Annealing of LiCoO2 films on flexible stainless steel for thin film lithium batteries

The LiCoO2 films were directly deposited on stainless steel (SS) using medium-frequency magnetron sputtering, and the effects of annealing parameters, such as ambiences, temperatures, holding times, and heating rates, were systematically compared based on surface morphologies, crystal structures, and electrochemical properties. The results demonstrate that an aerobic atmosphere with 3.5 Pa is the most important parameter to maintain the performance of LiCoO2 films. The influence of the annealing temperature (>550 degrees C) ranks second because the formed (101) or (104) planes of LiCoO2 facilitate Li+ migration. A short holding time of 20 min and a moderate heating rate of 3 degrees C/min are selected to reduce the oxidation or inter-diffusion between the LiCoO2 films and the SS substrate. Finally, the optimal annealing process is confirmed and corresponds to the initial discharge capacity of 37.56 mu A h/(cm(2) mu m) and the capacity retention of 83.81% at the 50th cycle.

采用中频磁控溅射技术将LiCoO₂薄膜直接沉积在不锈钢（SS）上，并基于表面形貌、晶体结构和电化学性能系统地比较了退火参数（如环境气氛、温度、保温时间和升温速率）的影响。结果表明，3.5 Pa的有氧气氛是保持LiCoO₂薄膜性能的最重要参数。退火温度（>550℃）的影响位居第二，因为形成的LiCoO₂的（101）或（104）晶面有利于Li⁺迁移。选择20分钟的短保温时间和3℃/分钟的适中升温速率，以减少LiCoO₂薄膜与SS基底之间的氧化或相互扩散。最后，确定了最佳退火工艺，其对应于第50次循环时的初始放电容量为37.56 μA·h/(cm²·μm)，容量保持率为83.81%。