分别采用钴和铝的硝酸盐、硫酸盐和氯化物作为原料,在245℃温度下水热处理24 h,制备纳米尖晶石型CoAl2O4蓝色料。通过3 M NaOH溶液调节Co-Al前驱体溶液的pH值。采用X射线衍射分析（XRD）、透射电镜（TEM）、差示扫描量热法-热重分析（DS...分别采用钴和铝的硝酸盐、硫酸盐和氯化物作为原料,在245℃温度下水热处理24 h,制备纳米尖晶石型CoAl2O4蓝色料。通过3 M NaOH溶液调节Co-Al前驱体溶液的pH值。采用X射线衍射分析（XRD）、透射电镜（TEM）、差示扫描量热法-热重分析（DSC-TG）,傅里叶红外光谱（FTIR）以及色度计对所得合成产物进行了表征分析。结果表明,钴、铝的硝酸盐为原料所得水热产物在三类原料中呈色最差;以硫酸钴和硫酸铝为原料、pH=11时所得产物的蓝度值最佳（b＊=-28.92）,随着pH值的变化,对产物的色度产生显著影响;钴、铝的氯化物为原料合成的产物为蓝色或者蓝绿色,能在9～11的较宽pH值范围内得到呈色稳定的蓝色料。水热产物呈现出绿色调的主要原因是部分Co^3＋取代了Al^3＋填充的CoAl2O4晶体中的八面体空隙,为六配位结构。展开更多
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
文摘分别采用钴和铝的硝酸盐、硫酸盐和氯化物作为原料,在245℃温度下水热处理24 h,制备纳米尖晶石型CoAl2O4蓝色料。通过3 M NaOH溶液调节Co-Al前驱体溶液的pH值。采用X射线衍射分析（XRD）、透射电镜（TEM）、差示扫描量热法-热重分析（DSC-TG）,傅里叶红外光谱（FTIR）以及色度计对所得合成产物进行了表征分析。结果表明,钴、铝的硝酸盐为原料所得水热产物在三类原料中呈色最差;以硫酸钴和硫酸铝为原料、pH=11时所得产物的蓝度值最佳（b＊=-28.92）,随着pH值的变化,对产物的色度产生显著影响;钴、铝的氯化物为原料合成的产物为蓝色或者蓝绿色,能在9～11的较宽pH值范围内得到呈色稳定的蓝色料。水热产物呈现出绿色调的主要原因是部分Co^3＋取代了Al^3＋填充的CoAl2O4晶体中的八面体空隙,为六配位结构。
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.
