Circuit Of Lithium-ion Battery Research Articles

In-situ monitoring of multiple signals evolution behaviour for commercial lithium-ion batteries during internal short circuit

Internal short circuit in lithium-ion batteries is a crucial hazard threatening. It is accurately difficult to monitor the internal signals in time of the lithium-ion batteries during the process of internal short circuit. Herein, a novel method is developed to monitor multiple signal evolution behaviour using a sealed tank and sensors. The internal signals of LFP batteries and NMC batteries exhibit different evolution behaviours, especially in the response sequence of pressure and gas. Battery capacity has an impact on ISC signal response sequence and time for LFP batteries, showing identical sequence and shorter time with the increase of capacity. The voltage and temperature are considered as sensitive signals for both LFP and NMC811 batteries that sensitive signals are defined based on their response speed. This operando technique provides a suitable platform for understanding the side reaction mechanism during thermal runaway in commercial LIBs.

Damage and Failure Boundaries and Prediction of External Short Circuit in Lithium-ion Battery

Damage and Failure Boundaries and Prediction of External Short Circuit in Lithium-ion Battery

Simulation study on internal short circuit of lithium ion battery caused by lithium dendrite

The internal short circuit of the lithium ion battery (LIB) is one of the main reasons that cause thermal runaway. Mechanical, thermal, and electrical abuse of LIBs may lead to irreversible growth of lithium dendrites. Short circuits will happen inside the battery if the separator is pierced by the lithium dendrites growing to a certain extent. In this paper, the internal short circuit of LIBs caused by lithium dendrites is simulated by finite element numerical simulation method. The thermal response characteristics of LIBs under various time, radius, and center distance of lithium dendrites are compared and analyzed. The results show that the heat production of short circuit in LIB caused by lithium dendrite is mainly contributed by the positive and negative electrodes. The short-circuit current, heat production power and maximum temperature of the battery increase with the increase of the lithium dendrite radius. Meanwhile, when the center distance of lithium dendrites increases, the short-circuit current and heat production power also increase. The greater the center distance of lithium dendrite, the greater the total heat production of the battery. For example, when the center distance of lithium dendrite is 2700 µm, the total heat production reaches 0.2161 J, which is 1.9 times that of 0 µm (0.1129 J). We believe that the simulation results related to lithium dendrites obtained by the three-dimensional electrochemical-thermal coupling model can provide relevant theoretical basis for the experimental research on the growth of lithium dendrites, short circuit and heat production in LIBs, and help to design safer LIBs.

Accurate Measurement of the Contact Resistance During Internal Short Circuit in Lithium-Ion Batteries

Accurate internal short circuit (ISC) resistance measurement is of vital importance to understanding and modeling the ISC process and consequent thermal runaway (TR) behaviors. The current measurement of ISC resistance usually cannot quantify the contact resistance of two directly-involved parties for the ISC, and the measured ISC resistance generally contains additional components (depending on the ISC modes). To this end, we propose a novel experimental methodology to accurately quantify the contact resistance during ISC. By a series of auxiliary experiments, we exclude the resistance contribution from non-direct-contact components (but are directly contacted with the direct-involving parties). Two representative scenarios of ISC, i.e., direct contact of electrodes and contact of conductive metallic plates with electrodes, are characterized by the proposed methodology. An additional ISC scenario is used to validate the effectiveness and accuracy of the proposed methodology. Results provide a powerful tool to characterize the contact resistance during ISC for future possible experiment design and theoretical modeling for the understanding of battery safety issues.

Modeling strategy for progressive failure prediction in lithium-ion batteries under mechanical abuse

The prediction for the internal failure of lithium-ion batteries (LIBs) under external mechanical abuse loading remains a challenge for safe design. This paper systematically studies the modeling approach for progressive failure simulation and short-circuit prediction. Hemispherical indentation experiments are conducted on a battery specimen containing 5 representative sandwich (RS) layers to examine the deformation and progressive failure behavior of battery components. Three different models, viz, a high-fidelity detailed model, an intermediate homogenized model and a fully homogenized model, are developed and employed to simulate the progressive failure in a multi-layer battery specimen. The simulation results obtained using the three models all correlate well with experimental phenomena, capturing the overall stress-strain response and ultimate failure of the battery structure. The numerical results can help us understand the failure behavior and the mechanism for mechanical abuse-induced short circuit in LIBs. The feasibility of the three models for use in progressive failure prediction is compared by analyzing the capability of the models in predicting the critical failure events, the computational efficiency of the models, and the feasibility to implement coupled mechanical-electrochemical-thermal simulations. The results of this work provide useful insights on practical choices for the modeling strategy and safety design of LIBs under mechanical abuse conditions. • Models of different precision level for mechanical abuse of LIBs are established. • Detailed model and intermediate model show good accuracy in failure predicting. • Fully homogenized model shows high efficiency and reasonable accuracy. • Modeling methods for short-circuit prediction are systematically discussed.

A novel semi-analytical solution for calculating the temperature distribution of the lithium-ion batteries during nail penetration based on Green’s function method

Lithium-ion batteries are now becoming the primary energy storage device for electric vehicles. However, thermal runaway caused by the internal short circuit in lithium-ion batteries draws attention to the safety issues. The dramatic temperature change of lithium-ion batteries can lead to fatal accidents. This paper aims to find a better way to estimate the lithium-ion batteries' temperature distribution under the nail penetration condition. Then a semi-analytical solution based on Green's function is derived at three different punching positions. A three-dimensional battery model is constructed by utilizing COMSOL Multiphysics software to simulate the characteristics of temperature distribution’s variation. The results show that the temperature distribution is related to the nail penetration position. When the punching position is near to the positive electrode of the battery, the temperature can reach the highest value compared with the other two nail penetration positions, the middle of the battery and the position that is far from the positive electrode. In addition, the simulation results are compared with the temperature curve drawn by solving the semi-analytical solution. It shows that these temperature curves follow a similar trend, and the difference between the simulation results and the semi-analytical solution is small with an error less than 5%.

Thermal Abuse Behavior of the LIR2450 Micro Coin Cell Battery Having Capacity of 120 mAh with Internal Short Circuit by Penetrating Element

Internal short circuit in lithium-ion battery by penetrating element leads to exothermic behavior due to accumulated heat. In the present study, investigations are conducted on the thermal behavior of the LIR2450 micro coin cell haivng capacity of 120 mAh, with internal short circuit by penetrating element. The experimental coin cell discharge study was conducted and validated with numerical study within ±5.0%. The effect of penetrating element size, location of penetrating element, state of charge, discharge rate, short-circuit resistance, and heat transfer co-efficient on maximum coin cell temperature and heat generation rate are analyzed. The penetrating element diameters of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 mm are considered. The effect of initial state of charge (SOC) is considered with 100%, 80%, 60%, and 40%. Three locations for penetrating element are considered with the center, the middle of the radius, and on the edge of the coin cell radius. The different discharge rates of 1C, 2C, 3C, and 4C are considered. The higher-penetrating element size of 3.5 mm with location at the center of the coin cell with 100% SOC showed maximum heat generation rate and maximum temperature of the coin cell. In addition, the optimum value of the dimensionless heat generation rate is obtained at dimensionless short-circuit resistance. The study provides comprehensive insights on the thermal behavior of the lithium-ion cell during thermal abuse condition with internal short circuit by penetrating element.

Online Detection of Soft Internal Short Circuit in Lithium-Ion Batteries at Various Standard Charging Ranges

Soft internal short circuit (ISCr) in lithium-ion batteries is a latent risk, and it is a primary reason for thermal runaway with blaze and explosion. Early detection of ISCr is necessary to ensure safe utilization of the batteries. Based on the applications of batteries, load currents are considerably diverse and occasionally do not satisfy the persistent excitation condition, resulting in inaccurate detection of soft ISCr with existing model-based methods. Using constant current for standard charging of the batteries, this study proposes a novel and accurate model-based algorithm to detect soft ISCr online irrespective of the specific type of load currents. An equivalent circuit model of the battery with ISCr is used to extract open circuit voltage of the battery. Enhanced relationship between open circuit voltage and state of charge is obtained to estimate ISCr resistance as a fault index. To improve estimation accuracy of the fault index, factors affecting the ISCr resistance are analyzed and considered. Experiments incorporating various charging ranges and soft ISCr conditions below 100 Ω are configured, and the proposed method is verified with experimental data. The results of the study indicate that the relative error of the estimated fault index does not exceed 6.4%; thereby, the battery management system is enabled to accurately detect an ISCr early.

Comparative study on substitute triggering approaches for internal short circuit in lithium-ion batteries

Internal short circuit is among the most common causes of thermal runaway in lithium-ion batteries. Substitute triggering approaches are of great significance to internal short circuit research. This paper compares the performance of five substitute triggering approaches for internal short circuit, including (1) triggering with phase-change materials, (2) shape-memory alloys, (3) using artificially induced dendrite growth, (4) equivalent resistance, and (5) nail penetration. The thermal-electrical coupled features, controllability, similarity to real accidents and repeatability of the test are discussed by experimental and modelling analysis. The results show that the triggering approaches with phase-change materials and shape-memory alloys are controllable to trigger specific types of the internal short circuit but complex in experimental preparation. The triggering approach by artificially induced dendrite growth may best simulate the self-induced internal short circuit in real-time applications but with poor controllability. The triggering approach using equivalent resistance can be beneficial for calibrating the electrochemical-thermal coupled model, but no real internal short circuit in tests. Nail penetration is the easiest one to be conducted but has poor repeatability. The four classes of the internal short circuit are analyzed to reveal the relationship between physic phenomenon and thermal runaway. This paper guides the study of internal short circuit mechanism and safety evaluation.

Performance and safety protection of internal short circuit in lithium-ion battery based on a multilayer electro-thermal coupling model

Internal short-circuited lithium-ion battery can generate much heat in a short time and that leads to local high temperature or even explosion. A multilayer electro-thermal coupling model considering the interplay of current at different positions is developed to study the performance of internal short circuit and penetration before the trigger of thermal runaway. The simulation result agrees with the experiment in a certain extent. This study will serve as a guideline for protective design of internal short circuit. It concludes that penetration is not a precise method to simulate the performance of one-layer internal short circuit from view of maximum temperature and effect of cell unit layers. Temperature of large capacity battery is higher relatively when internal short occurs. A new method, in which the battery is forced to external short circuit when the internal short circuit is detected, is proposed to protect the battery from internal short circuit. The battery is within safe range if the external short circuit resistance is small enough. More, the maximum temperature increases with the decrease of battery resistance. Decreasing the resistance may increase the thermal runaway risk while increasing the battery resistance is a good protective method.

Evaluation of Triggering Approaches of Internal Short Circuit in Lithium Ion Batteries

Internal short circuit (ISC) is one of the most common causes of thermal runaway (TR) for lithium ion batteries. Several causes of the ISC have been identified including mechanical defects, small impurities blended during manufacturing, lithium dendritic growth and mechanical deformation brought by nail penetration. In order to study the characteristics of ISC, substitute ISC test is an effective way. When designing an ISC substitute test, the ISC should be triggered with practicability, repeatability and reproducibility. Alternative triggering approaches by mechanical deformation, such as nail penetration test and blunt rod test, are under investigation. Unfortunately, as for the most dangerous case – spontaneously induced ISC, these kinds of approaches are unable to simulate the exact thermal-electrical behaviors. The spontaneously induced ISC still cannot be eliminated in practical operation, and threatens the safety of lithium ion batteries. To best simulate the spontaneously induced ISC, the substitute ISC triggering approaches need to meet following requirements: 1) simultaneously triggering ISC with voltage drop and temperature rise; 2) high repeatability; 3) ISC triggering under control with scheduled triggering fine and specific value of short resistance; 4) the heat generation by ISC completely absorbed by the cell; 5) the discharge caused by ISC diminish the state of charge of the cell; 6) the damage to cell materials similar with practical condition. Five substitute ISC triggering approaches were evaluated in this work: 1) phase change material (PCM); 2) shape memory alloy (SMA); 3) dendrite growth (DG); 4) equivalent resistance (ER); 5) nail penetration. Identical pouch cells with NMC cathode were selected in all test. The evaluations are carried out from the above six requirements mentioned above. Table 1 The evaluation results of different ISC triggering approaches PCM SMA DG ER Nail Penetration 1) Thermal-electrical characteristics Relatively obvious Relatively obvious Obvious Obvious Obvious 2) Repeatability High Middle High High Middle 3) Controllability ISC occurrence under control ,termination not, TR controlled by SOC and ISC type ISC occurrence under control ,termination not, TR controlled by SOC and ISC type ISC occurrence under control , termination not, TR controlled by ISC type ISC occurrence and termination under control, no TR ISC occurrence under control , termination not, TR controlled by SOC 4) Heat generation absorption Complete Complete Complete Partial Partial 5) Discharge effect Equal Equal Equal Equal Equal 6) The damage to the cell materials Half similar Half similar Very similar No damage Half similar The PCM triggering approach follows the work from NREL with minor difference. PCM are embed PCM during fabrication before electrolyte filling and SEI formation. 4 types of ISC, including aluminum-anode, copper-cathode, aluminum-copper and cathode-anode, can be all triggered by the PCM approach with an ISC temperature at 50oC. The SMA triggering approach embeds a controllable component SMA in cell during fabrication. It is also capable to trigger 4 types of ISC, with a triggering temperature of 70-80oC, which is the transformation temperature of SMA. Sample perpetration of the SMA triggering approach is shown in Fig. (a). The DG triggering approach embeds metal particles at positive electrode during fabrication. The growing dendrite intrudes the separator and ISC finally occurs during cycling. This approach is most promising to trigger real spontaneously induced ISC. The ER triggering approach puts an equivalent resistance between cell layers and a switch is used to control the occurrence and termination of ISC, as shown in Fig. (b). Results show that the voltage drop and the temperature rise are well simulated. In summary, the PCM and SMA triggering approaches embed controllable components inside the cell to trigger ISC under specific controllable conditions, and both are effective to simulate the thermal-electrical coupled characteristics. The DG triggering approach has great potential to simulate spontaneously induced ISC, which is of significance for the mechanism investigation of ISC. The ER triggering approach could not cast damage to the cell, but is beneficial to establish an ISC model. However, the repeatability and controllability of all approaches require further improvement. Figure 1

Detection of Internal Short Circuit in Lithium Ion Battery Using Model-Based Switching Model Method

Early detection of an internal short circuit (ISCr) in a Li-ion battery can prevent it from undergoing thermal runaway, and thereby ensure battery safety. In this paper, a model-based switching model method (SMM) is proposed to detect the ISCr in the Li-ion battery. The SMM updates the model of the Li-ion battery with ISCr to improve the accuracy of ISCr resistance R I S C f estimates. The open circuit voltage (OCV) and the state of charge (SOC) are estimated by applying the equivalent circuit model, and by using the recursive least squares algorithm and the relation between OCV and SOC. As a fault index, the R I S C f is estimated from the estimated OCVs and SOCs to detect the ISCr, and used to update the model; this process yields accurate estimates of OCV and R I S C f . Then the next R I S C f is estimated and used to update the model iteratively. Simulation data from a MATLAB/Simulink model and experimental data verify that this algorithm shows high accuracy of R I S C f estimates to detect the ISCr, thereby helping the battery management system to fulfill early detection of the ISCr.

Li-ion Battery Separators, Mechanical Integrity and Failure Mechanisms Leading to Soft and Hard Internal Shorts.

Separator integrity is an important factor in preventing internal short circuit in lithium-ion batteries. Local penetration tests (nail or conical punch) often produce presumably sporadic results, where in exactly similar cell and test set-ups one cell goes to thermal runaway while the other shows minimal reactions. We conducted an experimental study of the separators under mechanical loading, and discovered two distinct deformation and failure mechanisms, which could explain the difference in short circuit characteristics of otherwise similar tests. Additionally, by investigation of failure modes, we provided a hypothesis about the process of formation of local “soft short circuits” in cells with undetectable failure. Finally, we proposed a criterion for predicting onset of soft short from experimental data.

Mechanism of the entire overdischarge process and overdischarge-induced internal short circuit in lithium-ion batteries.

Lithium-ion batteries connected in series are prone to be overdischarged. Overdischarge results in various side effects, such as capacity degradation and internal short circuit (ISCr). However, most of previous research on the overdischarge of a cell was terminated when the cell voltage dropped to 0 V, leaving the further impacts of overdischarge unclear. This paper investigates the entire overdischarge process of large-format lithium-ion batteries by discharging the cell to −100% state of charge (SOC). A significant voltage platform is observed at approximately −12% SOC, and ISCr is detected after the cell is overdischarged when passing the platform. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that the overdischarge-induced ISCr is caused by Cu deposition on electrodes, suggesting possible Cu collector dissolution at the voltage platform near −12% SOC. A prognostic/mechanistic model considering ISCr is used to evaluate the resistance of ISCr (RISCr), the value of which decreases sharply at the beginning of ISCr formation. Inducing the ISCr by overdischarge is effective and well controlled without any mechanical deformation or the use of a foreign substance.