Battery testing provides a lot of information about how battery performance changes under a given set of conditions. Until recently, based on these results, the cause(s) of performance degradation could only be inferred. That is, there was not enough information to determine the true chemical and physical changes that produced the decline. For example, if resistance rise was observed, one did not know if it was caused by the growth of a resistive layer or, for instance, by the delamination of an electrode. Post-test diagnostics of the aged batteries can provide this additional information. Here, the results from physical, spectroscopic, metallographic, electrochemical tests are used to aid in the further development of a given technology. These techniques are used in a systematic fashion, similar to battery testing. This will make comparisons of failure modes within a given technology and, perhaps, across technologies easier.
For this work, batteries are taken apart in a large, inert-atmosphere glovebox. Samples of the battery materials (positive, separator, electrolyte, negative) are then characterized without exposure to air. Most of the needed characterization equipment has been integrated into the glovebox.