In the last decade the sol-gel process became a promising method to synthesize materials in form of coatings, nanoscale powders and porous systems. Several products or devices made with such a process already exist on the market. This paper briefly reviews the state of the art in the development of electrochromic coatings and devices and nanocrystalline solar cells achieved during the last decade using sol-gel derived pure and doped niobium pentoxide. Nb 2 O 5 ELECTROCHROMIC (EC) COATINGS AND DEVICESGeneral reviews on the preparation and on the properties of electrochromic coatings and devices prepared by the sol-gel method have been already published by Agrawal et al. [7] and the author [8-10].The first mention of a persistent but reversible optical change produced electrochemically in Nb 2 O 5 coatings was published by Reichman and Bard in 1980 [11]. Such an effect was observed on a niobium metallic disk oxidized at approximately 500 • C for 10 min. The blue coloring effect, seen in reflection under H + and later also under Li + insertion [12], was chemically stable and showed fast kinetics (1 to 2 s).Since then several more adequate deposition techniques have been used to obtain niobium oxide EC films among which CVD [13], DC magnetron sputtering [14], electrochemical method [15] and the dip or spin coating process via the sol-gel route [6]. Lee and Crayston [16] were the first to show that pure sol-gel Nb 2 O 5 coatings present an electrochromic effect. They prepared 5 to 10 µm thick coatings by spinning a hydrolyzed solution of NbCl 5 dissolved in ethanol on ITO coated glass. The films showed Pure niobium oxide sol-gel coatings and devices.

No abstract

To improve the cycle performance of lithium ion battery (LIB), boric acid tris-(2-oxo- [1,3]dioxolan-4-ylmethyl) ester (BATE) as a novel electrolyte additive in 1mol•L -1 LiPF 6 -EC:DMC (1:1 vol., Lithium Battery-grade) electrolyte was investigated. BATE derived from glycerol carbonate, which had the same ring structure as ethylene carbonate (EC). Additionally, the carbonyl group (-C=O) and electron deficient boron atom contained in the BATE molecular structure had been proved to be effective in maintaining the stability of the lithium salt (LiPF 6 ) and increasing the durability of the electrolyte for formation of a solid electrolyte interface (SEI) layer, which plays a critical role in the cycle life of lithium ion battery (LIB). The electrochemical measurements and investigations of the compound BATE as additive were carried out by charge-discharge test, electrochemical impedance spectroscope (EIS), cyclic voltammetry (CV) test and scanning electron microscope (SEM). Results confirmed that BATE decomposed on the graphite anode earlier than electrolyte solvents to form the solid electrolyte interface (SEI) film. BATE could improve cycle stability of the cell significantly, especially when addition of 1.0% BATE, the capacity retention was up to 98.1% after 20 cycles. And the internal resistance change of cell with cycles was decreased after 20 cycles.