Research on Low Temperature Performance of the F-doped LiFePO4/C Cathode Materials

2011 ◽  
Vol 14 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Borong Wu ◽  
Ying Zhang ◽  
Ning Li ◽  
Chunwei Yang ◽  
Zhaojun Yang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Cathode Materials ◽  
High Rate ◽  
Degree Of Polarization ◽  
Electrochemical Performances ◽  
Sem Images ◽  
Intrinsic Conductivity ◽  
Undoped Material ◽  
Structure Changes ◽  
Better Than

F-doped LiFePO4/C cathode materials were synthesized by two-step solid-state reaction route. The F-doped LiFePO4/C increases the intrinsic conductivity, the diffusion of lithium ions, also improves the high-rate and low-temperature performances of LiFePO4. The SEM images reveal some small morphology changes of the two kinds of the materials, so the improved properties may not due to grain size changes but crystal structure changes. The F-doped material has a higher capability at low temperature. At -20°C, with the rate of 0.5C, the discharge capacity was 82mAhg-1, higher than that of undoped material(65mAhg-1) and the result is better than the previous study[17](65mAhg-1 at the rate of 0.3C), and the disparity would enlarge with the rate increased. The CV plots indicate that the doped material reveals less degree of polarization. F-doping sample improves the electrical conductivity of material, accelerating the process of Li+ deintercalation, therefore, improving the electrochemical performances at low temperature.

Modification of Li- and Mn-Rich Cathode Materials via Formation of the Rock-Salt and Spinel Surface Layers for Steady and High-Rate Electrochemical Performances

2020 ◽  
Vol 12 (29) ◽  
pp. 32698-32711
Author(s):  
Sandipan Maiti ◽  
Hadar Sclar ◽  
Rosy ◽  
Judith Grinblat ◽  
Michael Talianker ◽  
...  
Keyword(s):  
Rock Salt ◽  
Cathode Materials ◽  
High Rate ◽  
Electrochemical Performances ◽  
Surface Layers

scholarly journals Enhanced Electrochemical Performances of Cobalt-Doped Li2MoO3 Cathode Materials

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 843 ◽  
Author(s):  
Zhiyong Yu ◽  
Jishen Hao ◽  
Wenji Li ◽  
Hanxing Liu
Keyword(s):  
Cathode Materials ◽  
Photoelectron Spectroscopy ◽  
Solid Phase ◽  
Phase Method ◽  
Electrochemical Performances ◽  
X Ray ◽  
Electrochemical Tests ◽  
Co Doping ◽  
Solid Phase Method ◽  
Better Than

Co-doped Li2MoO3 was successfully synthesized via a solid phase method. The impacts of Co-doping on Li2MoO3 have been analyzed by X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) measurements. The results show that an appropriate amount of Co ions can be introduced into the Li2MoO3 lattices, and they can reduce the particle sizes of the cathode materials. Electrochemical tests reveal that Co-doping can significantly improve the electrochemical performances of the Li2MoO3 materials. Li2Mo0.90Co0.10O3 presents a first-discharge capacity of 220 mAh·g−1, with a capacity retention of 63.6% after 50 cycles at 5 mA·g−1, which is much better than the pristine samples (181 mAh·g−1, 47.5%). The enhanced electrochemical performances could be due to the enhancement of the structural stability, and the reduction in impedance, due to the Co-doping.

LiMgxMn2−xO4 (x≤0.10) cathode materials with high rate performance prepared by molten-salt combustion at low temperature

2015 ◽  
Vol 41 (8) ◽  
pp. 9662-9667 ◽  
Author(s):  
Jijun Huang ◽  
Fangli Yang ◽  
Yujiao Guo ◽  
Cancan Peng ◽  
Hongli Bai ◽  
...  
Keyword(s):  
Low Temperature ◽  
Molten Salt ◽  
Cathode Materials ◽  
High Rate ◽  
Rate Performance ◽  
High Rate Performance

Li3V2(PO4)3 modified LiFePO4/C cathode materials with improved high-rate and low-temperature properties

Ionics ◽  
2013 ◽  
Vol 19 (12) ◽  
pp. 1861-1866 ◽  
Author(s):  
Zhipeng Ma ◽  
Guangjie Shao ◽  
Xu Wang ◽  
Jianjun Song ◽  
Guiling Wang
Keyword(s):  
Low Temperature ◽  
Cathode Materials ◽  
High Rate

Preparation and Electrochemical Performance of Mg-Doped LiNi0.4Co0.2Mn0.4O2 Cathode Materials by Urea Co-Precipitation

2012 ◽  
Vol 519 ◽  
pp. 152-155 ◽  
Author(s):  
Qian Zhang ◽  
Yan Sheng Zheng ◽  
Sheng Kui Zhong
Keyword(s):  
Electrochemical Performance ◽  
Layered Structure ◽  
Cathode Materials ◽  
Precipitation Method ◽  
Electrochemical Performances ◽  
Sem Images ◽  
Transfer Resistance ◽  
Co Precipitation ◽  
Charge Discharge ◽  
Mg Doped

The Mg-doped LiNi0.4Co0.2-xMn0.4MgxO2 cathode materials (x=0, 0.01, 0.02 and 0.03) were synthesized by a urea co-precipitation method. Its structure and electrochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and electrochemical performance tests. XRD studies indicate that the Mg-doped LiNi0.4Co0.2Mn0.4O2 samples perform the same layered structure as the undoped LiNi0.4Co0.2Mn0.4O2. SEM images show that the particle size of Mg-doped LiNi0.4Co0.2Mn0.4O2 is smaller than the undoped LiNi0.4Co0.2Mn0.4O2 sample. Charge-discharge tests confirm that the rate capacity and cycling performance of LiNi0.4Co0.2-xMn0.4MgxO2 are improved by Mg-doped. The optimal doping content of Mg is x=0.02 in the LiNi0.4Co0.2-xMn0.4MgxO2 samples, which can achieve high initial charge-discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Mg-doping. The improved electrochemical performances of the Mg-doped LiNi0.4Co0.2Mn0.4O2 cathode materials are attributed to the addition of Mg2+ ion by stabilizing the layered structure.

Rapid Freezing of Freeze-Etch Specimens

1980 ◽  
Vol 38 ◽  
pp. 752-755
Author(s):  
A. Elgsaeter ◽  
T. Espevik ◽  
G. Kopstad
Keyword(s):  
Low Temperature ◽  
Metal Surface ◽  
Relative Velocity ◽  
Thermal Contact ◽  
High Rate ◽  
Rapid Freezing ◽  
Temperature Decrease ◽  
Freeze Etching

The importance of a high rate of temperature decrease (“rapid freezing”) when freezing specimens for freeze-etching has long been recognized1. The two basic methods for achieving rapid freezing are: 1) dropping the specimen onto a metal surface at low temperature, 2) bringing the specimen instantaneously into thermal contact with a liquid at low temperature and subsequently maintaining a high relative velocity between the liquid and the specimen. Over the last couple of years the first method has received strong renewed interest, particularily as the result of a series of important studies by Heuser and coworkers 2,3. In this paper we will compare these two freezing methods theoretically and experimentally.

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