Influence of Carbon Nanotubes on the Performances of LiFePO4

2010 ◽  
Vol 148-149 ◽  
pp. 1133-1137
Author(s):  
Li Ming Feng ◽  
Teng Gai ◽  
Xue Wei
Keyword(s):  
Carbon Nanotubes ◽  
Particle Size ◽  
Electrical Resistivity ◽  
Carbon Source ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Specific Capacity ◽  
Doping Amount ◽  
Mechanical Mixing

To improve the performances of LiFePO4, a positive material in lithium battery, research on the influence of doping amount and doping form of carbon nanotubes (CNTS) on electrical resistivity, specific capacity, specific surface area and particle size distribution of LiFePO4 powder was conducted. The results indicated that, addition of CNTS significantly reduced the electrical resistivity no matter in pure LiFePO4 or LiFe0.98Mg0.02PO4; with same usage, coating of CNTS as carbon source performed better than mechanical grinding and mixing with LiFePO4. With the increase of CNTS content, a rising trend of both specific surface area (BET) and particle size (D50) in LiFePO4 powder was observed, but seeing a slight drop in discharge capacity under the rates of 0.2C and 0.5C. When the content of CNTS reached 3% (by mass) respectively through mechanical mixing and being added as carbon source, electrical resistivity of pure LiFePO4 dropped from over 105Ω•cm to 1868Ω•cm and 27Ω•cm accordingly, and that of LiFe0.98Mg0.02PO4 dropped from over 105Ω•cm to 4800Ω•cm.

Effects of Different Organic Carbon Sources on Properties of LiFePO4/C Synthesized by Spray-Drying

2014 ◽  
Vol 535 ◽  
pp. 725-728 ◽  
Author(s):  
Cheng Lu ◽  
Lin Chen ◽  
Yun Bo Chen ◽  
Yi Jie Gu ◽  
Meng Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Carbon Source ◽  
Organic Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Spray Drying ◽  
Specific Surface Area ◽  
Carbon Sources ◽  
Tap Density ◽  
Organic Carbon Sources

LiFePO4/C materials were synthesized by spray-drying using FePO4·2H2O, LiOH·H2O as raw materials, with three kinds of organic carbon sources: soluble starch, crystal sugar and glucose. The particle size, tap density, specific surface area, morphology, structure and electrochemical properties of the LiFePO4/C were tested and analyzed. The results indicate that the organic carbon source has no effect on the phase of LiFePO4, but has a remarkable influence on the tap density and specific surface area of LiFePO4. The LiFePO4/C synthesized with crystal sugar and glucose has higher tap density, smaller particle size and specific surface area. The LiFePO4/C synthesized with the glucose as the carbon source exhibited the most excellent electrochemical performance. The discharge capacities are 160.6, 148.5 and 114.1mAh/g respectively at 0.1C, 1C and 5C. Under low temperature 253K, the discharge capacity is 56.2% of that at 298K with 0.2C.

Three-dimensional graphene encapsulated hollow CoSe2-SnSe2 nanoboxes for high performance asymmetric supercapacitors

2022 ◽  
Author(s):  
Kainan Li ◽  
Ke Zheng ◽  
Zhifang Zhang ◽  
Kuan Li ◽  
Ziyao Bian ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
Specific Capacity ◽  
Three Dimensional ◽  
Hollow Structure ◽  
Large Specific Surface Area ◽  
Composite Aerogel

Abstract Construction of metal selenides with a large specific surface area and a hollow structure is one of the effective methods to improve the electrochemical performance of supercapacitors. However, the nano-material easily agglomerates due to the lack of support, resulting in the loss of electrochemical performance. Herein, we successfully design a three-dimensional graphene (3DG) encapsulation-protected hollow nanoboxes (CoSe2-SnSe2) composite aerogel (3DG/CoSe2-SnSe2) via a co-precipitation method coupled with self-assembly route, followed by a high temperature selenidation strategy. The obtained aerogel possesses porous 3DG conductive network, large specific surface area and plenty of reactive active sites. It could be used as a flexible and binder-free electrode after a facile mechanical compression process, which provided a high specific capacitance of 460 F g-1 at 0.5 A g-1, good rate capability of 212.7 F g-1 at 10 A g-1, and excellent cycle stability due to the fast electron/ion transfer and electrolyte diffusion. With the as-prepared 3DG/CoSe2-SnSe2 as positive electrodes and the AC (activated carbon) as negative electrodes, an asymmetric supercapacitor (3DG/CoSe2-SnSe2//AC) was fabricated, which delivered a high specific capacity of 38 F g-1 at 1A g-1 and an energy density of 11.89 W h kg-1 at 749.9 W kg-1, as well as a capacitance retention of 91.1% after 3000 cycles. This work provides a new method for preparing electrode material.

Physical Properties Variability of Zinc Powders Obtained by Electrochemical Method

2021 ◽  
Vol 316 ◽  
pp. 689-693
Author(s):  
K.D. Naumov ◽  
V.G. Lobanov
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Bulk Density ◽  
Surface Area ◽  
Specific Surface Area ◽  
Current Density ◽  
Zinc Concentration ◽  
Regulatory Change ◽  
Average Particle ◽  
Zinc Powders

The aim of this paper is to establish a regulatory change of zinc powders key physicochemical properties with varying electroextraction conditions. It was studied influence zinc concentration, alkali concentration and current density. Quantitative dependencies of zinc powders particle size and specific surface area from mentioned electroextraction parameters are shown. At increasing of zinc concentration, decreasing of NaOH concentration and decreasing of current density of powders particle size growth, correspondingly specific surface area is declined. It is indicated, that electrolytic zinc powders bulk density varies from 0.61 g/cm3 to 0.75 g/cm3 with a decrease of average particle size from 121 μm to 68 μm. In comparison, spherical powders bulk density used in various industries is currently 2.45-2.6 g/cm3. In all experiments, metal zinc content varied in the range of 91.1-92.5%, the rest - ZnO. To a greater extent, this indicator depends on powder washing quality from alkali and storage conditions.

The Influence of Fe/Al Molar Ratio on Microreactor-Based Catalyst Preparation and Carbon Nanotube Preparation

2021 ◽  
Vol 1036 ◽  
pp. 130-136
Author(s):  
Ting Qun Tan ◽  
Lei Geng ◽  
Yan Lin ◽  
Yan He
Keyword(s):  
Carbon Nanotubes ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Small Diameter ◽  
High Specific Surface Area ◽  
Detection Methods ◽  
Molar Ratio ◽  
High Catalytic Activity

In order to prepare carbon nanotubes with high specific surface area, small diameter, low resistivity, high purity and high catalytic activity, the Fe-Mo/Al2O3 catalyst was prepared based on the microreactor. The influence of different Fe/Al molar ratios on the catalyst and the carbon nanotubes prepared was studied through BET, SEM, TEM and other detection methods. Studies have shown that the pore structure of the catalyst is dominated by slit pores at a lower Fe/Al molar ratio. The catalytic activity is the highest when the Fe/Al molar ratio is 1:1, reaching 74.1%. When the Fe/Al molar ratio is 1:2, the catalyst has a higher specific surface area, the maximum pore size is 8.63 nm, and the four-probe resistivity and ash content of the corresponding carbon nanotubes are the lowest. The higher the proportion of aluminum, the higher the specific surface area of the catalyst and the carbon nanotubes, and the finer the diameter of the carbon nanotubes, which gradually tends to relax. The results show that when the Fe/Al molar ratio is 1:2, although the catalytic activity of the catalyst is not the highest, the carbon nanotubes prepared have the best performance.

scholarly journals Features of obtaining the catalyst for the synthesis of carbon nanotubes

2019 ◽  
Vol 81 (2) ◽  
pp. 261-267 ◽  
Author(s):  
E. A. Burakova ◽  
G. S. Besperstova ◽  
M. A. Neverova ◽  
A. G. Tkachev ◽  
N. V. Orlova ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Decomposition ◽  
Metal Oxide ◽  
Specific Surface ◽  
Surface Area ◽  
Nanostructured Materials ◽  
Specific Surface Area ◽  
Oxide System ◽  
Decomposition Stage ◽  
Al2o3 Catalyst

In this paper, the features of obtaining a Co-Mo/Al2O3 catalyst to synthesize carbon nanotubes (CNTs) by thermal decomposition were studied. It was revealed that the duration of the pre-catalyst thermal decomposition stage in the process of developing a metal oxide system has a significant impact on its activity in the synthesis of carbon nanostructured materials by chemical vapor deposition (CVD). It was proved that an effective catalyst for CNTs synthesis can be obtained by through thermal decomposition of the pre – catalyst, without calcination of the metal oxide system. The use of the Co-Mo/Al2O3 catalyst, synthesized in such a way, in the CVD process makes it possible to reduce the cost of synthesized CNTs. Using scanning electron microscopy, it was shown that the size of the grains, and specific surface area of the formed Co-Mo/Al2O3 catalyst depend on the thermal treatment conditions of the pre-catalyst. Under the conditions for the implementation of the pre-catalyst thermal decomposition stage (temperature, volume, duration, etc.), it is possible to contro not only the characteristics of the resulting catalyst (specific surface area, efficiency), but also the characteristics of the CNTs (diameter, degree of defectiveness). In the course of experiments, the optimal modes of implementation of the method for obtaining the Co-Mo/Al2O3 catalyst allowed forming a system with a specific surface area of ~ 108 m2/g. The use of the resulting catalyst in the synthesis of nanostructured materials provides a high specific yield of multi-walled CNTs with a diameter of 8-20 nm and a degree of defectiveness of 0.97.

scholarly journals Synthesis of Spherical Silica by Sol-Gel Method and Its Application as Catalyst Support

2011 ◽  
Vol 10 (2) ◽  
pp. 25
Author(s):  
Anirut Leksomboon ◽  
Bunjerd Jongsomjit
Keyword(s):  
Particle Size ◽  
Ethylene Glycol ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Weight Ratio ◽  
Gel Method ◽  
Sol Gel Method ◽  
Spherical Silica

In this present study, the spherical silica support was synthesized from tetraethyloxysilane (TEOS), water, sodium hydroxide, ethylene glycol and n-dodecyltrimethyl ammonium bromide (C12TMABr). The particle size was controlled by variation of the ethylene glycol co-solvent weight ratio of a sol-gel method preparation in the range of 0.10 to 0.50. In addition, the particle size apparently increases with high weight ratio of co-solvent, but the particle size distribution was broader. The standard deviation of particle diameter is large when the co-solvent weight ratio is more than 0.35 and less than 0.15. However, the specific surface area was similar for all weight ratios ranging from 1000 to 1300 m2/g. The synthesized silica was spherical and has high specific surface area. The cobalt was impregnated onto the obtained silica to produce the cobalt catalyst used for CO2 hydrogenation.</

Influence of Powder Particle Size of Slurries on Mechanical Properties of Porous Hydroxyapatite Ceramics

2005 ◽  
Vol 284-286 ◽  
pp. 365-368 ◽  
Author(s):  
Yin Zhang ◽  
Yoshiyuki Yokogawa ◽  
Tetsuya Kameyama
Keyword(s):  
Particle Size ◽  
Flexural Strength ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Particle Sizes ◽  
Wet Milling ◽  
Median Particle Size ◽  
Powder Characteristics ◽  
Median Particle

The effect of different particle sizes on the flexural strength and microstructure of three different types of hydroxyapatite (HAp) powders was studied. The powder characteristics of laboratory synthesized HAp powder (Lab1 and Lab2) were obtained through a wet milling method, and the median particle size and the specific surface area of powders are different with the dryness period. The median particle sizes of Lab1 and Lab2 are 0.34 µm and 0.74 µm, and the specific surface areas of Lab1 and Lab2 are 38.01 m2/g and 19.77 m2/g. The commercial HAp had median particle size of 1.13 µm and specific surface area of 11.62m2/g. The different powder characteristics affected the slip characteristics, and the flexural strength and microstructure of the sintered porous HAp bodies are also different. The optimum value for the minimum viscosity in these present HAp slip with respect to its solid loading and the optimum amount of the deflocculant were investigated. The flexural strengths of the porous HAp ceramics prepared by heating at 1200°C for 3 hrs in air were 17.59 MPa for Lab1 with a porosity of 60.48％, 10.51 MPa for Lab2 with a porosity of 57.75％, and 3.92 MPa for commercial HAp with a porosity of 79.37％.

A Simple Hydrothermal Synthesis of Cadmium Sulfide Wrapped on Graphene Nanocomposite for Supercapacitor Applications

2021 ◽  
Vol 21 (12) ◽  
pp. 5835-5845
Author(s):  
Ranjith Balu ◽  
Arivuoli Dakshanamoorthy
Keyword(s):  
Hydrothermal Synthesis ◽  
Specific Surface ◽  
Cadmium Sulfide ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Current Density ◽  
Specific Capacity ◽  
Cds Nanoparticles ◽  
Electrochemical Characteristics

Supercapacitor with high specific capacity is desirable for various energy storage and high powerdensity applications. Though Graphene has been the preferred material for high current density, nanocomposites have been attempted to increase the specific capacitance. Hydrothermal synthesis of cadmium sulfide/graphene (CdS/G) nanocomposite with CdS nanoparticles anchored/decorated over the graphene sheets is reported. The structural studies reveal the hexagonal phase of the prepared materials. The specific surface area (BET) and porosity is found to increase upon nanocomposite formation. The electrochemical characteristics such as cyclic voltammetry (CV), GCD and EIS of the CdS/G nanocomposite have been investigated. The capacitance of CdS/G nanocomposite almost doubled to 248 Fg−1 indicating the enhanced performance of the nanocomposite system and in addition it also showed excellent cycling stability of 74.8 percent after 1000 cycles. The supercapacitor investigated retained the initial energy density after charge-discharge, at 0.5 A/g for 1000 cycles. The graphene nanosheets increased the specific surface area and interfacial electron transfer of the composite material. It enhances the specific capacitance and cyclic stability of the supercapacitor device.

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