Potentiometric measurement of entropy change for lithium batteries

Zhang, Xiaofeng; Zhao, Yan; Patel, Yatish; Zhang, Teng; Liu, Weiming; Mu, Chunlai; Offer, Gregory J.; Ya, Yan

doi:10.1039/c6cp08505a

Cited by 53 publications

(68 citation statements)

References 69 publications

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“…Despite this, tab cooling is considered for industrial applications. 49 Pouch cell surface cooling is almost always applied uniformly across a cell surface 7,42 and is therefore quantifiable by considering the temperature difference between cell and cooling plate, and the measurable quality of the thermal interface. By contrast, pouch cell tab cooling is dependent on multiple geometric and thermal parameters, and consequently is very difficult to quantify.…”

Section: Literature Reviewmentioning

confidence: 99%

The Cell Cooling Coefficient: A Standard to Define Heat Rejection from Lithium-Ion Batteries

Hales

Diaz

Marzook

et al. 2019

J. Electrochem. Soc.

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Lithium-ion battery development is conventionally driven by energy and power density targets, yet the performance of a lithium-ion battery pack is often restricted by its heat rejection capabilities. It is therefore common to observe elevated cell temperatures and large internal thermal gradients which, given that impedance is a function of temperature, induce large current inhomogeneities and accelerate cell-level degradation. Battery thermal performance must be better quantified to resolve this limitation, but anisotropic thermal conductivity and uneven internal heat generation rates render conventional heat rejection measures, such as the Biot number, unsuitable. The Cell Cooling Coefficient (CCC) is introduced as a new metric which quantifies the rate of heat rejection. The CCC (units W.K −1) is constant for a given cell and thermal management method and is therefore ideal for comparing the thermal performance of different cell designs and form factors. By enhancing knowledge of pack-wide heat rejection, uptake of the CCC will also reduce the risk of thermal runaway. The CCC is presented as an essential tool to inform the cell down-selection process in the initial design phases, based solely on their thermal bottlenecks. This simple methodology has the potential to revolutionise the lithium-ion battery industry.

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Section: Literature Reviewmentioning

confidence: 99%

The Cell Cooling Coefficient: A Standard to Define Heat Rejection from Lithium-Ion Batteries

Hales

Diaz

Marzook

et al. 2019

J. Electrochem. Soc.

Self Cite

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“…where the terms e 1 and e 2 describe the energies per site of sublattice 1 and 2, respectively, dependent on j. The sublattice occupancies n 1 and n 2 in eqn (11) and (12) are explicitly determined by the index j while performing the summation in eqn 7, i.e. for N o M, n 1 = (N À j)/N and n 2 = j/N.…”

Section: Statistical Mechanical Modelmentioning

confidence: 99%

“…One class of promising techniques is based on thermodynamic measurements, a particular example of which is entropy profiling (EP). [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] This technique is based on the principle that the partial molar entropy change is proportional to the temperature response of the open circuit voltage (OCV) of a cell, by…”

Section: Introductionmentioning

confidence: 99%

“…They observed changes in the magnitudes of the peaks in profiles that were attributed to separate structural changes at the anode and cathode. A more comprehensive overview of entropy change measurements is available in a recent review by Zhang et al 11 Spinel lithium manganese oxide (LMO) electrodes are an attractive, low cost and non-toxic alternative to the many layered cathode structures currently used in commercial Li-ion cells. Entropy profiles of the stoichiometric compound, Li x Mn 2 O 4 (0 r x r 1), show two well defined peaks.…”

Section: Introductionmentioning

confidence: 99%

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Quantifying structure dependent responses in Li-ion cells with excess Li spinel cathodes: matching voltage and entropy profiles through mean field models

Schlueter

Genieser

Richards

et al. 2018

Phys. Chem. Chem. Phys.

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Measurements of the open circuit voltage of Li-ion cells have been extensively used as a non-destructive characterisation tool. Another technique based on entropy change measurements has also been applied for this purpose. More recently, both techniques have been used to make qualitative statements about aging in Li-ion cells. One proposed cause of cell failure is point defect formation in the electrode materials. The steps in voltage profiles, and the peaks in entropy profiles are sensitive to order/disorder transitions arising from Li/vacancy configurations, which are affected by the host lattice structures. We compare the entropy change results, voltage profiles and incremental capacity (dQ/dV) obtained from coin cells with spinel lithium manganese oxide (LMO) cathodes, Li1+yMn2-yO4, where excess Li y was added in the range 0 ≤ y ≤ 0.2. A clear trend of entropy and dQ/dV peak amplitude decrease with excess Li amount was determined. The effect arises, in part, from the presence of pinned Li sites, which disturb the formation of the ordered phase. We modelled the voltage, dQ/dV and entropy results as a function of the interaction parameters and the excess Li amount, using a mean field approach. For a given pinning population, we demonstrated that the asymmetries observed in the dQ/dV peaks can be modelled by a single linear correction term. To replicate the observed peak separations, widths and magnitudes, we had to account for variation in the energy interaction parameters as a function of the excess Li amount, y. All Li-Li repulsion parameters in the model increased in value as the defect fraction, y, increased. Our paper shows how far a computational mean field approximation can replicate experimentally observed voltage, incremental capacity and entropy profiles in the presence of phase transitions.

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“…where 2 is the battery temperature, 3 is the reaction progress, or more specifically the SoC, and 4 is the pressure. Generally, the entropy change is experimentally obtained by potentiometric or calorimetric measurements [80]. Since these methods usually require long measurement times, alternatives have been developed, such as electrothermal impedance spectroscopy (ETIS) [81] and an advanced measurement protocol for potentiometric methods that reduces the measurement time [82].…”

Section: Heat Generationmentioning

confidence: 99%

A review on various temperature-indication methods for Li-ion batteries

et al. 2019

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Temperature measurements of Li-ion batteries are important for assisting Battery Management Systems in controlling highly relevant states, such as State-of-Charge and State-of-Health. In addition, temperature measurements are essential to prevent dangerous situations and to maximize the performance and cycle life of batteries. However, due to thermal gradients, which might quickly develop during operation, fast and accurate temperature measurements can be rather challenging. For a proper selection of the temperature measurement method, aspects such as measurement range, accuracy, resolution, and costs of the method are important. After providing a brief overview of the working principle of Li-ion batteries, including the heat generation principles and possible consequences, this review gives a comprehensive overview of various temperature measurement methods that can be used for temperature indication of Li-ion batteries. At present, traditional temperature measurement methods, such as thermistors and thermocouples, are extensively used. Several recently introduced methods, such as impedance-based temperature indication and fiber Bragg-grating techniques, are under investigation in order to determine if those are suitable for largescale introduction in sophisticated battery-powered applications.

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Potentiometric measurement of entropy change for lithium batteries

Cited by 53 publications

References 69 publications

The Cell Cooling Coefficient: A Standard to Define Heat Rejection from Lithium-Ion Batteries

The Cell Cooling Coefficient: A Standard to Define Heat Rejection from Lithium-Ion Batteries

Quantifying structure dependent responses in Li-ion cells with excess Li spinel cathodes: matching voltage and entropy profiles through mean field models

A review on various temperature-indication methods for Li-ion batteries

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