In order to improve the cycle and rate performance of LiNi0.5Mn1.5O4, LiCr2 Ni0.5 Mn1.5 O （0≤Y≤0.15） particles were Y -Y -Y 4 synthesized by the sucrose-aided combustion method. The effects of Cr doping in LiNi0.5...In order to improve the cycle and rate performance of LiNi0.5Mn1.5O4, LiCr2 Ni0.5 Mn1.5 O （0≤Y≤0.15） particles were Y -Y -Y 4 synthesized by the sucrose-aided combustion method. The effects of Cr doping in LiNi0.5Mn1.5O4 on the structures and electrochemical properties were investigated. The samples were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, galvanostatic charge-discharge test and electrochemical impedance spectrum （EIS）. The results indicate that the LiCr2 Ni0.5 Mn1.5 O possess a spinel structure and small particle size, and LiCr0.2Ni0.4Mn1.4O4exhibits Y -Y -Y 4 the best cyclic and rate performance. It can deliver discharge capacities of 143 and 104 mA·h/g at 1C and 10C, respectively, with good capacity retention of 96.5% at 1C after 50 cycles.展开更多
Disposal of chromium （Cr） hexavalent form, Cr（Ⅵ）, in soils as additions in organic fertilizers, liming materials or plant nutrient sources can be dangerous since Cr（Ⅵ） can be highly toxic to plants, animals, a...Disposal of chromium （Cr） hexavalent form, Cr（Ⅵ）, in soils as additions in organic fertilizers, liming materials or plant nutrient sources can be dangerous since Cr（Ⅵ） can be highly toxic to plants, animals, and humans. In order to explore soil conditions that lead to Cr（Ⅵ） generation, this study were performed using a Paleudult （Dystic Nitosol） from a region that has a high concentration of tannery operations in the Rio Crande do Sul State, southern Brazil. Three laboratory incubation experiments were carried out to examine the influences of soil moisture content and concentration of cobalt and organic matter additions on soil Cr（Ⅵ） formation and release and manganese （Mn） oxide reduction with a salt of chromium chloride （CrCl3） and tannery sludge as inorganic and organic sources of Cr（Ⅲ）, respectively. The amount of Cr（Ⅲ） oxidation depended on the concentration of easily reducible Mn oxides and the oxidation was more intense at the soil water contents in which Mn（Ⅲ/Ⅳ） oxides were more stable. Soluble organic compounds in soil decreased Cr（Ⅵ） formation due to Cr（Ⅲ） complexation. This mechanism also resulted in the decrease in the oxidation of Cr（Ⅲ） due to the tannery sludge additions. Chromium（Ⅲ） oxidation to Cr（Ⅵ） at the solid/solution interface involved the following mechanisms： the formation of a precursor complex on manganese （Mn） oxide surfaces, followed by electron transfer from Cr（Ⅲ） to Mn（Ⅲ or Ⅳ）, the formation of a successor complex with Mn（Ⅱ） and Cr（Ⅵ）, and the breakdown of the successor complex and release of Mn（Ⅱ） and Cr（Ⅵ） into the soil solution.展开更多
基金Project(2007BA201055)supported by the National Science and Technology Support Program,China
文摘In order to improve the cycle and rate performance of LiNi0.5Mn1.5O4, LiCr2 Ni0.5 Mn1.5 O （0≤Y≤0.15） particles were Y -Y -Y 4 synthesized by the sucrose-aided combustion method. The effects of Cr doping in LiNi0.5Mn1.5O4 on the structures and electrochemical properties were investigated. The samples were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, cyclic voltammetry （CV）, galvanostatic charge-discharge test and electrochemical impedance spectrum （EIS）. The results indicate that the LiCr2 Ni0.5 Mn1.5 O possess a spinel structure and small particle size, and LiCr0.2Ni0.4Mn1.4O4exhibits Y -Y -Y 4 the best cyclic and rate performance. It can deliver discharge capacities of 143 and 104 mA·h/g at 1C and 10C, respectively, with good capacity retention of 96.5% at 1C after 50 cycles.
基金Supported by the Soil Testing Laboratory Project,Federal University of Rio Grande do Sul,Brazil.
文摘Disposal of chromium （Cr） hexavalent form, Cr（Ⅵ）, in soils as additions in organic fertilizers, liming materials or plant nutrient sources can be dangerous since Cr（Ⅵ） can be highly toxic to plants, animals, and humans. In order to explore soil conditions that lead to Cr（Ⅵ） generation, this study were performed using a Paleudult （Dystic Nitosol） from a region that has a high concentration of tannery operations in the Rio Crande do Sul State, southern Brazil. Three laboratory incubation experiments were carried out to examine the influences of soil moisture content and concentration of cobalt and organic matter additions on soil Cr（Ⅵ） formation and release and manganese （Mn） oxide reduction with a salt of chromium chloride （CrCl3） and tannery sludge as inorganic and organic sources of Cr（Ⅲ）, respectively. The amount of Cr（Ⅲ） oxidation depended on the concentration of easily reducible Mn oxides and the oxidation was more intense at the soil water contents in which Mn（Ⅲ/Ⅳ） oxides were more stable. Soluble organic compounds in soil decreased Cr（Ⅵ） formation due to Cr（Ⅲ） complexation. This mechanism also resulted in the decrease in the oxidation of Cr（Ⅲ） due to the tannery sludge additions. Chromium（Ⅲ） oxidation to Cr（Ⅵ） at the solid/solution interface involved the following mechanisms： the formation of a precursor complex on manganese （Mn） oxide surfaces, followed by electron transfer from Cr（Ⅲ） to Mn（Ⅲ or Ⅳ）, the formation of a successor complex with Mn（Ⅱ） and Cr（Ⅵ）, and the breakdown of the successor complex and release of Mn（Ⅱ） and Cr（Ⅵ） into the soil solution.
