Battery Thermal Performance Research Articles

Thermal Performance Analysis of the Battery Thermal Management Using Phase Change Material

In this paper, the phase change material passive thermal management system for the lithium ion battery module is established, in which the mock-up battery is used to replace the real battery for the simulation. The temperature rise characteristics of the battery and the melting process of the phase change material in the passive thermal management system are determined through the numerical simulation. The effect of the filling amount of the phase change material on battery thermal performance is also analyzed.

Parametric Analysis of Electrode Materials on Thermal Performance of Lithium-Ion Battery: A Material Selection Approach

Experimental studies in the battery thermal management have found that increased charging rates during battery cycling is the main reason behind the overheating of lithium-ion batteries. Many different electrode materials have been investigated for improving battery thermal performance and calendar life. The present work reports a way to parameterize and categorize electrode materials based on their thermal performance. A coupled thermo-chemical model was developed for deriving the heat generation by electrode particle of different materials. The heat generation associated with lithium-ion transport was computed from four possible mechanisms: polarization heating, entropic heating, joule heating and heating contribution from plastic deformation. The particle model was scaled to battery dimension to model thermal diffusion in the battery. The model was used to create a set of five material indexes that categorize the electrode materials based on their thermal performance under condition of excess loading. A parametric analysis was conducted to compare the thermal performance of six candidate electrode materials (for cathode and anode) using the merit indexes and the results were validated against past experimental data. The effect of variable charging rates on thermal generation was analyzed. Finally, the paper identified the material properties which affect the thermal performance of battery systems.

Thermal and electrical performance evaluations of series connected Li-ion batteries in a pack with liquid cooling

Lithium-ion batteries are widely used in electric and hybrid electric vehicles due to their wide nominal range and high power densities. However, operating temperature, which has a pronounced effect on battery thermal performance and electrical performance, needs to be maintained within a specified range. In the present study, a Li-ion battery pack has been tested under constant current discharge rates (e.g. 1C, 2C, 3C, 4C) and for a real drive cycle with liquid cooling. The experiments are performed using cold plates at 10°C, 20°C, 30°C, and 40°C coolant temperatures to obtain thermal and electrical parameters. For this, three 20Ah LiFePO4 prismatic cells are connected in series and a battery thermal management system is designed and developed for liquid cooling. To measure the temperature variation, 18 thermocouples are installed on the principal surface of all three cells: i.e., six on each cell. The results show that the battery pack temperature can be maintained within the required range at all four selected discharge rates with the coolant at 30°C. The discharge capacity of the battery pack increases with increasing coolant temperature and is found to achieve a maximum of 19.11 Ah at a 1C discharge rate with the coolant at 40°C.

Electrochemical modeling and performance evaluation of a new ammonia-based battery thermal management system for electric and hybrid electric vehicles

The operating temperatures of lithium ion battery packs in electrical vehicles and hybrid electrical vehicles need to be maintained in an optimum range for better performance and longer battery life. This paper proposes a new battery pack cooling system that utilizes the low saturation temperature of the fuel in ammonia based future hybrid electric vehicles. In the proposed cooling system, the batteries are partially submerged in to the liquid ammonia, and the liquid ammonia cools the battery by absorbing the heat and evaporating and the ammonia vapor cools the part of the battery not covered by liquid ammonia. The relationships between the performance of the battery cooling system and the maximum temperature (and the temperature distribution) in the battery are investigated for practical applications. The effect of the length of the battery that is submerged in to the liquid ammonia on the thermal performance of battery is studied and evaluated. The present results show that the proposed ammonia based cooling system offers a unique opportunity to maintain the operating temperature of the battery in an optimum range for consecutive charging and discharging phases at a high rate of 7.5C.

Prediction of Optimal Load and Performance of Thermal Batteries

Nowadays, the possibility of applying alternative energy sources is increasingly discussed. In terms of application, a Seebeck thermoelectric generator seems promising for the direct conversion of heat (preferably waste heat) into electricity. In order to increase the performance and thereby the effectiveness of different thermoelectric modules, especially advantageous thermoelectric properties of materials and also innovative design of thermoelectric devices are now solved. However, the achievement of maximum possible performance and operating efficiency is not determined solely by material efficiency and geometric dimensions of thermocouples connected in a thermal battery. It is also necessary to predict an optimum load of the specific source of energy in order to use material design improvements optimally and ensure longer life of thermal batteries. Their manufacturers, except the power input as a “heat consumption” and the maximum power output of a thermal battery (at a certain temperature difference between cold and heated walls), should also declare such load by an appliance, which is optimal for the given type of thermogenerator. The present paper, therefore, proposes a method for determining the optimum load of a thermal battery.

Thermo-electrochemical evaluation of lithium-ion batteries for space applications

Advanced energy storage and power management systems designed through rigorous materials selection, testing and analysis processes are essential to ensuring mission longevity and success for space exploration applications. Comprehensive testing of Boston Power Swing 5300 lithium-ion (Li-ion) cells utilized by the National Aeronautics and Space Administration (NASA) to power humanoid robot Robonaut 2 (R2) is conducted to support the development of a test-correlated Thermal Desktop (TD) Systems Improved Numerical Differencing Analyzer (SINDA) (TD-S) model for evaluation of power system thermal performance. Temperature, current, working voltage and open circuit voltage measurements are taken during nominal charge–discharge operations to provide necessary characterization of the Swing 5300 cells for TD-S model correlation. Building from test data, embedded FORTRAN statements directly simulate Ohmic heat generation of the cells during charge–discharge as a function of surrounding temperature, local cell temperature and state of charge. The unique capability gained by using TD-S is demonstrated by simulating R2 battery thermal performance in example orbital environments for hypothetical extra-vehicular activities (EVA) exterior to a small satellite. Results provide necessary demonstration of this TD-S technique for thermo-electrochemical analysis of Li-ion cells operating in space environments.

Ionic Permeability within Thermally-Activated Batteries

Thermally-activated (or molten salt) batteries utilize high melting temperature (> 300 ºC) salts as the electrolyte. Since the electrolyte is solid at room temperature, an advantage of these types of batteries is that there is no self-discharge prior to activation, which significantly increases the shelf life compared to conventional electrochemical batteries. To activate the battery, a heat source (usually an internal pyrotechnic) is required to melt the electrolyte and enable current flow. During the melting/activation process, the separator in each cell thins until the oxide binder supports the cell compaction force. An open question is what becomes of the melted electrolyte within the separator and electrodes during activation. The transport and infiltration of the electrolyte into the electrodes can reduce the internal impedance of the cell; however, excess electrolyte could cause shortage and failure of the battery. Therefore, an improved fundamental understanding of the governing transport properties of the electrolyte is needed to better predict the performance of thermal batteries during activation. In this work, we performed a series of fundamental studies to probe the ionic mobility and conductivity of the electrolyte. First, by utilizing a series of single cells frozen at various activated times, we performed electron probe microanalysis (EPMA) on the cell cross-sections to quantify the transport of bromine tracers. Through the use of image analysis techniques, we mapped out of the concentration of bromine throughout each cell and elucidated the complex process of electrolyte diffusion and flow. Next, using a custom-built pressure vessel cell, we quantified the permeability of the electrolyte through the oxide binder during and after activation. Furthermore, we investigated the effects of compaction pressure on both the permeability and internal impedance of the separator. Collectively, these experimental studies provide quantitative transport information about the electrolyte, which can be used to inform predictive models for battery activation and improve the understanding of the impact of separator compaction on electrolyte transport properties. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

Thermal Design for the Pouch-Type Large-Format Lithium-Ion Batteries: I. Thermo-Electrical Modeling and Origins of Temperature Non-Uniformity

This paper presents a multi-dimensional thermo-electrical model for pouch-type large-format lithium-ion batteries with high accuracy both spatially and temporally. The model includes a two-dimensional electrical model to calculate the current density over the current collector and a three-dimensional thermal model to calculate the temperature in the battery core. To improve the accuracy, key parameters are determined from carefully designed experiments, rather than taking from the literature. Thermal parameters are estimated using a joint experimental and computational method. Electrical contact resistance between the cable and the tab is estimated from a self-heating experiment. With the reliable input parameters, the predicted temperature evolution at multiple locations on the cell surface agrees well with the measured results, indicating high accuracy of the model. Using the validated model, sensitivity analysis is conducted to evaluate the relative importance of thermal parameters on battery thermal performance. It is found that the specific heat capacity has the greatest influence on the maximum temperature rise, while the in-plane thermal conductivity has the greatest influence on the maximum temperature variation. It is elucidated that the main cause for the temperature non-uniformity is the heat flux from the tab, rather than the non-uniformity of heat generation rate in the core.

Hydrothermal synthesized micro/nano-sized pyrite used as cathode material to improve the electrochemical performance of thermal battery

In this paper, single-phase pyrite with different particle sizes is prepared by hydrothermal method with the reactants of Na2S, S, and FeSO4. Compared with natural pyrite powder, synthesized pyrite nanocubes with small particle sizes and fine distribution have lower resistance, higher specific capacity and power density during the discharging process. The enlarging contacting surface area of pyrite with electrolytes will reduce the concentration polarization caused by the discharging current and improve the utilization efficiency of the pyrite materials. When pulse currents are loaded, compared with natural pyrite single-cell thermal battery, synthetic ones have smaller voltage drops and higher power density during the pulse discharging process. Influences of particle sizes on the thermal stability of the pyrite powders have also been investigated.

Effect of the addition of carbon black and carbon nanotube to FeS2 cathode on the electrochemical performance of thermal battery

Effect of the addition of conductive carbonaceous materials to the FeS2 (pyrite) cathode on electrochemical performance of thermal battery is investigated by adding carbon blacks (CBs) or multi-walled carbon nanotubes (MWCNTs) which has conductive network structures with various amounts from 0.1 to 1wt.%, compared to the amount of pure FeS2. Among the samples prepared with various amounts of CB or MWCNT addition, the 1wt.% CB-added sample exhibits the highest electrochemical properties. These results suggest that the improvement in the electrochemical performance of thermal batteries can be achieved by the addition of the conductive carbonaceous materials to pyrite electrode.

The Effect of Cooling Methods on the Performance of Solid Nitrogen Thermal Batteries

A test cryostat has been constructed to study thermal batteries. Solid nitrogen, used as a thermal battery, may be used as a temporary portable cooling system or a heat absorber for a superconducting fault current limiter system. The nitrogen was solidified via different cooling profiles. The performance of thermal batteries was determined by subjecting them to transient thermal events. It was found that slowly formed solid nitrogen performed best, by returning to operating temperature faster. The thermal contact degradation due to ‘dry-out’ was identified as a significant problem after a number of successive pulses when using rapidly formed solid nitrogen, yet did not present itself in slowly formed solid nitrogen, within experimental range.