Testing Chambers Knowledge

  In recent years, the global energy crisis and environmental pollution have become increasingly serious. As a clean and pollution-free energy storage, lithium-ion batteries are gradually applied to new energy vehicles, solar energy conversion energy storage equipment, mobile communication equipment and other fields.  At present, new energy vehicles with lithium-ion batteries appear in more and more cities, but some potential safety hazards are gradually exposed. According to the fire investigation report of new energy vehicles, the vast majority of fires are caused by the battery heat out of control. Improper use, accidental damage or defects of lithium-ion batteries may lead to explosion and fire.  Among many reasons that trigger the thermal runaway of the battery, acupuncture is an irreversible destructive behavior that causes the battery damage. When the battery is pierced by sharp objects or subjected to a large impact force, it will cause mechanical damage to the ba...

  1.Safety of lithium-ion battery under overheating condition The safety problems of lithium-ion batteries are mainly manifested by fire and explosion caused by uncontrolled heat. The causes of thermal runaway can be divided into external conditions and internal conditions. The internal temperature of the battery also keeps rising when the external temperature keeps rising.  When the temperature rises to a certain temperature, the diaphragm will be thermally closed and the positive and negative poles will be isolated for safety protection. However, if the diaphragm fails to close effectively, or the diaphragm melts and breaks, or other exothermic reactions occur inside the battery at the same time, so that the battery temperature continues to be high, it may cause safety problems. It can be seen that the safety problems caused by overheating are the result of the comprehensive action of internal and external conditions.   For example, when the temperature of lithium cobal...

  1.Classification of thermal runaway accident triggering There are many triggering reasons for the thermal runaway accident of lithium-ion power battery. According to the characteristics of triggering, it can be divided into three categories: mechanical trigger, electrical trigger and thermal trigger. The three types of trigger forms have certain internal relations.  Generally, mechanical trigger will cause short circuit and electric trigger, while electric trigger heat generation will cause thermal trigger, and thermal runaway caused by thermal trigger is the core of accident trigger. The mechanism analysis of other triggering forms cannot be separated from the study of thermal triggering mechanism.   Mechanical trigger includes crush , nail penetration , drop , etc., which is mainly characterized by deformation of the battery under force; Electric triggering includes external short circuit, internal short circuit, overcharge, over-discharge, etc. The main feature is t...

1.Introduction As a broadly applied power source for portable devices,lithiumion battery has advantages of high energy density, no memory effects, long cycle life, being environmental friendly,etc. After small lithium-ion batteries are dominant in the consumer electronies area, large lithium-ion batteries are developed, marching into automobile and power grid applications.   The application of lithium-ion battery brings about fire accidents and explosions, many researchers in the field of battery chemistry have studied and analyzed the reasons of battery failures under various conditions from a chemistry point of view. According to such studics, continuous improvements of battery components were made: various anode and cathode materials were developed to improve the chemical stability; a multilayer separator was designed to limit thermal runaway; proper additives were introduced into electrolyte to block chemical reactions or to discharge the battery itself for mitigation of overch...

  (3) Thermal abuse Thermal abuse refers to the simulation of improper battery use under high temperature, such as placing mobile phones in sun exposed cars, or placing mobile phones or electronic products in microwave ovens.  The external heat source directly acts on the lithium battery, causing complex internal chemical reactions, such as the decomposition of SEI film, the redox reaction between electrolyte and positive and negative electrode materials, which further evolves into heat runaway.  In addition, the diaphragm melts and shrinks at high temperature, leading to short circuit of positive and negative poles, which is very likely to cause fire or explosion. In the IEC62133: 2012 standard, only minor changes have been made to the heat abuse test, that is, small electric cores are kept at 130 ℃ for 10 min, and large electric cores are kept at 130 ℃ for 30 min. This is due to the increasing volume energy density and high capacity of single lithium ion battery. ...

  Lithium ion battery has the advantages of high specific energy, high voltage, long cycle life and low self discharge. It has become one of the main power supplies for portable electronic products such as mobile communication, notebook computers and electric tools. However, under misuse conditions (such as heating, overcharge, short circuit, vibration, extrusion, etc.), lithium-ion batteries may cause fire, explosion and even personal injury.  Therefore, the safety problem of lithium ion battery has become the bottleneck of its development. At present, many countries or testing institutions are studying new lithium battery safety technologies and formulating more scientific and perfect standards. For example, the testing standards applicable to lithium batteries for portable equipment are: 1EC62133, UL1642, JIS C8714, IFEE1625, UN38.3, etc.  This paper mainly analyzes and compares the differences between the 2002 edition and 2012 edition of the standard IEC62133 for lith...