In Situ X-ray Diffraction of LiCoO 2 in Thin-Film Batteries under High-Voltage Charging

作者：Tsuyoshi Ohnishi, Kazutaka Mitsuishi, Kazunori Takada · 发表于：ACS Applied Energy Materials · 年份：2021 · DOI：10.1021/acsaem.1c03046 · 被引用次数：33 · 研究领域：Advancements in Battery Materials、Advanced Battery Materials and Technologies、Advanced Battery Technologies Research

High Resolution Image Download MS PowerPoint Slide LiCoO 2 has been used as the cathode material employed in lithium-ion batteries since their development, and efforts to improve its performance are still in progress. For example, complete use of lithium provides a theoretical capacity as high as 274 mAh g –1; however, charge–discharge cycling with such a high capacity leads to rapid degradation. The degradation mechanism has been intensively studied in order to increase the practical capacity. Although phase transitions taking place in high-voltage charging have been considered to affect the cycling performance, side reactions induced by the high-voltage charging always overlap to blur the effects of phase transitions on the electrode properties. This study has unveiled the relation between the phase transition and electrode properties by employing a solid electrolyte that suppresses the side reactions efficiently. Electrochemical impedance spectroscopy combined with in situ X-ray diffraction shows clear correlation between phase transition from O3 to H1–3 and a drastic increase in the electrode resistance. The increasing resistance is attributable to formation of narrow interlayers with a gallery height of 4.2 Å that impede lithium-ion diffusion.