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Lithium-ion batteries are favored by the electric vehicle (EV) industry due to their high energy density, good cycling performance and no memory. However, with the wide application of EVs, frequent thermal runaway events have become a problem that cannot be ignored. The following is a comprehensive review of the research work on thermal runaway of lithium-ion batteries. Firstly, the functions of each part of the battery and the related flame-retardant modification are summarized. The thermal properties of the battery are improved by means of coating of cathode materials and adding anion receptors. Secondly, the thermal runaway behavior and its triggering mechanism are introduced, and the decomposition reactions of common cathode materials are analyzed. Finally, the methods of thermal runaway monitoring and thermal management are summarized to provide the reference for the safety of lithium-ion batteries.

Thermal runaway is one of the most critical safety challenges limiting the widespread deployment of lithium-ion batteries in electric vehicles, energy storage systems, and aerospace applications. With the continuous increase in battery energy density, the fault-to-failure transition becomes increasingly rapid, which makes early detection and effective intervention quite difficult. This review systematically summarizes the fundamental mechanisms underlying thermal runaway that drive the escalation of battery hazards. Existing thermal runaway prediction and early warning approaches are comprehensively classified into electrical, thermal, mechanical/gas, and data-driven categories. The detection principles, performance characteristics, and current limitations are critically analyzed. Furthermore, research progress in mitigation and suppression, including system-level thermal management, material-level approach, and structure modification, is discussed. This work aims to support the development of advanced early-warning technologies and to provide guidance for the design of safer next-generation lithium-ion battery systems.

With the widespread adoption of lithium iron phosphate (LFP) batteries in energy storage and electric vehicles, overcharge‐induced thermal runaway (TR) is recognized as a critical threat to battery safety. However, conventional voltage/temperature threshold‐based detection methods suffer from delayed responses, proving inadequate for early‐warning applications. To address these shortcomings, this research employs a common prismatic LFP battery, collecting multimodal data (gas emissions—H 2 /CO/HF, voltage, and temperature) through five stepwise overcurrent overcharging experiments. With the only consistent quantitative association among multimodal data, the time stamp was chosen to synchronize temporal alignment to enable both representing multimodal measurements at any given time point as a unified numeric array suitable for deep learning and quantitatively benchmarking algorithmic superiority. Based on this, a hybrid deep learning framework is developed to extract spatiotemporal features from multimodal electrochemical time‐series data, using integrated transformer layers and multiscale convolutional layers. Compared with experimental measurements, the proposed multimodal early‐warning model is demonstrated to surpass traditional voltage/temperature change rate threshold methods. Validation results indicate that the warning time was advanced by an average of 289 s across all overcharging conditions—ranging from 188 s (1.5 times current overcharge) to 492 s (0.5 times current overcharge)—which represents a 37.2% improvement. These results provide an intelligent safety monitoring strategy beyond single‐parameter thresholds and a time‐aligned multimodal learning paradigm that can be generalized to broader electrochemical safety diagnostics.

Highlights The prepared Ge/SA biomass aerogel with multiple crosslinked networks have excellent flame retardancy and thermal insulation properties. The prepared SAT/TPEE/EG composite phase change material (CPCM) has a thermal storage density as high as 811.9 J g –1 and good flame retardancy. In the composite material of CPCM coupled with aerogel, the CPCM continuously absorbs heat for the aerogel, thus maximizing heat transfer and spreading. Thermal runaway (TR) is considered a significant safety hazard for lithium batteries, and thermal protection materials are crucial in mitigating this risk. However, current thermal protection materials generally suffer from poor mechanical properties, flammability, leakage, and rigid crystallization, and they struggle to continuously block excess heat transfer and propagation once thermal saturation occurs. This study proposes a novel type of thermal protection material: an aerogel coupled composite phase change material (CPCM). The composite material consists of gelatin/sodium alginate (Ge/SA) composite biomass aerogel as an insulating component and a thermally induced flexible CPCM made from thermoplastic polyester elastomer as a heat-absorbing component. Inspired by power bank, we coupled the aerogel with CPCM through the binder, so that CPCM can continue to ‘charge and store energy’ for the aerogel, effectively absorbing heat, delaying the heat saturation phenomenon, and maximizing the duration of thermal insulation. The results demonstrate that the Ge/SA aerogel exhibits excellent thermal insulation (with a temperature difference of approximately 120 °C across a 1 cm thickness) and flame retardancy (achieving a V-0 flame retardant rating). The CPCM exhibits high heat storage density (811.9 J g −1 ), good thermally induced flexibility (bendable above 40 °C), and thermal stability. Furthermore, the Ge/SA-CPCM coupled composite material shows even more outstanding thermal insulation performance, with the top surface temperature remaining at 89 °C after 100 min of exposure to a high temperature of 230 °C. This study provides a new direction for the development of TR protection materials for lithium batteries.

Lithium-ion batteries have been extensively utilized in energy storage applications, with high-capacity lithium iron phosphate batteries being increasingly employed not only in energy storage power stations for grid stabilization but also in high-energy-demand vehicles, such as long-distance buses and trucks. As the deployment of these batteries has expanded, concerns regarding their safety have become more pronounced. This study investigated the thermal runaway gas production behavior of a 340 Ah high-capacity lithium iron phosphate battery under the combined effects of thermal and mechanical abuse at various locations. A comprehensive analysis was conducted on the thermal runaway gas temperature at different points above the battery, the surface temperature of the battery, and the mass loss of the battery before and after thermal runaway. Furthermore, the feasibility of mitigating thermal runaway in a passenger vehicle battery pack was explored through the use of a fire blanket and a cofferdam irrigation system. The results revealed that when thermal abuse alone triggered thermal runaway in the 340 Ah lithium iron phosphate battery, the safety valve remained closed for approximately 60 s without releasing thermal runaway gases, leading to a relatively low intensity of thermal runaway. However, continued mechanical abuse induced a secondary thermal runaway, which escalated in intensity. The study identified that the critical failure point occurred near the front of the battery, close to the safety valve, with minimal effect on the battery’s surface temperature. Experimental validation demonstrated that the combination of a fire blanket and cofferdam irrigation was effective in suppressing thermal runaway, extinguishing the fire and cooling the battery rapidly, while causing minimal damage to the vehicle. This research provided valuable insights into the establishment of thermal runaway warning thresholds and proposed novel strategies for mitigating thermal runaway events in high-capacity lithium-ion batteries. Graphical Abstract

LiFePO4 (LFP) lithium-ion batteries have gained widespread use in electric vehicles due to their safety and longevity, but thermal runaway (TR) incidents still have been reported. This paper explores the TR characteristics and modeling of LFP batteries at different states of charge (SOC). Adiabatic tests reveal that TR severity increases with SOC, and five stages are identified based on battery temperature evolution. Reaction kinetics parameters of exothermic reactions in each TR stage are extracted, and TR models for LFP batteries are established. The models accurately simulate TR behaviors at different SOCs, and the simulated TR characteristic temperatures also agree well with the experimental results, with errors of TR characteristic temperatures less than 3%. The prediction errors of TR characteristic temperatures under oven test conditions are also less than 1%. The results provide a comprehensive understanding of TR in LFP batteries, which is useful for battery safety design and optimization.

Thermal runaway (TR) propagation in lithium-ion battery (LIB) modules can increase fire hazards and damage electric vehicles. The incorporation of thermal insulation materials effectively mitigates heat transfer during TR propagation in a module. This work explores the relationship between the thermal insulation ability of a silica aerogel sheet (SAS) and the intensity of the TR of a LIB. Accelerating rate calorimetry (ARC) characterizes thermal runaway behavior in commercial prismatic lithium-ion batteries spanning LFP to NCM 811 energy densities. The intrinsic safety of a battery is related to its energy density, and among the examined batteries, NCM 811 exhibited the most violent TR. Two kinds of SASs with different aerogel gel contents (80 kg m −3 vs. 120 kg m −3 ) were synthesized via a sol‒gel approach followed by supercritical fluid drying and are referred to as SAS-A and SAS-B. Both SAS-A and SAS-B showed similar thermal insulation performance at 675 °C, whereas SAS-B showed better thermal insulation performance than SAS-A at 900 °C. The application of SAS-A successfully suppressed TR propagation in the LFP, NCM 111 and NCM 523 modules. Moreover, SAS-B can easily suppress TR propagation in the NCM 622 and NCM 811 modules. The appropriate aerogel content and thickness of the SAS should be considered based on the relationship between the severity of the TR of the LIB and the thermal insulation performance of the SAS. The SAS provides a new solution for the safer design of battery thermal management systems.

The lithium-ion battery (LIB) is a significantly and broadly used power storage system known for its high energy density and extended lifespan. However, it is vital to continue examining and addressing potential safety concerns that require further exploration and discussion. This study employed a pseudo-adiabatic calorimeter, vent sizing package 2, to assess the thermal runaway behaviour exhibited by 18650 LIBs under diverse charging conditions. Through calorimetric experimental trials, the charge levels of the batteries at 0%, 30%, 50%, 80%, and 100% were assessed. This allowed us to identify and evaluate the thermal characteristics that pose potential hazards or risks, such as apparent exothermic onset temperature ( T 0 ), self-heating rate (d T /d t ), pressure rise rate (d P /d t ), maximum temperature ( T max ), maximum pressure ( P max ), and pressure–temperature-time profiles. When a fully charged LIB experienced thermal runaway, it reached a T max of 902.9 ℃ and a P max of 1985.2 psig. These experimental findings can be utilised to estimate uncontrolled thermal behaviours and thermokinetic parameters across different charge states of the 18650 LIB. These results demonstrate practical applications as well as implications in designing batteries with proactive safety measures and can provide essential parameters for ensuring the process safety of commercial batteries, thereby preventing thermal damage. Based on the adiabatic temperature rise (∆ T ad ) and P max , the venting gas molar amount was also calculated through the ideal gas equation, and the generation of flammable gases was considered a significant factor in the uncontrolled combustion of LIBs.

The safety issues of lithium ion batteries (LIBs) have been serious as the popularity of LIBs in portable electronics and electric vehicles. It is necessary to understand the thermal runaway mechanism to effectively prevent thermal runaway. A series of nail penetration experiments are conducted to study the thermal runaway mechanism of lithium ion pouch cell in this work. It is observed that the pouch cell experiences four processes including nail penetration, internal short circuit, chemical reaction and thermal runaway during nail penetration. Additionally, four parameters, including state of charge (SOC), penetration speed, penetration position and nail diameter, are taken in the experiments to investigate the effect on thermal runaway. The results show that the cells with higher SOC and penetrated by bigger nail are easier to be triggered into thermal runaway and obtain higher temperature. The penetration position decides the location of the short circuit and the temperature distribution, and the steel nail has an influence on the temperature distribution of the cell. The results provide suggestions for the transportation, safe use and design of the cell.

In the open and closed space environments, the influence of spacing on battery pack thermal runaway propagation is studied. The mechanism of thermal runaway propagation for the lithium-ion battery pack is analyzed. The experimental results show that when the state of charge (SOC) of the battery is 100%, and the spacing is greater than 2 mm in the horizontal direction and 8 mm in the vertical arrangement, battery pack thermal runaway propagation hardly occurs in an open environment. In a closed environment, there is less chance of uncontrolled heat transmission in batteries when the rate of increase in the battery temperature is less than 0.66 °C s−1. When the horizontal spacing is more than 4 mm or the vertical spacing of the battery is more than 8 mm in a closed environment, thermal runaway propagation cannot occur in the batteries. The research results provide some reference for the arrangement of lithium-ion battery packs in transportation and storage.