Introduction to IEC Standards for Lithium-ion Batteries

Introduction to IEC Standards for Lithium-ion Batteries

IEC 61960:2011, "Single cells and battery packs containing alkaline or other non-acidic electrolytes: Portable lithium batteries (cells) or battery packs". The scope of application of this standard includes lithium secondary batteries for power, lithium secondary batteries for mobile communication products, and lithium secondary batteries for portable products. This standard specifies the performance testing, marking, labeling, dimensions and other requirements for lithium secondary batteries within the applicable scope. It is currently one of the few international standards that regulate the electrical performance index parameters (capacity, cycle life, internal resistance, etc.) of lithium battery cell products. It can accurately measure the discharge capacity index of secondary lithium cell battery products under different environmental temperatures, and at the same time, it can effectively assess their cycle life and capacity retention and capacity attenuation after long-term storage. The main test items include capacity testing of battery cells and battery packs, cycle life testing, etc.

IEC 61959:2004, "Single cells and battery packs containing alkaline or other non-acidic electrolytes: Mechanical tests for portable sealed lithium secondary cells or battery packs". The standard conducted vibration and free drop tests on lithium-ion secondary battery cells and battery packs within the applicable scope, simulating various mechanical tests of lithium-ion batteries subjected to external impacts under various working conditions.

IEC 62660:2022 is the latest version of this IEC standard. "Secondary Lithium-ion Batteries for Electric Road Vehicles" is the first safety standard in the IEC system specifically for power lithium batteries. Lithium-ion batteries for electric road vehicles are applicable to this IEC standard. Its content includes performance testing, reliability testing, abuse testing, and security requirements, etc.

IEC 60086-4:2019 is a safety standard for non-rechargeable lithium cells and batteries introduced by the European Union. The main test items include altitude simulation test, temperature cycling test, vibration test, mechanical shock test, external short circuit test, heavy hammer impact test, compression test, forced discharge test, abnormal charging test, free drop test, thermal abuse test, incorrect installation test, over-discharge test, etc.

IEC 62321:2021 is a testing standard for hazardous substances in electronic and electrical appliances issued by IEC. The ROHS Directive is a mandatory standard for access established by EU legislation. Its full name is the "Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Directive", which is mainly used to regulate the material and process standards of electrical and electronic products, making them more conducive to human health and environmental protection. Battery products entering the European market need to have ROHS certification. The standard used for ROHS certification is IEC 62321:2021. The determination of certain substances in battery products must meet the limit requirements of the standards.

Introduction to IEC62133 Standard

IEC 62133:2017, this standard mainly targets the safety requirements for single cells and battery packs containing alkaline or non-acidic electrolytes, as well as portable sealed single cells and battery packs (including lithium batteries, nickel-metal-hydride batteries, nickel-cadmium batteries, etc.). The test provisions of IEC 62133:2017 are divided into two major sections: nickel battery systems and lithium battery systems. IEC 62133-1:2017 covers nickel battery systems, while IEC 62133-2:2017 covers lithium battery systems. Compared with the national standard GB 31241-2022, GB 31241-2022 only sets safety requirements for portable lithium-ion batteries and battery packs, and does not put forward requirements for nickel-based batteries. GB 31241-2022 is more targeted and has more extensive and specific requirements. On the other hand, compared with GB 31241-2022, IEC62133-2:2017 does not have test provisions for battery pack protection circuits and system protection circuits. Overall, compared with IEC62133-2:2017, GB 31241-2022 has more and more comprehensive testing requirements. If foreign enterprises obtain the certificate of IEC62133-2:2017, when they conduct GB 31241-2022 tests, they can only recognize some of the test results in IEC62133-2:2017. For items such as vibration, shock and thermal abuse, the test results of IEC62133-2:2017 can be directly used. However, the test results in other aspects need to be redone.

According to the requirements of the new IEC 62133:2017, lithium batteries should pass relevant tests in accordance with the requirements of IEC 62281, and the test items are the same as those of UN38.3. UN38.3 is a transportation requirement proposed by the United Nations Air Transport Association for the transportation of lithium-ion batteries. Therefore, if the manufacturer can provide documents proving compliance with UN transportation requirements, the transportation test does not need to be conducted and can be directly determined as qualified.

The IEC 62133:2017 standard mainly includes the testing of the following items:

cell: Continuous low-rate charging, vibration, temperature cycling, external short circuit, internal short circuit, free drop, impact (collision), thermal misuse (thermal shock), compression, low air pressure, overcharging, forced discharge, high-rate charging protection function (lithium system), marking and packaging, transportation testing, incorrect installation (nickel system).

Battery: Vibration, shell stress at high temperature, temperature cycling, external short circuit, internal short circuit, free drop, impact (collision), marking and packaging, transportation test, overcharging (nickel system).

Among these testing and verification items, most are common routine testing items, but there are still some items that deserve attention and concern:

(1) Squeezing: The test object of this project is the battery cell. Although it is a common and routine project, it clearly requires that for square battery cells, the long and short axial directions need to be squeezed, that is, the two planes of the long and wide of the battery cell. Based on testing experience, when polymer flexible packaging battery cells are squeezed onto the width shaft (side), there are sometimes non-conforming phenomena such as combustion or explosion. Therefore, for polymer flexible packaging battery cells, it is recommended that this project be given special attention.

(2) Continuous low-rate charging. The test object of this project is the battery cell. The standard stipulates that fully charged battery cells should be continuously charged for 28 days in accordance with the charging method specified by the manufacturer. This project is not common in other safety standards. Given that the charging methods stipulated by battery manufacturers are basically constant current and constant voltage charging, this requires manufacturers to comprehensively consider the specified and limited charging current as well as the cut-off voltage at full charging. When necessary, the ability to withstand continuous charging must be taken into account in the design of the battery cell. High-risk items in IEC 62133:2017: thermal abuse test, squeeze test, 55-degree short circuit test, forced internal short circuit test, etc.

If an enterprise has obtained the IEC62133:2012 certificate and intends to convert it to the IEC62133:2017 version, we should pay attention to:

The new IEC62133:2017 standard splits lithium-based batteries and nickel-based batteries into two separate standards. Specifically, nickel-based batteries correspond to IEC 62133-1:2017, while lithium-based batteries correspond to IEC 62133-2:2017.

2. Lithium-based button batteries have been incorporated into the new IEC 62133-2:2017 standard.

3. Battery pretreatment: In the old version, the battery cells and batteries need to be charged and pre-treated under high and low temperature conditions respectively. In the new version, only the battery cells need to be charged and pre-treated according to the charging method claimed by the manufacturer.

4. External short-circuit test: In the old version, the external short-circuit test for battery cells was conducted in an environment of 20±5°C, and the external short-circuit test for batteries was carried out in an environment of 55±5°C. New version: The external short-circuit test of the battery cell is conducted in an environment of 55±5°C, and the external short-circuit test of the battery is carried out in an environment of 20±5°C.

5. Thermal shock test: Old version: Small cells are kept in an oven at 130±2°C for 10 minutes, and large cells for 30 minutes.

New version: Keep the battery cells in an oven at 130±2°C for 30 minutes;

6. Compression test: Old version: The test pressure is 13±1 KN. The test cut-off conditions are: the maximum pressure reaches; The voltage drops by one third. Undergo a 10% deformation; New version: The test pressure is 13 KN ± 0.78 KN. The test cut-off conditions are: the maximum pressure reaches; The voltage drops by one third.

The above are the main testing methods and standards for lithium-ion batteries and battery packs under the IEC system. There are still a large number of testing methods and standards under the IEC system. Due to space limitations, this article has not covered them. This article is merely a starting point for discussion and is only for reference by relevant personnel.