GB/T 39861-2021 in English

GB/T39861-2021 establishes a systematic electrochemical performance evaluation system for lithium manganese oxide cathode materials, focusing on standardizing the test methods of the two key indicators of discharge platform capacity ratio and cycle life. The standard is applicable to the research and development verification and quality control of lithium manganese oxide materials used in power batteries, energy storage batteries and other fields.

1. Pole preparation process

The positive electrode slurry is dispersed by sand mill, the solid content is controlled at 45%-55%, and the surface density deviation needs to be <5.0g/m². The negative electrode is slurried by planetary agitator, and the surface capacity is designed to be more than 1.1 times that of the positive electrode.

2. Key points of battery assembly

• The width of the diaphragm must meet the following requirements: Wc
• After winding, it needs to be dried in a vacuum oven at 80℃ for 24h, and nitrogen is replenished every 4h
• After liquid injection, it needs to be left for 24-36h for electrolyte infiltration

Discharge platform capacity ratio calculation formula: Pn=(Qn,U/Qn)×100%, where Qn,U is the 3.60V platform capacity, and the calculation result is rounded to 1 decimal place.

Cycle life judgment standard: When ηn=(Qn/Q1)×100% is lower than 80% for the first time, the previous number of cycles is the life value.

Environmental control requirements

It is recommended to operate in a dry room with a dew point ≤-20℃. The humidity in the general environment must be ≤20% and the temperature must be 20-30℃.

Key points of quality control

1. The compaction density of the positive electrode is controlled at 2.4-3.0g/cm³
2. The compaction density of the negative electrode is 1.45-1.65g/cm³
3. The formation system is strictly carried out in steps of 0.02C→0.05C→0.1C