scholarly journals Enhanced Electrochemical Performance of LiFePO4 Originating from the Synergistic Effect of ZnO and C Co-Modification

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 12
Author(s):  
Xiaohua Chen ◽  
Yong Li ◽  
Juan Wang
Keyword(s):  
Zinc Oxide ◽  
Charge Transfer ◽  
Lithium Ion Batteries ◽  
Electrochemical Impedance ◽  
Lithium Ion ◽  
Charge Transfer Resistance ◽  
Electron Conductivity ◽  
Spherical Particles ◽  
Commercial Application ◽  
Transfer Resistance

Olivine-structure LiFePO4 is considered as promising cathode materials for lithium-ion batteries. However, the material always sustains poor electron conductivity, severely hindering its further commercial application. In this work, zinc oxide and carbon co-modified LiFePO4 nanomaterials (LFP/C-ZnO) were prepared by an inorganic-based hydrothermal route, which vastly boosts its performance. The sample of LFP/C-xZnO (x = 3 wt%) exhibited well-dispersed spherical particles and remarkable cycling stability (initial discharge capacities of 138.7 mAh/g at 0.1 C, maintained 94.8% of the initial capacity after 50 cycles at 0.1 C). In addition, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) disclose the reduced charge transfer resistance from 296 to 102 Ω. These suggest that zinc oxide and carbon modification could effectively minimize charge transfer resistance, improve contact area, and buffer the diffusion barrier, including electron conductivity and the electrochemical property. Our study provides a simple and efficient strategy to design and optimize promising olivine-structural cathodes for lithium-ion batteries.

scholarly journals Electrochemical Impedance Spectroscopy on the Performance Degradation of LiFePO4/Graphite Lithium-Ion Battery Due to Charge-Discharge Cycling under Different C-Rates

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4507 ◽  
Author(s):  
Yusuke Abe ◽  
Natsuki Hori ◽  
Seiji Kumagai
Keyword(s):  
Charge Transfer ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Specific Capacity ◽  
Lithium Ion ◽  
Performance Degradation ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Charge Discharge

Lithium-ion batteries (LIBs) using a LiFePO4 cathode and graphite anode were assembled in coin cell form and subjected to 1000 charge-discharge cycles at 1, 2, and 5 C at 25 °C. The performance degradation of the LIB cells under different C-rates was analyzed by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy. The most severe degradation occurred at 2 C while degradation was mitigated at the highest C-rate of 5 C. EIS data of the equivalent circuit model provided information on the changes in the internal resistance. The charge-transfer resistance within all the cells increased after the cycle test, with the cell cycled at 2 C presenting the greatest increment in the charge-transfer resistance. Agglomerates were observed on the graphite anodes of the cells cycled at 2 and 5 C; these were more abundantly produced in the former cell. The lower degradation of the cell cycled at 5 C was attributed to the lowered capacity utilization of the anode. The larger cell voltage drop caused by the increased C-rate reduced the electrode potential variation allocated to the net electrochemical reactions, contributing to the charge-discharge specific capacity of the cells.

Electrochemical Decomposition of Poly(Vinylidene Fluoride) Binder for a Graphite Negative Electrode in Lithium-Ion Batteries

2017 ◽  
Vol 893 ◽  
pp. 127-131 ◽  
Author(s):  
Min Ji Kim ◽  
Chang Hee Lee ◽  
Mun Hui Jo ◽  
Soon Ki Jeong
Keyword(s):  
Lithium Ion Batteries ◽  
Vinylidene Fluoride ◽  
Electrochemical Impedance ◽  
Negative Electrode ◽  
Reduction Process ◽  
Lithium Ion ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Electrode Resistance ◽  
Poly Vinylidene Fluoride

To clarify the electrochemical decomposition of poly (vinylidene fluoride) (PVdF) used as a binder for lithium-ion batteries while simultaneously verifying the correlation between electrode resistance and the PVdF content in graphite negative electrodes, in this study, we applied lithium bis (trifluoromethanesulfonyl) imide, which suppresses graphite exfoliation, as a salt. As a result, the electrochemical decomposition of PVdF was observed at a higher potential than that at which the electrolyte was decomposed during the reduction process. Additionally, this study demonstrated (through electrochemical impedance spectroscopy analysis) that electrode resistances such as solid electrolyte interface and charge transfer resistance proportionally increased with the PVdF content.

Electrochemical Properties of P-Doped Silicon Thin Film Anodes of Lithium Ion Batteries

2013 ◽  
Vol 737 ◽  
pp. 80-84 ◽  
Author(s):  
Arenst Andreas Arie ◽  
Joong Kee Lee
Keyword(s):  
Electrical Conductivity ◽  
Electrochemical Properties ◽  
Lithium Ion Batteries ◽  
Specific Capacity ◽  
High Capacity ◽  
Lithium Ion ◽  
Charge Transfer Resistance ◽  
Commercial Application ◽  
Silicon Thin Film ◽  
Transfer Resistance

Silicon would seem to be a possible candidate to replace graphite or carbon as anode materials for lithium ion batteries based on its potential high capacity of 4200 mAhg-1. The main problem that must be solved for commercial application of silicon as anode material was the poor cyclic performance due to severe volume expansion during repeated charged-discharged cycles and its low electrical conductivity. In this work, we proposed Phosphorus doped (P-doped) Si films as anodes in lithium ion batteries. The electrochemical properties of the silicon based electrodes were examined by means of charge-discharge and impedance test. In comparison with the bare silicon electrode, the P type silicon electrode exhibited higher specific capacity of 2585 mAhg-1 until the 50th cycle. It was attributed to the improved electrical conductivity of Si film and reduced charge transfer resistance

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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