The cathode material Li 1+ x Mn 2O 4 was prepared by a modified citric acid complexation method. The influences of temperature, sintering time and n (Li)/ n (Mn) ratio on the structure of the products have been explor...The cathode material Li 1+ x Mn 2O 4 was prepared by a modified citric acid complexation method. The influences of temperature, sintering time and n (Li)/ n (Mn) ratio on the structure of the products have been explored, characterized and tested by XRD, TEM, BET measurements. The sample sintered at 750 ℃ for 12 h had greater charge/discharge capacity, better cyclic stability under electric current charge/discharge cycle. The initial capacity reached 120 mA·h/g with the charge/discharge efficieney of 98% and maintained 115 mA·h/g after 50 cycles.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 pure bixbyite Mn 2O 3 was prepared by first applying in situ redox precipitation hydrothermal synthesis method under the very mild conditions, and characterized by XRD, TEM, BET and TGA. The effects of alkalinity,...The pure bixbyite Mn 2O 3 was prepared by first applying in situ redox precipitation hydrothermal synthesis method under the very mild conditions, and characterized by XRD, TEM, BET and TGA. The effects of alkalinity, crystallization time and temperature on the product were investigated. The results demonstrated that the alkalinity has an obvious effect on the product whereas the crystallization time and temperature has only a little influence on the product. Too low alkalinity results in no formation of product, and too high alkalinity leads to no formation of pure product with a smaller particle size. Under optimized conditions, the pure bixbyite Mn 2O 3 powder with a better morphology and distribution can be obtained. The average diameter of product is approximate to 80 nm. The normal LiMn 2O 4 spinel used as cathode material can be prepared using as synthesized bixbyite Mn 2O 3 as manganese precursor at 650 ℃ for 2 h by solid state reaction.展开更多
文摘The cathode material Li 1+ x Mn 2O 4 was prepared by a modified citric acid complexation method. The influences of temperature, sintering time and n (Li)/ n (Mn) ratio on the structure of the products have been explored, characterized and tested by XRD, TEM, BET measurements. The sample sintered at 750 ℃ for 12 h had greater charge/discharge capacity, better cyclic stability under electric current charge/discharge cycle. The initial capacity reached 120 mA·h/g with the charge/discharge efficieney of 98% and maintained 115 mA·h/g after 50 cycles.
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 pure bixbyite Mn 2O 3 was prepared by first applying in situ redox precipitation hydrothermal synthesis method under the very mild conditions, and characterized by XRD, TEM, BET and TGA. The effects of alkalinity, crystallization time and temperature on the product were investigated. The results demonstrated that the alkalinity has an obvious effect on the product whereas the crystallization time and temperature has only a little influence on the product. Too low alkalinity results in no formation of product, and too high alkalinity leads to no formation of pure product with a smaller particle size. Under optimized conditions, the pure bixbyite Mn 2O 3 powder with a better morphology and distribution can be obtained. The average diameter of product is approximate to 80 nm. The normal LiMn 2O 4 spinel used as cathode material can be prepared using as synthesized bixbyite Mn 2O 3 as manganese precursor at 650 ℃ for 2 h by solid state reaction.
