A Look Inside Battery Cells
19 February 2021
Chemistry will dictate the theoretical capacity of a battery, but construction quality of the cell can significantly impact its longevity. Electrode creasing, electrode or separator wrinkling, electrolyte underfill, or poor lack of fusion in electrode tab welds are just some examples where subpar construction quality can lead to high resistance locations, localized heating, swelling, and potentially result in a catastrophic event.
We use a combination of techniques to assess overall cell quality. Some techniques include:
- Cyclic Voltammetry is a nondestructive, electrochemical test used to identify unwanted and irreversible side reactions in the cell.
- Radiography is used to perform nondestructive visual examination into the cell that can reveal folds, wrinkles, or poor jelly roll winding.
- Destructive Teardowns include disassembly of the cell with visual examination of the various battery components. This analysis often reveals clear indications of creasing, overheating, poorly welded connections, etc.
- Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy is used to examine the electrode material structure and identify any impurities.
It is difficult for consumers to know what quality of battery they have apart from purchasing on-brand or off-brand cells. Even so, some may be receiving counterfeit batteries. A thorough quality assessment can protect one's investment by assisting in choosing which manufacturer or distributor to work with.
We also use a similar approach in performing battery failure analyses. In addition to the techniques listed above, we perform the following:
- Device and battery protection circuitry examination
- Capacity tests with thermography
- Electrochemical Impedance Spectroscopy
- Material and metallographic analysis
For more information, please reach out to Taylor Kelly, PhD.