Tale of the tape: Sticky bits make better batteries
Scientists stick to their laser guns to improve lithium metal technology


Date:
July 14, 2020
Source:
Rice University
Summary:
Scientists use an industrial laser to turn adhesive tape into a
component for safer, anode-free lithium metal batteries.



FULL STORY ========================================================================== 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.

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.


========================================================================== Story Source: Materials provided by Rice_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Weiyin Chen, Rodrigo V. Salvatierra, Muqing Ren, Jinhang Chen,
Michael G.

Stanford, James M. Tour. Laser‐Induced Silicon Oxide for
Anode‐Free Lithium Metal Batteries. Advanced Materials,
2020; 2002850 DOI: 10.1002/adma.202002850 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200714121746.htm

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