| The Enhancement of Electrochemical Properties of Yttrium -Doped Single-Crystal Cathode Materials for High-Rate Charging and Discharging |
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Jeong H. Cho1, J. Hyuk Kim1, JM One1, SH Lee1, Min Seo Choi1, Yun Hyeok Choi1, San Kang2, Jong-Tae Son1 |
1Department of Nano-Polymer Science & Engineering, Korea National University of Transportation, 50, Daehak-ro, Daesowon-myeon, Chungju-si, 27469, Republic of Korea
2Department of Energy Materials Science & Engineering, Korea National University of Transportation, 50, Daehak-ro, Daesowon-myeon, Chungju-si 27469, Republic of Korea |
Correspondence:
Jong-Tae Son,
Email: jt1234@ut.ac.kr
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Received: 17 June 2025 • Accepted: 27 July 2025 |
| Abstract |
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Single-crystal cathode materials typically restrict lithium-ion (Li-ion) diffusion, which cause lower capacity and rate performance than those of traditional polycrystalline cathodes. Enhancing Li-ion transport is crucial for improving their electrochemical properties. This study investigates the effect of yttrium (Y) doping on improving Li-ion diffusion and electrochemical performance of single-crystal cathode materials.
Y-doped single-crystal cathodes were synthesized and characterized. Electrochemical impedance spectroscopy was used to measure charge transfer resistance before and after cycling. Li-ion diffusion coefficients were calculated. Rate capability and capacity retention were evaluated through charge/discharge tests at various C-rates. Y-doped samples exhibited a significant decrease in charge transfer resistance from 25.1 Ω–7.3 Ω before cycling and from 72.4 Ω–19.2 Ω after cycling—which reflected a reduction of approximately 70%. The Li-ion diffusion coefficient improved by 1.5 times, thereby reaching 2.85×10^-13 cm²/s. Capacity retention at a rate of 5C was 76.5%, with a discharge capacity of 140.67 mAhg⁻¹ than that of the initial capacity at 0.1 C. After high-rate cycling, the recovery capacity at 0.1 C recovered to 179.4 mAhg⁻¹, which indicated 97.4% reversibility. |
| Keywords:
Single crystal, Co-free cathode, Lithium-ion diffusion, Resistance reduction, High-rate performance |
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