Post mortem analysis to know everything about lifetime of batteries

It is possible to extract key information about the reasons for battery failure by a so-called post-mortem analysis of batteries. The history of the battery can also be discovered thanks to this technique.

It consists in opening the battery in safe conditions and analysing every single component to observe its degradation and the impact of the degradation on the battery performances. Indeed, ageing does not only refer to a loss of capacity, it can also be a large resistance or a slow charge and discharge (i.e. the battery cannot support high peaks of current). All this information will be part of the fingerprint of the battery and will be revealed when opening it.

The analysis can only be realised by experts that know every single details of the battery fabrication, type of use, performance, and most importantly the chemistry of the batteries.

To identify the fingerprints of the battery, a post-mortem analysis expert will use several cutting-edge tools. This can be a gigantic microscope that can look down the micron: a particle ten times smaller than a hair. This equipment is called a scanning electron microscope. Some particles might have detached, change form, meaning an inactivation of the active material; part of the porosity could be blocked hampering the transfer of ions from one matrix to another. All these degradation mechanisms will lead to a slow battery failure and its end of life.

It is usually accepted that the battery has reached the end of the life when reaching 80% of the initial capacity. Other tools can be used for the battery post-mortem. A meticulous analysis of the liquid electrolyte can be realised thanks to a Gas Chromatography technique (GC-MS), it enables to follow the degradation of the electrolyte: a key player for a battery as its degradation is one of the most common reason for battery failure and its flammability is a challenging risk for the end users.

In

total more than 15 cutting-edge experimental tools can be used for the battery analysis enabling to build a complete matrix of failure analysis. The comparison and complementarity of these analysis lead to a successful diagnostic of the battery failure.