Overview: This paper analyzes and compares domestic and international standards for performance and safety testing of power lithium batteries, focusing on aspects such as scope of application, test items, and rigor. It also summarizes and forecasts the construction and development of the domestic power lithium battery standard system.
Battery product standards, especially safety standards, are crucial for quality control and for regulating market order and promoting technological progress. This article introduces, summarizes, and analyzes common existing standards both domestically and internationally, and briefly discusses the problems existing in these standard systems.
I. International Standards for Power Lithium Batteries
Table 1 lists commonly used international lithium battery testing standards. Important standard-issuing organizations include the International Electrotechnical Commission (IEC), the International Organization for Standardization (ISO), Underwriters Laboratories (UL), the Society of Automotive Engineers (SAE), and relevant EU agencies.
Table 1 Commonly Used International Standards for Power Lithium Batteries
1. International Standards
The key standards for power lithium batteries published by the IEC include IEC 62660-1:2010 "Lithium-ion power battery cells for electric road vehicles - Part 1: Performance testing" and IEC 62660-2:2010 "Lithium-ion power battery cells for electric road vehicles - Part 2: Reliability and abuse testing". The UN Transport Committee's UN 38.3 "United Nations Recommendation on the Transport of Dangerous Goods - Standards and Test Manual" specifies requirements for lithium battery testing focusing on battery safety during transport.
ISO has established three standards for power lithium batteries: ISO 12405-1:2011 "Test procedure for lithium-ion power lithium battery packs and systems for electric vehicles - Part 1: High power applications", ISO 12405-2:2012 "Test procedure for lithium-ion power lithium battery packs and systems for electric vehicles - Part 2: High energy applications", and ISO 12405-3:2014 "Test procedure for lithium-ion power lithium battery packs and systems for electric vehicles - Part 3: Safety requirements". These standards address high-power batteries, high-energy batteries, and safety performance requirements, respectively, and aim to provide OEMs with selectable test items and test methods.
2. American Standards
UL2580:2011, "Batteries for Electric Vehicles," is an important standard for assessing the reliability of batteries in the event of misuse and their ability to protect people in the event of harm caused by misuse. This standard was revised in 2013.
SAE has a large and comprehensive standards system in the automotive field. SAE J2464:2009, "Safety and abuse testing of rechargeable energy storage systems for electric and hybrid electric vehicles," published in 2009, was one of the earliest manuals for testing automotive batteries for abuse in North America and around the world. It clearly indicates the scope of application for each test item and the data to be collected, and also provides recommendations on the number of samples required for each test item.
The SAE J2929:2011 Safety Standard for Lithium-ion Battery Systems for Electric and Hybrid Electric Vehicles, promulgated in 2011, is a safety standard proposed by SAE based on a summary of various previously promulgated standards related to power lithium-ion batteries. It includes two parts: tests for normal conditions that may occur during the operation of electric vehicles and tests for abnormal conditions.
SAEJ2380:2013 "Vibration Test of Electric Vehicle Batteries" is a classic standard for vibration testing of electric vehicle batteries. It is based on the statistical results of vibration load spectrum collection from actual vehicles on the road. The test method is more in line with the vibration conditions of actual vehicles and has important reference value.
3. Other organizational standards
The U.S. Department of Energy (DOE) is primarily responsible for energy policy formulation, energy industry management, and energy-related technology research and development. In 2002, the U.S. government established the FreedomCAR program, subsequently issuing the FreedomCAR Power-Assisted Hybrid Electric Vehicle Battery Test Manual and the Abuse Testing Manual for Energy Storage Systems in Electric and Hybrid Vehicles.
The German Association of the Automotive Industry (VDA) is an association formed by Germany to unify various standards in the domestic automotive industry. The standard it has issued is VDA2007 "Testing of Battery Systems for Hybrid Vehicles", which is mainly for the performance and reliability testing of lithium battery systems for hybrid vehicles.
The European Economic Commission (ECE) Regulation 100.2, "Uniform Regulations on Approval of Vehicles with Respect to Specific Requirements for Electric Vehicles," is a set of specific requirements for electric vehicles developed by the ECE. It is divided into two parts: the first part specifies the requirements for the whole vehicle in four aspects, namely motor protection, rechargeable energy storage systems, functional safety, and hydrogen emissions; the second part is a new set of specific requirements for the safety and reliability of rechargeable energy storage systems.
II. Domestic Power Lithium Battery Standards
In 2001, the Automotive Standardization Committee issued my country's first guiding technical document for lithium battery testing of electric vehicles, GB/Z18333.1:2011 "Lithium-ion Batteries for Electric Road Vehicles". This standard referenced IEC61960-2:2000 "Portable Lithium Batteries and Battery Packs - Part 2: Lithium Battery Packs", and was used for lithium batteries and battery packs in portable devices. The testing included performance and safety, but it only applied to 21.6V and 14.4V batteries.
In 2006, the Ministry of Industry and Information Technology issued QC/T743, "Lithium-ion Power Batteries for Electric Vehicles," which was widely used in the industry and was revised in 2012. GB/Z18333.1:2001 and QC/T743:2006 are standards for individual cells and modules, with a narrower scope of application, and their testing content is no longer suitable for the needs of the rapidly developing electric vehicle industry.
In 2015, the Standardization Administration of China issued a series of standards, including GB/T31484-2015 "Cycle Life Requirements and Test Methods for Power Batteries for Electric Vehicles", GB/T31485-2015 "Safety Requirements and Test Methods for Power Batteries for Electric Vehicles", GB/T31486-2015 "Electrical Performance Requirements and Test Methods for Power Batteries for Electric Vehicles", GB/T31467.1-2015 "Lithium-ion Power Battery Packs and Systems for Electric Vehicles - Part 1: High Power Application Test Procedures", GB/T31467.2-2015 "Lithium-ion Power Battery Packs and Systems for Electric Vehicles - Part 2: High Energy Application Test Procedures", and GB/T31467.3 "Test Procedures for Lithium-ion Power Battery Systems for Electric Vehicles - Part 3: Safety Requirements and Test Methods".
GB/T31485-2015 and GB/T31486-2015 are for safety and electrical performance testing of individual cells/modules, respectively. The GB/T31467-2015 series refers to the ISO12405 series and is applicable to the testing of battery packs or battery systems. GB/T31484-2015 is a test standard specifically for cycle life. Standard cycle life is used for individual cells and modules, while operating condition cycle life is used for battery packs and systems.
In 2016, the Ministry of Industry and Information Technology (MIIT) released the "Safety Technical Conditions for Electric Buses," which comprehensively considers aspects such as electric shock protection, water and dust protection, fire protection, charging safety, collision safety, and remote monitoring. It also draws on existing standards for traditional buses and electric vehicles, as well as local standards in Shanghai and Beijing, and sets higher technical requirements for power lithium batteries. Two new test items, thermal runaway and thermal runaway propagation, have been added and officially implemented on January 1, 2017.
Table 2 Commonly Used Domestic Power Lithium Battery Standards
III. Analysis of Domestic and International Power Lithium Battery Standards
An analysis of domestic and international standards for power lithium batteries reveals that most international standards were promulgated around 2010, have undergone numerous revisions, and new standards have been continuously introduced. GB/Z18333.1:2001 was issued in 2001, indicating that my country's electric vehicle lithium battery standards started relatively early globally, but their development has been relatively slow. After the publication of the QC/T743 standard in 2006, my country did not update its standards for a long period, and before the new national standard was published in 2015, there were no standards related to battery packs or systems. The aforementioned domestic and international standards differ in their scope of application, test items, test stringency, and judgment criteria.
1. Scope of application
The IEC 62660 series, QC/T 743, GB/T 31486, and GB/T 31485 are for testing at the individual battery cell and module level, while UL 2580, SAE J2929, ISO 12405, and GB/T 31467 series apply to testing battery packs and battery systems. Except for IEC 62660, most international standards cover battery pack or system-level testing, with SAE J2929 and ECE R100.2 even mentioning vehicle-level testing. This indicates that international standards development takes into account the application of batteries in vehicles and is more in line with practical application needs.
2. Test Item Content
All test items can be broadly categorized into two main types: electrical performance and safety reliability. Safety reliability can be further divided into mechanical reliability, environmental reliability, abuse reliability, and electrical reliability.
Mechanical reliability simulates the mechanical stresses experienced by a vehicle during operation, such as vibration simulating the bumps on the road surface; environmental reliability simulates the vehicle's tolerance in different climates, such as temperature cycling simulating the vehicle's condition when driving in areas with large temperature differences between day and night or in cold and hot regions; abuse reliability, such as fire, examines the safety of the battery when subjected to improper use; electrical reliability, such as protection-related tests, mainly examines whether the battery management system (BMS) can perform its protective function in critical situations.
Regarding individual battery cells, IEC 62660 is divided into two independent standards, IEC 62660-1 and IEC 62660-2, corresponding to performance and reliability testing, respectively. GB/T 31485 and GB/T 31486 evolved from QC/T 743. GB/T 31486 classifies vibration resistance as a performance test because this test examines the impact of battery vibration on battery performance. Compared to IEC 62660-2, GB/T 31485 has more stringent testing items, such as the addition of needle penetration and seawater immersion tests.
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. Regarding performance testing, DOE/ID-11069 includes additional test items compared to other standards, such as hybrid pulse power characteristics (HPPC), operating setpoint stability, calendar life, reference performance, impedance spectrum, module control verification testing, thermal management load, and system-level testing combined with life verification.
The standard's appendix details the methods for analyzing electrical performance test results. Among these, the HPPC test can be used to detect the peak power of power lithium batteries, and the derived DC internal resistance test method is widely used in battery internal resistance characteristic research. Regarding reliability, UL2580 includes additional tests compared to other standards, such as unbalanced battery pack charging, withstand voltage, insulation, continuous operation tests, and cooling/heating stability system failure tests. It also includes basic safety tests for battery pack components on the production line and strengthens safety review requirements for BMS, cooling system, and protection circuit design. SAEJ2929 requires fault analysis of each part of the battery system and the preservation of relevant documentation, including easily identifiable fault improvement measures.
The ISO 12405 series of standards covers both battery performance and safety. ISO 12405-1 is a battery performance testing standard for high-power applications, while ISO 12405-2 is a battery performance testing standard for high-energy applications. The former adds cold start and hot start testing. The GB/T 31467 series is a modified version of the ISO 12405 series standards, reflecting the development status of power lithium batteries in my country.
Unlike other standards, SAE J2929 and ECE R100.2 both involve high-voltage protection requirements, falling under the category of electric vehicle safety. In my country, relevant test items are specified in GB/T18384 and GB/T31467.3, which state that battery packs and battery systems must meet the relevant requirements of GB/T18384.1 and GB/T18384.3 before undergoing safety testing.
3. Strictness
For the same test items, the test methods and judgment criteria specified in different standards are not entirely the same. For example, regarding the state of charge (SOC) of the test sample, GB/T31467.3 requires the sample to be fully charged; ISO12405 requires a SOC of 50% for power batteries and 100% for energy batteries; ECE R100.2 requires the battery's SOC to be above 50%; UN38.3 has different requirements for different test items, and some test items require batteries that have been cycled.
In addition, it requires that high-simulation, thermal, vibration, shock, and external short-circuit tests must be conducted using the same sample, making it relatively more stringent. Regarding vibration testing, ISO 12405 requires samples to vibrate under different ambient temperatures, with recommended high and low temperatures of 75°C and -40°C, respectively. Other standards do not have this requirement.
Regarding the fire test, the test method and parameter settings in GB/T31467.3 are not much different from those in ISO12405.3. Both use the method of igniting fuel for preheating, direct fire and indirect fire. However, GB/T31467.3 requires that any flames on the sample must be extinguished within 2 minutes, while ISO12405 does not require a time limit for extinguishing the flames. The fire test in SAEJ2929 is different from the former two. It requires that the sample be placed in a heat radiation container, rapidly heated to 890°C within 90 seconds and maintained for 10 minutes, and that no component or substance pass through the metal mesh cover placed outside the test sample.
IV. Deficiencies of Existing Domestic Standards
Although the formulation and publication of relevant national standards have filled the gap in my country's power lithium battery pack systems and have been widely adopted, there are still shortcomings.
Regarding the testing objects: all standards only specify the testing of new batteries, and there are no relevant regulations or requirements for used batteries. Just because a battery is fine when it leaves the factory does not mean that it will still be safe after a period of use. Therefore, it is necessary to conduct the same test on batteries that have been used for different periods of time, which is equivalent to regular physical examinations.
Regarding the assessment of results: Current assessment criteria are broad and singular, only specifying no leakage, no casing rupture, no fire, and no explosion, lacking a quantifiable evaluation system. The European Automobile Research and Technology Development Committee (EUCAR) classifies the hazard level of batteries into eight levels, which offers some reference value.
Regarding testing items: GB/T31467.3 lacks testing content for battery packs and battery systems in terms of thermal management and thermal runaway. Thermal safety performance is crucial for batteries, and controlling the thermal runaway of individual cells to prevent its propagation is of great significance, as evidenced by the mandatory implementation of the "Safety Technical Conditions for Electric Buses." Furthermore, from the perspective of whole-vehicle application, for non-destructive reliability testing, such as environmental reliability testing, it is necessary to add electrical performance testing after the initial test to simulate the impact of environmental changes on vehicle performance.
Regarding testing methods: Cycle life testing of battery packs and battery systems takes too long, affecting product development cycles and is difficult to implement effectively. Developing a reasonable accelerated cycle life test is a challenge.
V. Summary
In recent years, my country has made significant progress in the formulation and application of standards for power lithium batteries, but a gap still exists compared to international standards. Besides testing standards, my country's lithium battery standard system is gradually improving in other areas. On November 9, 2016, the Ministry of Industry and Information Technology (MIIT) released the "Comprehensive Standardization Technical System for Lithium Batteries," outlining that the future standard system will include five main parts: basic general standards, materials and components, design and manufacturing processes, manufacturing and testing equipment, and battery products. Safety standards are of paramount importance; as power lithium battery products are updated and developed, testing standards must also improve corresponding verification and testing technologies to enhance the safety level of power lithium batteries.
