Adhesive tape and graphene triple the life of lithium metal batteries

TruckElectric

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This is similar to Tesla's new million mile battery. Rice University is in Houston.

Evidently Tesla and Jeff Dahn aren't the only ones working on a lithium metal technology with possible similar results. That's good though if Rice University's works out as well as Tesla's. We'll see......



Tale of the tape: Sticky bits make better batteries

Rice University scientists stick to their laser guns to improve lithium metal technology

HOUSTON – (July 14, 2020) – Where things get sticky happens to be where interesting science happens in a Rice University lab working to improve battery technology.

Using techniques similar to those they employed to develop laser-induced graphene, Rice chemist James Tour and his colleagues turned adhesive tape into a silicon oxide film that replaces troublesome anodes in lithium metal batteries.

For the Advanced Materials study, the researchers used an infrared laser cutter to convert the silicone-based adhesive of commercial tape into the porous silicon oxide coating, mixed with a small amount of laser-induced graphene from the tape’s polyimide backing. The protective silicon oxide layer forms directly on the current collector of the battery.

The idea of using tape came from previous attempts to produce free-standing films of laser-induced graphene, Tour said. Unlike pure polyimide films, the tape produced not only laser-induced graphene from the polyimide backing but also a translucent film where the adhesive had been. That caught the curiosity of the researchers and led to further experimentation.

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Long Description
At left, a copper current collector with a laser-induced silicon oxide coating created at Rice University. At right, a scanning electron microscope image of the coating created by lasing adhesive tape on the copper collector. Courtesy of the Tour Group

The layer formed when they stuck the tape to a copper current collector and lased it multiple times to quickly raise its temperature to 2,300 Kelvin (3,680 degrees Fahrenheit). That generated a porous coating composed primarily of silicon and oxygen, combined with a small amount of carbon in the form of graphene.

In experiments, the foamy film appeared to soak up and release lithium metal without allowing the formation of dendrites — spiky protrusions — that can short-circuit a battery and potentially cause fires. The researchers noted lithium metal tends to degrade fast during the battery’s charge and discharge cycles with the bare current collector, but no such problems were observed in anodes coated with laser-induced silicon oxide (LI-SiO).

“In traditional lithium-ion batteries, lithium ions are intercalated into a graphite structure upon charging and de-intercalate as the battery discharges,” said lead author Weiyin Chen, a Rice graduate student. “Six carbon atoms are used to store one lithium atom when the full capacity of graphite is used.

“But in a lithium metal anode, no graphite is used,” he said. “The lithium ions directly shuttle from the surface of the metal anode as the battery discharges. Lithium metal anodes are considered a key technology for future battery development once their safety and performance issues are solved.”

Lithium metal anodes can have a capacity 10 times higher than traditional graphite-lithium ion batteries. But lithium metal batteries that are devoid of graphite usually use excess lithium metal to compensate for losses caused by oxidation of the anode surface, Tour said.

“When there is zero excess lithium metal in the anodes, they generally suffer fast degradation, producing cells with very limited cycle life,” said co-author Rodrigo Salvatierra, an academic visitor in the Tour lab. “On the bright side, these ‘anode-free’ cells become lighter and deliver better performance, but with the cost of a short life.”

The researchers noted LI-SiO tripled the battery lifetimes over other zero-excess lithium metal batteries. The LI-SiO coated batteries delivered 60 charge-discharge cycles while retaining 70% of their capacity.

Tour said that could make lithium metal batteries suitable as high-performance batteries for outdoor expeditions or high-capacity storage for short-term outages in rural areas.

Using standard industrial lasers should allow industry to scale up for large-area production. Tour said the method is fast, requires no solvents and can be done in room atmosphere and temperature. He said the technique may also produce films to support metal nanoparticles, protective coatings and filters.

Co-authors are graduate students Muqing Ren and Jinhang Chen and postdoctoral researcher Michael Stanford. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice.

The Air Force Office of Scientific Research supported the project.

Source: Rice University




Another version of the same story from New Atlas

Adhesive tape and graphene triple the life of lithium metal batteries

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Lithium metal batteries could mark a big breakthrough in energy storage, and researchers have just found a potential solution to one of the key problems holding them back



Starting with adhesive tape and incorporating some advanced laser techniques, scientists at Rice University have developed a promising new electrode material for a battery architecture with massive potential. The team’s breakthrough could help overcome a long-standing problem with lithium metal batteries, a technology that promises to significantly improve on the performance of today’s solutions.

Lithium metal batteries are batteries in which the graphite traditionally used as the anode (one of the two electrodes) is replaced with pure lithium metal. Because this material offers very high energy density, lithium metal could make for batteries that charge much faster, and offer as much as 10 times the capacity.

But there are a few roadblocks standing in the way, one of which is the troublesome formation of tentacle-like protrusions called dendrites. These form on the surface of the anode during charging and can cause the battery to short circuit, fail or catch fire, so a great deal of battery research focuses on snuffing them out.

The latest breakthrough in this area comes from Rice University researchers, and begins with a strip of adhesive tape. The team applied the tape to the copper current collector that forms part of the lithium anode and treated it with lasers to heat it to an extreme temperature of 2,300 Kelvin (3,680 °F or 2,026 °C), which afforded it some very useful new properties.

31d46a564f89a364a63ea73968de%2F0720-adhesive-1-web.jpg

A copper current collector with a laser-induced silicon oxide coating created at Rice University can be seen on the left, with a scanning electron microscope image of the coating seen on the right
Tour Group/Rice University



This process transformed the tape into a porous coating made mostly of silicon and oxygen, along with small amounts of the wonder material graphene. Initial experiments with the film showed that it can serve as a protective layer on the current collector component, both absorbing and releasing lithium metal without giving growth to the harmful dendrites.

One of the consequences of replacing graphite with lithium metal anodes is an increased oxidation on the surface which greatly shortens their life, something researchers have looked to compensate for by adding excess amounts of lithium. There are positives to leaving it be, however.

“When there is zero excess lithium metal in the anodes, they generally suffer fast degradation, producing cells with very limited cycle life,” said co-author Rodrigo Salvatierra. “On the bright side, these ‘anode-free’ cells become lighter and deliver better performance, but with the cost of a short life.”

In its laser-induced silicon oxide protective coating, the Rice University team may have found a way to leverage these positives without the added burden of excess lithium. Its experiments showed that batteries fitted with its new coating exhibited triple the lifetime of other “zero-excess” lithium metal batteries, retaining 70 percent of their capacity over 60 charge and discharge cycles.

The team describes the technique as fast and safe, involving no solvents and able to be carried out at room temperature. It therefore has high hopes for its potential to be scaled up.

The research was published in the journal Advanced Materials.
 
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ajdelange

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So which do we think allows greater energy storage per mole of anode atoms?

C6 + Li+ + 1e- --> C6Li
or
Li + Li+ + 1e- --> 2Li
 

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There are other places already using interfacing layers in their batteries, so this is known. This is just another material and process.

But you'd have to make alot more tests to know how effective each materials are in practical-longterm use. And whether the additional steps are really cost-effective.

-Crissa
 
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