by Rechargeable batteries power much of our electronic age. But while they are reusable, they have a limited lifespan. A new study has shown why.
Our laptops, tablets and mobile phones rely on battery charging. In a lithium-ion battery, two electrodes store lithium ions; a positively charged anode and a negatively charged cathode. An electrolyte in the battery allows ions to move from the anode to the cathode. This movement initiates a chemical chain that leads to the release of charge-building electrons.
But new research from a team at Stanford University suggests that unwanted passengers move to the cathode along with the lithium ions. Hydrogen protons and electrons also break off from molecules in the electrolyte. These accumulate at the cathode, meaning the lithium ions cannot conduct charge as efficiently. The power these batteries store erodes over time.
This steady trickle of hydrogen is driven by a series of chemical reactions. Gang Wan, a physicist and chemist at Stanford University, explained Scientific news“Even if you don’t use the battery, it loses energy.”
Hydrogen is a small, ever-present element that is difficult to track. To discover the role it played in disabled batteries, Wan and his team had to replace the hydrogen with an XXL variant. This is deuterium, an isotope of hydrogen that contains one neutron and one proton, compared to hydrogen’s only proton.
Using the analytical techniques of mass spectrometry and X-ray imaging, Wan’s team tracked the deuterium as it moved within the battery. This showed that hydrogen was the driving force behind the declining battery charge.
Importantly, the study opens up a way to improve batteries by targeting the unwanted chemical changes these leaky hydrogen molecules produce. But it could also prompt some scrutiny of battery designers. Wan’s research shows that engineers in the race for more powerful batteries could increase the chance that cathodes will pull in loose hydrogen and shorten battery life.
More research will need to be done on different battery types to determine how universal the problem is.
If multiple batteries are subject to the law of leaking hydrogen, it can lead to improved batteries that last longer. Advances in battery life would not only mean less need to replace our gadgets, but also reduce the environmental impact of mining batteries.
The research was published in Science.
