Electrochemical Production of Silicon

Silicon solar cells are crucial devices for generating renewable energy to promote the energy and environmental fields. Presently, high-purity silicon, which is employed in solar cells, is manufactured commercially via the Siemens process. This process is based on hydrogen reduction and/or the thermal decomposition of trichlorosilane gas. The electrochemical process of producing silicon has attracted enormous attention as an alternative to the existing Siemens process. Thus, this article reviews different scientific investigations of the electrochemical production of silicon by classifying them based on the employed principles (electrorefining, electrowinning, and solid-state reduction) and electrolytes (molten oxides, fluorides, chlorides, fluorides–chlorides, ionic liquids [ILs], and organic solvents). The features of the electrolytic production of silicon in each electrolyte, as well as the prospects, are discussed

Scientific Assessment in support of the Materials Roadmap enabling Low Carbon Energy Technologies: Hydrogen and Fuel Cells

A group experts from European research organisations and industry have assessed the state of the art and future eeds for materials' R&D for hydrogen and fuel cell technologies. The work was performed as input to the European Commission's roadmapping exercise on materials for the European Strategic Energy Technology Plan. The report summarises the results, including key targets identified for medium term (2020/2030) and long term (2050) timescales.JRC.F.2-Cleaner energ

Brief history of early lithium-battery development

Lithium batteries are electrochemical devices that are widely used as power sources. This history of their development focuses on the original development of lithium-ion batteries. In particular, we highlight the contributions of Professor Michel Armand related to the electrodes and electrolytes for lithium-ion batteries

Electrodeposition and characterisation of nickel-niobium-based diffusion barrier metallisations for high temperature electronics interconnections

The control of interfacial microstructural stability is of utmost importance to the reliability of liquid solder interconnects in high temperature electronic assemblies. This is primarily due to excessive intermetallic compounds (IMCs) that can form and continuously grow during high temperature operation, which practically renders conventional barrier metallisations inadequate. In this study, electrically conducting, NbOx containing Ni coatings were developed using electrodeposition. Their suitability as a solder diffusion barrier layer was assessed in terms of the electrical conductivity and barrier property. The present work explores a novel electrochemical route to produce Ni-NbOx composite coatings of good uniformity, compactness and purity, from non-aqueous glycol-based electrolytes consisting of NiCl2 and NbCl5 as metal precursors. The effects of cathodic current density and NaBH4 concentrations on the surface morphology, composition and thickness of the coatings were examined. A combined study of Scanning Transmission Electron Microscopy (STEM) and Electrochemical Quartz Crystal Microbalance (EQCM) was conducted to understand the fundamental aspects of this novel electrodeposition process. The composite coatings generally exhibited good electrical conductivity. The reaction behaviour between a liquid 52In-48Sn solder and Ni-NbOx, with Nb contents up to 6 at.%, were studied at 200ºC. The results indicate that, Ni-NbOx with sufficient layer thickness and higher Nb content, offered longer service lifetime. Nb enrichment was generally observed at or close to the reaction front after high temperature storage, which suggests evident effectiveness of the enhanced diffusion barrier characteristics

Study of the Effects of Ionic Liquids as Electrolyte Addictive for Redox Flow Batteries

Master'sMASTER OF SCIENC

Solid Oxide Electrochemical Cells for High Temperature Hydrogen Production: Theory, Fabrication and Characterization

In this dissertation, the concept of water splitting using solid oxide photoelectrochemical cells (SOPCs) at high temperature was introduced and experimentally investigated. High temperature photoelectrochemical water splitting physically broadens the selection of potential applicable semiconductor materials and enables more visible sunlight absorption. This newly conceived concept provides a unique pathway for solar hydrogen production, as compared to conventional photoelectrochemical cells (PECs) that use wide band gap semiconductors in aqueous environments. The theoretical framework of SOPC was elaborated, followed by the experimental investigation to search for appropriate high temperature materials. Selected high temperature Schottky and p-n junction diodes, which were expected to be applicable to the photocatalytic/oxygen electrodes of SOPCs, were fabricated and evaluated. Their rectifying characteristics were characterized at elevated temperatures. Among those diodes, only LSM/TiO2 demonstrated acceptable rectifying properties up to 450 °C, indicating that such configuration may be applicable to the proposed SOPC. The further investigation was carried out on fabrication of the electrodes of SOPC and solid oxide fuel cell (SOFC) using fused deposition modeling (FDM), a technique of 3D printing. The goal was to directly print out ceramic substrates and eventually make porous electrodes. Ceramic filaments that consist of ceramic electrode materials and thermoplastics were fabricated in house. After experimenting many thermoplastics, Nylon 12 was identified as an ideal thermoplastic polymer to make composite ceramic filaments. The printouts were sintered in the furnace to burn out all the organics, leaving behind porous electrodes made of pure ceramics. The 3D printed cathodes on half SOFCs were evaluated and demonstrated comparable performance to conventional SOFCs using dip-coating method. Therefore, FDM provides a viable and low cost means to fabricate the porous electrodes of SOPC/SOFC