{"id":609537,"date":"2024-02-21T01:27:03","date_gmt":"2024-02-20T22:27:03","guid":{"rendered":"https:\/\/en.buradabiliyorum.com\/cobalt-free-electrodes-achieved-with-nickel-ions\/"},"modified":"2024-02-21T01:27:03","modified_gmt":"2024-02-20T22:27:03","slug":"cobalt-free-electrodes-achieved-with-nickel-ions","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/cobalt-free-electrodes-achieved-with-nickel-ions\/","title":{"rendered":"#Cobalt-free electrodes achieved with nickel ions"},"content":{"rendered":"
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\n Repulsive electrostatic interaction leads to Ni ion migration suppression and improved reversibility without cobalt (Co) ions. Credit: Yokohama National University
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Many electric vehicles are powered by lithium-ion batteries that rely on cobalt\u2014a scarce, expensive metal with high environmental and social<\/a> costs. A team of researchers from Japanese and French universities has now developed a practical nickel-based electrode material that opens new avenues to cobalt-free batteries for electric vehicles.<\/p>\n

The researchers detailed their findings in a study published<\/a> in the journal Energy Storage Materials.<\/i><\/p>\n

“There is an undeniable need for cobalt-free, high-energy electrode materials for lithium-ion batteries,” said Naoaki Yabuuchi from Yokohama National University.<\/p>\n

Lithium-ion batteries can be recharged when lithium ions flow from a positively charged electrode to a negatively charged electrode. In most lithium-ion batteries for portable electronics, the positive electrode contains lithium cobalt oxide (LiCoO2<\/sub>), a chemical compound that offers high stability and energy density.<\/p>\n

However, the limited, fraught supply chain of cobalt creates a bottleneck for large-scale batteries, including the ones used in electric vehicles. In addition, cobalt extraction generates toxic waste that contaminates land, air, and water.<\/p>\n

To address these issues, lithium nickel oxide (LiNiO2<\/sub>)\u2014which is similar in structure to LiCoO2<\/sub>\u2014often serves as a cobalt-free alternative for electrode material. However, key instability issues plague the compound, specifically a gradual loss of capacity at the high-voltage region, which is associated with nickel-ion migration.<\/p>\n

To improve electrode reversibility, nickel ions have been partially substituted by other metal ions, including reintroduced cobalt ions as well as manga<\/a>nese, aluminum and magnesium, to create “nickel-enriched layered materials” to serve as positive electrode materials.<\/p>\n

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“So far, 10\u201320 percent cobalt ions were necessary for nickel-based electrode materials,” Yabuuchi said. This, according to Yabuuchi, is still too much, and a unified understanding of how metal substitution can improve the process has not yet been established.<\/p>\n

To address this knowledge gap, Yabuuchi and collaborators dug deeper into the problematic phase transition. When lithium ions leave the cathode under the influence of an external field, nickel ions migrate to specific sites within the lithium layers. Although this process is reversible, the reversibility gradually degrades through continuous cycles until the capacity is completely lost\u2014a phenomenon not seen in cobalt-ion migration.<\/p>\n

Previous studies reported that tungsten doping in LiNiO2<\/sub> is an efficient app<\/a>roach to suppressing the detrimental phase transitions at high-voltage regions. Yabuuchi and collaborators tested the hypothesis that heavy, expensive tungsten ions could be substituted with other elements, specifically phosphorous\u2014a lighter, more abundant element.<\/p>\n

After detailed analysis on LiNiO2<\/sub> integrated with nanosized lithium phosphate (Li3<\/sub>PO4<\/sub>), the researchers observed that, under certain conditions, problematic nickel-ion migration was effectively suppressed due to repulsive electrostatic interaction from the extra nickel ions within the Li layers.<\/p>\n

Moreover, from these findings, Li-deficient LiNiO2<\/sub>, Li0.975<\/sub>Ni1.025<\/sub>O2<\/sub>, with the extra nickel ions in Li layers, is also synthesized using a simple methodology without phosphorus integration. Results also showed how Li0.975<\/sub>Ni1.025<\/sub>O2<\/sub> can effectively mitigate unfavorable nickel-ion migration, and deliver consistent reversibility without cobalt ions.<\/p>\n

“These findings open a new direction to develop high performance and practical cobalt-free nickel-based electrode materials with an extremely simple and cost-effective methodology,” Yabuuchi said. “This material achieved the ultimate goal for high-performance nickel-based electrode materials.”<\/p>\n

In future endeavors, the researchers plan to investigate the feasibility of a nickel-free material to support lithium-ion batteries.<\/p>\n

\n More information:<\/strong>
\n Itsuki Konuma et al, Unified understanding and mitigation of detrimental phase transition in cobalt-free LiNiO2<\/sub>, Energy Storage Materials<\/i> (2024). DOI: 10.1016\/j.ensm.2024.103200<\/a><\/p>\n<\/div>\n
\n Provided by
\n Yokohama National University
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Citation<\/strong>:
\n Cobalt-free electrodes achieved with nickel ions (2024, February 20)
\n retrieved 20 February 2024
\n from https:\/\/techxplore.com\/news<\/a>\/2024-02-cobalt-free-electrodes-nickel-ions.html<\/p>\n

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