Edge profile design and manufacturing is an important requirement of battery tabs; the polymer thickness, the tab metal thickness and other properties of the tab metal and polymer must be considered to ensure proper performance of the cell tab. A common failure point of a battery cell tab is where the polymer film seals around the edge of the tab, mitigating this type of failure mode will be discussed within
Critical things to consider:
- Prevention of leakage, correct shape for no voids after sealing
The profile of the edge should be designed with the thickness and flexibility of the polymer in mind. If the polymer is thin then a less aggressive taper is suitable, with a lower angled profile, so that the polymer is not thinned during manufacturing, rendering it weak. A thinner metal tip will allow better sealing of the polymer, without forming any voids, at a wider range of manufacturing settings.
- Perforation of the bag by sharp edges/thinned polymer
Sharp edges may pierce the outer sealing bag when sealing or when the cell is flexed; this would cause serious safety issues, increasing the likelihood of fire or personal harm. A profiled edge reduces how sharp the edge of the metal is and thus the potential of piercing the pouch.
- Reduced chance of cutting cell assemblers
Cell assembly operators may handle cell tabs whilst assembling cells so any sharp regions that may exist on the tab as a result of material manufacturing have the potential to injure operators. Edge profile preparation therefore will reduce occurrences of injury in operators.
- Metal hardness
Different tab metals will require different edge preparation process parameters; therefore, it is important to understand the relevant properties of the metal that is being processed to achieve optimal results. The hardness of the metal will influence the materials removal rate and thus needs to be accounted for. Processing speed and tool selection are some examples of the types of changes that may need to be made to process different materials.
In conclusion, edge preparation is a critical aspect of battery tab design and manufacturing with a large influence on safety. The tab failure mode and operator safety depend on the quality of the edge profile, so at ABM we invest a great deal of research and development into ensuring that the edge is of high quality.
For more information, and to find out if we can meet your specification, visit www.avocetbattery.com to learn more about our products, services, and how we can assist your battery needs.