Synthesis and Electrochemical Properties of Spherical LiFePO4/C Composite via Spray Drying

2015 ◽  
Vol 1120-1121 ◽  
pp. 554-558 ◽  
Author(s):  
Juan Mei Wang ◽  
Bing Ren ◽  
Ying Lin Yan ◽  
Qing Zhang ◽  
Yan Wang
Keyword(s):  
Diffusion Coefficient ◽  
Electrochemical Properties ◽  
Spray Drying ◽  
Electrochemical Impedance ◽  
Retention Rate ◽  
Lithium Ion ◽  
Constant Current ◽  
Ion Diffusion ◽  
Electrochemical Tests ◽  
Li Ion

In this work, spherical LiFePO4/C composite had been synthesized by co-precipitation and spray drying method. The structure, morphology and electrochemical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscope (TEM), constant current charge-discharge tests and electrochemical impedance spectroscopy (EIS) tests. The spherical LiFePO4/C particles consisted of a number of smaller grains. The results showed that the morphology of LiFePO4/C particles seriously affected the Li-ion diffusion coefficient and electrochemical properties of lithium ion batteries. Electrochemical tests revealed the spherical LiFePO4/C composite had excellent Li-ion diffusion coefficient which was calculated to be 1.065×10-11 cm2/s and discharge capacity of 149 (0.1 C), 139 (0.2 C), 133 (0.5 C), 129 (1 C) and 124 mAhg-1(2 C). After 50 cycles, the capacity retention rate was still 93.5%.

scholarly journals Effect of Ni2+ on Lithium-Ion Diffusion in Layered LiNi1−x−yMnxCoyO2 Materials

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 465
Author(s):  
Yuanyuan Zhu ◽  
Yang Huang ◽  
Rong Du ◽  
Ming Tang ◽  
Baotian Wang ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Lithium Ion ◽  
Ion Diffusion ◽  
Local Coordination ◽  
Excellent Electrochemical Performance ◽  
Layered Cathode Materials ◽  
Li Ion ◽  
Dynamics Simulations ◽  
And Diffusion ◽  
Lithium Ion Diffusion

LiNi1−x−yMnxCoyO2 materials are a typical class of layered cathode materials with excellent electrochemical performance in lithium-ion batteries. Molecular dynamics simulations are performed for LiNi1−x−yMnxCoyO2 materials with different transition metal ratios. The Li/Ni exchange ratio, ratio of anti-site Ni2+ to total Ni2+, and diffusion coefficient of Li ions in these materials are calculated. The results show that the Li-ion diffusion coefficient strongly depends on the ratio of anti-site Ni2+ to total Ni2+ because their variation tendencies are similar. In addition, the local coordination structure of the Li/Ni anti-site is analyzed.

scholarly journals Electrospun Separation Material for Lithium-Ion Batteries: Synthesis and Study of Physical and Electrochemical Properties

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 18
Author(s):  
Semen V. Makhov ◽  
Aleksandr V. Ivanishchev ◽  
Arseni V. Ushakov ◽  
Dmitry V. Makhov
Keyword(s):  
Electrochemical Properties ◽  
Polyvinylidene Fluoride ◽  
Electrochemical Impedance ◽  
Reference Electrode ◽  
Lithium Ion ◽  
Physicochemical Characteristics ◽  
Synthesis Conditions ◽  
Electrochemical Tests ◽  
Working Electrode ◽  
Wide Range

The paper presents a comprehensive study of the physicochemical and electrochemical properties of a new nano-microporous non-woven composite separation material for a lithium-ion battery based on nano- and microfibers of polyvinylidene fluoride (PVDF) and its copolymer with polytetrafluoroethylene (PTFE), obtained by capillary-less electrospinning. A technique for the synthesis of separation material was developed, and the composition of the polymeric solution and the electrospinning conditions were optimized to produce polymer nano-microfibers with the required physicochemical characteristics. The optimal synthesis conditions for the separation material were determined. Higher porosity of the separation material and increased wettability in the most common electrolyte compositions contribute to the higher conductivity of the obtained separation material in comparison with the widely used commercial separation materials based on polypropylene (PP). The working characteristics of the separation material were studied in laboratory half-cells with a working electrode based on Li4Ti5O12, as well as a lithium metal counter electrode and a reference electrode. Charge-discharge tests of cells were performed in a wide range of variation of currents: From 0.1 to 25 C. A decrease in the total polarization of the working electrode and an increase in the cycled capacity at comparable currents in comparison with a cell with a PP-based separator were noted. The state of the electrodes and the separator in the cell was monitored using electrochemical impedance spectroscopy: The polarization resistances of the electrodes in different frequency ranges were determined, and the diffusion coefficient of lithium ions in the Li4Ti5O12 electrode was estimated in various lithiation states and at different stages of electrochemical tests, which were in the interval of 10−10 to 10−9 cm2·s−1.

Research on Lithium Ion Battery Material LiCoO2 for Hybrid Supercapacitor

2011 ◽  
Vol 287-290 ◽  
pp. 1565-1568 ◽  
Author(s):  
Sheng Li Zhang ◽  
Li Hua Ma ◽  
Xiao Gang Li ◽  
Yan Hua Song ◽  
Wei Li
Keyword(s):  
Leakage Current ◽  
Composite Electrode ◽  
Electrochemical Impedance ◽  
Retention Rate ◽  
Specific Capacity ◽  
Lithium Ion ◽  
Impedance Spectrum ◽  
Constant Current ◽  
Electrochemical Impedance Spectrum ◽  
Hybrid Supercapacitor

The electrochemical performance of capacitor was studied with LiCoO2/AC as composite cathode and activated carbon (AC) as anode, in 1.0 mol/L LiPF6/EC+DMC electrolyte. Cyclic Voltammetary, Constant-Current Charge and Discharge, Electrochemical Impedance Spectrum (EIS) and Leakage Current Test were tested to study the characteristics of supercapacitors. The results illustrate that recharging voltage of hybrid supercapacitor can reach to 3.0 V and show good capacitance characteristics. The supercapacitor can rapidly charge and discharge and show good cycling performance. There is a great effect to the performance of the capacitors by adopting different proportional composite electrode. When the ratio of composite electrode is 6:4, we get maximum symmetrical Cyclic Voltammetary and short charge-discharge time only 26.4min; When the ratio is 7:3, the minimum AC impedance of 26.2W can be attained and least leakage current is only 19.92mA/g; When the ratio is 5:5, the best first specific capacity can reach to 70.17F/g but a lower capacity retention rate is 74.86%.

Calcium Doping Effects on the Electrochemical Properties of LiFePO4/C Cathode Materials for Lithium-Ion Batteries

2012 ◽  
Vol 560-561 ◽  
pp. 499-505 ◽  
Author(s):  
George Ting Kuo Fey ◽  
Cyun Jhe Yan ◽  
Yi Chuan Lin ◽  
Kai Pin Huang ◽  
Yung Da Cho ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Electronic Conductivity ◽  
Rate Capability ◽  
Lithium Ion ◽  
Ion Diffusion ◽  
Solid State Method ◽  
X Ray ◽  
Doping Effects ◽  
Li Ion ◽  
Calcium Doping

This Olivine LiFe1-xCaxPO4/C composites (x=0 - 0.014) were synthesized by a solid-state method using sebasic acid as a carbon source. The structure and electrochemical properties of the LiFe1-xCaxPO4/C compounds were studied. The X-ray diffractometer (XRD) results indicated that Ca2+ doping did not affect the structure of the samples, but the unit cell volume of doped sample are slightly increased. Electrochemical measurements showed that the LiFe0.99Ca0.01PO4/C composite delivered a discharge capacity of 149 mAh g-1 at a 0.2 C-rate between 4.0 and 2.8 V, probably due to the significant improvement of electronic conductivity and Li+ ion diffusion. Besides, the cell can sustain a 20 C-rate, and this rate capability is equivalent to charge or discharge in 3 min.

scholarly journals Femtosecond Laser Processing of Thick Film Cathodes and Its Impact on Lithium-Ion Diffusion Kinetics

2019 ◽  
Vol 9 (17) ◽  
pp. 3588 ◽  
Author(s):  
Wilhelm Pfleging ◽  
Petronela Gotcu
Keyword(s):  
Diffusion Coefficient ◽  
Thick Film ◽  
Active Material ◽  
Lithium Ion ◽  
Chemical Diffusion ◽  
Chemical Diffusion Coefficient ◽  
Ion Diffusion ◽  
Femtosecond Laser Processing ◽  
Specific Discharge ◽  
Li Ion

Quantitative experiments of lithiation/delithiation rates were considered for a better understanding of electrochemical intercalation/deintercalation processes in laser structured thick film cathodes. Besides galvanostatic cycling for evaluation of specific discharge capacities, a suitable quantitative approach for determining the rate of Li-ion insertion in the active material and the rate of Li-ion transport in the electrolyte is expressed by chemical diffusion coefficient values. For this purpose, the galvanostatic intermittent titration technique has been involved. It could be shown that laser structured electrodes provide an enhanced chemical diffusion coefficient and an improved capacity retention at high charging and discharging rates.

Influence of VC and FEC Additives on Interphase Properties of Carbon in Li-Ion Cells Investigated by Combined EIS & EQCM-D

2020 ◽  
Author(s):  
Paul Kitz ◽  
Matthew Lacey ◽  
Petr Novák ◽  
Erik Berg
Keyword(s):  
Electrochemical Impedance ◽  
Solid Electrolyte Interphase ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Gas Analysis ◽  
Side Reactions ◽  
Ion Diffusion ◽  
Battery Cell ◽  
Anode Passivation ◽  
Order Of Magnitude ◽  
Li Ion

<div>The electrolyte additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are well known for increasing the lifetime of a Li-ion battery cell by supporting the formation of an effective solid electrolyte interphase (SEI) at the anode. In this study combined simultaneous electrochemical impedance spectroscopy (EIS) and <i>operando</i> electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) are employed together with <i>in situ</i> gas analysis (OEMS) to study the influence of VC and FEC on the passivation process and the interphase properties at carbon-based anodes. In small quantities both additives reduce the initial interphase mass loading by 30 to 50 %, but only VC also effectively prevents continuous side reactions and improves anode passivation significantly. VC and FEC are both reduced at potentials above 1 V vs. Li<sup>+</sup>/Li in the first cycle and change the SEI composition which causes an increase of the SEI shear storage modulus by over one order of magnitude in both cases. As a consequence, the ion diffusion coefficient and conductivity in the interphase is also significantly affected. While small quantities of VC in the initial electrolyte increase the SEI conductivity, FEC decomposition products hinder charge transport through the SEI and thus increase overall anode impedance significantly. </div>

Lithium Ion Diffusion Through Glassy Carbon Plate

1997 ◽  
Vol 496 ◽  
Author(s):  
M. Inaba ◽  
S. Nohmi ◽  
A. Funabiki ◽  
T. Abe ◽  
Z. Ogumi
Keyword(s):  
Diffusion Coefficient ◽  
Glassy Carbon ◽  
Lithium Ion ◽  
Ion Diffusion ◽  
Irreversible Capacity ◽  
Oxidation Current ◽  
Current Curve ◽  
Carbon Plate ◽  
Lithium Ion Diffusion

ABSTRACTThe electrochemical permeation method was applied to the determination of the diffusion coefficient of Li+ion (DLi+) in a glassy carbon (GC) plate. The cell was composed of two compartments, which were separated by the GC plate. Li+ions were inserted electrochemically from one face, and extracted from the other. The flux of the permeated Li+ions was monitored as an oxidation current at the latter face. The diffusion coefficient was determined by fitting the transient current curve with a theoretical one derived from Fick's law. When the potential was stepped between two potentials in the range of 0 to 0.5 V, transient curves were well fitted with the theoretical one, which gaveDLi+ values on the order of 10−8cm2s−1. In contrast, when the potential was stepped between two potentials across 0.5 V, significant deviation was observed. The deviation indicated the presence of trap sites as well as diffusion sites for Li+ions, the former of which is the origin of the irreversible capacity of GC.

scholarly journals Impact of Surface Chemistry of Silicon Nanoparticles on the Structural and Electrochemical Properties of Si/Ni3.4Sn4 Composite Anode for Li-Ion Batteries

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 18
Author(s):  
Tahar Azib ◽  
Claire Thaury ◽  
Fermin Cuevas ◽  
Eric Leroy ◽  
Christian Jordy ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Electrochemical Properties ◽  
Large Scale ◽  
Silicon Nanoparticles ◽  
Lithium Ion ◽  
Li Ion Batteries ◽  
Chemical Homogeneity ◽  
Electrochemical Behaviors ◽  
Pure Silicon ◽  
Li Ion

Embedding silicon nanoparticles in an intermetallic matrix is a promising strategy to produce remarkable bulk anode materials for lithium-ion (Li-ion) batteries with low potential, high electrochemical capacity and good cycling stability. These composite materials can be synthetized at a large scale using mechanical milling. However, for Si-Ni3Sn4 composites, milling also induces a chemical reaction between the two components leading to the formation of free Sn and NiSi2, which is detrimental to the performance of the electrode. To prevent this reaction, a modification of the surface chemistry of the silicon has been undertaken. Si nanoparticles coated with a surface layer of either carbon or oxide were used instead of pure silicon. The influence of the coating on the composition, (micro)structure and electrochemical properties of Si-Ni3Sn4 composites is studied and compared with that of pure Si. Si coating strongly reduces the reaction between Si and Ni3Sn4 during milling. Moreover, contrary to pure silicon, Si-coated composites have a plate-like morphology in which the surface-modified silicon particles are surrounded by a nanostructured, Ni3Sn4-based matrix leading to smooth potential profiles during electrochemical cycling. The chemical homogeneity of the matrix is more uniform for carbon-coated than for oxygen-coated silicon. As a consequence, different electrochemical behaviors are obtained depending on the surface chemistry, with better lithiation properties for the carbon-covered silicon able to deliver over 500 mAh/g for at least 400 cycles.

Improved Li-ion diffusion process in TiO2/rGO anode for lithium-ion battery

2017 ◽  
Vol 727 ◽  
pp. 998-1005 ◽  
Author(s):  
Juan Li ◽  
Jianfeng Huang ◽  
Jiayin Li ◽  
Liyun Cao ◽  
Hui Qi ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Lithium Ion Battery ◽  
Lithium Ion ◽  
Ion Diffusion ◽  
Li Ion

Electrochemical Properties of Carbon-Coated NbO2 as a Negative Electrode for Lithium-Ion Batteries

2016 ◽  
Vol 724 ◽  
pp. 87-91 ◽  
Author(s):  
Chang Su Kim ◽  
Yong Hoon Cho ◽  
Kyoung Soo Park ◽  
Soon Ki Jeong ◽  
Yang Soo Kim
Keyword(s):  
Electrochemical Properties ◽  
Lithium Ion Batteries ◽  
Ball Milling ◽  
Carbon Coating ◽  
Electrochemical Impedance ◽  
Active Material ◽  
Negative Electrode ◽  
Lithium Ion ◽  
Transfer Resistance ◽  
Carbon Coated

We investigated the electrochemical properties of carbon-coated niobium dioxide (NbO2) as a negative electrode material for lithium-ion batteries. Carbon-coated NbO2 powders were synthesized by ball-milling using carbon nanotubes as the carbon source. The carbon-coated NbO2 samples were of smaller particle size compared to the pristine NbO2 samples. The carbon layers were coated non-uniformly on the NbO2 surface. The X-ray diffraction patterns confirmed that the inter-layer distances increased after carbon coating by ball-milling. This lead to decreased charge-transfer resistance, confirmed by electrochemical impedance spectroscopy, allowing electrons and lithium-ions to quickly transfer between the active material and electrolyte. Electrochemical performance, including capacity and initial coulombic efficiency, was therefore improved by carbon coating by ball-milling.

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