What are the Different Types of 21700 Battery Positive Caps?
Blog | Published by Alex on July 29, 2025
The positive caps of 21700 cells mainly come in several types, with slight variations depending on their application, manufacturing process, and manufacturer.
| Type Name |
Description |
| ① Flat Top |
The top is flat without any protrusion. Commonly used in electric vehicles, battery packs, and power modules. Ideal for spot welding and compact stacking. |
| ② Button Top |
The positive terminal has a small protruding bump. Typically used in flashlights, power tools, and other spring-contact devices. |
| ③ Welded Tab Cap |
The cap has pre-welded nickel strips or tabs for easy integration into battery packs. |
The Special Types (Less Common)
| Type |
Description |
| ④ Safety Valve Cap |
Integrated with a PTC thermistor or explosion-proof valve. Used in high-safety applications such as electric vehicles. |
| ⑤ Vent Cap |
Designed with a small vent hole for gas release or inspection. Common in experimental or specialized cells. |
Different Positive Caps of 21700 Battery Application Recommendations
- Power Battery Packs (e.g., EVs, energy storage): Mostly use flat top with spot welding.
- Consumer Electronics (e.g., flashlights, toys): Prefer button top.
- Automated Welding Lines: Use welded tab caps or cells with pre-welded nickel strips.
- Customized Designs: Choose cap types with vent holes or pressure valves based on BMS or module requirements.
Related Articles
What is 21700 Battery Safety Vent?
What is 21700 Tabless Design?
