LiMn2O4薄膜的快速退火制备及其性质

为了获得电化学性能优良的锂离子薄膜电池正极材料,采用快速退火技术制备L iMn2O4薄膜,用X射线衍射、扫描电子显微镜检测和分析了薄膜的物相及表面形貌;用循环伏安、恒流充放电研究了L iMn2O4薄膜的电化学性质。结果表明,制备的L iMn2O4薄膜均匀、致密、无龟裂;在退火温度从700℃升高到850℃的过程中,薄膜容量从34μAh/(cm2.μm)逐步升高到40μAh/(cm2.μm);当退火时间从1 m in延长到4 m in时,薄膜容量由36μAh/(cm2.μm)升高到41μAh/(cm2.μm),但当退火时间进一步延长到8 m in时,薄膜容量下降到39.5μAh/(cm2.μm);对于不同温度退火2 m in制备的薄膜而言,800℃退火得到的L iMn2O4薄膜经100次循环后的每次容量损失为0.021%,循环性能最好;对于750℃不同退火时间制备的L iMn2O4薄膜来说,退火时间为4 m in时得到的薄膜循环性能最好,经100次循环后每次容量损失仅为0.025%,表明快速退火制备的L iMn2O4薄膜具有优良的循环性能。

Preparation and Characterization of LiMn 2O 4 Thin Films by Rapid Thermal Annealing

Cathode material LiMn_2O_4 thin films were prepared by rapid thermal annealing.The phase identification and study of surface morphology were carried out by X-ray diffraction and scanning electron microscopy.Electrochemical properties were examined by cyclic voltammetry and galvanostatic charge-discharge experiments.The results show that the film prepared by this method is homogeneous,dense and crack-free.The capacity of the film increases from 34 μAh/(cm~2·μm) to 40 μAh/(cm~2·μm) as the annealing temperature increaes from 700 ℃ to 850 ℃,and from 36 μAh/(cm~2·μm) to 41 μAh/(cm~2·μm) as annealing time increases from 1 minute to 4 minutes.However,when the annealing time reaches 8 minutes,the capacity decreases to 39.5 μAh/(cm~2·μm).For the thin films annealed for 2 minutes at different temperature,the film annealed at 750 ℃ has the best cycling behavior with a capacity loss of 0.021% per cycle after being cycled 100 times.While for the thin films annealed at 750 ℃ for different time,the film annealed for 4 minutes has the best cycling behavior with a capacity loss of 0.025% per cycle after being cycled 100 times.These show that LiMn_2O_4 thin film prepared by rapid thermal annealing possesses excellent cycling behavior.