Approach to determine the entropy coefficient of a battery by numerical optimization

Lenz, Martin; Hoehl, Tobias; Zanger, Lukas; Pischinger, Stefan

doi:10.1016/j.jpowsour.2020.228841

Cited by 12 publications

(6 citation statements)

References 19 publications

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“…The consistency in each cells operational characteristics was verified in preliminary experiments, yielding highly consistent nominal capacity (5.84 ± 0.02 Ah) during a 0.05 C discharge from 100% SOC at 25 °C. Focussing on just one cell chemistry allows for the most in-depth investigation and procedural optimisation and aligns with the analysis of Lenz et al, 29 who found the potentiometric procedure performed to a similar extent across a range of different lithium-ion cells and cell chemistries.…”

Section: Experimental Apparatussupporting

confidence: 59%

A Standardised Potentiometric Method for the Effective Parameterisation of Reversible Heating in a Lithium-Ion Cell

Hales,

Bulman

2024

J. Electrochem. Soc.

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Lithium-ion batteries generate heat, degrading faster and becoming unsafe at high temperature. Yet many battery models do not consider the contribution of reversible, entropic heating when evaluating the rate of heat generation from a cell or battery pack. This leads to temperature prediction errors in battery management systems, increased safety risk, and reduced lifetime of the battery pack. Here, a standardised potentiometric method is proposed, allowing anyone with access to a typical battery lab to reliably and accurately extract the entropy coefficient for any electrochemical cell, the key parameter for the inclusion of reversible heating in a battery model. The proposed method takes 7.4 days to complete, representing a reduction of 90% compared to some methods proposed in the literature. Results highlight the importance of moving away from the multiple temperature steps, and the temperature step increases that dominate the existing literature. These arguments are justified through the observation and introduction of voltage relaxation following both kinetic and thermal excitation. These phenomena are termed post-kinetic-potentialisation and post-thermalisation-potentialisation. Post-thermalisation-potentialisation is not discussed in any published literature yet represents an important behavioural trait for any lithium-ion cell with a non-negligible length scale and thermal diffusivity.

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Section: Experimental Apparatussupporting

confidence: 59%

A Standardised Potentiometric Method for the Effective Parameterisation of Reversible Heating in a Lithium-Ion Cell

Hales,

Bulman

2024

J. Electrochem. Soc.

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“…A value of 0.002 has been found in the literature [ 38 ], but the case under investigation does not produce a good agreement between the model and experimental values. Since the capability to model a thermal system of the battery is directly related to the accuracy of the determination of its reversible heat generation coefficient [ 41 ], for the tested battery, an evaluation has been performed on purpose. The experiment has been set in the laboratory, consisting in heating the battery inside a chamber and measuring the voltage using the bidirectional power supply.…”

Section: 1d Thermal Modeling Of the Batterymentioning

confidence: 99%

Carbon and Graphene Coatings for the Thermal Management of Sustainable LMP Batteries for Automotive Applications

Sequino¹,

Sebastianelli²,

Vaglieco³

2022

Materials

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The increment of battery temperature during the operation caused by internal heat generation is one of the main issues to face in the management of storage systems for automotive and power generation applications. The temperature strongly affects the battery efficiency, granting the best performance in a limited range. The investigation and testing of materials for the improvement of heat dissipation are crucial for modern battery systems that must provide high power and energy density. This study presents an analysis of the thermal behavior of a lithium-polymer cell, which can be stacked in a battery pack for electric vehicles. The cell is sheltered with layers of two different materials: carbon and graphene, used in turn, to dissipate the heat generated during the operation in natural convection. Optical diagnostics in the infrared band is used to evaluate the battery surface temperature and the effect of the coatings. Experiments are performed in two operating conditions varying the current demand. Moreover, two theoretical correlations are used to estimate the thermal parameters of the battery with a reverse-logic approach. The convective heat transfer coefficient h and the specific heat capacity cp of the battery are evaluated and provided for the Li-ion battery under investigation for different coatings’ conductivity. The results highlight the advantage of using a coating and the effect of the coating properties to reduce the battery temperature under operation. In particular, graphene is preferable because it provides the lowest battery temperature in the most intense operating condition.

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“…coefficient, the value is selected as 0.5 mV/K 42,43 ; R is the internal resistance of the battery which changes varying with the state of charge (SOC) and temperature.…”

Section: Battery Thermal Modelmentioning

confidence: 99%

“…According to the Bernardi heat generation rate model, assuming a uniform and stable heat source inside the battery, q can be determined as 41 :

q=\frac{1}{{V}_{\text{bat}}}[{I}^{2}R-I{T}_{\text{bat}}\frac{\partial E}{\partial {T}_{\text{bat}}}],

where I is the current; E is the open‐circuit voltage; V is the volume;

\partial E/\partial T

represents the temperature coefficient, the value is selected as 0.5 mV/K 42,43 ; R is the internal resistance of the battery which changes varying with the state of charge (SOC) and temperature.…”

Section: Modeling Of Battery Cooling Systemmentioning

confidence: 99%

Thermal characteristics of Li‐ion battery based on phase change material‐aluminum plate‐fin composite heat dissipation

Liu

Gan

Chen

et al. 2022

Energy Science & Engineering

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A reliable battery thermal management system (BTMS) not only can effectively decrease the maximum temperature but also maintain the temperature uniformity of the lithium-ion (Li-ion) battery after grouping. Nevertheless, considering the deficiency of a single heat dissipation method, there exist challenges in efficient heat dissipation structure design, especially at high discharge rates. In this work, a composite heat dissipation structure of battery module with phase change material (PCM)-aluminum plate-fin is proposed. Meanwhile, the transient effects of different discharge rates, melting points, and thickness of PCM on the thermal characteristics of the module are analyzed. Results show that the maximum temperature of the module with PCM-aluminum plate-fin can be reduced by 25.8°C, 11.0°C, and 10.2°C respectively at 4 C discharge rate compared with natural convection, aluminum plate-fin, and paraffin PCM, and the maximum experimental error among them is less than 5%. During 2-5 C discharging, the melting rate of phase change increases first and then decreases, which leads to the trend of the maximum temperature and maximum temperature difference of the module rising with bending twice. When the ambient temperature is 25°C, the paraffin PCM with a melting point of 28°C is implemented for battery cooling because of its more rapid melting and heat absorption. The increase in PCM thickness is beneficial to the heat dissipation of the module. The optimal PCM thickness of 3 mm can realize temperature uniformity control within 2.5°C.

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Approach to determine the entropy coefficient of a battery by numerical optimization

Cited by 12 publications

References 19 publications

A Standardised Potentiometric Method for the Effective Parameterisation of Reversible Heating in a Lithium-Ion Cell

A Standardised Potentiometric Method for the Effective Parameterisation of Reversible Heating in a Lithium-Ion Cell

Carbon and Graphene Coatings for the Thermal Management of Sustainable LMP Batteries for Automotive Applications

Thermal characteristics of Li‐ion battery based on phase change material‐aluminum plate‐fin composite heat dissipation

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