Layered LiNi1/3Co1/3Mn1/3O2 as the cathode materials for lithium ion batteries was synthesized with the co-precipitated metal carbonate as the precursor. The effects of Ti-F co-substitution on the structure and electr...Layered LiNi1/3Co1/3Mn1/3O2 as the cathode materials for lithium ion batteries was synthesized with the co-precipitated metal carbonate as the precursor. The effects of Ti-F co-substitution on the structure and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were studied by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), electrochemical impedance spectroscopy(EIS) and galvanostatic charge-discharge experiments. Ti-F co-substitution leads to the change in the content of transition metal ions with a low valence, thereby induces an expansion in lattice volume. Furthermore, the increase of charge-transfer resistances during the cycling was suppressed by Ti-F co-substitution. The initial discharge capacity of substituted sample is 165.23 mA·h/g and the capacity retention rate is 94.9% up to 20 cycles.展开更多
量子点敏化太阳能电池(Quantum Dot-Sensitized Solar cells,QDSCs)制备工艺简单,制造成本低廉,是一种有希望的新型太阳能电池。QDSCs利用量子点具有光谱吸收强、尺寸可调和多激子效应等优点,能够提高其光电转换效率;同时,利用无机量子...量子点敏化太阳能电池(Quantum Dot-Sensitized Solar cells,QDSCs)制备工艺简单,制造成本低廉,是一种有希望的新型太阳能电池。QDSCs利用量子点具有光谱吸收强、尺寸可调和多激子效应等优点,能够提高其光电转换效率;同时,利用无机量子点替代染料作为敏化剂,能够解决染料敏化太阳能电池(DSCs)的稳定性问题。但是,QDSCs光电转换效率较低是制约其应用的主要问题。近年来,通过改变和调控对电极的材料和电子特性提高QDSCs的光电效率的方法受到了广泛关注。本文综述了QDSCs对电极材料的制备方法、微观形貌和晶体结构;重点分析了金属化合物、复合材料、杂化材料、多元金属硫族化合物、导电聚合物和碳材料对电极对量子点敏化太阳能电池的电荷转移阻抗、光电性能等参数的影响;并分析影响其电催化活性和电子传输性能的主要因素。最后,提出通过表面修饰、复合和杂化等方法构筑新型对电极材料,进而改善和提高QDSCs转换效率和稳定性,是今后的研究重点和研究方向。展开更多
To improve the low-temperature performances of Li-ion cells, three types of linear carboxylic ester-based electrolyte, such as EC/EMC/EA（1：1：2, mass ratio）, EC/EMC/EP（1：1：2, mass ratio） and EC/EMC/EB（1：1：2,...To improve the low-temperature performances of Li-ion cells, three types of linear carboxylic ester-based electrolyte, such as EC/EMC/EA（1：1：2, mass ratio）, EC/EMC/EP（1：1：2, mass ratio） and EC/EMC/EB（1：1：2, mass ratio）, were prepared to substitute for industrial electrolyte（EC/EMC/DMC）. Then, 18650-type Li Mn2O4-graphite cells（nominal capacity of 1150 mA ·h） were assembled and studied. Results show that the cells containing three types of electrolyte are able to undertake 5C discharging current with above 93% capacity retention at-20 °C. Electrochemical impedance spectra show that the discharge capacity fading of Li-ion cells at low temperature is mainly ascribed to the charge transfer resistance increasing with temperature decreasing. In comparison, the cells containing electrolyte of 1.0 mol/L LiPF6 in EC/EMC/EA（1：1：2, mass ratio） have the highest capacity retention of 90% at-40 °C and 44.41% at-60 °C, due to its lowest charge-transfer resistance.展开更多
文摘Layered LiNi1/3Co1/3Mn1/3O2 as the cathode materials for lithium ion batteries was synthesized with the co-precipitated metal carbonate as the precursor. The effects of Ti-F co-substitution on the structure and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were studied by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), electrochemical impedance spectroscopy(EIS) and galvanostatic charge-discharge experiments. Ti-F co-substitution leads to the change in the content of transition metal ions with a low valence, thereby induces an expansion in lattice volume. Furthermore, the increase of charge-transfer resistances during the cycling was suppressed by Ti-F co-substitution. The initial discharge capacity of substituted sample is 165.23 mA·h/g and the capacity retention rate is 94.9% up to 20 cycles.
文摘量子点敏化太阳能电池(Quantum Dot-Sensitized Solar cells,QDSCs)制备工艺简单,制造成本低廉,是一种有希望的新型太阳能电池。QDSCs利用量子点具有光谱吸收强、尺寸可调和多激子效应等优点,能够提高其光电转换效率;同时,利用无机量子点替代染料作为敏化剂,能够解决染料敏化太阳能电池(DSCs)的稳定性问题。但是,QDSCs光电转换效率较低是制约其应用的主要问题。近年来,通过改变和调控对电极的材料和电子特性提高QDSCs的光电效率的方法受到了广泛关注。本文综述了QDSCs对电极材料的制备方法、微观形貌和晶体结构;重点分析了金属化合物、复合材料、杂化材料、多元金属硫族化合物、导电聚合物和碳材料对电极对量子点敏化太阳能电池的电荷转移阻抗、光电性能等参数的影响;并分析影响其电催化活性和电子传输性能的主要因素。最后,提出通过表面修饰、复合和杂化等方法构筑新型对电极材料,进而改善和提高QDSCs转换效率和稳定性,是今后的研究重点和研究方向。
基金Project(2007BAE12B01)supported by the National Key Technology Research and Development Program of ChinaProject(20803095)supported by the National Natural Science Foundation of China
文摘To improve the low-temperature performances of Li-ion cells, three types of linear carboxylic ester-based electrolyte, such as EC/EMC/EA（1：1：2, mass ratio）, EC/EMC/EP（1：1：2, mass ratio） and EC/EMC/EB（1：1：2, mass ratio）, were prepared to substitute for industrial electrolyte（EC/EMC/DMC）. Then, 18650-type Li Mn2O4-graphite cells（nominal capacity of 1150 mA ·h） were assembled and studied. Results show that the cells containing three types of electrolyte are able to undertake 5C discharging current with above 93% capacity retention at-20 °C. Electrochemical impedance spectra show that the discharge capacity fading of Li-ion cells at low temperature is mainly ascribed to the charge transfer resistance increasing with temperature decreasing. In comparison, the cells containing electrolyte of 1.0 mol/L LiPF6 in EC/EMC/EA（1：1：2, mass ratio） have the highest capacity retention of 90% at-40 °C and 44.41% at-60 °C, due to its lowest charge-transfer resistance.
