采用脉冲激光沉积 (PLD) 方法在镀 Pt 的 Si 衬底上制备了 LiCoO₂ 薄膜, 运用 XRD、Raman 光谱、SEM 和循环伏安等方法对其结构与电化学性能进行表征, 在此基础上着重采用电位间歇滴定技术 (PITT) 对其 Li 离子表观扩散进行了分析. 结果表明, 600 ℃ 制备的 LiCoO₂ 薄膜为 HT-LiCoO₂ 相, 呈柱状晶结构, 平均晶粒尺寸在 100 nm 以下, 结晶度高, 并且具有明显的 [001] 择优取向, 但少量缺 Li. 伏安循环曲线表明, 该 LiCoO₂ 薄膜具有良好的电化学可逆性, 但只在 3.9 V (vs Li/Li⁺) 附近出现一对氧化还原峰. PITT 测试表明, PLD 方法制备的 HT-LiCoO₂ 薄膜的 Li 离子扩散系数在 10^-8-10^-9 cm²/s, 与其它方法 (如射频磁控溅射) 制备的 HT-LiCoO₂ 薄膜相比, 扩散系数高 1-2 个数量级; 并且 PLD 方法制备的 HT-LiCoO₂ 薄膜中 Li 离子扩散系数与相变有关, 在两相共存区, 由于相界钉扎的作用, Li 离子扩散系数比其它区域小 1-2 个数量级.

The structure of LiCoO₂ films prepared with the pulsed laser deposition (PLD) method was characterized by XRD, Raman spectroscopy and SEM, and their electrochemical properties were evaluated with cyclic voltammetry (CV). Results showed that the LiCoO₂ films deposited at 600°C have a well-crystallized columnar HT-LiCoO₂ structure with the average grain size less than 100 nm and a strong [001] preferred orientation, while these films contain trace amount of CO₃O₄. CV tests indicated that the HT-LiCoO₂ films have good electrochemical reversibility but only a pair of redox peaks near 3.9 V (vs Li) were observed in the cyclic voltammograms. Potentiostatic intermittent titration technique (PITT) measurements revealed that the lithium ion diffusion coefficient of the HT-LiCoO₂ films can reach 10^-8-10^-9 cm²/s, 1-2 orders of magnitude faster than those prepared by other methods including R. F. magnetron sputtering and, in the voltage range between 3.85-3.95 V (vs Li) the diffusion coefficient was 1-2 orders of magnitude lower than other voltage ranges. The former should be ascribed to the grain refinement of PLD-deposited HT-LiCoO₂ films and existence of many voids, while the later may be due to the hindrance arising from phase boundary movement.