Beyond getting batteries more efficient, one of the challenges that the electric car faces is minimize its degradation and extend its useful life. The more degraded it is, the lower its capacity and therefore its range between charges.
This degradation is related to use, as it is loaded and unloaded by rolling at its controls. But it is also decisive self-dischargeA new study has reportedly determined why it occurs, which could be an important step toward reducing it.
Batteries that discharge less when not in use
When a electric car If it is left unused for a long period of time, for a month or more, its battery will eventually discharge. In other words, that energy is lost even if it is not used because the battery self-discharges.
This process is explained, According to scientists at the US Department of Energy’s (DOE) Argonne National Laboratorya series of chemical reactions that occur in the battery and cause a loss of performance over time, thus shortening its useful life. And it affects any device with a rechargeable electrochemical battery.
“The process Slowly consumes the battery’s valuable functional materials and deposits unwanted byproducts on the surface of battery components. This leads to continued degradation of battery performance,” explains Zonghai Chen, senior chemist at Argonne.
The explanations of Why does the battery self-discharge occur? has been on the table for some time. For example, the loss of lithium or the release of oxygen from the cathodes of the cells have been pointed out. But a new study published in Science signed by a research team from several American universities and laboratories, including Argonne, claim to have found the key to this process.
This new research validates a cathode hydrogenation mechanism as a cause of self-discharge of the cells of a battery. Each cell of a lithium-ion battery, remember, is made up of two metal electrodes (anode and cathode) and an electrolyte. The electrolyte transfers ions (charge-carrying particles) between the cathode and the anode that store the lithium.
This is how a lithium-ion battery deteriorates over time. (Source: SLAC National Accelerator Laboratory Stanford, California, USA)
This has been proven thanks to Analyze the functioning of a battery at the molecular level. Or more specifically, its cells and how the nickel, manganese and cobalt atoms behave inside the cathode. They have done this by analyzing it in the Advanced Photon Source (APS), one of the largest existing facilities for high-energy X-ray light sources based on storage rings.
Thus, they found that self-discharge occurred by “the accumulation of protons at the charged cathode, which was triggered by the decomposition of the electrolyte”they explain in the publication. “This mechanism, based on a surface hydrogenation reaction, differs from the widely accepted model based on lithium diffusion from the electrolyte to the cathode.”
Smaller, cheaper and more efficient lithium-ion batteries. This new discovery could serve as a basis for improving the performance of lithium batteries, minimising their degradation by reducing the self-discharge rate. Or rather, it paves the way for achieving a suitable chemical composition for cathode materials.
“By reducing self-discharge, we can design a smaller, lighter and more economical battery. without sacrificing battery performance at the end of its useful life,” says Chen.
Except for the lower cost, which is precisely what solid-state batteries boast, which use an electrolyte other than lithium (liquid) for a solid one. According to their creators, in a device of similar size they offer greater autonomy, shorter recharging times and a lower risk of fire.
Although these revolutionary batteries have not yet been fitted as standard in any car, brands such as Toyota and Nissan are already developing them. However, their transition to mass production is still being resisted due to their high cost, which they hope will be reduced.
But this new step for lithium-ion batteries could be a new answer to improve the existing ones before the arrival of solid-state batteries.
Source: www.motorpasion.com
