The standards of battery products, especially safety standards, are an important basis for quality and an important means to regulate market order and promote technological progress. This article mainly introduces and summarizes the existing common standards at home and abroad, and briefly discusses the problems in these standard systems.
Foreign power lithium-ion battery standards
Table 1 lists the commonly used foreign lithium-ion battery test standards. The standard issuing bodies mainly include the International Electrotechnical Commission (IEC), the International Organization for Standardization (ISO), the Underwriters Laboratories (UL), the American Society of Automotive Engineers (SAE), and relevant European Union agencies.
Table 1 Commonly used foreign power lithium-ion battery standards
1. International standards
The standards for power lithium-ion batteries released by IEC mainly include IEC 62660-1:2010 "Lithium-ion power battery monomers for electric road vehicles Part 1: Performance test" and IEC 62660-2:2010 "Lithium-ion power batteries for electric road vehicles Monomer Part 2: Reliability and abuse testing. UN 38. 3 "United Nations Recommendations Standards and Test Manuals on the Transport of Dangerous Goods" promulgated by the United Nations Transportation Commission requires that lithium battery testing be aimed at the safety of batteries during transportation.
The ISO standards for power lithium-ion batteries are ISO 12405-1:2011 "Electric Drive Vehicles-Lithium-ion Power Battery Packs and System Test Procedures Part 1: High Power Applications", ISO 12405-2:2012 "Electricity Driving vehicles-Lithium-ion battery packs and system test procedures Part 2: High-energy applications and ISO 12405-3:2014 "Electrically driven vehicles-Lithium-ion battery packs and system test procedures Part 3: Safety requirements 》, aiming at high-power batteries, high-energy batteries and safety performance requirements, the purpose is to provide optional test items and test methods for OEMs.
2. American Standard
UL 2580:2011 "Batteries for Electric Vehicles" mainly evaluates the reliability of battery abuse and the ability to protect people when abuse causes harm. The standard was revised in 2013.
SAE has a huge and complete standard system in the automotive field. SAE J2464: 2009 "Safety and Abuse Testing of Rechargeable Energy Storage Systems for Electric and Hybrid Electric Vehicles", issued in 2009, is a very early batch of vehicle battery abuse test manuals applied in North America and the global region, which clearly states that The scope of application of each test item and the data to be collected also give recommendations on the number of samples required for the test item.
SAE J2929: 2011 "Safety Standards for Electric and Hybrid Battery Systems" issued in 2011 is a safety standard proposed by SAE on the summary of various power battery related standards promulgated before, including two parts: Electric vehicles may appear during driving The normal condition test and abnormal condition test.
SAE J2380: 2013 "Vibration Test of Electric Vehicle Battery" is a more classic standard for the vibration test of electric vehicle batteries. Based on the statistical results of the vibration load spectrum of actual vehicle road driving, the test method is more in line with the actual vehicle vibration situation. It has important reference value.
3. Other organizational standards
The US Department of Energy (DOE) is mainly responsible for energy policy formulation, energy industry management, and energy-related technology research and development. In 2002, the US government established the "Freedom CAR" project, and successively issued the Freedom CAR power-assisted hybrid electric vehicle battery test manual and the electric and hybrid vehicle energy storage system abuse test manual.
The German Automobile Industry Association (VDA) is an association formed by Germany to unify various standards of the domestic automobile industry. The standards promulgated are VDA 2007 "Battery System Test for Hybrid Electric Vehicles", mainly for lithium-ion battery systems of hybrid vehicles Performance and reliability testing.
The European Economic Commission (ECE) R100. 2 "Uniform Regulations on Approval of Vehicles with regard to Special Requirements for Electric Vehicles" is a specific requirement formulated by ECE for electric vehicles. The whole is divided into two parts: The first part The charging energy storage system, functional safety and hydrogen emissions are regulated in four aspects. The second part is the new specific requirements for the safety and reliability of the rechargeable energy storage system.
Domestic power lithium-ion battery standards
In 2001, the Automobile Standardization Committee promulgated my country's first technical guidance document for lithium-ion battery testing of electric vehicles GB/Z 18333. 1: 2011 "Lithium-ion Battery for Electric Road Vehicles". When this standard was formulated, it referred to IEC 61960-2:2000 "Portable Lithium Batteries and Accumulators Part 2: Lithium Batteries" for lithium-ion batteries and battery packs used in portable equipment. The test contents include performance and safety, but only applicable For 21.6V and 14.4V batteries.
In 2006, the Ministry of Industry and Information Technology issued QC/T 743 "Lithium-ion Power Battery for Electric Vehicles", which is widely used in the industry and was revised in 2012. GB/Z 18333. 1: 2001 and QC/T 743: 2006 are standards for the monomer and module level, the scope of application is narrow, and the test content is no longer suitable for the needs of the rapidly developing electric vehicle industry.
In 2015, the National Standardization Management Committee promulgated a series of standards, GB/T 31484-2015 "Cycle life requirements and test methods for power batteries for electric vehicles", GB/T 31485-2015 "Safety requirements and test methods for power batteries for electric vehicles" ", GB/T 31486-2015 "Electrical vehicle power battery electrical performance requirements and test methods" and GB/T 31467. 1-2015 "Lithium-ion power battery pack and system for electric vehicle Part 1 high power application test regulations, GB/T 31467. 2-2015 "Lithium-ion power battery packs and systems for electric vehicles Part 2 High Energy Application Test Regulations, GB/T 31467. 3 "Lithium-ion power battery systems for electric vehicles Test Procedures Part 3 Safety Requirements and test methods.
GB/T 31485-2015 and GB/T 31486-2015 are for the safety and electrical performance testing of monomers/modules respectively. GB/T 31467-2015 series refers to the ISO 12405 series and is suitable for battery pack or battery system testing. And GB/T 31484-2015 is a test standard specifically for cycle life, using standard cycle life for monomers and modules, and working cycle life for battery packs and systems.
In 2016, the Ministry of Industry and Information Technology released the "Technical Conditions for the Safety of Electric Passenger Cars", which comprehensively considers the aspects of personnel electric shock, water and dust protection, fire protection, charging safety, collision safety, remote monitoring, etc., and fully draws on the existing traditional passenger cars and electric vehicles Standards and local standards such as Shanghai and Beijing put forward higher technical requirements for power batteries, adding two test items for thermal runaway and thermal runaway expansion, which were officially implemented on January 1, 2017.
Table 2 Domestic commonly used power lithium-ion battery standards
Standard analysis of power lithium-ion batteries at home and abroad
Analysis of power lithium-ion battery standards at home and abroad Most of the international standards were promulgated around 2010, with more revisions, and new standards have been introduced. GB/Z 18333. 1: 2001 was issued in 2001, which shows that my country's electric vehicle lithium-ion battery standard is not too late to start in the world, but the development is relatively slow. Since the QC/T 743 standard was released in 2006, there has been no standard update for a long time in my country, and there was no standard for battery packs or systems before the new national standard was released in 2015. The above-mentioned domestic and foreign standards differ in the scope of application, the content of the test items, the rigor of the test items, and the judgment criteria.
1. Scope of application
IEC 62660 series, QC/T 743, GB/T 31486 and GB/T 31485 are for battery cell and module level tests, UL2580, SAE J2929, ISO12405 and GB/T 31467 series are suitable for battery packs and battery systems test. Except for IEC 62660, other standards are basically related to battery pack or system level testing. SAE J2929 and ECE R100. 2 even mentioned the test of vehicle level. This shows that the development of foreign standards has more taken into account the application of batteries in the whole vehicle, which is more in line with the needs of practical applications.
2. Test items
Overall, all test items can be divided into two categories: electrical performance and safety reliability, and safety reliability can be divided into mechanical reliability, environmental reliability, abuse reliability, and electrical reliability.
Mechanical reliability, which simulates the mechanical stress suffered by the vehicle during driving, such as vibration, which simulates the bumps of the vehicle on the road; Environmental reliability, which simulates the tolerance of the vehicle in different climates, such as temperature cycling, which simulates the vehicle When the temperature difference between day and night is large or when driving back and forth in cold and hot areas; Abuse of reliability, such as fire, to investigate the safety of the battery when it is used improperly; Electrical reliability, such as protection test items, mainly to investigate battery management Whether the system (BMS) can play a protective role at a critical time.
In terms of battery cells, IEC 62660 is divided into two independent standards IEC 62660-1 and IEC 62660-2, respectively corresponding to performance and reliability tests. GB/T 31485 and GB/T 31486 are evolved from QC/T 743. In GB/T 31486, vibration resistance is classified as a performance test, because this test item is to examine the impact of battery vibration on battery performance. Compared with IEC 62660-2, GB/T 31485 test items are more stringent, such as the addition of acupuncture and seawater immersion.
In terms of battery pack and battery system testing, whether it is electrical performance or reliability, the US standard covers the most test items. In terms of performance testing, DOE/ID-11069 has more test items than other standards including mixed pulse power characteristics (HPPC), operating set point stability, calendar life, reference performance, impedance spectrum, module control inspection test, thermal management load And system level testing combined with life verification, etc.
In the appendix of the standard, the analysis method of the electrical performance test results is introduced in detail. Among them, the HPPC test can be used to detect the peak power of the power battery. The DC internal resistance test method derived from this has been widely used in the study of the internal resistance characteristics of the battery. In terms of reliability, UL2580 has more test items than other standards: unbalanced battery pack charging, withstand voltage, insulation, continuity test and cooling/heating stability system failure test, etc., and also includes battery pack components on the production line The basic safety test has strengthened the safety review requirements in terms of BMS, cooling system and protection circuit design. SAE J2929 proposes to perform fault analysis on each part of the battery system, and save relevant document materials, including improvement measures for easy identification of 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, and 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 my country's power battery and is modified according to the content of the ISO 12405 series standard.
Different from other standards: SAE J 2929 and ECE R100. 2 both involve high-voltage protection requirements and belong to the category of electric vehicle safety. The relevant test items in my country are in GB/T 18384, and GB/T 31467. 3 states that the battery pack and battery system must meet the relevant requirements of GB/T 18384. 1 and GB/T 18384. 3 before conducting safety tests.
3. Strictness
For the same test items, the test methods and judgment criteria specified in different standards are also different. For example, for the state of charge (SOC) of the test sample, GB/T 31467. 3 requires the sample to be fully charged; ISO 12405 requires the power type battery SOC to be 50% and the energy type battery SOC to be 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 require a recycled battery.
In addition, it is also required that the high-level simulation, thermal test, vibration, shock and external short circuit must 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. Other standards do not have this requirement.
For the fire test, the experimental method and parameter settings in GB/T 31467. 3 are not much different from ISO 12405. 3, and they are all preheated, direct fired and indirect fired by means of igniting fuel, but GB/T 31467. 3 It is required that the sample must be extinguished within 2 min if it has a flame, and ISO 12405 does not require a time to extinguish the flame. The fire test in SAE J2929 is different from the first two. It requires the sample to be placed in a heat radiation container and quickly heated up to 90s to Keep at 890°C for 10 minutes, and no components or substances should pass through the metal mesh cover placed outside the test sample.
Insufficiency of existing domestic standards
Although the formulation and release of relevant national standards fill the gap in my country's power lithium-ion battery combination system and are widely adopted, there are still deficiencies.
Test object: All standards only stipulate the test of new batteries. There are no relevant regulations and requirements for used batteries. There is no problem when the battery is shipped from the factory. It does not mean that it is still safe after a period of use, so it is necessary to use a different time. The same test of the battery is equivalent to regular physical examination.
Judgment of results: The current judgment is based on a broad and single basis, only the provisions of no leakage, no shell rupture, no fire and no explosion, lack of quantifiable evaluation system. The European Commission for Automotive Research and Technology (EUCAR) classifies the degree of battery damage into 8 levels, which has certain reference significance.
In terms of test items: GB/T31467. 3 lacks the test contents of the battery pack and battery system in terms of thermal management and thermal runaway, and thermal safety performance is critical to the battery. How to control the thermal runaway of the single battery and make the thermal runaway Not spreading is of great significance. The mandatory implementation of "Safety Technical Conditions for Electric Passenger Cars" also illustrates this point. In addition, from the perspective of vehicle application, for non-destructive reliability tests, such as environmental reliability, it is necessary to increase electrical performance tests after the test is completed, to simulate the impact of the performance 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 it is difficult to perform well. How to develop a reasonable accelerated cycle life test is difficult.
Summary
In recent years, my country has made great progress in the formulation and application of power lithium-ion battery standards, but there is still a certain gap with foreign standards. In addition to testing standards, my country's lithium ion battery standard system in other areas is gradually improving. On November 9, 2016, the Ministry of Industry and Information Technology released the "Comprehensive Standardization Technology System for Lithium Ion Batteries", pointing out that the future standard system includes basic general, materials and components, design and manufacturing processes, manufacturing and testing equipment, battery products, etc. Among them, the safety standards are of great importance. With the update and development of power battery products, the test standards also need to improve the corresponding inspection and testing technology, thereby enhancing the safety level of power batteries.
