Capacity Fade Of Cells Research Articles

Effect of Anion Receptor Additives on Electrochemical Performance of Lithium-Ion Batteries

Four boron-based anion receptors were investigated as electrolyte additives for lithium-ion batteries. The electrochemical performance of lithium-ion cells was found to strongly depend on the structure of the anion receptor added to the electrolyte. The capacity retention of the lithium-ion cell was slightly improved by adding 0.07 M bis(1,1,1,3,3,3-hexafluoroisopropyl)pentafluorophenylboronate additive, whereas the addition of 2,5-bis(trifluoromethylphenyl)tetrafluoro-1,3,2-benzodioxaborole dramatically deteriorated the electrochemical performance. The addition of a certain type of anion receptor can promote the electrochemical decomposition of the electrolyte, resulting in high interfacial impedance and accelerated capacity fading of lithium-ion cells. Ab initio calculations showed that the electrochemical performance of anion receptors had good correlation to the degree of localization of the lowest unoccupied molecular orbital at the boron center of anion receptors, which can potentially be used in th...

Effect of SEI on Capacity Losses of Spinel Lithium Manganese Oxide/Graphite Batteries Stored at 60°C

The discharge capacities of spinel-type Li 1.1 Mn 1.9 O 4 /graphite cells charged in electrolytes with solid electrolyte interphase (SEI)-forming additives are investigated after being stored at 60°C. The presence of Mn deposits on the anode surface, which is responsible for the capacity fading of cells, is clearly shown by means of open-circuit voltage, ex situ X-ray diffraction, and energy-dispersive spectrometry measurements. Unlike fluoroethylene carbonate, using vinylene carbonate as an SEI former leads to a noticeable improvement in the discharge capacity retention of cells that were stored for 20 days at 60°C.

On Reasons for Capacity Fade of Lithium-sulfur Cells during Cycling

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Modeling capacity fade in lithium-ion cells

Battery life is an important, yet technically challenging, issue for battery development and application. Adequately estimating battery life requires a significant amount of testing and modeling effort to validate the results. Integrated battery testing and modeling is quite feasible today to simulate battery performance, and therefore applicable to predict its life. A relatively simple equivalent-circuit model (ECM) is used in this work to show that such an integrated approach can actually lead to a high-fidelity simulation of a lithium-ion cell's performance and life. The methodology to model the cell's capacity fade during thermal aging is described to illustrate its applicability to battery calendar life prediction.

Mathematical modeling of the capacity fade of Li-ion cells

A capacity fade prediction model has been developed for Li-ion cells based on a semi-empirical approach. Correlations for variation of capacity fade parameters with cycling were obtained with two different approaches. The first approach takes into account only the active material loss, while the second approach includes rate capability losses too. Both methods use correlations for variation of the film resistance with cycling. The state of charge (SOC) of the limiting electrode accounts for the active material loss. The diffusion coefficient of the limiting electrode was the parameter to account for the rate capability losses during cycling.

Aerospace and military battery applications

This paper gives a review of the papers presented at the IEEE 17th Annual Battery Conference on Applications and Advances, Long Beach, CA, USA, 2002. The topics covered are: Li batteries for satellites, capacity fade of Li-ion cells cycled at different temperatures, Ni-H/sub 2/ battery lifetime, batteries for Mars-exploring vehicles, Li-ion cell performance enhancement at low temperatures, navy service batteries, and US Army man portable applications and mobile power challenges.

Performance study of commercial LiCoO 2 and spinel-based Li-ion cells

The performance of Cell-Batt ® Li-ion cells and Sony 18650 cells using non-stoichiometric spinel and LiCoO 2, respectively, as positive electrode material has been studied under several modes of charging. During cycling, the cells were opened at intermittent cycles and extensive material and electrochemical characterization was done on the active material at both electrodes. Capacity fade of spinel-based Li-ion cells was attributed to structural degradation at the cathode and loss of active material at both electrodes due to electrolyte oxidation. For the Sony cells both primary (Li +) and secondary active material (LiCoO 2)/C) are lost during cycling.

Studies on Capacity Fade of Spinel-Based Li-Ion Batteries

The performance of Cell-Batt® Li-ion cells using nonstoichiometric spinel as the positive electrode material has been studied at different charging rates. The capacity of the cell was optimized based on varying the charging current and the end potential. Subsequent to this, the capacity fade of these batteries was studied at different charge currents. During cycling, cells were opened at intermittent cycles and extensive material and electrochemical characterization was done on the active material at both electrodes. For all charge currents, the resistance of both the electrodes does not vary significantly with cycling. This result is in contrast with cells made with cathode where the increase in cathode resistance with cycling causes the fade in capacity. Comparison of cyclic voltammograms of spinel and carbon electrode before and after 800 cycles reveals a decrease in capacity with cycling. Low rate charge-discharge studies confirmed this loss in capacity. The capacity loss was approximately equally distributed between both electrodes. On analyzing the X-ray diffraction patterns of the spinel electrode that were charged and discharged for several cycles, it can be seen that apart from the nonstoichiometric spinel phase, an additional phase slowly starts accumulating with cycling. This is attributed to the formation of defect spinel product according to a chemical reaction, which also leads to MnO dissolution in the electrolyte. Energy dispersive analysis by X-ray of the carbon samples shows an increase in Mn content with cycling. These studies indicate that capacity fade of spinel-based Li-ion cells can be attributed to (i) structural degradation at the cathode and (ii) loss of active materials at both electrodes due to electrolyte oxidation. © 2001 The Electrochemical Society. All rights reserved.

Studies on capacity fade of lithium-ion batteries

The capacity fade of Sony 18650S Li-ion cells has been analyzed using cyclic voltammetry, impedance spectroscopy and electron probe microscopic analysis (EPMA). The surface resistance at both the positive (LiCoO 2) and negative (carbon) electrodes were found to increase with cycling. This increase in resistance contributes to decreased capacity. Impedance data reveal that the interfacial resistance at LiCoO 2 electrode is larger than that at the carbon electrode. The impedance of the positive electrode (LiCoO 2) dominates the total cell resistance initially and also after 800 charge–discharge cycles. EPMA analysis on carbon electrodes taken from the fresh and cycled cell show the presence of oxidation products in the case of cycled cells. No change in the electrolyte resistance is seen with cycling.

00/02643 The mechanism of capacity fade of rechargeable alkaline manganese dioxide zinc cells

00/02643 The mechanism of capacity fade of rechargeable alkaline manganese dioxide zinc cells

The mechanism of capacity fade of rechargeable alkaline manganese dioxide zinc cells

Recent experiments showed, that in contrast to traditional opinion, if the cathode was protected by anode limitation the capacity fade of Rechargeable Alkaline Manganese Dioxide Zinc (RAM™) cells was not caused by the EMD cathode, but by the gelled zinc anode. The key is the electrolyte. The cathode competition for the electrolyte and the increasing requirement of chemically formed ZnO for more electrolyte caused an electrolyte deficiency at the front face of the anode and finally caused precipitation of zincate and passivation of zinc. The crust is a mixed material of precipitation and passivation products. The low solubility ZnO is formed by decomposition of electrochemically generated zincate ions [Zn(OH) 4] 2− and also by recombination of zinc with oxygen during overcharge. The progressively thickened “crust” at the front face of the anode increases the resistance, then finally causes the cell to fade. The crusting is a redistribution of active material and electrolyte between the front and rear of the cylindrical gelled zinc anode. More electrolyte and proper charging can delay such a “crusting” phenomenon.

FTIR Spectroscopy of Metal Oxide Insertion Electrodes: A New Diagnostic Tool for Analysis of Capacity Fading in Secondary Cells

Fourier transform infrared spectroscopy (FTIR) has been applied to the study of oxide insertion compounds used in rechargeable lithium batteries. The mechanisms responsible for capacity fading during normal cycling of cells in both the 3 and 4 V regions were determined by examination of spectra obtained from electrodes following 25 cycles at charge and discharge rates of C/6. In the 3 V region, electroactive material becomes electronically disconnected from the rest of the electrode due to fracture of the oxide particles and/or expansion and contraction of the active material during the cubic‐to‐tetragonal phase transformation. In the upper voltage region, the active electrode material is gradually converted to a lower voltage defect spinel phase via dissolution of manganese in the electrolyte.

Precision cycling and coulombic efficiency measurements on Li/MoS 2 and Li,Al/FeS cells

The use of a high precision cell and battery cycler to enhance the information obtained from constant current cycling is described. Using prototype Li/MoS 2 cells provided by Moli Energy Limited, it is shown that coulombic efficiencies measured to ±0.03% can be used to predict the cell's cycle life. Other measurements were used to test a percolation theory of the cell's capacity fade. Measurements of voltage relaxations during current interrupts of Li,Al/FeS cells produced by Electrofuel Inc. are described briefly.