Lithium scandium phosphate-based electrolytes for solid state lithium rechargeable microbatteries

Li₃Sc₂(PO₄)₃ is a promising candidate for use as an electrolyte in solid state lithium rechargeable microbatteries due to its stability in air, ease of preparation, and resistance to dielectric breakdown. The room temperature ionic conductivity was optimized resulting in an increase of over two orders of magnitude to 3×10⁻⁶S/cm. The formation of Li₃(Sc_2−xM_x)(PO₄)₃, where M=Al³⁺ or Y³⁺, resulted in the decrease of porosity, greater sinterability, and considerable enhancement of the ionic conductivity. Yttrium substitutions enhanced the conductivity slightly while aluminum increased the room temperature ionic conductivity to 1.5×10⁻⁵S/cm for x=0.4. Preliminary electron beam evaporation of Li₃Sc₂(PO₄)₃ yielded amorphous thin films with ion ic conductivity as high as 5×10⁻⁵S/cm and a composition of Li_4.8Sc_1.4(PO₄)₃.     

Solid-state lithium/polyacetylene battery

A solid-state lithium/iodine battery has been formed by directly contacting metallic lithium with iondine-doped polyacetylene. The procedure is similar to that used for the well-known lithium/iodine-polyvinylpyridine system. The advantage of the system proposed here may be related to the extraordinary electrical properties of polyacetylene which, when doped with iodine, acquires a very high electrical conductivity over a wide range of halogen concentration.     

Characterization of sprayed and sputtered thin films for lithium ion microbatteries

We have investigated the preparation of thin films of anode and cathode materials for all oxide solid state lithium ion microbatteries. Thin films of LiCoO₂ and Li_4/3Ti_5/3O₄ have been deposited by both spray pyrolysis and RF magnetron sputtering. The structural and electrochemical properties of high temperature-LiCoO₂ thin films have been determined. Spray pyrolysis prepared higher quality LiCoO₂ thin films. Both sprayed and sputtered Li_4/3Ti_5/3O₄ thin films exhibited interesting lithium intercalation capacity. However, it has been demonstrated that RF magnetron sputtering is more efficient than spray pyrolysis for optimizing the interface between Li_4/3Ti_5/3O₄ and the substrate material. Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996     

MnO thin film cathode for rechargeable microbatteries

Thin films of MnO were deposited by electron beam evaporation using a MnO or MnO₂ source. The thin films were charaterized by X-ray and electron diffraction. The Coulomb titration curve reveals a potential plateau of 2.9 V over the composition range 0.05<x<2.0. The chemical diffusion coefficient of lithium in thin films at 15°C is 2.7×10⁻¹⁴ cm²/s for 0<x<0.01 and 2.2×10⁻¹⁵ cm²/s for 0.02<x<0.06. Good reversibility for lithium insertion and extraction is demonstrated by cyclic voltammetry.     

Laser direct write of planar alkaline microbatteries

We are developing a laser engineering approach to fabricate and optimize alkaline microbatteries in planar geometries. The laser direct-write technique enables multicapability for adding, removing and processing material and provides the ability to pattern complicated structures needed for fabricating complete microbattery assemblies. In this paper, we demonstrate the production of planar zinc–silver oxide alkaline cells under ambient conditions. The microbattery cells exhibit 1.55-V open-circuit potentials, as expected for the battery chemistry, and show a flat discharge behavior under constant-current loads. High capacities of over 450 Ahcm^-2 are obtained for 5-mm² microbatteries. PACS 82.47.Cb; 81.16.Mk; 82.45.Fk     

Materials design and optimization for thin-film microbatteries

Considerable effort has been invested in developing thin-film solid microbatteries as possible integrated components in microelectronics. Advances have been made particularly in the engineering of lithium/amorphous inorganic electrolyte/layered compound cells fabricated using various evaporation techniques. The main features of these cells are influenced by the characteristics of the fast ionic conductor and the insertion compound layers which are discussed in detail in this work. Design and optimization of lithium-microbattery components are discussed. Different electrochemical systems using lithium borate-glass films as solid electrolytes have been fabricated and characterized. Thin-film active cathodic materials include transition-metal dichalcogenides such as TiS₂, MoS₂, non-transition-metal chalcogenides such as InSe and transition-metal oxides such as MoO₃, V₂O₅, V₆O₁₃ films. Particular attention is paid to the structural and transport properties of these materials and their behaviour in electrochemical lithium cells are presented. Thermodynamics and kinetics are studied as functions of the growth conditions of thin-film components. The physical properties are discussed in relation to the electrochemical cell behavior and battery performance. Paper presented at the 1st Euroconference on Solid State Ionics, Zakynthos, Greece, 11–18 Sept. 1994.     

XPS investigations achieved on the first cycle of V2O5 thin films used in lithium microbatteries

Vanadium pentoxide thin films, usable as positive electrode in microbatteries, have been prepared by radio frequency magnetron sputtering in a pure argon or mixed argon/oxygen plasma. Depending on the oxygen pressure in the discharge gas, we have obtained either crystallized or amorphous thin films. These two kinds of thin films having different electrochemical behavior, an extensive X-ray photoelectron spectroscopy (XPS) study (especially suited for thin films analysis) was carried out. The main redox processes occurring during the first discharge–charge cycle were identified. In addition, depending on the crystalline or amorphous character of the samples, we have noticed some differences concerning the kinetic of reduction. Furthermore, the growth of a surface layer between the cathode and the liquid electrolyte was evidenced upon the discharge as well as its partial dissolution upon the charge.     

Solid-state synthesis of graphite carbon-coated Li4Ti5O12 anode for lithium ion batteries

Graphites are widely used for their high electrical conductivity and good thermal and chemical stability. In this work, graphitic carbon-coated lithium titanium (Li₄Ti₅O₁₂/GC) was successfully synthesized by a simple one-step solid-state reaction process with the assistance of sucrose without elevating sintering temperature. The lattice fringe of 0.208 nm clearly seen from the high-resolution transmission electron microscopy (HRTEM) images was assigned to graphite (010). The average grain size of the as-prepared Li₄Ti₅O₁₂/GC was about 100–200 nm, 1 order smaller than that of pure Li₄Ti₅O₁₂ prepared similarly. The rate performance and cycle ability were significantly improved by the hybrid conducting network formed by graphitic carbon on the grains and amorphous carbon between them. The specific capacity retention rate was 66.7 % when discharged at a rate of 12C compared with the capacity obtained at 0.5C. After 300 cycles, the capacity retention was more than 90 % at a high rate of 15C.     

Electrochemical behaviour of sputtered c-V2O5 and LiCoO2 thin films for solid state lithium microbatteries

Here are reported for the first time electrochemical data on all-solid-state lithium microbatteries using crystalline sputtered V₂O₅ thin films as cathode materials and LiPON as solid electrolyte. The stable specific capacity of 30 µAh/cm² found with a 2.4 µm thick film competes very well with the best values obtained for solid state microbatteries using amorphous films. With the challenge of decreasing the temperature of heat treatment for sputtered LiCoO₂ thin films, we show that a temperature of 500 °C combined with an optimized bias sputtering (-50 V) allows to get highly crystalline deposits, to minimize the presence of Co₃O₄ and to suppress any trace of the cubic phase. At the same time the theoretical specific capacity is reached in the 4.2 V-3 V range and a good cycling behaviour is achieved with a high capacity of 50 µAh/cm²/µm after 140 cycles at 10 µA.cm².     

Solid-state quantum computation station

Solid-state quantum computation station belongs to the group 2 of manipulation of quantum state in the Synergetic Extreme Condition User Facility. Here we will first outline the research background, aspects, and objectives of the station,followed by a discussion of the recent scientific as well as technological progress in this field based on similar experimental facilities to be constructed in the station. Finally, a brief summary and research perspective will be presented.     

Solid-state electrochemical gas sensors

The solid-state electrochemical principle has been a selective and accurate way of sensing chemical components in various environments, including liquid metal, for an extended period of time. Since after Carl Wagner’s interpretation of zirconia, there appeared many advances in chemical sensor applications. The electrochemical techniques for the chemical measurements have, in general, several major advantages compared to other methods. The information of interest is directly converted into electrical signal which may be employed in electronic circuits. Electrochemical measurements are always selective for the quantities that undergo the electrochemical redox reaction. In most cases, reactions at equilibrium are considered, but techniques have also been developed to be able to use kinetic limit. Furthermore, the signal is independent of materials properties, such as the ionic conductivity or impurity as long as it is a predominant ionic conductor. Depending on the type of application, voltage or current measurements are employed. While potentiometric method commonly allows measuring chemical species over a wide range of concentration, amperometric sensors generally cover a quite limited range but have a much higher resolution. In this paper, various principles of electrochemical techniques to measure the chemical quantities are introduced. And there are many examples of the status of researches on electrochemical sensors, such as oxygen sensor, carbon dioxide sensor, NO _x sensor, SO _x sensor, and hydrogen sensor.     

Solid-state polymeric dye lasers

This paper presents a review of the organic solid-state polymer materials, which have become established as a new laser media. The photostability of these materials is discussed. Different types of solid-state lasers built around these materials are also reviewed.     

Solid-state wetting on nanopatterned substrates

We review some recent results on the morphology of heteroepitaxial overlayers deposited on nanopatterned substrate surfaces. We mainly focus on modeling based on kinetic Monte Carlo (KMC) simulations. On arrays of parallel grooves or arrays of pillars, we find three main classes of states similar to those known for liquids: (i) Cassie–Baxter states, where solid islands sit on top of the substrate structure; (ii) Wenzel states, where solid islands are in contact with the bottom of the substrate; and (iii) solid imbibition (also denoted as capillary filling for parallel grooves), where the solid forms a film in the substrate surface structure. This multi-stability is controlled by the wettability parameter χ, and shape transitions exhibit hysteresis. We discuss the dynamics of the collapse of a Cassie–Baxter to Wenzel state, and the collapse of the Wenzel state to an imbibition film. We also discuss the possibility to grow crystals in the CB state on nanopatterned substrates. During growth, the crystals formed in CB state merge, leading to a continuous polycrystalline overlayer where the size of the grains is controlled by the distance between pillars.     

全固态塑料电致变色器件

电致变色器件是一种典型的光学薄膜和电子学薄膜相结合的光电子薄膜器件,能够在外加低压驱动的作用下实现可逆的色彩变化。将电致变色材料制备在塑料衬底上,将极大地推动电致变色器件的应用。讨论了全固态塑料电致变色器件的制备工艺和电致变色特性,通过采用低压反应离子镀工艺分别在ITO塑料衬底上制备了WO3和NiO电致变色薄膜。采用高分子聚合物MPEO-LiClO4作电解质,制备plastic/ITO/WO3/MPEO-LiClO4/NiO/ITO/plastic透射型全固态塑料电致变色器件。在二电极电池石英盒中采用恒电位方式测试全固态塑料电致变色器件的电致变色特性,驱动电压为±3V。采用分光光度计直接测试透射光谱的变化,测试范围为300～900nm,经过十几次循环后达到稳定的变色,变色调制范围达到30%左右,器件样品显示出均匀深蓝色的电致变色效果。实验结果证明了所提出的全固态塑料电致变色器件的制备工艺的可行性。     

Solid-state polymerization and polymer crystallization

Effects of the molecular and crystal structures of polymerizable substances on their radiation-induced solid-state polymerization are considered for two cases; the solid state polymerization of cyclic oligomers of formaldehyde and the canal polymerization of some monomers.

Cyclic oligomers of formaldehyde (–CH₂–O–)m from m = 3 to 6 are transformed into three-dimensionally oriented crystalline polyoxymethylene by irradiation. The polymer crystals are characteristically oriented, depending upon the parent oligomer crystal structures. A small amount of an oriented, unstable modification (orthorhombic) polyoxymethylene is also obtained in X-ray in-source polymerization of hexoxane.

Highly 1,4-trans tactic polymerization of 2,3-dichloro-1,3-butadiene and 2,3-dimethy1-1,3-butadiene in the thiourea canals is shown by structural evidence, based upon the crystal structure determinations of the monomerthiourea complexes, the polymer-thiourea complexes, and the resultant polymers for both dienes. The conversion of the monomer-thiourea complexes to the polymer-thiourea complexes by irradiation is performed, retaining the original single crystal habit, though in the canals the monomer-monomer distances are shortened by polymerization. The polymer samples obtained from the single crystals of polymer-thiourea complexes by removal of thiourea are uniaxially oriented and have unusual fine structures.     

Solid-state NMR studies of supercapacitors

Electrochemical double-layer capacitors, or ‘supercapacitors’ are attracting increasing attention as high-power energy storage devices for a wide range of technological applications. These devices store charge through electrostatic interactions between liquid electrolyte ions and the surfaces of porous carbon electrodes. However, many aspects of the fundamental mechanism of supercapacitance are still not well understood, and there is a lack of experimental techniques which are capable of studying working devices. Recently, solid-state NMR has emerged as a powerful tool for studying the local environments and behaviour of electrolyte ions in supercapacitor electrodes. In this Trends article, we review these recent developments and applications. We first discuss the basic principles underlying the mechanism of supercapacitance, as well as the key NMR observables that are relevant to the study of supercapacitor electrodes. We then review some practical aspects of the study of working devices using ex situ and in situ methodologies and explain the key advances that these techniques have allowed on the study of supercapacitor charging mechanisms. NMR experiments have revealed that the pores of the carbon electrodes contain a significant number of electrolyte ions in the absence of any charging potential. This has important implications for the molecular mechanisms of supercapacitance, as charge can be stored by different ion adsorption/desorption processes. Crucially, we show how in situ NMR experiments can be used to quantitatively study and characterise the charging mechanism, with the experiments providing the most detailed picture of charge storage to date, offering the opportunity to design enhanced devices. Finally, an outlook for future directions for solid-state NMR in supercapacitor research is offered.     

Solid-state tapered optical fibre devices

In this paper we report two novel evanescent-field devices based on tapered singlemode optical fibres. In both devices single-mode optical fibre is tapered to waist diameters of around 2 m such that transmission remains close to 100%. In the first device successive coating layers of sol-gel containing fluorescent material are baked on. The major application is in the field of sensing through changes in the absorption and fluorescence characteristics. In the second device, the taper is immersed in a solution of poly(vinyl acetate), also containing fluorescent material. This solidifies, creating a solid-state device. Applications are miniaturized amplifiers and lasers.