A new way to prevent lithium plating in electric vehicle (EV) batteries could lead to faster charging times, according to researchers behind the work.

The method was developed and tested in a study at Queen Mary University of London, in collaboration with other researchers in the UK and US.

Lithium plating can occur in lithium-ion batteries during fast charging. When lithium ions build up on the surface of the battery's negative electrode instead of inserting into it, they form a layer of metallic lithium that continues growing. This can damage the battery, shorten its lifespan, and cause short-circuits that can lead to fires and explosions.

However, the process can be “significantly mitigated” by optimising the microstructure of the graphite negative electrode, which is made up of tiny, randomly distributed particles, according to research leader Dr Xuekun Lu.

The researchers found that fine-tuning the size and shape of the particles in the electrode enabled a homogeneous reaction and reduced local lithium saturation, which in turn suppressed lithium plating and improved the battery's performance.

“Our research has revealed that the lithiation mechanisms of graphite particles vary under distinct conditions, depending on their surface morphology, size, shape and orientation. It largely affects the lithium distribution and the propensity of lithium plating,” said Dr Lu. “Assisted by a pioneering 3D battery model, we can capture when and where lithium plating initiates and how fast it grows. This is a significant breakthrough that could have a major impact on the future of electric vehicles.”

By improving understanding of the physical processes of lithium redistribution within graphite particles during fast charging, the researchers said the study provided new insights into developing fast-charging protocols.

As well as faster charging times, the study also found that refining the microstructure of the graphite electrode can improve the battery's energy density, meaning that electric cars could travel further on a single charge.

Improvements to charging speed, battery lifetime and safety could make EVs a more attractive option for drivers, the research announcement added.

Extracted from IMechE website, read more here

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