| 학회 | 한국공업화학회 |
| 학술대회 | 2010년 봄 (05/13 ~ 05/14, BEXCO(부산)) |
| 권호 | 14권 1호 |
| 발표분야 | Energy Storage and Conversion |
| 제목 | Electrode Function and Its Mechanisms of Lithium Transition Metal Oxyanion Compounds |
| 초록 | The lithium ion battery is the most advanced energy storage system and have conquered the portable electronics, but it has been considered not sustainable for large scale application as expensive cobalt in cathode must be obtained from limited natural resources. It also involves safety risks as a cathode functions as a strong oxidizing agent for organic electrolyte. Materials science is about to solve the problem by combination of abundant Fe and covalent (PO4)3 unit with fixed oxygen. This has led to use LiFePO4 with olivinetype structure as a cathode material in lithium batteries. We have recently explored compounds with the lightest small triangle oxyanion, (BO3)3, instead of heavier tetrahedral (PO4)3-. A large theoretical capacity of 220 mAh/g is calculated based on the chemical formula, LiFeBO3, which is much larger than that of LiFePO4, 170mAh/g. Our experiments have shown practical performances with ＞190mAh/g capacity at ca. 3V is readily available for LixFeBO3 at room temperature by careful sample preparation. In addition to the conventional approach with size minimization and carbon coating, a huge positive impact by avoiding surface poisoning by contact with ambient atmosphere is emphasized. After the optimization, 80% of the initial capacity is retained even at high rate at 2C with negligible cycle degradation. Both experiments and ab initio calculation confirmed a solidsolution behavior between isostructural end members/intermediates with a very small volume change (ca. 2%) suitable for reversible reaction. Further good news is in the finding during abinitio calculation that there is no thermodynamic limitation toward theoretical capacity of 220mAh/g. Borates, instead of heavier and larger phosphates, can be an exciting new avenue for exploring novel electrode materials for advanced lithium batteries. |
| 저자 | Atsuo Yamada |
| 소속 | The Univ. of Tokyo |
| 키워드 | lithium-ion batteries; battery materials; cathode; phosphate; olivinetype structure |
