Testing Data of Cell Thermal Runaway and Analysis of Gas Production
Testing Data of Cell Thermal Runaway and Analysis of Gas Production,
Analysis of Gas Production,
▍What is CB Certification？
IECEE CB is the first genuine international system for mutual recognition of electrical equipment safety test reports. NCB (National Certification Body) reaches a multilateral agreement, which enables manufacturers to obtain national certification from other member countries under CB scheme on the basis of transferring one of the NCB certificates.
CB certificate is a formal CB scheme document issued by authorized NCB, which is to inform other NCB that the tested product samples conform to present standard requirement.
As a kind of standardized report, CB report lists relevant requirements from IEC standard item by item. CB report not only provides results of all required testing, measurement, verification, inspection and assessment with clearness and non-ambiguity, but also including photos, circuit diagram, pictures and product description. According to the rule of CB scheme, CB report will not take effect until it presents with CB certificate together.
▍Why we need CB Certification?
- Directly recognized or approved by member countries
With CB certificate and CB test report, your products can be exported to some countries directly.
- Convert to other countries certificates
The CB certificate can be directly converted to the certificate of its member countries, by providing the CB certificate, test report and difference test report (when applicable) without repeating the test, which can shorten the lead time of certification.
- Ensure the Safety of Product
The CB certification test considers the product’s reasonable use and foreseeable safety when misused. The certified product proves the satisfactory of the safety requirements.
▍Why MCM?
● Qualification: MCM is the first authorized CBTL of IEC 62133 standard qualification by TUV RH in mainland China.
● Certification and testing capability: MCM is among the first patch of testing and certification third party for IEC62133 standard, and has finished more than 7000 battery IEC62133 testing and CB reports for global clients.
● Technical support: MCM possesses more than 15 technical engineers specialized in testing as per IEC 62133 standard. MCM provides clients with comprehensive, accurate, closed-loop type of technical support and leading-edge information services.
The safety of energy storage system is a common concern. As one of the critical components of energy storage system, the safety of lithium-ion battery is particularly important. As thermal runaway test can directly evaluate the risk of fire occurring in energy storage system, many countries have developed corresponding test methods in their standards to assess the risk of thermal runaway. For example, IEC 62619 issued by the International Electrotechnical Commission (IEC) stipulates the propagation method to evaluate the influence of thermal runaway of the cell; Chinese national standard GB/T 36276 requires thermal runaway evaluation of the cell and thermal runaway test of the battery module; The U.S. Underwriters Laboratories (UL) publishes two standards, UL 1973 and UL 9540A, both of which assess thermal runaway effects. UL 9540A is specially designed to evaluate from four levels: cell, module, cabinet, and heat propagation at installation level. The results of thermal runaway test can not only evaluate the overall safety of the battery, but also allow us to quickly understand the thermal runaway of cells, and provide comparable parameters for the safety design of cells with similar chemistry. The following group of testing data for thermal runaway is for you to understand the characteristics of thermal runaway on each stage and the materials in the cell.Stage 1: The temperature rises steadily with an external heating source. At this time, the heat production rate of the cell is 0℃/min (0~ T1), the cell itself does not heat, and there is no chemical reaction inside.Stage 2 is SEI decomposition. With the increase of temperature, SEI film begins to dissolve when it reaches about 90℃ (T1). At this time, the cell will have a slight self-heat release, and it can be seen from Figure 1(B) that the temperature rise rate fluctuates.Stage 3 is the electrolyte decomposition stage (T1~ T2). When temperature reaches 110℃, the electrolyte and the negative electrode, as well as the electrolyte itself will occur a series of decomposition reaction, producing a large amount of gas. The continuously generating gas makes the pressure inside the cell increase sharply, reaching the pressure relief value, and the gas exhausting mechanism opens (T2). At this time, much gas, electrolytes and other substances release, taking away part of the heat, and the temperature increasing rate becomes negative.
