随着电动汽车和大规模储能电网的快速发展,锂离子电池将不可避免地面临有限的能量密度无法满足日益增长的需求和成本不断上升的两大困境。室温钠-硫电池因具有高能量密度和低成本的优势而备受关注,但其存在多硫化钠的“穿梭效应”导致...随着电动汽车和大规模储能电网的快速发展,锂离子电池将不可避免地面临有限的能量密度无法满足日益增长的需求和成本不断上升的两大困境。室温钠-硫电池因具有高能量密度和低成本的优势而备受关注,但其存在多硫化钠的“穿梭效应”导致电池的循环性能较差的问题,亟需解决。在此,本文提出将纳米TiO_(2)颗粒构筑于多通道炭纤维以稳定硫,从而实现室温钠-硫电池电化学性能的提高。首先通过静电纺丝和热处理技术制得有纳米TiO_(2)负载的多通道炭纤维载体材料,后续采用熔融扩散载硫方法制备出硫基复合正极材料。纳米TiO_(2)颗粒的加入可增强了对多硫化物的吸附力,同时促进其向Na2S2和Na2S的快速转化。在0.1 A g^(−1)电流密度条件下,电极材料经循环100次后的比容量为445.1 mAh g^(−1),库仑效率接近100%;即使在电流密度为2 A g^(−1)时,经500次循环,该电极材料仍保持有300.5 mAh g^(−1)的容量,显现出优异的倍率和循环性能。通过表征测试手段与理论计算相结合,验证了纳米TiO_(2)颗粒的加入可增强碳基材料对多硫化物的吸附作用。这项工作有望为高性能室温钠-硫电池正极材料的优化设计提供理论依据与技术指导。展开更多
Nanocomposites based on styrene-b-(ethylene-co-butylenes)-b-styrene triblock copolymer(SEBS), polypropylene (PP) and organomontmorillonite (OMMT) were prepared using melt intercalation by a twin mill. The nanostructur...Nanocomposites based on styrene-b-(ethylene-co-butylenes)-b-styrene triblock copolymer(SEBS), polypropylene (PP) and organomontmorillonite (OMMT) were prepared using melt intercalation by a twin mill. The nanostructure of SEBS/PP/OMMT hybrids was characterized by X-ray diffractometry(XRD) and transmission electron microscopy(TEM). The d001 space of OMMT and SEBS/PP/OMMT hybrid increases from 1.30 nm to 3.52 nm and 4.06 nm, respectively which indicate, that the C16 and SEBS/PP could intercalate in the silicate layers and expand the basal spacing. The formation of intercalated structure was also confirmed by TEM. The results show that the individual silicates are well dispersed in the elastomer matrix. The glass transition temperature (tg) of PS block of SEBS was investigated by dynamic mechanical analysis (DMA). It is shown that there are remarkable enhancements in tg of PS block containing a small mass fraction of OMMT. tg of PS in SEBS of the nanocomposites has been increased about 39℃when containing 4% OMMT. The influence of OMMT on the dynamic storage moduli is temperature dependent. Below 50℃the SEBS/PP/OMMT composites with higher OMMT contents show higher dynamic storage moduli. OMMT has the function of reinforcing SEBS/PP elastomers. However, the influence of OMMT on the mechanical properties of the nanocomposites is not significant according to the tensile test and tear test.展开更多
Sodium-sulfur(Na-S)and potassium-sulfur(K-S)batteries for use at room temperature have received widespread attention because of the abundance and low cost of their raw materials and their high energy density.However,t...Sodium-sulfur(Na-S)and potassium-sulfur(K-S)batteries for use at room temperature have received widespread attention because of the abundance and low cost of their raw materials and their high energy density.However,their development is restricted by the shuttling of polysulfides,large volume expansion and poor conductivity.To overcome these obstacles,an effective approach is to use carbon-based materials with abundant space for the sulfur that has sulfiphilic sites to immobilize it,and a high electrical conductivity.Hollow carbon spheres(HCSs)with a controllable structure and composition are promising for this purpose.We consider recent progress in optimizing the electrochemical performance of Na-/K-S batteries by using these materials.First,the advantages of HCSs,their synthesis methods,and strategies for preparing HCSs/sulfur composite materials are reviewed.Second,the use of HCSs in Na-/K-S batteries,along with mechanisms underlying the resulting performance improvement,are discussed.Finally,prospects for the further development of HCSs for metal−S batteries are presented.展开更多
文摘随着电动汽车和大规模储能电网的快速发展,锂离子电池将不可避免地面临有限的能量密度无法满足日益增长的需求和成本不断上升的两大困境。室温钠-硫电池因具有高能量密度和低成本的优势而备受关注,但其存在多硫化钠的“穿梭效应”导致电池的循环性能较差的问题,亟需解决。在此,本文提出将纳米TiO_(2)颗粒构筑于多通道炭纤维以稳定硫,从而实现室温钠-硫电池电化学性能的提高。首先通过静电纺丝和热处理技术制得有纳米TiO_(2)负载的多通道炭纤维载体材料,后续采用熔融扩散载硫方法制备出硫基复合正极材料。纳米TiO_(2)颗粒的加入可增强了对多硫化物的吸附力,同时促进其向Na2S2和Na2S的快速转化。在0.1 A g^(−1)电流密度条件下,电极材料经循环100次后的比容量为445.1 mAh g^(−1),库仑效率接近100%;即使在电流密度为2 A g^(−1)时,经500次循环,该电极材料仍保持有300.5 mAh g^(−1)的容量,显现出优异的倍率和循环性能。通过表征测试手段与理论计算相结合,验证了纳米TiO_(2)颗粒的加入可增强碳基材料对多硫化物的吸附作用。这项工作有望为高性能室温钠-硫电池正极材料的优化设计提供理论依据与技术指导。
基金Project(040A02) supported by Key Science Foundation of Shanghai Higher Education Project(P1502) supported by Shanghai Leading Academic Discipline.
文摘Nanocomposites based on styrene-b-(ethylene-co-butylenes)-b-styrene triblock copolymer(SEBS), polypropylene (PP) and organomontmorillonite (OMMT) were prepared using melt intercalation by a twin mill. The nanostructure of SEBS/PP/OMMT hybrids was characterized by X-ray diffractometry(XRD) and transmission electron microscopy(TEM). The d001 space of OMMT and SEBS/PP/OMMT hybrid increases from 1.30 nm to 3.52 nm and 4.06 nm, respectively which indicate, that the C16 and SEBS/PP could intercalate in the silicate layers and expand the basal spacing. The formation of intercalated structure was also confirmed by TEM. The results show that the individual silicates are well dispersed in the elastomer matrix. The glass transition temperature (tg) of PS block of SEBS was investigated by dynamic mechanical analysis (DMA). It is shown that there are remarkable enhancements in tg of PS block containing a small mass fraction of OMMT. tg of PS in SEBS of the nanocomposites has been increased about 39℃when containing 4% OMMT. The influence of OMMT on the dynamic storage moduli is temperature dependent. Below 50℃the SEBS/PP/OMMT composites with higher OMMT contents show higher dynamic storage moduli. OMMT has the function of reinforcing SEBS/PP elastomers. However, the influence of OMMT on the mechanical properties of the nanocomposites is not significant according to the tensile test and tear test.
文摘Sodium-sulfur(Na-S)and potassium-sulfur(K-S)batteries for use at room temperature have received widespread attention because of the abundance and low cost of their raw materials and their high energy density.However,their development is restricted by the shuttling of polysulfides,large volume expansion and poor conductivity.To overcome these obstacles,an effective approach is to use carbon-based materials with abundant space for the sulfur that has sulfiphilic sites to immobilize it,and a high electrical conductivity.Hollow carbon spheres(HCSs)with a controllable structure and composition are promising for this purpose.We consider recent progress in optimizing the electrochemical performance of Na-/K-S batteries by using these materials.First,the advantages of HCSs,their synthesis methods,and strategies for preparing HCSs/sulfur composite materials are reviewed.Second,the use of HCSs in Na-/K-S batteries,along with mechanisms underlying the resulting performance improvement,are discussed.Finally,prospects for the further development of HCSs for metal−S batteries are presented.
