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Explosion and Heating Reasons of EV Li-ion Battery Pack

  The thermal stability of lithium-ion batteries is sensitive to temperature, overcharging, compression, or collision, and is prone to combustion and even explosion. Improving the safety of lithium-ion batteries to avoid safety accidents is one of the key technologies for electric vehicles.   The fundamental reason for the combustion or explosion of lithium-ion batteries is the rapid increase in temperature caused by thermal runaway , ultimately reaching the ignition point and causing combustion, or the production of a large amount of gas due to the reaction, resulting in an explosion due to the internal pressure exceeding the pressure that the shell can withstand.   For lithium-ion battery packs in electric vehicles, a large number of individual batteries are assembled in battery boxes.The thermal coupling effect between batteries makes thermal management more complex, coupled with the harsh working environment of electric vehicles, which results in large fluctuations in...
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About Cylinderical Li-ion Battery Safety Test

  The safety of lithium ion batteries refers to their ability to suppress initial external disturbances and cause unsafe behavior during normal use or abuse. Cylindrical lithium ion batteries have a higher specific energy, and the battery shell is made of steel. When the battery experiences abnormal heat loss, the internal heat of the battery accumulates, generating higher pressure, and may explode, causing harm to the outside world and users.  Due to differences in control panels and customer understanding of the battery, battery abuse is inevitable in actual use. Therefore, especially for cylindrical lithium-ion batteries, the safety of the battery is not only to prevent smoke, fire, liquid leakage, and explosion under various standard tests, but also to avoid personal injury caused by the above problems in the case of customer abuse.   The main production and technical advantages of cylindrical lithium ion batteries are still controlled by Japanese and Korean enterpris...
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Li-ion Battery Crush Test

  Due to the limitations of materials, battery technology, and manufacturing processes, lithium ion batteries have always had a significant fire risk during their use. The safety of lithium ion batteries under collision and crush has always been a focus of attention.   Generally, the fundamental reason for a fire caused by external forces on a lithium ion battery is that an internal short circuit occurs inside the battery due to severe deformation and damage, resulting in severe electrochemical reactions and high heat generation inside the battery, ultimately leading to thermal runaway and combustion and explosion of the battery.   Researchers have obtained the failure behavior of cylindrical lithium ion batteries under different mechanical external forces through mechanical integrity experiments and numerical simulations. Some researchers have discovered the thermal runaway behavior of the 18650 lithium ion battery under various crush methods, and found that even if the ...
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Safety Evaluation System of Lithium ion Battery

  As lithium-ion batteries are widely used in aviation, aerospace, new energy vehicles and other fields, their safety risks and problems in the process of use are increasingly prominent.  Especially under abuse conditions (such as high temperature, short circuit, overcharge and discharge, vibration, extrusion and impact, etc.), they are prone to smoke, fire and even explosion.  Therefore, their safety indicators are also highly valued internationally. At present, a number of international organizations and countries in the world have introduced corresponding lithium battery standards and inspection requirements, and have investigated the safety performance of lithium ion batteries from different perspectives.  This paper discusses the safety standards of lithium-ion batteries, analyzes the test purposes and methods of different safety standards, and focuses on the analysis of the test methods and influencing factors of internal short circuit which has a great impact ...
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Lithium Battery Buring and Explosion Test

  Lithium-ion batteries are widely used in new energy vehicles. In recent years, the explosion accidents of new energy vehicles have caused widespread concern and attention to their safety. Lithium-ion batteries may burn and explode under extreme conditions such as overcharge, collision and high temperature, and it is very difficult to put out.   1.Analysis of buring process and characteristics of lithium-ion battery   Lithium-ion battery is mainly composed of positive electrode, negative electrode, diaphragm, electrolyte, shell and other components. The cathode material is usually lithium intercalated transition metal oxide or polyanion compound; The anode material is mostly graphite. The electrolyte is mainly composed of organic mixed solution and lithium salt. The diaphragm is mainly used to isolate the positive and negative materials, prevent the short circuit caused by the passage of electrons, and let the ions in the electrolyte pass through.  When the battery ...
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Safety Testing Standards for Power Li-ion Battery – Part 2

  1.5 Nail Penetration The nail penetration test evaluates the safety of the battery by penetrating the steel needle through the sample at a certain speed. The steel needle passes through the battery, damaging the integrity of the electrode and diaphragm, resulting in a short circuit in the battery and continuous heat generation.  The severity level of nail penetration test is relatively high, and only three of the standards introduced in this article include this test. According to the difference of the test samples, the test parameters (needle depth, steel needle diameter, needle speed, etc.) of the needle test are quite different. SAEJ2464 200 and GB/T31485-2015 both require the steel needle to remain in the sample for 1h after penetrating the sample, but FreedomCAR does not specify.   1.6 Rollover The rollover test simulates the rollover and overturn that the vehicle may encounter in an accident, which is also called rotation in some standards (UL2580-2013, SAEJ2929 2...
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Safety Testing Standards for Power Li-ion Battery – Part 1

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  In recent years, countries around the world have continuously increased policy support for new energy vehicles, and car companies such as Tesla have also launched new models. It has led to the rapid growth of the global electric vehicle market.  However, the fire and explosion accidents of electric vehicles have occurred many times, making the safety issue the focus of consumers. In this context, countries and relevant international organizations have issued standards for the safety testing of power batteries to standardize the safe use of power batteries.   At present, the international technical standards/specifications related to the safety of power batteries are shown in the figure. Among them, the standards issued by ISO (International Organization for Standardization), IEC (International Electrotechnical Commission) and SAE International (Society of Automotive Engineers) are international standards, which have strong reference significance for national standards, ...
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