全固态薄膜锂离子电池快锂离子固态电解质的研究

All-solid-state thin film lithium battery (TFB) is a thinned lithium battery which consists of positive and negative thin film electrode and solid-state electrolyte. The thickness of a typical all-solid-state lithium battery is usually less 20 μm. It could be used in smart cards, sensors and microelectromechanical systems as well. Solid electrolyte is one of the key components for all solid-state thin film lithium-ion battery. It plays a crucial role to the property of battery and is the main obstacle for the development and application of next generation all solid-state thin film lithium ion battery with high power. Developing electrolyte materials and improving ion conductivity are the major objectives for researchers in this field. On the purpose of selecting suitable electrolyte for thin-film lithium ion batteries, other issues including the interface and chemical stability between electrode and the electrolyte, and the feasibility of thin-film preparation with low temperature preparation condition should be considered. In this project, the fabrication and physical chemistry properties of Li10GeP2S12 thin film and nitrided Li2S-P2S5，Li10GeP2S12 or Li2S-GeS2 thin film will be investigated firstly.These thin film electrolyte based sulfur will be prepared by using advanced physical deposition methods such as pulsed laser depositiom，radio frequency sputtering，electron beam evapor coupled gas plasma and son on. To characterize the physical and chemical property of a thin film electrlyte and battery, many approaches can be used, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and so on.Its electrochemical performance of thin film batteries are evaluated by galvanostsic cycling and cyclic voltammograms. The sandwich structures and all-solid-state thin-film lithium batteries with using thin film electrolyte based sulfur will be fabricated to investigate the kinetic performance by AC impedance.The ionic and electronic transport characterization of thin film electrolyte based sulfur as well as the activation energy of interface between electrodes and solid electrolyte will be achieved by analysizing various temperature AC impedance.It will be unfolded with lithium transport mechanisms based on nanometer-size effects, the thickness, the morphology and the structure of these thin film electrolyte based sulfur. The characters of an all solid-state thin film battery using thin film electrolyte based sulfur will be clarified.The high-quality interface between electrolyte/electrode and high lithium conducivity of thin film electrolyte based sulfur as well as and low temperature preparation condition should play an important role in the realization of high-performance all-solid-state rechargeable battery for practical use.

为了解决全固态薄膜电池的应用瓶颈，提高全固态薄膜电池的能量与功率密度，研究快锂离子电导的固体电解质薄膜显得非常重要。本项目拟开展Li10GeP2S12电解质薄膜与氮化的Li2S-P2S5，Li10GeP2S12或Li2S-GeS2等硫系固态电解质薄膜制备研究。采用先进物理沉积薄膜技术如电子蒸发与气体等离子体技术相结合等尝试制备这些基于硫系的新型快锂离子导体薄膜，探索不同沉积薄膜技术制备硫系固态电解质薄膜的特征。设计与优化多层薄膜沉积工艺，制备性能优良的基于硫系电解质薄膜的全固态薄膜锂离子电池，使其性能达到国际水平。结合电化学、纳米离子学、谱学等多个学科的技术，测量基于新型硫系固态电解质的全固态薄膜电池的电化学特性。研究在不同薄膜厚度，不同薄膜形貌，不同薄膜结构的硫系快锂离子导体的导电机理，以及硫系固态电解质薄膜和薄膜电极之间的界面物理化学。为全固态薄膜锂离子电池的实用化打下坚实的基础。

二次化学电源体系发展迅速，并有逐步取代现有的一次能源体系的趋势。尤其是锂离子电池，是目前应用得比能量最高的化学电源，已经开始大量应用于手提电脑、数码相机等电子产品中。然而，目前商业化的锂离子基本上是采用有机液体作为电解质层，其始终存在一定的安全性隐患。例如电池内部短路是现代电池生产工业无法完全避免爆炸燃烧等问题，而且这种安全隐患具有不定期爆发、难以预检预测的特征。能够从根本上解决上述问题的途径是发展全固态电化学储能器件，以固体电解质替代有机电解液的全固态锂电池。在本项目中我们发现了一种新的小分子固态电解质 为(LiI)(1+x)I(2-x)(HPN)2。利用固相合成法制备未知的LiIHPN单晶样品。在LiIHPN单晶结构中，每个锂离子被四个原子配位，两个锂原子通过两个HPN分子形成的12圆环相连接，两个相邻的环通过碘原子形成空间网状结构。LiIHPN的电化学窗口约为5.5V，电势阶跃测试表明LiIHPN是单纯的锂离子导体。LiIHPN和LiIHPN-LiI固体电解质的离子电导率测试表现为典型的Arrhenius行为。室温下，LiIHPN和LiIHPN-LiI的离子电导率分别为2.3*10-8和1.8*10-6S/cm。在85℃时LiIHPN-LiI的电导率可达1.0*10-3 S/cm。 在本项目中我们我们发现了一种新型的无机固态电解质薄膜及其制备新技术，可以应用于全固态电池及其制备方面。通过这些工作，拓展了人们对锂离子固态电解质基础研究的深刻认识，有助于推动固态锂离子电池在应用领域的发展。