溅射功率对氧化锡薄膜结构和电化学性能的影响

应用射频磁控溅射技术在硅基底上制备氧化锡薄膜,着重研究溅射功率对薄膜结构和电化学性能的影响.XRD,SEM分析及恒电流充放电测试表明,随着溅射功率的增大,薄膜的结晶程度提高;生长速率和晶粒尺寸增大;电池的贮锂容量减少,且首圈不可逆容量损失增大.溅射功率对薄膜的电化学性能有较大的影响.     

TiS2原子薄膜厚度对其热电性质影响的理论研究

本文采用玻尓兹曼输运方程与密度泛函计算相结合的方法,理论研究了薄膜厚度对二维TiS₂原子薄膜热电性能的影响。随着厚度的减小,薄膜的能带变平,电子有效质量增大而群速度减小,这造成了塞贝克系数的增大和电导率的减小。而且,薄膜的功率因子及最优载流子浓度也随厚度的减小而减小。我们讨论了薄膜功率因子减小的物理机制,并与其他二维体系的实验结果进行了比较分析。     

TiS_2原子薄膜厚度对其热电性质影响的理论研究

本文采用玻尓兹曼输运方程与密度泛函计算相结合的方法,理论研究了薄膜厚度对二维TiS2原子薄膜热电性能的影响。随着厚度的减小,薄膜的能带变平,电子有效质量增大而群速度减小,这造成了塞贝克系数的增大和电导率的减小。而且,薄膜的功率因子及最优载流子浓度也随厚度的减小而减小。我们讨论了薄膜功率因子减小的物理机制,并与其他二维体系的实验结果进行了比较分析。     

纳米二氧化钒薄膜的制备及红外光学性能

采用双离子束溅射方法在Si3N4/SiO2/Si基底表面沉积氧化钒薄膜, 在氮气气氛下热处理获得二氧化钒薄膜. 利用X射线衍射(XRD)、扫描电子显微镜(SEM)和X射线光电子能谱(XPS)研究了热处理温度对氧化钒薄膜晶体结构、表面形貌和组分的影响, 利用傅里叶变换红外光谱(FT-IR)对二氧化钒薄膜的红外透射性能进行了测试分析. 结果表明, 所制备的氧化钒薄膜以非晶态V2O5和四方金红石结构VO2为主, 经400 ℃、2 h热处理后获得了(011)择优取向的单斜金红石结构纳米VO2薄膜, 提高热处理温度至450 ℃, 纳米结构VO2薄膜的晶粒尺寸减小. FT-IR结果显示,纳米VO2薄膜透射率对比因子超过0.99, 高温关闭状态下透射率接近0. 小晶粒尺寸纳米VO2薄膜更适合在热光开关器件领域应用.     

电化学沉积CdSe纳晶薄膜的性能及沉积机理

电化学沉积是半导体薄膜制备的一种简便方法,常用于Ⅱ-族化合物半导体薄膜的制备.通过电沉积条件的适当改变可成功地在导电衬底上制备半导体纳晶薄膜^[1].CdSe薄膜作为一种透光性好、导电性好的半导体材料,可进行光学性能和光电性能方面的研究,而半导体纳晶多孔电极的光电化学特性与体材料之间有很大不同.本文采用电化学沉积法制备了CdSe纳晶薄膜并研究了其性能,通过扫描隧道显微镜(STM)形貌分形分析进一步研究其沉积机理.     

聚乙烯醇缩丁醛准固态电解质薄膜的制备和性能表征

研究了聚乙烯醇缩丁醛准固态电解质薄膜的制备及相关性能.通过向聚乙烯醇缩丁醛中加入适量造孔剂和辅助剂制备电解质薄膜,研究了薄膜制备过程中的相关影响因素和不同孔隙率的电解质薄膜对电池光电转换效率的影响.实验表明,通过向0.200g聚乙烯醇缩丁醛中加入6.000g碳酸钙、0.310g氯化钙和0.150g葡萄糖所制备的电解质薄膜性能最优,用其制备的染料敏化太阳能电池光电转换效率η=4.720%(开路电压Voc=0.7194V,短路电流密度Jsc=10.014mA·cm-2,填充因子FF=0.6559),达到相同条件下液态电解质电池的88%以上.薄膜电解质制备简单,封装方便,所用原料无毒无害,具有一定的发展潜力.     

氮掺杂二氧化钛-氧化镍双层薄膜的光电致色特性

以金属钛为靶材、O2/N2/Ar混合气氛为溅射气体,在导电玻璃(ITO)表面磁控溅射一层薄膜,再经300-500℃退火处理制备了氮掺杂TiO2薄膜.采用X射线衍射(XRD)、X光电子能谱(XPS)、扫描电子显微镜(SEM)和紫外-可见吸收光谱等对薄膜的微观结构、光学特性和光电化学性能等进行了研究.进而采用化学沉积的方法在TiO2-xNx薄膜表面沉积上一层多孔NiO薄膜,研究表明,制备的ITO/TiO2-xNx/NiO双层薄膜具有明显的光电致色特性,400℃退火处理的氮掺杂TiO2薄膜具有最高的光电流响应,经氙灯照射1h后,薄膜从无色变成棕色,500nm波长处光透过率从79.0%下降至12.6%.     

恒电位脉冲法制备聚苯胺薄膜及其表征

采用恒电位脉冲法制备聚苯胺薄膜, 利用扫描电子显微镜(SEM)、红外光谱(IR)、X射线衍射(XRD)及荧光光谱对所制备的薄膜进行比较与表征. 分别考察了循环周期、占空比及脉冲时间对薄膜形貌的影响. SEM形貌分析结果表明, 随着占空比的减小, 聚苯胺薄膜表面颗粒细化; 随循环周期的增加, 聚苯胺薄膜由片层结构转变为纵向生长的颗粒状结构. 荧光光谱分析结果表明, 聚苯胺薄膜具有光致发光性能, 发射峰位置约520 nm, 且发光强度随占空比的增大而增强. 电化学性能测试结果表明, 恒电位脉冲电位法制备的聚苯胺薄膜具有良好的电容特性.     

气相合成SnO2超微粒薄膜研究

用直流气体放电活化反应蒸发法在玻璃基片上沉积的SnO2超微粒薄膜,研究其过程中各工艺参数对薄膜结构的影响及作用机理.结果表明, SnO2超微粒薄膜粒径随氧分压增加而增大;蒸镀时间的延长有助于SnO2的生成,也使薄膜发生晶化;而增加放电电压,则薄膜出现外延单晶生长趋势.     

真空蒸镀法制备锡薄膜及其嵌锂电化学性能

采用真空蒸镀法在铜片基底上沉积锡薄膜作为锂离子电池负极材料,对所制备的锡薄膜采用扫描电子显微镜、X射线衍射表征,研究了其表面形貌和组成。 将制备的薄膜在手套箱中组装成CR2032型钮扣式电池,进行电化学测试,研究其电化学性能。 实验结果表明,在相同蒸发时间和基底温度的条件下,随着蒸发功率的增加,沉积的锡颗粒逐渐增大,相应的电化学性能降低。 以蒸发功率200 W、基底温度150 ℃制得的样品粒径为100~200 nm,含有Cu6Sn5合金相,以0.2C倍率充放电循环20周后放电容量达527 mA·h/g。     

以LiCoO2为阴极的全固态薄膜锂电池的研究

Amorphous and oriented polycrystalline LiCoO2 thin films, used as cathode material for an all-solid-state thin film battery, were fabricated by using RF magnetron sputtering and annealed at different temperatures. The morphology and structure of LiCoO2 thin films were characterized by scanning electron microscopy and X-ray diffraction. All-solid-state thin film batteries, comprised of LiCoO2 cathode films with different structures, lithium phosphorous oxynitride electrolyte film and metallic lithium anode film, was successfully prepared and their properties were examined by chronopotentiometry. Results showed that the structure and crystallinity of the LiCoO2 films strongly influenced the electrochemical performance of all-solid-state thin film lithium batteries. Worth nothing was the battery with an oriented polycrystalline LiCoO2 film it exhibited the best electrochemical performance, and delivered a discharge capacity of ～55.4 μAh/cm2μm. Furthermore, when subjected to over 450 charge/discharge cycles, that battery suffered no obvious fode in capacity.     

Effect of fullerene coating on silicon thin film anodes for lithium rechargeable batteries

To improve the electrochemical performances of Si thin film anodes for lithium rechargeable batteries, fullerene thin films are prepared by plasma-assisted evaporation methods to be used as coating materials. Analyses via Raman and X-ray photoelectron spectroscopy indicate that amorphous polymeric films originated from fullerene are formed on the surface of the silicon thin film. The electrochemical performance of these fullerene-coated silicon thin film as an anode material for rechargeable lithium batteries has been investigated by cyclic voltammetry, charge/discharge tests, and electrochemical impedance spectroscopy. The fullerene-coated Si thin films demonstrated a high specific capacity of above 3,000 mAh g⁻¹ as well as good capacity retention for 40 cycles. In comparison with bare silicon anodes, the fullerene-coated silicon thin film showed superior and stable cycle performance which can be attributed to the fullerene coating layer which enhances the Li-ion kinetic property at the electrode/electrolyte interface.     

含氮磷酸锂薄膜在空气中的稳定性

利用射频(RF)磁控溅射方法制备了含氮磷酸锂(LiPON)薄膜. 采用SEM、XRD、XPS等技术以及交流阻抗法和电位线性扫描法, 研究了空气湿度对LiPON薄膜形貌、组成和性能的影响. 结果表明, LiPON薄膜在湿度为40%的空气环境中放置24 h后, 将发生明显的水解反应, 使LiPON薄膜表面形貌变得疏松、局部突起; PH3和NH3的产生, 使薄膜中磷元素和氮元素含量减少, 而Li2CO3的生成, 则使薄膜中碳元素和氧元素含量有明显的增加. LiPON电解质薄膜形貌和组成的变化, 造成了薄膜电化学性能的严重恶化.     

TiO2/P(VdF-HFP)杂化纤维微孔膜的制备及其电化学性能

用电纺法制备了TiO₂/P(VdF-HFP)(聚偏氟乙烯-六氟丙烯共聚物)杂化纤维微孔膜, 用SEM观察了杂化纤维微孔膜的形貌, 并测算了这类由超细纤维相互搭接而形成的微孔膜的孔隙率. 这种微孔膜吸附LiPF₆/EC-DMC-EMC(碳酸乙烯酯-二甲基碳酸酯-碳酸甲乙酯)电解质溶液后得到凝胶聚合物电解质膜. 用电化学方法测试了聚合物电解质膜的离子电导率、锂离子迁移数等参数, 并研究了TiO₂纳米晶的掺入对聚合物电解质电化学性能的影响. 结果表明, TiO₂的掺入降低了P(VdF-HFP)聚合物基体的结晶度, 改善了凝胶聚合物电解质的低温电化学性能.     

Xylene as a New Polymerizable Additive for Overcharge Protection of Lithium Ion Batteries

The electrochemical properties and overcharge protection mechanism of xylene as a new polymerizable electrolyte additive for overcharge protection of lithium ion batteries were studied by cyclic voltammetry tests, charge- discharge performance and battery power capacity measurements. It was found that when the battery was overcharged, xylene could electrochemically polymerize at the overcharge potential of 4.3—4.7 V (vs. Li/Li＋) to form a thin polymer film on the surface of the cathode, thus preventing voltage runaway. On the other hand, the use of xylene as an overcharge protection electrolyte additive did not influence the normal performance of lithium ion batteries.     

Electrochemical supercapacitor application of pervoskite thin films

We have explored electrochemically deposited pervoskite nanocrystalline porous bismuth iron oxide (BiFeO₃) thin film electrode from alkaline bath for electrochemical supercapacitors. The pervoskite BiFeO₃ nanocrystalline thin film electrode showed comparable specific capacitance of 81 F g⁻¹ and electrochemical supercapacitive performance and stability in an aqueous NaOH electrolyte to that of commonly used ruthenium based pervoskites.     

一种铂网栅薄层光谱电化学池的制作及表征

以铂网栅电极作工作电极,设计制作了一种应用于紫外-可见光谱电化学研究的新型光透薄层电化学池（OTTLE）,并以铁氰化钾-亚铁氰化钾体系对此光谱化学池进行了表征。铁氰化钾-亚铁氰化钾体系在该池中有良好的循环伏安特性,并可获得良好的紫外-可见光谱。测得的克式量电位E^0,电子转移数n与文献结果一致。     

温度对石墨电极性能的影响

运用电化学阻抗谱(EIS)并结合循环伏安法(CV)研究了石墨电极25和60 ℃时在1 mol·L-1 LiPF6-EC(碳酸乙烯酯):DEC(碳酸二乙酯):DMC(碳酸二甲酯)电解液中, 以及60 ℃时在1 mol·L-1 LiPF6-EC:DEC:DMC+5%VC(碳酸亚乙烯酯)电解液中的首次阴极极化过程. 发现高温下(60 ℃)石墨电极在1 mol·L-1 LiPF6-EC:DEC:DMC电解液中可逆循环容量衰减的主要原因在于其表面无法形成稳定的固体电解质相界面(SEI)膜. 实验结果显示, VC添加剂能够增进高温下石墨电极表面SEI膜的稳定性, 进而改进石墨电极的循环性能.     

Influence of highly efficient PbS counter electrode on photovoltaic performance of CdSe quantum dots-sensitized solar cells

PbS electrode with high catalytic activity to S_n ^2? reduction certificated by the measurements of electrochemical impedance spectroscopy and cyclic voltammetry was prepared by a simple method. The high catalytic activity makes it be a low-cost alternative counter electrode to platinum (Pt) to be used in quantum dots-sensitized solar cells (QDSSCs) based on polysulfide electrolyte. The photovoltaic performance enhancement of the quantum dots (QDs)-sensitized semiconductor thin films due to the PbS counter electrode was evaluated by fabricating QDSSCs based on CdSe QDs-sensitized ZnO (SnO₂) thin film. CdSe QDs-sensitized ZnO thin film has the lower internal total series resistance and electron transmission time, the higher electron lifetime and electron collection efficiency than the CdSe QDs-sensitized SnO₂ thin film. Replacing the Pt counter electrode with the PbS counter electrode leads to more improvement on the short circuit photocurrent density for QDSSC based on the ZnO thin film than the SnO₂ thin film. Therefore, the process to limit the photovoltaic performance of CdSe QDs-sensitized solar cell and the possible way to improve the photovoltaic performance were analyzed.     

Studies of the interfacial properties of an electroplated Sn thin film electrode/electrolyte using in situ MFTIRS and EQCM

Sn thin film electrodes were prepared by electroplating in an acidic sulfate bath containing SnSO4. During charge/discharge processes, the interfacial properties between a Sn thin film electrode and an electrolyte of 1 mol.L(-1) LiPF6 in a mixture of ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1 vol %) were investigated by using cyclic voltammetry (CV), electrochemical quartz crystal microbalance (EQCM), and in situ microscope Fourier transform infrared reflection spectroscopy (in situ MFTIRS). The processes of alloying/dealloying of lithium with Sn and the decomposition of the electrolyte on the Sn electrode were characterized quantitatively by surface mass change and at the molecule level. EQCM studies demonstrated that the mass accumulated per mole of electrons (mpe) was varied in different electrochemical processes. In the process of electrolyte decomposition, the measured mpe is smaller than the theoretical value, whereas it is higher than the theoretical value in the process of alloying/dealloying. The reduction products, ROCO2Li, of the electrolyte involved in charge/discharge processes were determined by in situ MFTIRS. The solvation/desolvation of lithium ion with solvent molecules, which is induced by the alloying/dealloying of lithium with Sn, was evidenced by shifts of relevant IR bands of C=O, C-O, and C-H. The current studies clearly revealed the details of interfacial reactions involved in lithium ion batteries employing a Sn thin film as the anode.