The Powder Brushed On The Electrode Prevents Dendrite Formation To Obtain A High-capacity Cell
Among the many different designs being explored by scientists in the pursuit of better batteries, lithium metal is one structure with great potential, according to New Atlas. One problem holding back the technology, however, is the formation of antennae-like growths called dendrites that can quickly cause batteries to fail. Rice University scientists have come up with a promising solution to this problem in the form of a fine powder that can be brushed on the surface of the electrodes to ensure that they continue to be used.
Lithium-metal batteries will use pure lithium metal instead of graphite as the anode, one of the battery's two electrodes. The material offers a very high energy density that can make batteries charge faster and provide up to 10 times more capacity, but so far getting them to work reliably over long periods has proved difficult.
As the battery cycles, dendrites begin to form on the anode and can cause the battery to short circuit, fail or catch fire. We've seen some interesting potential solutions, and Rice University scientists have been responsible for more than a few, with nanotube films, tape, and laser processing just a few recent examples.
In their latest work, battery scientists led by chemist James Tour attempt to solve this problem with a novel scrub treatment. The technique starts by scrubbing the anode to create a textured surface, into which a powder made of phosphorus and sulfur is brushed. This causes the powder to react with the lithium metal anode, forming a fine protective film that alters its surface energy.
"This provides a metal-composite surface that prevents loss of lithium metal from the anode, which is a common problem with lithium-metal batteries," Tour said. "The capacity of lithium metal batteries far exceeds that of conventional lithium-ion batteries, but lithium metals tend to be difficult to charge repeatedly."
The film has the effect of adjusting the anode surface to promote a more uniform behavior during cycling, thus promoting the life of the battery. It went through 340 charging cycles in test batteries and saw that they retained 70% more capacity than off-the-shelf batteries. The film also performed well in another key indicator of battery degradation, maintaining ultra-low polarization for more than 4,000 hours, about eight times longer than an anode without the film.
