The future of batteries - Preventing self-discharge in lithium metal batteries

While batteries are one of the key drivers towards the world reaching net zero targets, there are still a number of issues that need to be resolved with current commercial batteries to ensure these are reliable power sources which can keep the world going, in an energy space beyond traditional fossil fuels.

One such issue with batteries is the phenomenon of self-discharge – when you leave a fully-charged device for a number of hours or days only to find that it has lost some or all of its charge, despite sitting idle and unused. Such an issue has puzzled and frustrated lithium-ion battery manufacturers for some time, with much research being conducted into the phenomenon.  

The crux of the issue has been found to be the ‘sticky tape’-like material used in commercial battery cells to hold the electrodes together. Within this ‘sticky tape’-like structure there is a chemical decomposition over time, which creates a molecule that leads to the unwanted self-discharge.

The material used with the ‘sticky tape’-like material is found in every plastic bottle around the world, with researchers not considering (until now) it could be such a simple factor that has such a huge impact on the self-discharge phenomenon with lithium-ion batteries.

To be more specific, research has discovered that the polyethylene terephthalate, or PET, in the tape decomposes and creates the molecule that leads to the self-discharge; with the molecule being termed a redox shuttle because it can travel to the positive side of the electrode, then to the negative side and then back to the positive side, shuttling between the electrodes and that creates the self-discharge, just like lithium is supposed to do. The problem is that the shuttle molecule is doing it all the time in the background, even when no lithium is supposed to move when the battery is just sitting there.

The research into the self-discharge phenomenon, and how it may be resolved, has already caught the attention of industrial heavyweights seeking ways to improve their batteries' performance, and could be a huge phase shift in how batteries are produced from now on. Currently, the self-discharge phenomenon, and how it may be resolved, is highly important to battery manufacturers and tech giants alike looking to advance their technologies.

Such research could ultimately lead to a fix that involves replacing the PET tape with a more stable material that won't degrade.

Therefore, it seems that a relatively minor improvement in current battery technology could provide a huge leap forward in the reliability of currently lithium-ion battery technology, ultimately allowing the world to put greater faith in the technology in the journey towards net zero.