The standard of battery products, especially the safety standard, is an important basis for quality and an important means to regulate market order and promote technological progress. This paper mainly introduces and summarizes the common standards at home and abroad, and briefly discusses the problems existing in these standards system.
1、 Foreign power lithium ion battery standards
Table 1 lists the commonly used test standards for lithium-ion batteries abroad. The standards are issued by the International Electrotechnical Commission (IEC), the international organization for Standardization (ISO), UL, SAE and other relevant institutions in the European Union.
Table 1 common standards for power lithium ion batteries abroad
1. International standards
The power lithium-ion battery standards issued by IEC mainly include IEC 62660-1:2010 lithium ion power battery monomer for electric road vehicles Part 1: performance testing and IEC 62660-2:2010 lithium ion power battery monomer for electric road vehicles Part 2: reliability and abuse test. UN 38.3 "UN recommendation standard and test manual on the transport of dangerous goods" issued by the United Nations Transport Commission requires lithium batteries to be tested for their safety during transportation.
ISO standards for power lithium-ion batteries include ISO 12405-1:2011 electric drive vehicles - Test procedures for lithium ion power battery packs and systems - Part 1: high power applications, ISO 12405-2:2012 test procedures for lithium ion power battery packs and systems - Part 2: high energy applications, and ISO 12405-2:2012 12405-3:2014 electric drive vehicles - lithium ion power battery pack and system test procedures Part 3: Safety requirements, respectively for high-power battery, high-energy battery and safety performance requirements, the purpose is to provide optional test items and test methods for vehicle manufacturers.
2. American Standard
UL 2580:2011 battery for electric vehicles mainly evaluates the reliability of battery abuse and the ability to protect personnel in case of abuse. The standard was revised in 2013.
SAE has a huge and perfect standard system in the automotive field. SAE j2464:2009 "safety and abuse testing of rechargeable energy storage system for electric and hybrid electric vehicles" issued in 2009 is one of the earliest vehicle battery abuse test manuals applied in North America and the world. It clearly points out the applicable scope of each test item and the data to be collected, and gives suggestions on the number of samples required for the test items.
SAE j2929:2011 electric and hybrid battery system safety standard issued in 2011 is a safety standard proposed by SAE on the basis of summarizing various power battery related standards issued before. It includes two parts: routine test and abnormal condition test that may occur during the driving of electric vehicle.
SAE j2380: 2013 "vibration test of electric vehicle battery" is a classic standard for vibration test of electric vehicle battery. Based on the statistical results of vibration load spectrum collected by actual vehicle on road, the test method is more in line with the actual vehicle vibration situation, and has important reference value.
3. Other organizational standards
The Department of energy (DOE) is mainly responsible for energy policy formulation, energy industry management and energy related technology research and development. In 2002, the U.S. government set up the "free car" project, and successively issued the battery test manual for the power assisted hybrid electric vehicle and the abuse test manual for the energy storage system of electric and hybrid electric vehicles.
The German automobile industry association (VDA) is an association formed by Germany to unify various standards of domestic automobile industry. The standard issued by VDA 2007 "battery system test for hybrid electric vehicles" is mainly aimed at the performance and reliability test of lithium-ion battery system of hybrid electric vehicles.
The Economic Commission for Europe (ECE) r100.2 "Uniform provisions on the approval of vehicles with regard to special requirements for electric vehicles" is a specific requirement formulated by ECE for electric vehicles, which is divided into two parts In the first part, the motor protection, rechargeable energy storage system, functional safety and hydrogen emission are regulated. In the second part, the specific requirements for the safety and reliability of the rechargeable energy storage system are added.
2、 Domestic power lithium ion battery standard
In 2001, the automotive Standardization Committee issued the first guiding technical document for lithium-ion battery testing of electric vehicles in China (GB / Z 18333.1:2011 lithium ion batteries for electric road vehicles). However, IEC part 21.2-2000 for lithium-ion batteries and 612.14 for portable batteries are included in the IEC standard for the safety of lithium batteries.
In 2006, the Ministry of industry and information technology issued QC / T 743 "lithium ion power batteries for electric vehicles", which was widely used in the industry and revised in 2012. Both GB / Z 18333.1:2001 and QC / T 743:2006 are standards for monomer and module level, and their application scope is narrow, and the test content can not meet the needs of the rapid development of electric vehicle industry.
In 2015, the National Standardization Administration Committee issued a series of standards, including GB / T 31484-2015 cycle life requirements and test methods for traction batteries for electric vehicles, GB / T 31485-2015 safety requirements and test methods for power batteries for electric vehicles, GB / T 31486-2015 electrical performance requirements and test methods for power batteries for electric vehicles, and GB / T 31467 1-2015 lithium ion power battery packs and systems for electric vehicles - Part 1: test procedures for high power applications; GB / T 31467.2-2015 lithium ion power battery packs and systems for electric vehicles - Part 2: test procedures for high energy applications; GB / T 31467.3 test procedures for lithium-ion power battery systems for electric vehicles - Part 3: Safety requirements and test methods.
GB / T 31485-2015 and GB / T 31486-2015 are respectively for the safety and electrical performance test of single unit / module. GB / T 31467-2015 series refers to ISO 12405 series and is applicable to the test of battery pack or battery system, while GB / T 31484-2015 is the test standard for cycle life, which adopts standard cycle life for monomer and module and working cycle life for battery pack and system.
In 2016, the Ministry of industry and information technology issued the safety technical conditions for electric buses, which comprehensively considered personnel electric shock, water and dust protection, fire protection, charging safety, collision safety, remote monitoring, etc., and fully drew on the existing relevant standards of traditional passenger cars and electric vehicles, as well as Shanghai, Beijing and other local standards, put forward higher technical requirements for power batteries, adding thermal runaway and thermal Two test items were extended out of control, which were formally implemented on January 1, 2017.
Table 2 domestic standards for power lithium ion batteries
3、 Analysis of domestic and international power lithium ion battery standards
Analysis of power lithium ion battery standards at home and abroad, most of the international standards were issued around 2010, and many new standards were revised. GB / Z 18333.1:2001 was issued in 2001. It can be seen that China's lithium ion battery standard for electric vehicles started not late in the world, but its development was relatively slow. Since the release of QC / T 743 standard in 2006, there is no standard update in China for a long time, and there is no standard about battery pack or system before the new national standard is issued in 2015. There are differences in the scope of application, contents of test items, strictness of test items and judgment criteria between the above standards at home and abroad.
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, while ul2580, SAE j2929, iso12405 and GB / T 31467 series are applicable to battery pack and battery system testing. In addition to IEC 62660, other standards basically involve battery pack or system level test. SAE j2929 and ECE r100.2 even mentioned vehicle level test. This shows that the foreign standard formulation takes more into account the application of battery in the vehicle, which is more in line with the requirements of practical application.
2. Test item content
On the whole, all test items can be divided into 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 of the vehicle in the process of driving, such as vibration, simulates the bumping of the vehicle on the road; environmental reliability, which simulates the endurance of the vehicle in different climate, such as temperature cycle, simulates the situation of the vehicle in large temperature difference between day and night or driving back and forth in cold and hot areas; Abuse of reliability, such as fire, is to investigate the safety of batteries in case of improper use; electrical reliability, such as protection test items, is mainly to investigate whether the battery management system (BMS) can play a protective role in critical times.
In terms of battery cell, IEC 62660 is divided into two independent standards IEC 62660-1 and IEC 62660-2, corresponding to performance and reliability tests respectively. GB / T 31485 and GB / T 31486 are evolved from QC / T 743. Vibration resistance is classified as performance test in GB / T 31486, because the test item is to investigate the effect of battery vibration on battery performance. Compared with IEC 62660-2, the test items of GB / T 31485 are more stringent, such as adding acupuncture and seawater immersion.
In terms of battery pack and battery system test, whether it is electrical performance or reliability, the American Standard covers the most test items. In terms of performance test, DOE / id-11069 has more test items than other standards, such as hybrid pulse power characteristic (HPPC), operation set point stability, calendar life, reference performance, impedance spectrum, module control inspection test, thermal management load and system level test combined with life verification.
In the appendix of the standard, the analysis method of electrical performance test results is introduced in detail. Among them, HPPC test can be used to detect the peak power of power battery. The DC internal resistance test method derived from this has been widely used in the research of battery internal resistance characteristics. 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 fault test. It also includes the basic safety test of battery pack components on the production line, and strengthens the safety review requirements in BMS, cooling system and protection circuit design. SAE j2929 proposed to analyze the failure of each part of the battery system, and save the relevant documents, including the improvement measures to identify the fault easily.
ISO 12405 series standards include both battery performance and safety. ISO 12405-1 is the battery performance test standard for high-power applications, and ISO 12405-2 is the battery performance test standard for high-energy applications. The former includes cold start and hot start. The GB / T 31467 series is modified according to the ISO 12405 series standards and the development status of power batteries in China.
Different from other standards, SAE J 2929 and ECE r100.2 both involve high voltage protection requirements and belong to the safety category of electric vehicles. In GB / T 18384 and GB / T 31467.3, it is pointed out in GB / T 18384.3 that battery pack and battery system shall meet the relevant requirements of GB / T 18384.1 and GB / T 18384.3 before safety test.
For the same test items, the test methods and 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 that the SOC of the power battery is 50%, and that of the energy battery is 100%; ECE r100.2 requires that the SOC of the battery be more than 50%; UN38.3 has different requirements for different test items, and some test items also need recycled batteries.
In addition, high simulation, thermal test, vibration, shock and external short circuit must be tested with the same sample, which is relatively strict. For vibration testing, ISO 12405 requires samples to vibrate at different ambient temperatures. The recommended high and low temperatures are 75 ℃ and - 40 ℃, respectively. Other standards do not have this requirement.
For the fire test, the test methods and parameter settings in GB / T 31467.3 are similar to those in ISO 12405.3. They are preheating, direct firing and indirect firing by igniting fuel. However, GB / T 31467.3 requires that samples with flame must be extinguished within 2 min, while ISO 12405 does not require the time for flame extinction The fire test in j2929 is different from the former two. It requires that the sample be placed in a thermal radiation container, rapidly raise the temperature to 890 ℃ within 90 s and maintain for 10 min, and no component or substance passes through the metal mesh cover placed outside the test sample.
4、 Insufficient domestic standards
Although the formulation and release of relevant national standards fill the gap in the power lithium-ion battery combination system in China and are widely used, there are still deficiencies.
Test objects: all the standards only stipulate the test of new batteries, and there are no relevant regulations and requirements for used batteries. There are no problems when the batteries leave the factory, which does not mean that they are still safe after using for a period of time. Therefore, it is necessary to carry out the same test on the batteries used for different times, which is equivalent to regular physical examination.
Results: the current judgment basis is broad and single, only no leakage, no shell rupture, no fire and no explosion provisions, lack of quantifiable evaluation system. The European Commission for automotive research and technology development (eucar) divides the hazard degree of batteries into eight grades, which has certain reference significance.
In terms of test items: GB / t31467.3 lacks the test contents of battery pack and battery system in terms of thermal management and thermal runaway, and thermal safety performance is very important for battery. It is of great significance to control thermal runaway of single battery so as to prevent thermal runaway from spreading. The compulsory implementation of safety technical conditions for electric bus also illustrates this point. In addition, from the vehicle application level, for non-destructive reliability test, such as environmental reliability, it is necessary to add electrical performance test after the test to simulate the impact of environmental changes on vehicle performance.
Test method: the cycle life test of battery pack and battery system takes too long, which affects the product development cycle and is difficult to be carried out well. How to develop a reasonable accelerated cycle life test is a difficulty.
In recent years, great progress has been made in the formulation and application of power lithium-ion battery standards in China, but there is still a certain gap with foreign standards. In addition to the detection standards, other aspects of the standard system of lithium-ion batteries in China are also gradually improved. On November 9, 2016, the Ministry of industry and information technology issued the comprehensive standardization technology system for lithium ion batteries, pointing out that the future standard system includes five parts: basic general purpose, materials and components, design and manufacturing process, manufacturing and testing equipment, battery products, etc. among them, safety standards are of great importance. With the update and development of power battery products, the test standards need to be improved accordingly In order to enhance the safety level of power battery.