Lithium-ion battery test standards in china
Most of the international standards for power lithium-ion battery standards are promulgated around 2010, with more revisions and new standards. GB/Z 18333. 1: 2001 was issued in 2001. It can be seen that China's electric vehicle lithium-ion battery standard is not too late to start in the world, but the development is relatively slow. Since the release of the QC/T 743 standard in 2006, there has been no standard update in China for a long time, and there is no standard for battery packs or systems before the release of the new national standard in 2015. The above-mentioned domestic and foreign standards differ in terms of scope of application, content of test items, rigor of test items, and criteria for judgment.
1 Scope of application
IEC 62660 series, QC/T 743, GB/T 31486 and GB/T 31485 are for battery cell and module level testing. UL2580, SAE J2929, ISO12405 and GB/T 31467 series are suitable for battery and battery systems. test. In addition to IEC 62660, other standards are basically related to battery pack or system level testing. SAE J2929 and ECE R100. 2 even mention vehicle-level testing. This shows that the standardization of foreign countries takes into account the application of the battery in the whole vehicle, which is more in line with the needs of practical applications.
2 test item content
All test items can be divided into two categories: electrical performance and safety reliability. Safety and reliability can be divided into mechanical reliability, environmental reliability, abuse reliability and electrical reliability.
Mechanical reliability, simulating the mechanical stresses that the vehicle is subjected to during driving, such as vibrations simulating the bumps of the vehicle on the road surface; environmental reliability, simulating the vehicle's tolerance in different climates, such as temperature cycling simulating the vehicle When the temperature difference between day and night is large or when driving back and forth in cold and hot areas; abuse reliability, such as fire, to check the safety of the battery when it is improperly used; electrical reliability, such as protection test items, mainly to investigate battery management The system (BMS) can protect it at critical times.
In terms of battery cells, IEC 62660 is divided into two separate standards, IEC 62660-1 and IEC 62660-2, for performance and reliability testing. GB/T 31485 and GB/T 31486 are evolved from QC/T 743. In GB/T 31486, vibration resistance is attributed to the performance test because it is to examine the effect of battery vibration on battery performance. Compared with IEC 62660-2, the GB/T 31485 test items are more stringent, such as increased acupuncture and seawater immersion.
In terms of battery pack and battery system testing, the US standard covers the most test items, both in terms of electrical performance and reliability. In terms of performance testing, DOE/ID-11069 has more mixed pulse power characteristics (HPPC), run set point stability, calendar life, reference performance, impedance spectrum, module control test, thermal management load than other standards. And system level testing combined with life verification.
The analysis method of the electrical performance test results is described in detail in the standard appendix. The HPPC test can be used to detect the peak power of the power battery. The DC internal resistance test method derived from it has been widely used in the study of the internal resistance characteristics of the battery. In terms of reliability, the UL2580 has more test items than other standards: unbalanced battery pack charging, withstand voltage, insulation, continuity test, and cooling/heating stabilization system failure test, as well as battery components for the production line. The basic safety test, in terms of BMS, cooling system and protection circuit design, strengthens the security review requirements. SAE J2929 proposes to perform failure analysis on various parts of the battery system and to save relevant documentation, including improvements to identify faults.
The ISO 12405 series of standards includes both battery performance and safety. ISO 12405-1 is a battery performance test standard for high power applications. ISO 12405-2 is a battery performance test standard for high energy applications. The former has more cold start and Hot start two items. The GB/T 31467 series combines the development status of China's power battery and is modified according to the contents of the ISO 12405 series standard.
Different from other standards: SAE J 2929 and ECE R100. 2 both involve the requirements of high voltage protection and belong to the category of electric vehicle safety. China's relevant test items in GB/T 18384, GB/T 31467. 3 pointed out that the battery pack and battery system to meet the relevant requirements of GB/T 18384. 1 and GB/T 18384. 3 before conducting safety tests.
For the same test items, the test methods and criteria specified in the different standards are also different. For example, for the state of charge (SOC) of the test sample, the sample is required to be fully charged in GB/T 31467. 3; the SOC of the power battery is 50% in ISO 12405 and the SOC of the energy battery is 100%; ECE R100. 2 The SOC of the battery is required to be more than 50%; UN38. 3 has different requirements for different test items, and some test items also need to circulate the battery.
In addition, high-simulation, thermal testing, vibration, shock, and external short-circuiting are required to be tested with the same sample, which is relatively more stringent. For vibration testing, ISO 12405 requires samples to vibrate at different ambient temperatures. The recommended high and low temperatures are 75 ° C and -40 ° C, respectively, and other standards do not.
For the fire test, the experimental methods and parameter settings in GB/T 31467. 3 are similar to those of ISO 12405. 3, which are preheated, directly fired and indirectly fired by means of igniting fuel, but GB/T 31467. 3 If the sample requires a flame to be extinguished within 2 minutes, ISO 12405 does not require the time for the flame to extinguish. The fire test in SAE J2929 is different from the previous two. It requires the sample to be placed in a heat radiation container and heated rapidly within 90 seconds. 890 ° C for 10 min, and no components or substances shall pass through the metal mesh placed outside the test sample.
4. Insufficient existing domestic standards
Although the formulation and publication of relevant national standards have filled the gap in China's power lithium-ion battery assembly system and have been widely adopted, there are still deficiencies.
Test object: All standards only stipulate the test of new battery. There are no regulations and requirements for the used battery. The battery has no problem at the factory. It does not mean that it is safe after using for a period of time. Therefore, it is necessary to use different time. The battery is tested the same, which is equivalent to a regular medical examination.
Judgment of results: The current judgment is based on a broad and single basis, and there are only provisions for no leakage, no shell rupture, no fire and no explosion, and a lack of quantifiable evaluation system. The European Commission for Automotive Research and Technology Development (EUCAR) divides the degree of damage of batteries into eight grades, which has certain reference significance.
Test items: GB/T31467. 3 lacks battery pack and battery system test content in thermal management and thermal runaway, and thermal safety performance is critical to the battery, how to control the thermal runaway of the single cell, so that the thermal runaway situation It does not spread and is of great significance. The enforcement of the "Safety Technical Conditions for Electric Buses" also illustrates this point. In addition, from the perspective of vehicle application, for non-destructive reliability testing, such as environmental reliability, it is necessary to increase the electrical performance test after the end of the test to simulate the impact of the vehicle after undergoing environmental changes.
Test method: The cycle life test of the battery pack and battery system takes too long, affects the product development cycle, and is difficult to perform well. How to develop a reasonable accelerated cycle life test is a difficult point.
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