A multi-institution team has a solution for troublesome cathode cracking in a unique battery type. As is often the case elsewhere in life, it seems the breakdown happens after too much stress, according to the findings.
The research, described in a news release from the Ulsan National Institute of Science and Technology and Kyungpook National University in South Korea, includes experts from the University of Glasgow. It's work that could eventually improve power packs for electric vehicles and other tech.
The experts are studying single-crystal lithium-nickel-manganese oxide, or LMO, cathodes. They describe the component as key to "high-performance batteries," aside from cracking concerns.
When batteries operate, ions move between the anode and cathode through an electrolyte. This work is part of innovations happening around the world that are geared to find cheaper, better-performing materials for the parts. While safe and reliable, common lithium-ion packs require expensive metals and minerals that can get tied up in foreign supply chains.
LMO "is gaining attention as a high-capacity, cost-effective cathode material owing to its high operating voltage … and the absence of expensive cobalt in its chemical composition," per the release.
Experts said the single-crystal cathodes can store more energy per pound and last longer, though polycrystals are more common, per the report.
Single crystals are "continuous … without grain boundaries, reducing inter-particle cracking and mitigating undesirable chemical reactions with electrolytes. However, during high-rate charging and discharging, internal cracks can still develop within the crystal structure, compromising performance and longevity," the team wrote.
The cracks are associated with stress during charge-discharge cycles. It's instigated by "non-uniform lithium-ion diffusion within the crystal," the report added.
As with other forms of stress, the solution includes support. When magnesium was added to the crystal structure, it formed bolstering pillars, enhancing ion mobility and reducing tension. Tests showed the additive worked well under rapid operations with reduced cracking, according to the release.
"This study provides a clear understanding of the mechanical degradation mechanisms in single-crystal cathodes," professor Hyeon Jeong Lee stated, adding that the findings are "crucial for the commercialization of next-generation high-performance batteries."
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Cost 💰 Government experts in the United States are studying single-crystal cathodes, as well. And in Japan, a team is working on other additives to improve sodium-ion batteries.
It's all part of the shift to cleaner technology. On the road, batteries power EVs that prevent thousands of pounds of heat-trapping air pollution compared to gas-burners, according to U.S. energy data. And while we'll need tens of millions of tons of deposits for tech to power the switch, Sustainability by Numbers reported that less mining will actually be required since 16.5 billion tons of fossil fuels are hauled from the earth annually.
For their part, U.S. EV sales have jumped from 22,000 to more than two million since 2011. Experts estimate that there will be more than 78 million on roads by 2035, all according to the Bureau of Labor Statistics and Edison Electric Institute. The reduced tailpipe exhaust is a big win, too, as medical experts have linked it to increased cancer and other health risks.
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