Nano-spinel Li x Mn 2 O 4 (0.6≤x≤1.0)was synthesized by two steps of copre cipitation and calcination.The influences of calcination temperature,time and Li /Mn ratio on the crystal structure and the particle size of...Nano-spinel Li x Mn 2 O 4 (0.6≤x≤1.0)was synthesized by two steps of copre cipitation and calcination.The influences of calcination temperature,time and Li /Mn ratio on the crystal structure and the particle size of Li x Mn 2 O 4 were investigated.It was shown that the higher the calcination temperature,the more complete the crystal structure,and the larger the partic le size.Moreover,the influence of c alcination time on the crystal structure was insignificant when it was more than 3h at 700℃.With the increase of x in Li x Mn 2 O 4 in the range of 0.6～1.0,the d 111 and lattice parameter a increased fi rst and then decreased.The electrochemical properties of nano-spinel LiMn 2 O 4 using as cathode material of lithium-ion battery were studied.The low di scharge capacity might be due to the irreversible capacity loss brou ght by the large surface area and latt ice vacancies of the nano-spinel.展开更多
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
文摘Nano-spinel Li x Mn 2 O 4 (0.6≤x≤1.0)was synthesized by two steps of copre cipitation and calcination.The influences of calcination temperature,time and Li /Mn ratio on the crystal structure and the particle size of Li x Mn 2 O 4 were investigated.It was shown that the higher the calcination temperature,the more complete the crystal structure,and the larger the partic le size.Moreover,the influence of c alcination time on the crystal structure was insignificant when it was more than 3h at 700℃.With the increase of x in Li x Mn 2 O 4 in the range of 0.6～1.0,the d 111 and lattice parameter a increased fi rst and then decreased.The electrochemical properties of nano-spinel LiMn 2 O 4 using as cathode material of lithium-ion battery were studied.The low di scharge capacity might be due to the irreversible capacity loss brou ght by the large surface area and latt ice vacancies of the nano-spinel.
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.
