- Researchers have made a breakthrough in anode-free lithium-ion batteries
- A new gel electrolyte could solve one of the technology's biggest problems
- This could unlock improved longevity and safety for the lithium-ion EV cells
Researchers at the Columbia University School of Engineering and Applied Science claim to have developed a new gel electrolyte that will help stabilize anode-free lithium-ion batteries. This should improve the safety and longevity of this emerging battery technology, while presenting a cost-saving to manufacturers.
Anode-free lithium-ion batteries have been explored for a number of years, with a South Korean research team using an anode-free lithium metal battery architecture last year to double the volumetric density of a battery, without increasing its size.
Eliminating the anode frees up more internal space, allowing an increased amount of active material to be packed into the same volume. This is like managing to squeeze more fuel into the same-sized fuel tank, according to Interesting Engineering.
The major issues facing the technology have been safety and battery longevity, as anode-free lithium-metal batteries have suffered from uneven lithium deposition during charging sessions.
This means the lithium can form sharp, needle-like structures (dubbed dendrites), which can pierce internal components and cause dangerous short circuits and thermal runaway events.
But according to Interesting Engineering, which cites research findings first published in the journal Joule, the Columbia University School of Engineering and Applied Science researchers found a solution to this problem in a gel electrolyte.
To get very technical for a moment, the team used a “parasitic salt-phobic polymer network in their electrolyte design”, which “selectively repels lithium ions while attracting solvent molecules”.
In relatively plain speak, the gel electrolyte is divided at the nanoscale into different compositions. This allows the formation of a protective layer on the lithium surface that prevents harmful dendrites from forming.
During lab experiments, the researchers found that the gel electrolyte retained over 80% of its capacity under near-real-world conditions, while improving the battery’s thermal stability, which would mean less energy consumed by an EV in either heating or cooling the pack for optimum operation temperatures.
Apparently, the gel electrolyte also withstood extensive drilling without any thermal runaway. In contrast, batteries with conventional liquid electrolytes ignited or exploded during testing.
In real world application, the researchers believe that a gel electrolyte in an anode-free lithium-ion battery could lead to EV packs with greater energy density, longer lifetimes and safer operation – all without the costs involved in developing all-new electrolyte formulations.
Much of the talk around the future of electric vehicles revolves around solid-state battery packs, which have been referred to as the “holy grail” answer to many electric vehicle issues, such as slow charging speeds, poor range, overly heavy packs and lingering safety issues.
But the technology is still very much in its infancy and, despite some Chinese companies claiming they are pushing it into production, it remains a much more expensive proposition than the current lithium-ion offerings.
“There is still plenty of life left in lithium-ion technology,” explains Akhil Krishnan, VP Product Line for the Volvo EX60. “Of course, I am excited about the future of solid-state, but we have already made great progress with lithium-ion,” he adds.
Working alongside Breathe, a battery software company that uses simulations and models to help get the most out of EV batteries, Volvo has proven that lithium-ion tech delivers. The upcoming Volvo EX60 boasts a WLTP range of over 500 miles and consistent fast-charging speeds in all conditions.
Yan Zhao, co-founder at Breathe Battery Technologies says that convincing the next 25% of car buyers to go electric is going to be one of the toughest tasks yet. “Their buying decisions will be very price sensitive,” he says.
This is where improvements in lithium-ion batteries can assist, as it allows for greater range and faster charging speeds without passing on the costs of emerging battery technologies on to customers.
As is the way with the internal combustion engine that, even after more than a century, continues to see improvements in performance and efficiency, lithium-ion technology will only get better over the next three to five years, according to the experts.
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