South Korean battery maker SK On said it has achieved a significant advance in cathode material research, developing a high-density, large-area single-crystal cathode electrode in collaboration with Seoul National University.
The findings, published in the journal Nature Energy, address long-standing challenges associated with conventional polycrystalline cathode materials, which are prone to cracking and gas generation during manufacturing and repeated charge-discharge cycles.
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Most lithium-ion batteries currently use polycrystalline cathodes composed of aggregated crystals. By contrast, single-crystal cathodes consist of particles formed from a single crystal, a structure that improves mechanical stability, reduces cracking and enhances cycle life and energy density.
The research team, led by Prof. Kisuk Kang of Seoul National University, developed a novel synthesis route to overcome manufacturing hurdles associated with high-nickel single-crystal cathodes. Such materials typically require prolonged high-temperature processing, which can lead to cation disorder and degraded performance.
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To mitigate these issues, the researchers introduced an intermediate sodium-based cathode stage followed by an ion-exchange process to lithium. The approach enabled the production of ultra-high-nickel single-crystal cathode particles with sizes of around 10 micrometres—roughly twice those of conventional cathodes—while maintaining structural integrity and minimizing defects.
According to the study, the new cathodes showed markedly improved performance, including lower internal stress, 25 times less gas generation than polycrystalline counterparts, and energy density reaching up to 77% of the theoretical crystal limit.
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“This research clearly demonstrates SK On’s technological competitiveness in battery materials,” said 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 said they plan follow-up studies to further refine the materials, including testing more advanced compositions and combining single-crystal particles of different sizes to push energy density higher.