Aging Mechanisms of LiFePO[sub 4] Batteries Deduced by Electrochemical and Structural Analyses

Liu, Ping; Wang, John; Hicks-Garner, Jocelyn; Sherman, Elena; Soukiazian, Souren; Verbrugge, Mark W.; Tataria, Harshad; Musser, J.; Finamore, Peter

doi:10.1149/1.3294790

Cited by 306 publications

(225 citation statements)

References 51 publications

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“…The differentiation analysis of the discharge profiles as well as in situ reference electrode measurements revealed loss of lithium as well as degradation of the carbon anode [33], whereas Dubarry et al [35] reported that the cells suffer severe degradation at 60°C and that the electrochemical milling of grains could explain the observed degradation as it might cause loss of active material in the positive electrode by isolating grains from the percolation pathway, which may also induce a loss of Li inventory, due to SEI formation on the fresh surface created, especially at elevated temperatures. Safari et al [37] identified the depletion of cyclable lithium and the partial loss of graphite active-material particles as the two contributors to the capacity decline of the cells aged by cycling and storage at 25 and 45°C.…”

Section: Introductionmentioning

confidence: 99%

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Calendar aging of a graphite/LiFePO4 cell

Kassem

Bernard

Revel

et al. 2012

Journal of Power Sources

276

124

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Graphite/LFP commercial cells are stored under 3 different conditions of temperature (30°C, 45°C, and 60°C) and SOC (30, 65, and 100%) during up to 8 months. Several non-destructive electrochemical tests are performed at different storage times in order to understand calendar aging phenomena. After storage, all the cells except those stored at 30°C exhibited capacity fade. The extent of capacity fade strongly increases with storage temperature and to a lesser extent with the state of charge. From in-depth data analysis, cyclable lithium loss was identified as the main source of capacity fade. This loss arises from side reactions taking place at the anode, e.g. solvent decomposition leading to the growth of the solid electrolyte interphase. However, the existence of reversible capacity loss also suggests the presence of side reactions occurring at the cathode, which are less prominent than those at the anode. The analyses do not show any evidence about active-material loss in the electrodes. The cells do not suffer substantial change in internal resistance. According to EIS analysis, the overall impedance increase is 70% or less.

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Section: Introductionmentioning

confidence: 99%

“…It is safe, because of a high thermal stability, and has a low toxicity and a low cost compared to cathodes such as LiCoO 2 . Several aging studies concerned with life performance of LFP-based cells are found in the literature [26][27][28][29][30][31][32][33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Calendar aging of a graphite/LiFePO4 cell

Kassem

Bernard

Revel

et al. 2012

Journal of Power Sources

276

124

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“…Again, lithium inventory loss is found to be the main cause of the capacity degradation of the LFP-based cell. Liu et al [64,65] investigated the discharge profiles using a differential analysis, and they confirmed that the loss of reversible Li is responsible for most of capacity fade. They also used external lithium source to replenish the cycled cathode which has lost 30 % of its capacity after 2,730 cycles.…”

Section: Sphericalmentioning

confidence: 95%

Precipitated silica as filler for polymer electrolyte based on poly(acrylonitrile)/sulfolane

Kurc

2014

J Solid State Electrochem

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The aim of the present work was to perform a preliminary study of the physicochemical properties of hybrid organic-inorganic gel electrolytes for Li-ion batteries based on the PAN/TMS -poly(acrylonitrile)/sulfolane -polymeric matrix and surface-modified precipitated silicas. Modifications were done by means of the so-called dry method using silane U-511 3-methacryloxypropyltrimetoxysilane. Scanning electron microscopy (SEM), noninvasive back scattering method (NIBS), specific surface area (BET), the degree of modification of the silica fillers-Fourier-transform infrared spectroscopy (FT-IR), impedance analysis, and charging/ discharging were carried out. It is found that the silica fillers were homogeneously dispersed in the polymeric matrix, which enhanced conductivity and electrochemical stability of porous polymer electrolytes. Applicability of the prepared gel electrolytes for the Li-ion technology was estimated on the basis of specific conductivity measurements. It was shown that modification of the silica surface by the silane causes an increase in the gel-specific conductivity by about 2 orders of magnitude as compared to gel with unmodified silica.

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“…Commonly used reference electrodes are inserted into the cell prior to the sealing of the outer casing material; [15][16][17][18] however, this approach is not amenable to mass production and may alter the performance of the cell relative to one without an inserted reference electrode. Liu et al 6 utilized a reference electrode by removing the end cap of a cylindrical cell and immersing both the cell and reference electrode in an electrolyte-filled vessel, with the reference electrode located outside of the cell. 19 These researchers conducted a cycle-aging regime on a cell in this configuration and reported voltage of the negative electrode (vs.…”

mentioning

confidence: 99%

Development and Use of a Lithium-Metal Reference Electrode in Aging Studies of Lithium-Ion Batteries

Belt

Bernardi

Utgikar

2014

J. Electrochem. Soc.

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The development and implementation of an in situ lithium-metal reference electrode for use in lithium-ion cells is described. The reference electrode is inserted into cylindrical, commercially available 1.2 Ah lithium-ion cells via perforation of the cell's outer metallic casing. The reference electrode is used to investigate voltage characteristics of the individual electrodes throughout calendar (i.e., zero duty) aging and duty cycle aging regimes. The response of the electrode voltages (vs. reference) to a given current pulse prior to and during interruptions of the aging regime indicates that the resistance of the positive-electrode is much larger than that of the negative electrode. Prior to aging, the ratio of the positive electrode resistance to that of the negative electrode is approximately two. After aging, the resistance of the positive electrode nearly triples, resulting in a ratio of approximately six, with the resistance of the negative electrode remaining approximately unchanged for both calendar-and cycle-aging regimes. The changes in the cell's coulombic capacity at various discharge rates are also characterized and indicate the additional contribution of cycle aging over the calendar aging alone to the capacity loss of cells. Furthermore, both "charge depletion" and "charge sustaining" cycle aging were investigated and indicates the added stress of charge depletion operation. The service life of rechargeable lithium-ion batteries has certainly improved from the early days 1,2 by using more robust materials and better manufacturing methods and has resulted in the wide-spread adoption of these batteries. While many aging parameters can affect life, such as depth-of-discharge, discharge or charge rate, and stateof-charge (SOC), increased temperature has been shown to greatly accelerate the aging processes and is very often used to expediently obtain aging information.3-5 Aging is generally characterized by measurements of coulombic capacity and power (and/or resistance) at specified reference conditions during temporary interruptions of a certain aging regime. Proposed degradation mechanisms by Liu et al. for capacity loss 6 focus on buildup of a solid-electrolyte interphase (SEI) 7 on the negative electrode and for resistance rise focus on decrepitation (micro-cracking, structural disordering, and dissolution) of the active material of the positive electrode.8-10 Although the cell voltage (i.e., positive vs. negative electrode) response is typically measured during aging studies, the employment of a reference electrode allows changes in the cell voltage to be ascribable to contributions from the individual electrodes.c The use of a reference electrode can therefore add crucial information to the understanding of the degradation mechanisms that lead to cell aging and is the primary focus of this work. The development of an in situ lithium-metal reference electrode is described, whereby the electrode is placed within the cell through a perforation and provides direct contact with the liquid electro...

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Aging Mechanisms of LiFePO[sub 4] Batteries Deduced by Electrochemical and Structural Analyses

Cited by 306 publications

References 51 publications

Calendar aging of a graphite/LiFePO4 cell

Calendar aging of a graphite/LiFePO4 cell

Precipitated silica as filler for polymer electrolyte based on poly(acrylonitrile)/sulfolane

Development and Use of a Lithium-Metal Reference Electrode in Aging Studies of Lithium-Ion Batteries

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