K.W. Kim

Electrochemical properties of sulfur electrode containing nano Al2O3 for lithium/sulfur cell

To prevent the dissolution of lithium polysulfides into liquid electrolyte and to promote the lithium/sulfur redox reaction, nano-sized Al2O3 particles having large specific surface area were added into sulfur electrode. The effects of nano-sized Al2O3 particles on the electrochemical properties of sulfur electrode for lithium/sulfur battery were investigated using CV measurements, charge/discharge tests and ionic conductivity measurements of liquid electrolyte. From the results, the sulfur electrode containing nano Al2O3 particles showed good cycle performance and higher discharge capacity of 660 mAh g−1-sulfur than that of the sulfur electrode without nano Al2O3. It is therefore concluded that the addition of nano-sized Al2O3 particles gives the beneficial effects of preventing the dissolution of lithium polysulfides into liquid electrolyte.

Sulphur–carbon composites for Li/S batteries

Abstract Structural and electrochemical properties of various types of sulphur–carbon composites were reviewed to propose approaching ways for the development of lithium/sulphur battery with high energy density and good cycle performance. To improve the electrochemical properties of a sulphur cathode, carbon and polymer materials are applied to sulphur composites: multiwalled nanotube (MWNT), graphene, CMK-3 and activated carbon; and polyaniline (PANi), polyacrylonitrile and polythiophene (PTh). These can serve conducting paths and a polysulphide reservoir to enhance the electrical conductivity of the sulphur cathode and effectively prevent dissolution of polysulphides. And the composites are categorised in two parts such as mixed type sulphur composites and embedded type sulphur composites. Among the sulphur–carbon composites, the hollow carbon capsule/S composite prepared by a geometric control and an infusion method of sulphur in sulphur carbon composite electrode, demonstrated the best electrochemical properties.

Electrochemical properties of magnesium electrolyte with organic solvent

Three kinds of electrolytes are investigated to find out the proper electrolyte for magnesium battery. Propylene carbonate electrolyte using magnesium salt of Mg(ClO4)2 shows a higher ionic conductivity than that of dimethyl carbonate and tri(ethyleneglycol dimethyl)ether (TRGDME) but low decomposition potential. The TRGDME electrolyte with 0.5?M Mg(ClO4)2 has a higher ionic conductivity of 6 ? 10?4 ?S?cm?1 than that of dimethyl carbonate, but the decomposition voltage of the electrolyte is over 3.0?V which can be used for Mg/S cell.

Fabrication of ZnO nanorods by electrochemical deposition process and its photovoltaic properties

Abstract ZnO nanorod arrays were successfully prepared on indium doped tin oxide by electrochemical deposition in a solution of 0·0015M Zn nitrate [Zn(NO3)2.6H2O] and 0·028M methenamine (C6H12N4). The morphology of ZnO nanorods was affected by growth condition to control the current density. The fabricated ZnO nanorods were characterised by field emission scanning electron microscopy and X-ray diffraction. The photovoltaic properties of the ZnO nanorods, as potential materials for dye sensitised solar cells, were evaluated using a 1·5 solar simulator.

Effect of Fe addition on cycle performance of FeS2 cathode for Li/FeS2 battery

Abstract The effect of Fe addition on the cycle performance of FeS2 cathode for Li/FeS2 cell was investigated. In Li/FeS2 cell without Fe addition, a large voltage drop was observed in the initial discharge process, and the cell showed poor cycle performance during 40 charge/discharge cycles. On the other hand, the Li/FeS2 cell with 10 wt-%Fe delivered a higher discharge capacity of ∼670 mAh g−1 FeS2 in the first discharge and exhibited better cycle performance than the cell without Fe addition. The rate capability of the cell was also greatly improved by the addition of Fe in the FeS2 cathode.

Physical and electrochemical properties of nanostructured nickel sulphide as cathode material for lithium ion batteries

Abstract Nanostructured nickel sulphide as a cathode material for lithium ion batteries was fabricated. The large surface area of the reaction between electrodes and electrolyte offers high energy density and capacity. In addition, metal sulphides have high theoretical capacity. Nickel nanowires were fabricated by electrochemical deposition using an anodic aluminium oxide template with a diameter of 200 nm. The fabricated nickel nanowires were carried out with sulphuration treatment. The morphology and microstructure of the nanowires were characterised with field emission SEM, X-ray diffraction, TEM and X-ray photoelectron spectroscopy. Nickel sulphide nanowires were applied for lithium ion batteries, and charge/discharge tests were carried out with the galvanostatic method.

Effects of TiO2 buffer layer on carbon nanotube grown on Ti substrate by thermal chemical vapour deposition and their electrochemical properties

Abstract Non-conductive substrates, such as silicon wafers, have usually been used to synthesise carbon nanotubes (CNTs). However, in applications such as electrodes, it is desirable to have CNTs grown on conductive buffer layer and conductive substrates. Vertically aligned multiwall CNTs were grown on Ni/TiO2/Ti substrates by thermal chemical vapour deposition. The experimental parameters are synthesis temperature, time and buffer layer thickness. The synthesised multiwall CNTs have an outer diameter of ∼100 nm and length of about 5–10 μm. Li/multiwall CNT cell with multiwall CNTs on Ti substrate exhibited good charge/discharge behaviour and slow capacity fading. The samples were characterised by means of field emission scanning electron microscopy, Raman spectroscopy analysis, transmission electron microscopy and electrochemical test.