In accordance with CQC11-464112-2015, Safety Certification Rules for Lithium-ion Cells and Batteries for Portable and Stationary Electronic Equipment, the cell division rules of GB 31241 have been revised. The specific changes are as follows: 

1. Cell
1. Same positive and negative electrode materials, separator and electrolyte;
2. Same safety design (such as the pressure relief valve);
3. Same shape and dimensions (cylindrical, prismatic and so on);
4. Same assembly method (wound or stacked);
5. Same type (hard case or pouch);
6. Same nominal voltage and a rated capacity variation within 20%.

2. Battery pack
1. Same nominal voltage and rated capacity;
2. Same type of cells used (including series and parallel arrangement);
3. Same design and layout of the protection circuit;
4. Built-in and external types are assessed separately.

Sampling principles and quantities
In principle, samples are submitted as follows:
1. Sampling principle: for cells, the series models within the same unit are divided into intervals by descending 20% steps from the largest capacity; the model with the largest capacity in each interval is subjected to all test items, while the models with the middle capacity (or the nearest) and the smallest capacity (or the nearest) are tested respectively under clauses 6.1 (external short circuit at high temperature), 6.2 (overcharge) and 7.6 (crush);
2. Sample quantities:
a. 24 cells (up to 6 additional spare samples may be submitted);
b. 37 battery packs (up to 3 additional spare samples may be submitted).
Notes:
1) Under GB 31241-2022, both cells and battery packs require capacity testing;
2) The parameters of a battery pack must match those of the cells it contains.