SK On announces breakthrough in cathode research
Battery manufacturers currently use polycrystalline cathode materials, which consist of multiple crystals aggregated within each particle. During the calendering process or charge-discharge cycles, the interfaces between these crystals can cause cracks and gas formation.
In contrast, single-crystal cathode materials comprise particles that each form a single crystal. This structure makes them less prone to cracking, improving stability and cycle life. Additionally, single-crystal cathode materials enhance battery stability and energy density.
SK On and a research team led by Prof. Kisuk Kang from Seoul National University have now successfully developed such single-crystal cathode materials. The results have been published in the journal ‘Nature Energy.’
Complex manufacturing process
Synthesising single-crystal cathode materials that achieve both large particle size and structural stability is a significant challenge. This is especially true for high-nickel cathode materials, which require high-temperature, long-duration heat treatment to form single crystals. This process can cause cation disorder, leading to reduced battery performance and cycle life.
To address these challenges, researchers from SK On and Seoul National University developed a novel synthesis method. This method enables the production of large-grained single-crystal cathode particles with high structural stability. By using an intermediate stage involving sodium cathodes followed by an ion-exchange reaction to lithium, they successfully created ultra-high-nickel cathodes with particle sizes of approximately 10 micrometres and minimal structural defects. These particles are roughly twice as large as those in conventional cathode materials.
In addition to high energy density, these novel cathodes demonstrated excellent mechanical and chemical stability. Due to the absence of cation disorder, they experienced lower structural stress, produced 25 times less gas than conventional polycrystalline cathodes, and achieved an energy density of up to 77% of the theoretical crystal density.
Follow-up studies planned
“This research clearly demonstrates SK On’s technological competitiveness in battery materials,” said Dr Kisoo Park, Head of the Future Technology Institute at SK On. “We will continue to strengthen our technological leadership through innovative research and development with academia.”
SK On and Seoul National University are already planning follow-up studies to advance these next-generation cathode materials further. These studies will explore even more advanced material compositions and synthesis techniques. Additionally, the researchers aim to combine single-crystal particles of varying sizes in optimal ratios to increase energy density further.
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