The big problem with lithium ion batteries is their degradation over time. A chemical adjustment can change it

It doesn’t matter if it’s a mobile phone, a laptop, the Nintendo Switch or a Dyson: as you use it, the battery life will reduce. Yes, lithium ion batteries they have changed the world and for years they have been the absolute standard in consumer electronics, but degradation over time is their endemic evil. While we look for alternatives To this technology, a research team has found a promising solution in a seemingly simple chemical tweak.

The advance. The main idea of ​​this research is not to change the main materials of the battery, but simply to add a small amount of an additive: lithium difluorophosphate. Its existence is not new, but this research led by Professor Chunsheng Wang of the University of Maryland reveals how effective it is in stabilizing batteries.

Why is it important. Because lithium ion batteries are present everywhere and this modification would extend their useful life using standard, low-cost chemistry. The result of their experiment is that with this additive, batteries can be optimized to maximize power and energy, or to achieve greater useful life and stability.

For practical purposes, the study shows how with this adjustment they maintained a significantly higher capacity after hundreds of charge and discharge cycles. As Wang explains.“It is a relatively simple modification of current batteries.” Or what is the same, after having run security tests and long cycles, “it could realistically reach consumers.”

Brief notes on the mechanism of a battery. Lithium ion batteries are made up of a negative anode and a positive cathode and have a porous separator between the two. The assembly is immersed in an electrolyte whose mission is to allow lithium ions to move between electrodes during charging and discharging.

With the discharge, the anode releases electrons to the electrical circuit (gives electricity to the device) and ions to the electrolyte, meeting again at the cathode. Upon charging, an external source (the charger) reverses the process by “pumping” the ions back to the anode to store the energy in the chemical structure. The degradation of its capacity with use occurs due to the irreversible loss of lithium in secondary chemical reactions and due to mechanical fatigue of the electrodes.

Basic diagram of the operation of a lithium ion battery. Walter Davison. Via: Wikimedia

In detail. If we delve a little deeper into the previous explanation, the solid electrolyte interface (SEI) appears, a thin layer that forms on the anode during the first charges. In standard batteries, this layer is fragile and breaks down with use, consuming lithium and reducing battery life.

Through a simple reaction inspired by organic chemistry, this additive makes the electrolyte more prone to accepting electrons, making degradation more controlled. In short, it helps to form a more robust, elastic and uniform SEI, thus acting as a kind of shield that prevents the electrolyte from reacting parasitically with the electrodes. In addition, it is a flexible chemistry that can be adjusted to be more or less protective and the presence of the additive minimizes the presence of cracks in the cathode.

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Cover | John Cameron