New cobalt-free lithium-ion battery reduces costs without sacrificing performance

Date:
July 16, 2020
Source:
University of Texas at Austin
Summary:
Researchers say they've cracked the code to a cobalt-free
high-energy lithium-ion battery, eliminating the cobalt and opening
the door to reducing the costs of producing batteries while boosting
performance in some ways.



FULL STORY ==========================================================================
For decades, researchers have looked for ways to eliminate cobalt from
the high-energy batteries that power electronic devices, due to its high
cost and the human rights ramifications of its mining. But past attempts haven't lived up to the performance standards of batteries with cobalt.


========================================================================== Researchers from the Cockrell School of Engineering at The University
of Texas at Austin say they've cracked the code to a cobalt-free
high-energy lithium-ion battery, eliminating the cobalt and opening
the door to reducing the costs of producing batteries while boosting performance in some ways. The team reported a new class of cathodes --
the electrode in a battery where all the cobalt typically resides --
anchored by high nickel content. The cathode in their study is 89%
nickel. Manganese and aluminum make up the other key elements.

More nickel in a battery means it can store more energy. That increased
energy density can lead to longer battery life for a phone or greater
range for an electric vehicle with each charge.

The findings appeared this month in the journal Advanced Materials. The
paper was written by Arumugam Manthiram, a professor in the Walker
Department of Mechanical Engineering and director of the Texas Materials Institute, Ph.D.

student Steven Lee and Ph.D. graduate Wangda Li.

Typically, increased energy density leads to trade-offs, such as a
shorter cycle life -- the number of times a battery can be charged
and discharged before it loses efficiency and can no longer be fully
charged. Eliminating cobalt usually slows down the kinetic response of
a battery and leads to lower rate capability -- how quickly the cathode
can be charged or discharged.

However, the researchers said they've overcome the short cycle life and
poor rate capability problems through finding an optimal combination of
metals and ensuring an even distribution of their ions.

Most cathodes for lithium-ion batteries use combinations of metal
ions, such as nickel-manganese-cobalt (NMC) or nickel-cobalt-aluminum
(NCA). Cathodes can make up roughly half of the materials costs for
the entire battery, with cobalt being the priciest element. At a price
of approximately $28,500 per ton, it is more expensive than nickel,
manganese and aluminum combined, and it makes up 10% to 30% of most
lithium-ion battery cathodes.

"Cobalt is the least abundant and most expensive component in battery cathodes," Manthiram said. "And we are completely eliminating it."
The key to the researchers' breakthrough can be found at the atomic level.

During synthesis, they were able to ensure the ions of the various
metals remained evenly distributed across the crystal structure in
the cathode. When these ions bunch up, performance degrades, and that
problem has plagued previous cobalt-free, high-energy batteries, Manthiram said. By keeping the ions evenly distributed, the researchers were able
to avoid performance loss.

"Our goal is to use only abundant and affordable metals to replace
cobalt while maintaining the performance and safety," Li said, "and to
leverage industrial synthesis processes that are immediately scalable." Manthiram, Li and former postdoctoral researcher Evan Erickson worked
with UT's Office of Technology Commercialization to form a startup called TexPower to bring the technology to market. The researchers have received grants from the U.S. Department of Energy, which has sought to decrease dependency on imports for key battery materials.

Industry has jumped on the cobalt-free push -- most notably an effort
from Tesla to eliminate the material from the batteries that power
its electric vehicles. With large government organizations and private companies focused on reducing dependence on cobalt, it's no surprise
that this pursuit has become competitive. The researchers said they
have avoided problems that hindered other attempts at cobalt-free,
high-energy batteries with innovations on the right combination of
materials and the precise control of their distribution.

"We are increasing the energy density and lowering the cost without
sacrificing cycle life," Manthiram said. "This means longer driving
distances for electric vehicles and better battery life for laptops
and cellphones."

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


========================================================================== Journal Reference:
1. Wangda Li, Steven Lee, Arumugam Manthiram. High‐Nickel NMA: A
Cobalt‐Free Alternative to NMC and NCA Cathodes for
Lithium‐Ion Batteries. Advanced Materials, 2020; 2002718 DOI:
10.1002/adma.202002718 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200716101612.htm

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