Department of Advanced Materials and Energy Engineering , Dongshin University , Naju 58245 , Republic of Korea.
Department of Nanochemistry , Gachon University , Seongnam 13120 , Republic of Korea.
ACS Appl Mater Interfaces. 2019 Nov 27;11(47):44293-44299. doi: 10.1021/acsami.9b15608. Epub 2019 Nov 14.
Electron beam damage from transmission electron microscopy of layered lithium transition-metal oxides is a threshold phenomenon that depends on the electron beam energy, which we demonstrate in this study by varying the accelerating voltage of a scanning transmission electron microscope. The electron beam irradiation experiment shows that Ni in LiNiO has much lower threshold energy for displacement than Co in LiCoO, which is supported by DFT calculations predicting that Ni has lower migration energy. The transition-metal ions are reduced from the oxidation state of +3 to +2 during migration from their original positions to the lithium sites, and Ni is more easily reduced than Co because of its electronic configuration. In addition, the high-energy electron beam induces oxygen release, which is another symptom of degradation of materials that occurs more strongly in Ni-containing materials with ion displacement.
透射电子显微镜下层状锂过渡金属氧化物的电子束损伤是一种阈值现象，取决于电子束能量，我们通过改变扫描透射电子显微镜的加速电压在这项研究中证明了这一点。电子束辐照实验表明，在 LiNiO 中 Ni 的位错迁移阈值能比 LiCoO 中的 Co 低得多，这一结果得到了 DFT 计算的支持，计算表明 Ni 的迁移能更低。过渡金属离子在从其原始位置迁移到锂位的过程中，价态从+3 降低到+2，由于其电子构型，Ni 比 Co 更容易被还原。此外，高能电子束会诱导氧释放，这是材料降解的另一个症状，在具有离子位移的含 Ni 材料中更为强烈。
