Stepped heating tests for Ternary li-cell and LFP cell,
LFP,

▍Certification Overview

Standards and Certification Document

Test standard: GB31241-2014: Lithium ion cells and batteries used in portable electronic equipment―Safety requirements
Certification document: CQC11-464112-2015: Secondary Battery and Battery Pack Safety Certification Rules for Portable Electronic Devices

Background and Date of implementation

1. GB31241-2014 was published on December 5^th, 2014;

2. GB31241-2014 was mandatorily implemented on August 1^st, 2015. ;

3. On October 15th, 2015, Certification and Accreditation Administration issued a technical resolution on additional testing standard GB31241 for key component “battery” of the audio and video equipment, information technology equipment and telecom terminal equipment. The resolution stipulates that the lithium batteries used in the above products need to be randomly tested as per GB31241-2014, or obtain a separate certification. 

Note: GB 31241-2014 is a national compulsory standard. All the lithium battery products sold in China shall conform to GB31241 standard. This standard will be used in new sampling schemes for national, provincial and local random inspection.

▍Scope of Certification

GB31241-2014 Lithium ion cells and batteries used in portable electronic equipment―Safety requirements
Certification documents is mainly for mobile electronic products that are scheduled to be less than 18kg and can be often carried by users. The main examples are as follows. The portable electronic products listed below do not include all products, so products not listed are not necessarily outside the scope of this standard.

Wearable equipment: Lithium-ion batteries and battery packs used in equipment need to meet standard requirements.

▍Why MCM?

● Qualification recognition: MCM is a CQC accredited contract laboratory and a CESI accredited laboratory. The test report issued can be directly applied for CQC or CESI certificate;

● Technical support: MCM has ample GB31241 testing equipment and is equipped with more than 10 professional technicians to conduct in-depth research on testing technology, certification, factory audit and other processes, which can provide more accurate and customized GB 31241 certification services for global clients.

In the new energy automobile industry, ternary lithium batteries and lithium iron phosphate batteries have always been the focus of discussion. Both have their advantages and disadvantages. The ternary lithium battery has high energy density, good low-temperature performance, and high cruising range, but the price is expensive and not stable. LFP is cheap, stable, and has good high-temperature performance. The disadvantages are poor low-temperature performance and low energy density. In the development process of the two batteries, due to different policies and development needs, two types play against each other up and down. But no matter how the two types develop, the safety performance is the key element.
Lithium-ion batteries are mainly composed of negative electrode material, electrolyte and positive electrode material. The chemical activity of the negative electrode material graphite is close to that of metallic lithium in the charged state. The SEI film on the surface decomposes at high temperatures, and the lithium ions embedded in the graphite react with the electrolyte and the binder polyvinylidene fluoride to release a lot of heat. Alkyl carbonate organic solutions are commonly used as electrolytes, which are flammable. The positive electrode material is usually a transition metal oxide, which has a strong oxidizing property in the charged state, and is easily decomposed to release oxygen at high temperature. The released oxygen undergoes an oxidation reaction with the electrolyte, and then releases a large amount of heat.Therefore, from the point of view of materials, lithium-ion batteries have a strong risk, especially in the case of abuse, safety issues are more prominent. In order to simulate and compare the performance of two different lithium-ion batteries under high temperature conditions, we conducted the following stepped heating test.