Tech Briefs Magazine - December 2021 - 37

Power & Energy
Safer, Less Expensive, Fast-Charging Aqueous Battery
A new anode for aqueous batteries uses seawater as an electrolyte.
University of Houston, Texas
ithium-ion batteries are critical for
modern life, powering laptops, cellphones,
and other devices; however,
there is a safety risk - the batteries can
catch fire. Zinc-based aqueous batteries
avoid the fire hazard by using a waterbased
electrolyte instead of the conventional
chemical solvent. But uncontrolled
dendrite growth limits their ability to provide
the high performance and long life
needed for practical applications.
Researchers have created a new 3D
zinc-manganese nano-alloy anode that
results in a stable, high-performance, dendrite-free
aqueous battery using seawater
as the electrolyte. The discovery offers
L
promise for energy storage and other
applications including electric vehicles.
The team also developed an in situ optical
visualization technique, allowing them
to directly observe the reaction dynamics
on the anode in real time. The platform
provides direct evidence and visualization
of the reaction kinetics. Testing determined
that the novel 3D zinc-manganese
nano-alloy anode re mained stable without
degrading throughout 1,000 hours of
charge/discharge cycling under high current
density.
The anode is the electrode that releases
current from a battery, while electrolytes
are the medium through which
the ionic charge flows between the cathode
and anode. Using seawater as the
electrolyte rather than highly purified
water offers another avenue for lowering
battery cost.
Traditional anode materials used in
aqueous batteries have been prone to
dendrites - tiny growths that can cause
the battery to lose power. The new strategy
efficiently minimizes and suppresses
dendrite formation in aqueous systems by
controlling surface reaction thermodynamics
with a zinc alloy and reaction
kinetics by a three-dimensional structure.
For more information, contact Jeannie
Kever at jekever@uh.edu.
Preventing Short-Circuiting in Next-Generation Lithium
Batteries
The approach could advance the potential of high-powered, solid-electrolyte lithium batteries.
Massachusetts Institute of Technology, Cambridge
s researchers push the boundaries
of battery design, seeking to pack
ever greater amounts of power and energy
into a given amount of space or
weight, one of the more promising technologies
being studied is lithium-ion batteries
that use a solid electrolyte material
between the two electrodes, rather than
the typical liquid. But such batteries
have been plagued by a tendency for
branch-like projections of metal called
dendrites to form on one of the electrodes,
eventually bridging the electro -
lyte and shorting out the battery cell.
Researchers have found a way to prevent
such dendrite formation, potentially
unleashing the potential of this new
type of high-powered battery. Solid-state
batteries have been a long-sought technology
for two reasons: safety and energy
density. But the only way to reach the
energy densities that are interesting is to
use a metal electrode. And while it's possible
to couple that metal electrode with
a liquid electrolyte and still get good
energy density, that does not provide the
A
Oxide
cathode
Solid electrolyte
Li metal
anode
NaK
liquid
Tech Briefs, December 2021
Cov
Solid electrolyte
Solid metal
(dark)
Liquid metal
(light)
These diagrams illustrate the two different configurations the researchers used to minimize dendrite
formation - one using a semisolid electrode and one using a liquid layer between the solid
electrode and the solid electrolyte. (Credit: Courtesy of the researchers)
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Tech Briefs Magazine - December 2021

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