[3A01-07] Topical symposium

10:30 AM - 11:00 AM JST(1:30 AM - 2:00 AM UTC)

[3A04【依頼講演】] Functionally graded site engineering in epitaxial cathode thin films: spatial control of dopant site selectivity for lithium-ion batteries

*Kenichi Kaminaga¹, Kanta Suzuki¹, Daigo Nanasawa², Hiroyuki Setoyama³, Fumitsuna Teshima⁴, Kiyohisa Tanaka⁴, Daisuke Shibata⁵, Shingo Maruyama^1,7, Shintaro Yasui^2,6, Yuji Matsumoto¹ (1. Tohoku University (Japan), 2. ZC, Science Tokyo (Japan), 3. SAGA-LS (Japan), 4. UVSOR (Japan), 5. SR center (Japan), 6. MSL, Science Tokyo (Japan), 7. Shizuoka University (Japan))

High-rate capability and long-term cycling stability often trade off in lithium-ion battery cathodes, as uniform doping typically improves charge transport or structural stability at the expense of the other. Here, we propose Functionally Graded Site Engineering (FGSE), which couples dopant concentration gradients with site-selective substitution. In La-doped LiCoO₂ thin-film cathodes, synchrotron spectroscopy and DFT+U calculations revealed that local La concentration controls the preferred substitution site: Co sites in La-dilute regions and Li sites in La-rich regions. This enables a graded cathode where the current-collector side promotes electronic conduction, while the electrolyte-facing side forms a structurally robust region that suppresses degradation. The resulting integrated cathode showed high capacity retention even at 20 C and improved structural integrity after cycling, demonstrating FGSE as a route to integrating multiple functions within one crystalline material.

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