In comparison to conventional fossil fuel-powered vehicles, the power of electric vehicles (EVs) is far more limited: it is governed entirely by batteries and the performance metrics that they’re capable of achieving. This is something that’s currently standing in the way of further developments in EVs, especially the problems of slow charging times and relatively weak power.
This could be about to change, however: according to their research paper published in the journal Energy & Environmental Science, scientists from the South Korean Pohang University of Science and Technology (POSTECH) claim to have found a way to overcome the issue of slow charging times with a new lithium-ion (Li-ion) battery electrode material that brings much faster charging times without limiting energy density.
An example of automotive lithium-ion battery technology, which is positioned on the exposed undercarriage of an electric vehicle (the Nissan Leaf). Image Credit: Wikimedia Commons.
An Intermediate Phase
To date, many approaches to fast charging have involved researchers reducing the particle size of electrode materials. This has major disadvantages because it reduces the volumetric energy density of the batteries, leading to a trade-off between fast charging and energy density. This isn’t something that EV manufacturers can afford to do, particularly when so-called ‘range anxiety’ has already been identified as a major barrier to widespread adoption among consumers.
“The conventional approach has always been a trade-off between its [the given battery’s] low energy density and the rapid charge and discharge speed due to the reduction in the particle size,” said lead researcher Byoungwoo Kang.
In an attempt to solve this problem, the POSTECH researchers looked at introducing an intermediate phase in the phase transition during charge cycles. They correctly identified that this could be used to generate high power without reducing energy density or particle size through rapid charging and discharging—therefore enabling the development of long-lasting, rapid charging Li-ion batteries.
The POSTECH researchers’ results, as published in their study, reflects that an intermediate phase can dramatically reduce the change in volume between the two phases in a particle.
According to the researchers, this intermediate phase can help create an entirely new phase within the particle. This, they say, brings further improvements in the speed of insertion and removal of lithium in the particle.
As a result, the Li-ion battery electrodes were able to charge up to 90% in just six minutes and discharge by 54% in 18 seconds. This is a promising sign and could signal further developments in the future for high-power Li-ion batteries.
As Kang added: “This research has laid the foundation for developing lithium-ion batteries that can achieve quick charging and discharging speed, high energy density, and prolonged performance”.