The commercial graphite(CG)is the conventional anode material for lithium ion batteries(LIBs)due to its low delithiation voltage plateau(below 0.5 V)and extraordinary durability.Nevertheless,the further promotion of e...The commercial graphite(CG)is the conventional anode material for lithium ion batteries(LIBs)due to its low delithiation voltage plateau(below 0.5 V)and extraordinary durability.Nevertheless,the further promotion of energy density of LIBs is restricted by the limited capacity below 0.5 V of CG.Here,based on the supercritical CO2 exfoliation technique,the production of multi-layered graphene(MLG)is achieved from the pilot scale production line.The great merit of the exfoliated MLG anode is that the voltage plateau below 0.5 V is broadened obviously as compared to those of natural graphite and CG.Additionally,no obvious lithium dendrites are observed for MLG during the lithiation process.The large delithiation capacity under the low voltage plateau of MLG is mainly benefited from the combination of Li intercalation and boundary storage mechanism,which is further confirmed by the density functional theory calculations.The LiFePO4/MLG full cell can afford the satisfactory electrochemical property with respect to the capacity,energy density and ultralong cycling stability(90%capacity retention after 500 cycles at 2 C),significantly better than that of LiFePO4/CG.Besides,this developed technique not only dedicates to producing the high-performance anode for LIBs but also opens a door for the mass production of MLG in the industrial scale.展开更多
Basic magnesium carbonate microspheres with a red blood cell (RBC)-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the sel...Basic magnesium carbonate microspheres with a red blood cell (RBC)-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the self-assembly, sodium dodecyl benzene sulfonate served as a template for the formation of Mg(OH)2 spherical micelles and also as a reactant precursor that releases CO2 to react with Mg(OH)2. The growth of the microspheres is driven by the continuous generation of new hydrophobic centers because of the consumption of hydrophilic poles (--SO3-). The surfactant-directed self-assembly can be applied to the synthesis of other carbonate or metallic oxide self-assemblies, indicating that it is a universal self-assembly method for amphiphilic molecules.展开更多
We have developed a one-step process for the synthesis of basic magnesium sulfate (5Mg(OH)2-MgSO4-3H20, abbreviated as 513MOS) whiskers from MgSO4,7H20 and MgO by refluxing at atmospheric pressure. The process sho...We have developed a one-step process for the synthesis of basic magnesium sulfate (5Mg(OH)2-MgSO4-3H20, abbreviated as 513MOS) whiskers from MgSO4,7H20 and MgO by refluxing at atmospheric pressure. The process shows potential for the low-cost mass production of controlled- structure whiskers. Their 0.3-1.0 μm diameter and 40-80 μm length correspond to an aspect ratio of 40-260. The 513MOS whisker morphology is related closely to MgSO4 concentration and reflux time. The optimized MgSO4 concentration is 1.2-1.5 mol/L with a 25-30 h reflux time. X-ray diffractometry revealed that the b-axis is the predominant growth direction of the whiskers. Their growth mechanism is by the relatively slow liquid-phase deposition of Mg2+, OH-, and SO42-. The long reaction time and high MgSO4 concentration are conducive to the formation of 513MOS whiskers under gentle reaction conditions. Porous MgO whiskers with a fibrous structure were obtained after calcination of the 513MOS whiskers at 1020 ℃.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21706283 and 21776308)Beijing Talents Foundation(No.2017000020124G010)+1 种基金Science Foundation of China University of Petroleum,Beijing(No.2462017YJRC003)the Joint Open Fund of Jiangsu Collaborative Innovation Center for Ecological Building Material and Environmental Protection Equipment and Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province(No.JH201812)。
文摘The commercial graphite(CG)is the conventional anode material for lithium ion batteries(LIBs)due to its low delithiation voltage plateau(below 0.5 V)and extraordinary durability.Nevertheless,the further promotion of energy density of LIBs is restricted by the limited capacity below 0.5 V of CG.Here,based on the supercritical CO2 exfoliation technique,the production of multi-layered graphene(MLG)is achieved from the pilot scale production line.The great merit of the exfoliated MLG anode is that the voltage plateau below 0.5 V is broadened obviously as compared to those of natural graphite and CG.Additionally,no obvious lithium dendrites are observed for MLG during the lithiation process.The large delithiation capacity under the low voltage plateau of MLG is mainly benefited from the combination of Li intercalation and boundary storage mechanism,which is further confirmed by the density functional theory calculations.The LiFePO4/MLG full cell can afford the satisfactory electrochemical property with respect to the capacity,energy density and ultralong cycling stability(90%capacity retention after 500 cycles at 2 C),significantly better than that of LiFePO4/CG.Besides,this developed technique not only dedicates to producing the high-performance anode for LIBs but also opens a door for the mass production of MLG in the industrial scale.
基金supported by the National Natural Science Foundation of China(No.21206191)the Science Foundation of China University of Petroleum,Beijing(No.2462013YXBS007)
文摘Basic magnesium carbonate microspheres with a red blood cell (RBC)-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the self-assembly, sodium dodecyl benzene sulfonate served as a template for the formation of Mg(OH)2 spherical micelles and also as a reactant precursor that releases CO2 to react with Mg(OH)2. The growth of the microspheres is driven by the continuous generation of new hydrophobic centers because of the consumption of hydrophilic poles (--SO3-). The surfactant-directed self-assembly can be applied to the synthesis of other carbonate or metallic oxide self-assemblies, indicating that it is a universal self-assembly method for amphiphilic molecules.
文摘We have developed a one-step process for the synthesis of basic magnesium sulfate (5Mg(OH)2-MgSO4-3H20, abbreviated as 513MOS) whiskers from MgSO4,7H20 and MgO by refluxing at atmospheric pressure. The process shows potential for the low-cost mass production of controlled- structure whiskers. Their 0.3-1.0 μm diameter and 40-80 μm length correspond to an aspect ratio of 40-260. The 513MOS whisker morphology is related closely to MgSO4 concentration and reflux time. The optimized MgSO4 concentration is 1.2-1.5 mol/L with a 25-30 h reflux time. X-ray diffractometry revealed that the b-axis is the predominant growth direction of the whiskers. Their growth mechanism is by the relatively slow liquid-phase deposition of Mg2+, OH-, and SO42-. The long reaction time and high MgSO4 concentration are conducive to the formation of 513MOS whiskers under gentle reaction conditions. Porous MgO whiskers with a fibrous structure were obtained after calcination of the 513MOS whiskers at 1020 ℃.