Using water soluble organic compound as matrix, Carbon-coated LiMn2O4 was synthesized successfully. Co-doped LiMn2O4 was also synthesized. Physical and electrochemical performances were investigated by XRD, IR, SEM an...Using water soluble organic compound as matrix, Carbon-coated LiMn2O4 was synthesized successfully. Co-doped LiMn2O4 was also synthesized. Physical and electrochemical performances were investigated by XRD, IR, SEM and electrochemical testing. The results showed that due to a better conductivity and stabilization of Co-doped LiMn2O4, the electrochemical performances of LiMn2O4 were improved. And Carbon-coated LiMn2O4 also showed a good property because of the reduction of Mn dissolution. Comparatively speaking, Carbon-coated LiMn2O4 showed a more stable electrochemical performance.展开更多
Li x Mn 2O 4 spinels were prepared by in situ redox precipitation hydrothermal synthesis method, and characterized by XRD, BET, TGA, TEM and SEM etc. , and the effects of many factors on the properties of as prepared ...Li x Mn 2O 4 spinels were prepared by in situ redox precipitation hydrothermal synthesis method, and characterized by XRD, BET, TGA, TEM and SEM etc. , and the effects of many factors on the properties of as prepared Li x Mn 2O 4 samples were investigated. The results demonstrated that Li x Mn 2O 4 spinels can be synthesized under milder conditions by in situ redox precipitation hydrothermal synthesis method. Li x Mn 2O 4 spinels are cubic and symmetrical, and have a better stability at less than 700 ℃, their surface areas and particle sizes were strongly affected by crystallization temperature and time, pH value, calcination temperature and time. The optimal conditions of Li x Mn 2O 4 synthesis were determined as follows: the alkalinity(pH value) was 9; the crystallization temperature and time were more than 240 ℃ and 48 h, respectively; the calcination temperature and time were between 700-750 ℃ and 6-12 h, respectively; the molar ratio of Li to Mn was less than 1.2/2.展开更多
The ion-exchanger LiMg0.5Mn1.5O4 of spinel type was prepared by the common precipitation/heated crystallization method, and was acid modified. Its properties of ion-exchange for alkali ions such as saturation capacity...The ion-exchanger LiMg0.5Mn1.5O4 of spinel type was prepared by the common precipitation/heated crystallization method, and was acid modified. Its properties of ion-exchange for alkali ions such as saturation capacity of exchange, distribution coefficient and the pH titration curve have been determined. LiMg0.5Mn1.5O4 was characterized by X-ray diffraction. These results show that this inorganic ion-exchanger has better remembering and selectivity of ion exchange, and higher capacity of exchange for Li+, the capacity of exchange reaches 32.39 mg·g-1 for Li+.展开更多
Spinel LiNi0.05Mn1.95O4 cathode material for lithium ion batteries was synthesized by solid-state reaction from coprecipitated Ni-Mn hydroxide precursors and characterized by X-ray diffraction(XRD),scanning electron m...Spinel LiNi0.05Mn1.95O4 cathode material for lithium ion batteries was synthesized by solid-state reaction from coprecipitated Ni-Mn hydroxide precursors and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and galvanostatic charge-discharge tests. It is found that LiNi0.05Mn1.95O4 powder has an ordered cubic spinel phase(space group Fd 3m) and exhibits superior rate capability. After 450 cycles,the LiNi0.05Mn1.95O4/carbonaceous mesophase spheres(CMS) Li-ion batteries can retain 96.0% and 93.3% capacity at 5C and 10C charge/discharge rate,respectively,compared with 85.3%(5C) and 80.5%(10C) retention for LiMn2O4 batteries. However,the initial discharge capacity of LiNi0.05Mn1.95O4/CMS batteries at 1C charge/discharge rate(96.20 mA·h/g) is slightly lower than that of the LiMn2O4 batteries(100.98 mA·h/g) due to the increased average oxidation state of Mn in LiNi0.05Mn1.95O4.展开更多
文摘Using water soluble organic compound as matrix, Carbon-coated LiMn2O4 was synthesized successfully. Co-doped LiMn2O4 was also synthesized. Physical and electrochemical performances were investigated by XRD, IR, SEM and electrochemical testing. The results showed that due to a better conductivity and stabilization of Co-doped LiMn2O4, the electrochemical performances of LiMn2O4 were improved. And Carbon-coated LiMn2O4 also showed a good property because of the reduction of Mn dissolution. Comparatively speaking, Carbon-coated LiMn2O4 showed a more stable electrochemical performance.
文摘Li x Mn 2O 4 spinels were prepared by in situ redox precipitation hydrothermal synthesis method, and characterized by XRD, BET, TGA, TEM and SEM etc. , and the effects of many factors on the properties of as prepared Li x Mn 2O 4 samples were investigated. The results demonstrated that Li x Mn 2O 4 spinels can be synthesized under milder conditions by in situ redox precipitation hydrothermal synthesis method. Li x Mn 2O 4 spinels are cubic and symmetrical, and have a better stability at less than 700 ℃, their surface areas and particle sizes were strongly affected by crystallization temperature and time, pH value, calcination temperature and time. The optimal conditions of Li x Mn 2O 4 synthesis were determined as follows: the alkalinity(pH value) was 9; the crystallization temperature and time were more than 240 ℃ and 48 h, respectively; the calcination temperature and time were between 700-750 ℃ and 6-12 h, respectively; the molar ratio of Li to Mn was less than 1.2/2.
文摘The ion-exchanger LiMg0.5Mn1.5O4 of spinel type was prepared by the common precipitation/heated crystallization method, and was acid modified. Its properties of ion-exchange for alkali ions such as saturation capacity of exchange, distribution coefficient and the pH titration curve have been determined. LiMg0.5Mn1.5O4 was characterized by X-ray diffraction. These results show that this inorganic ion-exchanger has better remembering and selectivity of ion exchange, and higher capacity of exchange for Li+, the capacity of exchange reaches 32.39 mg·g-1 for Li+.
文摘Spinel LiNi0.05Mn1.95O4 cathode material for lithium ion batteries was synthesized by solid-state reaction from coprecipitated Ni-Mn hydroxide precursors and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and galvanostatic charge-discharge tests. It is found that LiNi0.05Mn1.95O4 powder has an ordered cubic spinel phase(space group Fd 3m) and exhibits superior rate capability. After 450 cycles,the LiNi0.05Mn1.95O4/carbonaceous mesophase spheres(CMS) Li-ion batteries can retain 96.0% and 93.3% capacity at 5C and 10C charge/discharge rate,respectively,compared with 85.3%(5C) and 80.5%(10C) retention for LiMn2O4 batteries. However,the initial discharge capacity of LiNi0.05Mn1.95O4/CMS batteries at 1C charge/discharge rate(96.20 mA·h/g) is slightly lower than that of the LiMn2O4 batteries(100.98 mA·h/g) due to the increased average oxidation state of Mn in LiNi0.05Mn1.95O4.
