Jingwen Weng

USTC & CityU HK

Adding flame retardant additives is an effective approach to improve the safety of lithium-ion battery electrolytes. This study discusses the inhibiting effects of three flame retardant additives on the combustion characteristics of electrolyte and carbonate mixed solvent under low pressure. The experimental results show that the inhibition of flam...

With an increasingly wider application of the lithium-ion battery (LIB), specifically the drastic increase of electric vehicles in cosmopolitan cities, improving the thermal and fire resilience of LIB systems is inevitable. Thus, in-depth analysis and performance-based study on battery thermal management system (BTMs) design have arisen as a popula...

Given that many safety standards for lithium-ion cells include a saltwater immersion test and the possibility of cell immersion by water by accident, this work prepares five kinds of cells by varying immersion time and saltwater concentration to explore the influence of saltwater immersion on the topographic, electrochemical and thermal characteris...

Exit choice is essential for pedestrian safety and evacuation efficiency during the context of an emergency. Cumulative prospect theory is a widespread realistic decision-making theory that can transform choice outcomes and probabilities into subjective terms and integrate them as a parameter of cumulative prospect value (CPV), which determines the...

Grouping is a common phenomenon that occurs everywhere. The leader-follower relationship inside groups has often been qualitatively characterized in previous models using simple heuristics. However, a general method is lacking to quantitatively explain leadership in an evacuating group. To understand the evolution of single-group dynamics throughou...

The widespread application of lithium-ion batteries as the practice facility of energy storage has come alongside much unforeseen fire safety and thermal runaway issues that leads to increasing research interests. A comprehensive understanding of the thermal features of battery packs and the heat exchange process of energy storage systems is impera...

Although lithium-ion batteries are increasingly being used to achieve cleaner energy, their thermal safety is still a major concern, particularly in the fields of energy-storage power stations and electric vehicles with high energy-storage density. Therefore, the battery thermal management systems (BTMs) have been extensively applied, among which p...

Phase change material (PCM) cooling performs excellently in lithium-ion battery (LIB) thermal management. In order to improve the thermal conductivity of PCM, the new thermally-conductive composite phase change material (CPCM) was prepared with the paraffin wax (PA), expanded graphite (EG), and SiC/SiO2 by physical adsorption method. The structure...

A series of experiments were carried out in this study to investigate the sensitivity of lithium-ion batteries with different capacities to overcharge and over-discharge conditions; whereby, two nominal capacities (2100 and 3000 mAh) were included. It is observed that batteries experience a serious degradation in the process of overcharge cycling;...

The widespread use of lithium‐ion battery (LIB) urgently needs a thermal management system with excellent performance to manage it. Phase change material (PCM) has been adapted for thermal management of LIB because it can absorb a mass of energy without additional power. In this research, the thermal conductivity of PCM is improved, and its cooling...

In advanced battery thermal management systems for electric vehicles, liquid cooling (LC) is typically coupled with a phase-change material (PCM) cooling for secondary heat dissipation. However, a continuous LC consumes a considerable amount of energy without considering the operating conditions. In this study, the thermal behaviors of tubular PCMs...

Three types of cell samples (fresh cell, 60°C stored cell, and −10°C stored cell) were prepared to demonstrate the impact of abusive‐temperature storage on the topographic, electrochemical, and safety characteristics of lithium‐ion cells; besides that, the sensitivity of the three cell samples to typical abusive conditions is also discussed. In com...

The present work carries out a comparative study to illustrate the safety performance of two new-format cells (22650 and 26650) in the thermal runaway tests induced by over-heating and overcharge tests, referred by the traditional 18650 cells. In addition, a long-term cycling test is also performed to evaluate the electrochemical characteristics of...

When a lithium-ion battery is thermally out of control, the internal heat is mainly coming from the mutual reaction of the internal components of the battery. It is well known that the breakdown and combustion of carbonate solvents inside lithium-ion batteries contribute a large part of the heat when thermal runaway occurs. Therefore, it is necessa...

Hydrogen plays an increasingly significant role in solving the greenhouse effect and energy crisis as a clean fuel that can be obtained by renewable energy, and as a storable energy carrier. As a prerequisite for process safety of hydrogen, issues such as hydrogen embrittlement, fire, and explosion, have been of great interest to research scholars...

This work prepares five kinds of cell samples, i.e. the fresh cell, the cell degrades to 90% SOH (state of health) after high-temperature cycling, the cell degrades to 80% SOH after high-temperature cycling, the cell degrades to 90% SOH after low-temperature cycling and the cell degrades to 80% SOH after low-temperature cycling to reveal the electr...

Herein, a series of experiments were performed to illustrate the impact of safety vents on the evolution of thermal runaway behaviors of 18650-size lithium-ion batteries. Meanwhile, the effect of safety vents on the thermal safety of batteries with different states of charge (SOC), i.e. 0%, 50% and 100% and cathode chemistries, i.e. lithium nickel...

The present work carries out a series of thermal runaway experiments to explore the impact of charging and charging rate on the thermal runaway behaviors of lithium-ion cells, in which five charging rates (0C, 0.5C, 1C, 2C and 4C) and three initial states of charge (SOC), i.e. 25%, 50% and 75% are included. The thermal runaway process of 18650 lith...

Thermal runaway severely affects the lithium batteries under conditions of non-normal forces or thermal abuse. In this study, a novel flame retardant flexible composite phase change material is successfully prepared, and a battery module based on it is designed and experimentally investigated. Herein, paraffin with high latent heat is performed as...

New strategy on alleviating battery fire without reducing energy density is studied. • Pioneering study on thermal runaway propagation under different gas dilutions. • X-ray CT images and energy-dispersive spectrometry reveal cell internal structures. • Different flame patterns under different oxygen levels are verified by theory. A R T I C L E I N...

Nitrated cellulose (NC) is highly susceptible to thermal runaway such as combustion or explosion during decomposition. Preventing and mitigating the related accidents require more comprehensive analysis of its thermal stability and chemical decomposition kinetics. To understand the effect of combustion on the decomposition mechanism of NC, it is ne...

Majority existing organic composite phase change materials (CPCMs) are flammable that result in thermal hazards such as fire and explosions in battery modules. Furthermore, the performance of PCM-based battery modules in extreme conditions like thermal runaway has not been studied adequately. In this study, a tubular CPCM-cell structure is designed...

Phase change materials (PCMs) are widely used in battery thermal management system (BTMS). Most previous research on BTMS has focused on single temperature environment or protocol, without verifying their effectiveness in volatile working environments, which affects battery heat accumulation and dissipation. In this study, a series of experiments i...

Ethanol is often used as a humectant during the storage of nitrocellulose (NC). To mitigate the fire hazard of NC, which is a highly flammable compound, during storage, and to understand the fire hazards of NC–ethanol mixtures, it is imperative to study the thermal behavior of NC–ethanol mixtures and determine the optimal range of ethanol content i...

The mitigation of battery thermal runaway propagation remains challenging in the application of lithium-ion batteries, and safety enhancement remains a popular topic for battery thermal management. In this study, an aluminum honeycomb (AH) design module is proposed for a battery thermal management module, and its effects on TM and TR propagation ar...

Temperature is an important factor affecting the working efficiency and service life of lithium-ion battery (LIB). This study carried out the experiments on the thermal performances of Sanyo ternary and Sony LiFePO4 batteries under different working conditions including extreme conditions, natural convection cooling and phase change material (PCM)...

The purpose of a battery thermal management system (BTMS) is to maintain the battery safety and efficient use as well as ensure the battery temperature is within the safe operating range. The traditional air-cooling-based BTMS not only needs extra power, but it could also not meet the demand of new lithium-ion battery (LIB) packs with high energy d...

In order to investigate the thermal failure propagation behaviors of lithium batteries, a sequence of full-scale burning tests were conducted. The results showed that the average mass loss and total heat release of an individual cell are 5.8 g and 31.9 kJ, respectively. The battery pack fire exhibited intermittent propagation behaviors due to the h...

To better understand the boiling liquid expanding vapor explosions (BLEVE) risk in the fluorine chemical industry, the detailed BLEVE properties of 1,1-difluoroethane were investigated based on fire dynamics simulator code of computational fluid dynamics in this work. The BLEVE fireball was modeled using appropriate numerical models and parameters....

Considering the complexity of working environment and the sensitivity of lithium-ion batteries, a series of experiments are performed in the present work to investigate the impact of high-temperature environment on the optimal cycle rate of lithium-ion batteries. Two ambient temperatures (26 and 70 °C) and four cycle rates (0.5 C, 1 C, 2 C and 3 C)...

Because of the multi-layer structure and the diversified connection modes of most battery modules, systematically investigating the thermal failure propagation principles and mechanisms of lithium-ion batteries is critical to provide early warnings and protection for thermal runaway. In this work, a series of experimental studies and mathematical d...

In the current work, a series of experiments are carried out to investigate the degradation behavior of lithium‐ion batteries during overcharge cycling, as well as the influence of ambient temperature on the degradation. In which, different charge cut‐off voltages (4.5, 4.8, and 5.0 V) and ambient temperatures (0°C, 20°C, 50°C, and 70 °C) are inclu...

In view of the flammability of phase change materials (PCMs), a safer structure design for thermal insulation protection is crucial in a PCM-based battery thermal management system. In this work, a series of experiments is performed on battery modules with and without PCM and/or aerogel to investigate their heat dissipation capability and thermal i...

Battery modules with phase change material (PCM) cooling inevitably suffer from heat-storage saturation and poor secondary-heat dissipation, especially in high-temperature environments or hot regions. To optimize thermal management, this study firstly explores the thermal behaviors of PCMs with different phase change temperatures (PCTs) in a high-t...

As an excellent option that has wide application in the thermal management system to ensure the safety of lithium-ion batteries, phase change material (PCM) cooling technology is highly desirable but the low thermal conductivity of PCMs limits its application. Herein, a series of experiments are conducted with and without fins to investigate the ef...

A set of experiments are performed in the present work to investigate the degradation behavior of lithium‐ion battery during overdischarge cycling, as well as the influence of a high‐temperature environment on the degradation. Among, different discharge cut‐off voltages (1.0, 0.5, and 0.2 V) are included. During the overdischarge process, batteries...

The environmental pressure effect on thermal runaway and fire behaviors in the 18650 lithium-ion battery (LIB) with various cathodes and states of charge (SOC) are experimentally investigated in this work. The fire hazards were characterized by the combustion process, total mass loss (TML) and total heat release (THR). The TML and THR increase with...

As one of the most promising new energy sources, the lithium-ion battery (LIB) and its associated safety concerns have attracted great research interest. Herein, a comprehensive review on the thermal hazards of LIBs and the corresponding countermeasures is provided. In general, the thermal hazards of the LIB can be caused or aggravated by several f...

A set of experiments were carried out at reduced and elevated temperatures (−10, −5, 0, 20, 50, 60 and 70 °C)to investigate the homogeneity of lithium-ion batteries under abusive temperature environment in combination with different cycle rates (1C, 2C, 3C and 4C). Based on the experimental results, we found that the surface temperature of battery...

A series of thermal failure researches were conducted to explore the effects of parameters on the failure propagation behavior within battery modules, including the gap between batteries, the state of charge (SOC)and traditional phase change material (PCM). Based on the results, obvious domino phenomena were revealed during the process of thermal f...

The aim of this study was to evaluate the transport phenomena of smoke flow and vertical temperature distribution in a 21-story stairwell with multiple fire locations and openings. A large eddy simulation (LES) method was used to model the smoke flow in a stairwell model with a set of simulation parameters, wherein the fire heat release rate (HRR)...

In the current work, a series of experiments were carried out under low and normal temperature conditions (0 and 20 °C) to research the influence of low temperature on the performance of lithium-ion batteries (LIBs). Besides this, a commercial insulation material (IM) was employed to research its effect on preventing damage in a battery exposed to...

As known, it is common for lithium ion battery (LIB) to be used under extreme circumstances, among the high temperature circumstance is included. Herein, a series of experiments were conducted at elevated temperatures of 50, 60, and 70°C to examine the performance of LIB. Besides, the application of phase change material (PCM) under such condition...

A lithium-ion battery (LIB) may experience overcharge or over-discharge when it is used in a battery pack because of capacity variation of different batteries in the pack and the difficulty of maintaining identical state of charge (SOC) of every single battery. A series of experiments were established to investigate the thermal and fire characteris...

Thermal failure propagation is one of the most severe challenges for battery modules and it usually aggravates the thermal hazards, further resulting in serious accidents. This work conducted two groups of experiments to investigate the influence of discharging treatment and module shape on the thermal failure propagation of battery modules, where...

The thermal failure propagation is one of the most severe challenges for battery pack and it usually aggravates the thermal hazards, further resulting in serious accidents. A series of thermal failure researches were conducted to explore the effects of state of charge (SOC), the number of heaters, failure location and pack size on the thermal failu...