September 07, 2019 by Luke James
New research has brought safe, lightweight, and long-lasting lithium metal batteries closer to being a reality, and they could disrupt the $30bn lithium-ion battery market.
This is all thanks to a new coating that prevents the building up of dendrites in the battery. The breakthrough came from researchers at Stanford University and the SLAC National Accelerator Laboratory.
Implementation of lithium metal batteries requires further research and developments that solves the heterogeneity and instability issues associated with naturally formed solid-electrolyte interphase (SEI). Over time, these tentacle-like dendrites can penetrate Li-metal batteries' electrolyte cores and cause them to fail through combustion or short-circuiting.
The results of this joint research effort, published in Joule, demonstrate that in laboratory tests, the battery coating significantly extends battery life. By limiting the dendrites that pierce the Li-metal electrolyte cores, the combustion issue is significantly mitigated.
“We’re addressing the holy grail of lithium metal batteries,” said Zhenan Bao, a professor of chemical engineering, who is senior author of the paper along with Yi Cui, professor of materials science and engineering and of photon science at SLAC.
A graphical depiction of the conductive network present in lithium metal batteries. Image obtained from Joule.
The Stanford team and SLAC tested their new coating where dendrites typically form, on the anode of a Li-metal battery. They combined their own coated anodes with other components to create a battery that was fully operational and still delivered 85% of its original power after 160 charging cycles. To put this into context, regular Li-metal batteries only deliver around 30% of their original power after a similar number of cycles.
It has been said that dendrites have prevented lithium metal batteries from coming to fruition and being used in the next generation of electric vehicles.
Viewed as a replacement for degenerative Li-ion batteries, Li-metal batteries can hold at least a third more power per pound. And, because they use lightweight lithium for the +ve end (rather than graphite), they are much lighter.
“The capacity of conventional lithium-ion batteries has been developed almost as far as it can go,” said Stanford PhD student David Mackanic, co-lead author of the study. “So, it’s crucial to develop new kinds of batteries to fulfil the aggressive energy density requirements of modern electronic devices.”
The hope for Li-metal batteries is that they will be widely used in electric vehicles that require long-lasting and reliable sources of power.
While any battery that currently uses Li-ion batteries would benefit hugely from lighter, longer-lasting Li-metal batteries, it is a game changer for electric vehicles, the range of which would increase by several orders of magnitude.
The challenge, however, is getting Li-metal batteries with this promising coating out of the laboratory and into EVs. While the coating is an improvement on current Li-metal battery iterations, it only solves some of the problems.
“While use in electric vehicles may be the ultimate goal, commercialiation would likely start with consumer electronics to demonstrate the battery’s safety first,” said Cui.
It will likely be several years until we start seeing real-world implementation of Li-metal batteries in EVs and other consumer products.
