Battery Characteristics Research Articles

Numerical simulation study on the impact of convective heat transfer on lithium battery air cooling thermal model

To enhance the accuracy of lithium battery thermal models, this study investigates the impact of temperature-dependent convective heat transfer coefficients on the battery’s air cooling and heat dissipation model, based on the sweeping in-line robs bundle method proposed by Zukauskas. By calculating and fitting the relationship between the convective heat transfer coefficient and temperature at flow rates of 0.05 m/s, 0.15 m/s, 0.25 m/s, and 0.35 m/s, it was found that the relationship is complex. An electrochemical-thermal coupling model was established using the operational characteristics of lithium batteries, and a thermal runaway reaction kinetics model was created using isothermal thermal runaway experiments and least squares optimization. The temperature-dependent convective heat transfer coefficient was then integrated into both models. Numerical simulations revealed that during normal discharge, the maximum temperature difference in the battery when the convective heat transfer coefficient is a function of temperature is less than 1 % compared to when it is constant. However, in the high-temperature thermal runaway model, the impact of temperature-dependent convective heat transfer coefficients on the thermal runaway critical parameters is minimal at flow rates of 0.05 m/s and 0.15 m/s. When the flow rate increases to 0.25 m/s and 0.35 m/s, the impact on the trigger time of thermal runaway is 17.34 % and 18.07 %, respectively. Experimental validation and research results indicate that the temperature effect on the convective heat transfer coefficient should be considered in high-temperature thermal runaway and thermal management models to calculate the convective heat transfer more accurately within the battery pack, improving model accuracy and reducing the risks of thermal runaway.

Optimization of liquid cooling plate considering coupling effects of heat generation and aging characteristics in power batteries

The heat generation and aging characteristics of power batteries exhibit a strong coupling relationship, and thus designing liquid cooling plates (LCPs) requires considering both aspects to achieve optimal thermal management. In this study, an electric-thermal-aging model (ETAM) correlating internal resistance, capacity, and temperature was developed. Based on this model, the effects of a serpentine LCP on the heat generation and aging characteristics of battery pack under different operating conditions were investigated using a combined simulation of zero-dimensional numerical model and three-dimensional CFD methods. Furthermore, the LCP channel widths in the length and width directions and the number of channels were optimized using orthogonal tests, artificial neural networks, and genetic algorithms, aiming to minimize battery capacity degradation. Results showed that increasing the mass flow rate of the coolant reduced the maximum temperature, temperature difference, capacity loss, and aging inconsistency of the battery pack. Conversely, reducing the coolant inlet temperature could decrease the maximum temperature and capacity loss but increased the temperature difference and aging inconsistency of the battery pack. The orthogonal test results indicated that the number of channels had the greatest impact on the heat generation and aging characteristics of the battery pack, followed by the channel width in the length direction, and the channel width in the width direction had the least impact. After optimization, the maximum temperature of the battery pack decreased by 0.57 %, the maximum temperature difference increased by 1.41 %, and the average capacity degradation decreased by 0.20 %. Moreover, with the increasing mass flow rate, the pressure drop reduction improved from 27.90 % to 33.90 %. This study may provide guidance for the design of LCPs that take battery aging into account.

Investigation of thermal runaway characteristics of lithium-ion battery in confined space under the influence of ventilation and humidity

The thermal runaway (TR) characteristics of batteries in tunnels with ventilation and humidity have not been well-understood. This paper employed experimentally investigated battery TR under the influence of ventilation and humidity, examining the TR process and hazard evolution. The results show that the characteristic time of thermal runaway increased exponentially with increasing wind speed, while the characteristic temperature decreased exponentially. At 3 m/s wind speed, TR onset time exceeded 20 min, and TR onset temperature decreased by 39.8 %. The influence range of the smoke threat initially increased and then decreased with increasing wind speed. The threat was greatest at 1 m/s, with dimensionless peak temperature rise (ΔTpeak/T0) and CO concentrations of 6.1 and 1383 ppm, respectively, on the downwind side. Increased humidity in the tunnel further delayed TR and reduced its threat. A wind speed of 1 m/s corresponding to a humidity of 85–90 % was found to be the optimal condition for mitigating thermal runaway in humidified tunnel. The input heat and self-generated heat are the main causes of triggering thermal runaway and increasing battery temperature, both of which are influenced by wind speed and humidity. This paper provides a deep insight on the TR hazards in complex confined space.

Experimental Study on Thermal Runaway Characteristics of High-Nickel Ternary Lithium-Ion Batteries under Normal and Low Pressures

High-nickel (Ni) ternary lithium-ion batteries (LIBs) are widely used in low-pressure environments such as in the aviation industry, but their attribute of high energy density poses significant fire hazards, especially under low pressure where thermal runaway behavior is complex, thus requiring relevant experiments. This study investigates the thermal runaway characteristics of LiNi0.8Mn0.1Co0.1O2 (NCM811) 18650 LIBs at different states of charge (SOCs) (75%, 100%) under various ambient pressures (101 kPa, 80 kPa, 60 kPa, 40 kPa). The results show that, as the pressure is decreased from 101 kPa to 40 kPa, the onset time of thermal runaway is extended by 28.2 s for 75% SOC and by 40.8 s for 100% SOC; accordingly, the onset temperature of thermal runaway increases by 19.3 °C for 75% SOC and by 33.5 °C for 100% SOC; the maximum surface temperature decreases by 70.8 °C for 75% SOC and by 68.2 °C for 100% SOC. The cell mass loss and loss rate slightly decrease with reduced pressure. However, ambient pressure has little impact on the time and temperature of venting as well as the voltage drop time. SEM/EDS analysis verifies that electrolyte evaporates faster under low pressure. Furthermore, the oxygen concentration is lower under low pressure, which consequently leads to a delay in thermal runaway. This study contributes to understanding thermal runaway characteristics of high-Ni ternary LIBs and provides guidance for their safe application in low-pressure aviation environments.

Improving the efficiency and stability of betavoltaic batteries based on understanding efficiency fluctuations and gaps with theoretical limits

Wide-bandgap semiconductors are regarded as preferred materials for preparing semiconductor conversion devices in betavoltaic batteries due to their high theoretical conversion efficiency (ηc). However, there are a few comprehensive analytical studies on why the experimental values of ηc are generally much lower than the theoretical limit of ηc (ηc-limit) and how to improve ηc and its stability. In this work, combined with the energy deposition distributions of Ti3H2, 63Ni, and 147Pm2O3 radioactive sources in SiC obtained from Monte Carlo simulations, a multi-physical mechanism, multi-parameter coupling numerical model was established. This model can comprehensively analyze the output characteristics of betavoltaic batteries under the influence of actual device structural and material parameter changes. Our results show that changes in structural and material parameters cause significant variations in the collection efficiency (Q) of the radiation-generated electron–hole pair (RG-EHP). Considering structural parameters are easy to control, instabilities in actual SiC material parameters, which include electron diffusion length (Ln), hole diffusion length (Lp), and surface recombination velocity (S), are the main reason that ηc fluctuates significantly and is generally far lower than ηc-limit. Due to differences in the distribution of RG-EHP produced by different radioactive sources in SiC, the dominant parameters causing ηc fluctuations differ. By analyzing differences in recombination loss mechanisms under different radioactive sources, the device structures were designed in a targeted manner to make ηc closer to ηc-limit. Meanwhile, when the SiC material quality fluctuates, the stability of ηc increases by 58.5%, 35.3%, and 48.2% under Ti3H2, 63Ni, and 147Pm2O3, respectively.

Comparison of NaNi1/3Fe1/3Mn1/3O2 and Na4Fe3(PO4)2(P2O7) cathode sodium-ion battery behavior under overcharging induced thermal runaway

It is expected that the safety characteristics of sodium-ion batteries are higher than that of lithium-ion batteries, but the response of sodium-ion batteries with different material systems under thermal runaway is still lacking in-depth analysis. In this study, the thermal runaway characteristics of NaNi1/3Fe1/3Mn1/3O2 and Na4Fe3(PO4)2(P2O7) cathode pouch sodium-ion batteries are compared. First, thermal runaway experiments analyze the electro-thermal–mechanical-gas response of the two kinds of sodium-ion batteries. Based on this, the sodium plating and gas generation process under overcharge conditions are analyzed using coin batteries and in-situ cells coupled with optical microscopy. By combining the macro and micro characteristics at different stages of thermal runaway, this study elucidates the thermal runaway characteristics and corresponding causes of the two kinds of cathode material sodium-ion batteries. The results provide a foundation for subsequent research on the materials of sodium-ion batteries and methods for monitoring thermal runaway.

Dual Functional Propylene Carbonate Co-Solvent for High Performance Aqueous Zinc-Ion Batteries

In response to the global rise in energy demand, extensive research has spurred the development of batteries with high energy density, affordable cost, and safety. The present Li-ion batteries are attractive due to their high energy density, but their cost and geopolitical accessibility of raw materials, along with safety-related issues, have led researchers to shift their attention towards aqueous batteries.1,2 In aqueous systems, zinc metal has been regarded as the most promising candidate due to its high specific capacity, low redox potential of Zn-metal, environmental friendliness, and low cost. However, challenges such as the dendritic growth of zinc, hydrogen evolution, corrosion, structural degradation and dissolution of oxide cathodes, and poor coulombic efficiencies (CEs) limit their scope. To address these issues, various studies demonstrate the usage of organic co-solvents and additives such as DMSO3, DMC4, etc. at different concentrations in the electrolytes. However, the overall efficiency of the battery performance is hindered due to the large amount requirements of these additives.Along this line, we have studied the electrochemical properties of a hybrid water-highly polar propylene carbonate-based electrolyte, which suppresses water-derived parasitic reactions occurring at both the Zn anode and the V2O5 cathode.5 We have observed a significant enhancement in the battery characteristics, such as high coulombic efficiency and stable capacity, merely by tuning the solvation structure of the electrolyte. Upon a small addition of PC (20 wt.%) in 1M Zn(OTf)2 electrolyte, water molecules solvating Zn2+ ions are replaced by carbonate and triflate anions. The solvated Zn-ion species were further electrochemically reduced to form a ZnF2-rich solid electrolyte interphase (SEI), as demonstrated by post-cycling XPS studies. Moreover, the spectroscopy studies suggest the strong interaction of highly basic carbonyl oxygen of PC with water molecules, which in turn suppresses the dissolution of the cathode, enabling exceptional capacities of ∼300 mAh g−1 over 900 cycles at 1 A g−1. We further demonstrate the significance of the dielectric constant and polarity of an additive or cosolvent in the aqueous zinc ion battery electrolyte by contrasting the performance of cyclic propylene carbonate with acyclic dimethyl carbonate.Reference O. Schmidt, A. Hawkes, A. Gambhir, and I. Staffell, Nature Energy, 2, 1–8 (2017)M. M. Thackeray, C. Wolverton, and E. D. Isaacs, Energy Environ. Sci., 5, 7854–7863 (2012)L. Cao ,D. Li, E. Hu, J. Xu, T. Deng, L. Ma, Y. Wang, X. Q. Yang, and C. Wang, J. Am. Chem. Soc., 142, 21404–21409 (2020)Y. Dong, L. Miao, G. Ma, S. Di, Y. Wang, L. Wang, J. Xua, and N. Zhang, Chem. Sci., 12, 5843–5852 (2021)B. Kakoty, R. Vengarathody, S. Mukherji, V. Ahuja, A. Joseph, C. Narayana, S. Balasubramanian, and P. Senguttuvan, J. Mater. Chem. A, 10, 12597–12607 (2022)

Monolithic Integration of Organic Solar Cell and Secondary Battery with Shared Electrode As a Photo-Rechargeable Energy Device

The solar cell-secondary battery energy system has been widely used as decentralized power generation and energy-storage system to reduce reliance on fossil fuel-based generation and mitigate fluctuations in solar cell energy supply. This typically involves power conversion by connecting two energy devices through charge controllers such as maximum power point tracker (MPPT) and pulse width modulator (PMW), which are technically mature and ensure reliable energy conversion and storage within the system. In the era of the fourth industrial revolution, characterized by the hyper-connectivity and hyper-mobility of the internet of things and wearable devices, solar-based integrated energy systems are emerging as a promising independent power source. To make devices more cost-effective, miniaturized, and energy efficient, many researchers are developing integrated energy devices that directly connect two energy devices without relying on a charge controller, a so-called "monolithic" form. However, most integrated devices reported to date still utilize a simple four-electrode structure. While this may visually resemble a monolithic device, it is functionally and structurally limited in its integration capabilities. To maximize the benefits expected from monolithic integrated devices, such as reduced process costs, miniaturization, and increased efficiency, it is essential to implement energy devices with three-electrode structures that share core components such as the electrode of the devices. In this regard, studies have been reported to realize a three-electrode energy device by utilizing the anode (or cathode) of a solar cell, which is a power generation device, as the electrode of an energy storage device, but there is a limitation that the energy density per unit area is low due to the use of a supercapacitor as the storage device, and the overall efficiency of the integrated device is low.In this study, we report on the design and implementation of a three-electrode integrated energy device sharing an electrode to improve the performance (e.g., areal capacity, energy efficiency). This integrated device uses an organic solar cell as the power generation device and a silver-zinc secondary battery as the energy storage device, and they share a silver electrode with each other. The shared silver electrode acts as a multifunctional layer that simultaneously serves as the positive electrode of the solar cell, the electrical connection between the solar cell and the secondary battery, and the cathode active material of the secondary battery. On the device perspective, by using a secondary cell instead of a capacitor, we have significantly increased the areal capacity. In order to further improve the efficiency of the integrated energy device, we applied the following three design strategies to the battery design. First, through the composition design of active ions in the electrolyte, the operating voltage of the secondary battery was matched to the same level as the maximum output voltage of the solar cell. This allows the solar cell to operate at its maximum power conversion efficiency when it charges the battery. Second, we improved the fast-charging characteristics of silver-zinc battery by ensuring that the area near the silver electrode surface is supersaturated with silver anion species during battery operation. This allows the secondary battery to accept the high-power density supplied by the solar cell at a low overvoltage, improving the efficiency of the integrated device. Finally, by applying a gel electrolyte with an optimized ratio of electrolyte components (gelling agent, hardener, salt, and plasticizer), we prevented the failure of the solar cell due to the penetration of electrolyte components and ensured the stable operation of the secondary battery. In conclusion, the aforementioned design improvements enabled the high-performance silver-zinc battery to be recharged near the maximum power point of the solar cell, achieving the highest photo conversion-storage efficiency (PSE) of any organic solar cell-based integrated energy system to date. In this presentation, the design and implementation of a solar cell-battery integrated energy device in a three-electrode configuration sharing a silver electrode will be presented in detail. In addition, secondary battery design strategies will be discussed to maximize the efficiency of the integrated device during high-power charging from solar cells.

(Invited) Advanced Electrode Fabrication for Enhanced Battery Performance

In recent years, the highly emerging EV market evokes intensive search for more advanced batteries with higher energy density to increase the driving range and further reduce the cost. Compared to consumer electronics, automotive industry generally has critical requirements for specific characteristics of EV battery cells. Among many critical requirements on specific characteristics of EV batteries, cost and energy density are always interconnected as the main factors being considered in new battery cell designs. For advanced EV battery development, aside from scientific discovery, it’s very important to understand how cell designs, material properties, and the scaling up process play an important role in the final cost, energy density, and commercial feasibility of the batteries. When researching any new materials, In this talk, we will discuss what OEM is looking for and how to further unleash the power of battery chemistry and cell design as well as the manufacturing scaling up to expedite the advanced battery technologies for vehicle application.

Energy Management System for an Industrial Microgrid Using Optimization Algorithms-Based Reinforcement Learning Technique

The climate crisis necessitates a global shift to achieve a secure, sustainable, and affordable energy system toward a green energy transition reaching climate neutrality by 2050. Because of this, renewable energy sources have come to the forefront, and the research interest in microgrids that rely on distributed generation and storage systems has exploded. Furthermore, many new markets for energy trading, ancillary services, and frequency reserve markets have provided attractive investment opportunities in exchange for balancing the supply and demand of electricity. Artificial intelligence can be utilized to locally optimize energy consumption, trade energy with the main grid, and participate in these markets. Reinforcement learning (RL) is one of the most promising approaches to achieve this goal because it enables an agent to learn optimal behavior in a microgrid by executing specific actions that maximize the long-term reward signal/function. The study focuses on testing two optimization algorithms: logic-based optimization and reinforcement learning. This paper builds on the existing research framework by combining PPO with machine learning-based load forecasting to produce an optimal solution for an industrial microgrid in Norway under different pricing schemes, including day-ahead pricing and peak pricing. It addresses the peak shaving and price arbitrage challenges by taking the historical data into the algorithm and making the decisions according to the energy consumption pattern, battery characteristics, PV production, and energy price. The RL-based approach is implemented in Python based on real data from the site and in combination with MATLAB-Simulink to validate its results. The application of the RL algorithm achieved an average monthly cost saving of 20% compared with logic-based optimization. These findings contribute to digitalization and decarbonization of energy technology, and support the fundamental goals and policies of the European Green Deal.

Thermal Runaway Characteristics of Ni-Rich Lithium-Ion Batteries Employing Triphenyl Phosphate-Based Electrolytes

Abstract Enhancing the safety performance of high-energy-density lithium-ion batteries is crucial for their widespread adoption. Herein, a cost-effective and highly efficient electrolyte additive, triphenyl phosphate (TPP), demonstrates flame-retardant properties by scavenging hydrogen radicals in the flame, thereby inhibiting chain reactions and flame propagation to enhance the safety performance of graphite/LiNi0.8Co0.1Mn0.1O2 (Gr/NCM811) pouch cells. The results reveal that the capacity retention of cells without flame retardants, and those with the addition of 1 wt%, 3 wt%, 5 wt%, and 10 wt% TPP is 96.4%, 92.1%, 84.15%, 40.8%, and 12.4% (at 1/2C 300 cycles), respectively. Furthermore, compared to cells without flame retardants, the highest temperature during thermal runaway (TR) decreases by 8.3%, 26.9%, 35.1%, and 38.8% with the addition of 1 wt%, 3 wt%, 5 wt%, and 10 wt% TPP, respectively. Through comprehensive analysis of the impact of flame-retardant additives on battery electrochemical performance and safety, it is determined that the optimal addition amount is 3 wt%. At this level, there are no significant flames during battery abuse, the triggering temperature for TR increases by 26.6 ℃, and the maximum temperature decreases by 157 ℃. Moreover, even after 300 cycles at 1/2C, a capacity of 814.5 mAh is retained, with a capacity retention rate of 84.1%. This study provides valuable insights into mitigating TR in high-energy-density power batteries.

Structure and Physicochemical Properties of Solutions of Lithium Polysulfides in Tetrasolvate of Lithium Perchlorate with Sulfolane Molecular Dynamics Modeling.

Lithium polysulfides are intermediate products formed during the discharge and charge of lithium-sulfur batteries and have good solubility in electrolyte solutions. Therefore, the properties and structure of solutions of lithium polysulfides in electrolyte solutions affect the energy characteristics of the lithium-sulfur battery. In this work, the structure and physicochemical properties (density, ionic conductivity, and self-diffusion coefficients) of solutions of lithium disulfide, tetrasulfide, and octasulfide in lithium perchlorate tetrasolvate with sulfolane in a wide range of concentrations (0.2-12 M) were studied using the molecular dynamics method. With increasing concentrations of lithium polysulfides, the proportion of sulfur atoms in the coordination sphere of the lithium cation increases and the proportion of sulfolane molecules decreases. It has been established that the ability of the polysulfide anion to act as a bridging ligand leads to the formation of clusters, including lithium perchlorate, lithium polysulfides, and sulfolane. It has been shown that the tendency to form clusters increases with an increasing number of sulfur atoms in the polysulfide anion. At high concentrations of lithium polysulfides, regardless of their size, the electrolyte system becomes a single cluster. With an increase in the concentration of lithium polysulfides in the electrolyte system, its density increases and the ionic conductivity and diffusion coefficients of the system components decrease.

Optimization of the deep extreme learning machine using the seagull algorithm for state of health prediction of lithium batteries

Abstract The ability to predict the State of Health (SOH) of lithium-ion batteries with precision is essential for guaranteeing their safe and consistent performance. Notwithstanding, measuring internal resistance and capacity accurately during live battery operation is an ongoing challenge. Existing SOH prediction models often fall short in terms of precision. To tackle this issue, a novel SOH estimation technique for lithium-ion batteries has been proposed. This technique uses electrochemical impedance spectroscopy and the Seagull Optimization Algorithm simultaneously with a Deep Extreme Learning Machine (SOA-DELM). The impedance characteristics of lithium-ion batteries are taken into account, with real and imaginary components and the modulus extracted as the health factor (HF). Then, the seagull algorithm ascertains the optimal structural parameter solutions for the DELM network. An estimation model is subsequently created by using the Seagull algorithm-optimized DELM, which aids in accurate SOH prediction for aging batteries. The proposed methodology is assessed by using an aged electrochemical impedance dataset, namely, 45 mAh commercial button batteries made with active materials composed of lithium cobaltate and graphite for positive and negative ends respectively. This openly accessible dataset is available in Nature Communications. Upon validation, the methodology proves to be highly precise.

Classification of cathode materials for lithium-ion batteries of new energy electric vehicles based on safety and dynamic performance

The severe environmental pollution caused by fossil fuels has driven the demand for new energy vehicles. The choice of cathode materials for lithium-ion batteries is a major difficulty to be overcome in the development of new energy vehicles. Based on the performance characteristics of new energy vehicle batteries in actual use, this paper classifies the six most widely used cathode electrode materials in the new energy vehicle market. Firstly, the temperature data of power batteries with different cathode materials in the overcharge experiment and acupuncture experiment were collected to characterize the safety performance of power batteries. Then the maximum specific discharge capacity and operating voltage data of the battery were collected, and the maximum specific discharge energy of the battery was calculated to study the dynamic performance of the vehicle. After that, the safety performance and dynamic performance of each index is compared. Finally, according to the safety performance and dynamic performance of the corresponding power battery, the six cathode materials are divided into three types: power type, safety type, and balanced type. According to the classification results, it can be concluded that the design of balanced cathode materials with both safety and dynamic performance is the best development route for future new energy vehicle batteries.

Application of wireless energy delivery system in automobile charging

With the popularity of electric vehicles, wireless charging technology has become a key area to address the convenience of charging electric vehicles. The aim of this study is to explore the principles of wireless energy transfer technology and its application in the field of electric vehicles. We first provide a background introduction to the field of electric vehicles, emphasising the importance of wireless charging technology. Subsequently, we delve into the charging and discharging characteristics of power batteries to better understand the need for energy transfer. Then, we carefully selected wireless charging methods suitable for electric vehicles and developed a corresponding wireless charging system architecture. In this paper, we also provide theoretical analyses of two major wireless energy transfer technologies, including electromagnetic coupled wireless energy transfer and resonant wireless energy transfer, as well as exploring the principles of RF wireless energy transfer technology. Finally, we propose an architecture for a static wireless charging system including five modules: pre-processing, transmission, reception, charging control and battery load. The contribution of this study is to provide an in-depth research and a comprehensive theoretical foundation for wireless charging technology in the field of electric vehicles, which helps to improve the charging efficiency and convenience of electric vehicles.

Exploring the Impact of Lanthanum on Sodium Manganese Oxide Cathodes: Insight into Electrochemical Performance

This investigation focuses on nominally La‐doped Na0.67MnO2, exploring its structural, electrochemical, and battery characteristics for Na‐ion batteries. X‐ray diffraction analysis reveals formation of composite materials containing three distinct phases: P2‐Na0.67MnO2, NaMn8O16, and LaMnO3. The bond structures of the powders undergo scrutiny through Fourier‐transform infrared and Raman analyses, revealing dependencies on the NaO, MnO, and LaO structures. X‐ray photoelectron spectroscopy and energy‐dispersive X‐ray dot mapping analyses show that the La ions are unevenly dispersed within the samples, exhibiting a valence state of 3+. Half‐cell tests unveil similarities in redox peaks between the cyclic voltammetry analysis of La‐doped samples and P2‐type Na0.67MnO2, with a reduction in peak intensities as La content increases. Electrochemical impedance spectroscopy model analysis indicates direct influences of La content on the half‐cell's resistive elements values. The synergistic effect of composite material with multiple phases yields promising battery performances for both half and full cells. The highest initial capacity value of 208.7 mAh g−1, with a 57% capacity fade, among others, is observed, and it diminishes with increasing La content. Full cells are constructed using an electrochemically presodiated hard carbon anode, yielding a promising capacity value of 184.5 mAh g−1 for sodium‐ion battery studies.

Methodology for fast testing of carbon-based nanostructured 3D electrodes in vanadium redox flow battery

Progress in material chemistry is manifested daily by the variety of prepared functional materials, often with nanodimensional structuring. The electrodes for vanadium redox flow batteries have been shown to benefit from incorporating nanostructured materials such as carbon nanotubes. However, the methods of such incorporation are far from optimal, relying mainly on physical deposition or insertion into a binder. Here, we describe a technique for integrating carbon-based rod-like nanomaterials into a vanadium redox flow battery and a methodology for fast nanomaterial performance testing. The technique is based on creating a fixed nanomaterial bed sandwiched between two graphite felt electrodes, forming a 3D flow-through electrode in the battery. Performing various positive and negative control experiments, we show the beneficial effect of a nanostructured bed on the primary battery characteristics obtained from short-term electrochemical experiments. We characterize carbon nanotubes exhibiting promising electrochemical behavior in vanadium electrolytes, as observed in our previous study. The load curves obtained from charge-discharge steps at various current densities and electrolyte flow rates revealed considerable differences in the performance of the tested materials, with few-walled carbon nanotubes reaching unsurpassable characteristics. At room temperature, with 50 %-SOC-working solutions and the highest tested linear velocity of 14.6 cm/min, the evaluated power density for this material reached values above 500 mW/cm2. For comparison, thermally treated graphite felt, used as a benchmark material, provided a power density of around 300 mW/cm2 under identical conditions. Although developed for vanadium redox flow batteries, the method enables testing tube-like and rod-like (nano-)materials for flow electrochemical systems.

Characteristics of all organic redox flow battery (AORFB) active species TEMPO-methyl viologen at different electrolyte solution

Characteristics of all organic redox flow battery (AORFB) active species TEMPO-methyl viologen at different electrolyte solution

Suppression of lithium-ion battery thermal runaway propagation by zirconia ceramics and aerogel felt in confined space

The thermal runaway (TR) behavior of lithium-ion batteries (LIBs) in confined space tends to be more severe compared to open space, highlighting the critical need to suppress thermal runaway propagation (TRP) in such environments. This work explores the use of different thicknesses of 5 % yttria-stabilized zirconia ceramic plates and aerogel felts to form a 3-mm-wide composite material designed to suppress TRP. The materials are chosen for their respective high surface radiant reflectance, high thermal conductivity, strong thermal insulation, and flame retardancy. The study begins with an analysis of the physical properties of zirconia ceramics and aerogel felts, emphasizing their roles in thermal management. Subsequently, the TRP characteristics of batteries with various states of charge (SOCs) in confined space are investigated. This includes an examination of the effectiveness of zirconia ceramics in suppressing TRP. The experimental results indicate that the effect of cell SOC on the TRP behavior of the battery module is significantly amplified in confined space, largely due to the confined flame dynamics. Furthermore, it is demonstrated that the combination of zirconia and aerogel felt materials can effectively suppress TRP. The optimal configuration is found to be a composite of 2 mm zirconia ceramic and 1 mm aerogel felt. This combination leverages the high radiant heat barrier properties of zirconia ceramics and the excellent thermal insulation of aerogel felts, providing a synergistic effect that significantly enhances TRP suppression.

Diffusion-Equation-Based Electrical Modeling for High-Power Lithium Titanium Oxide Batteries

Lithium titanium oxide (LTO) batteries offer superior performance compared to graphite-based anodes in terms of rapid charge/discharge capability and chemical stability, making them promising candidates for fast-charging and power-assist vehicle applications. However, commonly used battery models often struggle to accurately describe the current–voltage characteristics of LTO batteries, particularly before the charge/discharge cutoff conditions. In this work, a novel electrical model based on the solid-phase diffusion equation is proposed to capture the unique electrochemical phenomena arising from the diffusion mismatch between the positive and negative electrodes in high-power LTO batteries. The robustness of the proposed model is evaluated under various loading conditions, including constant current and dynamic current tests, and the results are compared against experimental data. The experimental results for LTO batteries exhibit remarkable alignment with the model estimation, demonstrating a maximum voltage error below 3%.