthesizing was notably shortened to 1 ...Nanosized orthorhombic LiMnO2 was successfully synthesized using Mn2O3 and LiOH.H2O as starting materials.Not only the reaction temperature was lower, but the reaction time for synthesizing was notably shortened to 1 h.In this hydrothermal process, the cations of the starting materials were capable of mixing and interacting in ionic scale, which resulted in the rapid formation of o-LiMnO2 powders at relatively low temperature. The particle size conformed by transmission electron microscopy is around 50-150 nm. Benefiting from its small particle size and good uniformity, the obtained o-LiMnO2 can reach the maximum discharge capacity of 163 mA-h.g^-1 at 0.1 C rate after several cycles. X-ray diffraction data and electrochemical properties suggested the phase transformation from orthorhombic LiMnO2 to defect-type spinel LiMn204 with minor Li2MnO3, which resulted in the capacity fading during cycling.展开更多
文摘Orthorhomic LixMnO2 was synthesized by rheological phase reaction method. The thermal decomposition of the precursor was characterized by thermogravimetry analysis (TG). The product was characterized by X-Ray diffraction (XRD). Scan Electron Microscope (SEM), and electrochemical measurements. The electrodes of Li1.05MnO2 and Li1.10MnO2 showed a discharge capacity of 114.7 mAh·g-1, and 118.5 mAh·g-1, respectively after 40 cycles.
基金This work was supported by the National Natural Science Foundation of China(Grant No.20301002)Beijing Nova Fund(Grant No.H013610350112).
文摘Using Mn(OH)2 as precursor, LiOH as lithiat- ing agent and (NH4)2S2O8 as oxidant, layered o-LiMnO2 was obtained by a novel method——in situ oxidation-intercalation under mild conditions (80℃). The product was characterized by XRD, ICP, TEM and Li-NMR. The results reveal that 7 orthorhombic LiMnO2 with high purity and good crystallin- ity can be obtained by this method. During electrochemical tests, a LiMnO2/Li cell shows an initial reversible capacity of 208 mAh·g?1 and a reversible capacity of 180 mAh·g?1 after 30 cycles at room temperature.
基金supported by the National Natural Science Foundation of China under grant No.59972026.
文摘Orthorhombic LiMnO2 cathode materials were synthesized successfully at lower temperature by sol-gel method. When LiMnO2 precursor prepared by sol-gel method was fired in air, the product was a mixture of spinel structure LiMn2O4 and rock-salt structure Li2MnO3, whereas in argon single-phase orthorhombic LiMnO2 could obtain at the range of 750℃ to 920℃. The substitution of Mn by Zn2+ or Co3+ in LiMnO2 led to the structure of LiMnO2 transiting to Qα-LiFeO2. The results of electrochemical cycles indicated that the discharged capacity of orthorhombic-LiMnO2 was smaller at the initial stages, then gradually increased with the increasing of cycle number, finally the capacity stabilized to certain value after about 10th cycles. This phenomenon reveals that there is an activation process for orthorhombic LiMnO2 cathode materials during electrochemical cycles, which is a phase transition process from orthorhombic LiMnO2 to tetragonal spinel Li2Mn2O4. The capacity of orthorhombic LiMnO2 synthesized at lower temperature is larger than that synthesized at high temperature.
基金supported by the National Natural Science Foundation of China under grant No.50372058.
文摘Nanosized orthorhombic LiMnO2 was successfully synthesized using Mn2O3 and LiOH.H2O as starting materials.Not only the reaction temperature was lower, but the reaction time for synthesizing was notably shortened to 1 h.In this hydrothermal process, the cations of the starting materials were capable of mixing and interacting in ionic scale, which resulted in the rapid formation of o-LiMnO2 powders at relatively low temperature. The particle size conformed by transmission electron microscopy is around 50-150 nm. Benefiting from its small particle size and good uniformity, the obtained o-LiMnO2 can reach the maximum discharge capacity of 163 mA-h.g^-1 at 0.1 C rate after several cycles. X-ray diffraction data and electrochemical properties suggested the phase transformation from orthorhombic LiMnO2 to defect-type spinel LiMn204 with minor Li2MnO3, which resulted in the capacity fading during cycling.
