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02582 Characterization of Li2Mn4O9 cathode material by thermogravimetry
06
Electrical power supply and utilization (scientific, technical)
the polarization potential is built up at the interface. The high dielectric constant of ferroelectric films also enhances dipole polarization, substantially improving the Hz gas-induced polarization potential. The results obtained from this experiment reveal the possibility of fabricating largescale, silicon-based ferroelectric thin film gas sensors and related electronic devices, even though research is still in its early stages.
The water formed during stack operation was collected through the outlet of the hydrogen gas and air manifolds. Since the temperature at the centre of the stack was slightly higher than desired, it is recommended that two more cooling plates be added to achieve a more uniform temperature and better stack performance.
Development of prismatic lithium-ion cells using aluminum alloy casing
99102586
Bipolar MIM nonlinear electric components, manufacturing and crystal display panels using thereof 99lO2580
Inoue. T. et al.
Jpn. Kokai Tokkyo Koho, JP 10 270,778 [98 270.7781, (Cl. 9 Ott 1998, Appl. 97/90,312, 25 March, 1997, 15 pp. (In
HOlL49/02), Japanese) The MIM non-linear components described comprise a first conductor film (made from tantalum or tantalum alloy prepared by anodization), a watercontaining insulator film and a second conductor film successively laminated on a substrate. The distribution of the water concentration in the insulator film decreases along the depth towards the first conductor film, reaching a maximum peak near the surface of the second conductor film according to caesium secondary ion SIMS analysis on hydrogen spectra for the water. The maximum peak in thermal desorption spectra occurs in the temperature range 220°C ? 5°C. The insulator films, for example tantalum oxide films, give the components a large non-linearity coefficient, which generates a steep increase in the voltage-current relationship.
Carbon powders for secondary 99lO2581 anodes and their manufacture
lithium battery
Yekoyama, A. et al. Jpn. Kokai Tokkyo Koho JP 10 289,719 [98 289,719], (Cl. HOlM4/58), 27 Ott 1998, Appl. 971110,132, 11 Apr 1997, 6 pp. (In Japanese) Amorphous coal- or petroleumtype pitch is non-graphitized and infusibilized using crvstalization (arauhitiziation) inhibitors. Carbonization then produces the titie carbon poGde;s which lIa;e average particle sizes of S-30 p.m, crystal lattice size dclll,2 of 3.70-3.85 A and less than 0.1% content of elements such as sulfur an d halogens. The carbon powders produce secondary lithium battery anodes with a ~400 mAh/g capacity and good cycling performance.
Characterization of Li2Mn409 cathode material by thermogravimetry
99102582
Dallek, S. Proc. Power Sources Conf., 1998, 38, 378-381. Thermogravimetry (TG) was used to characterize spine1 Li2Mn409 cathode material-for rechargeable lithium batteries. In this paper, a new TG method was developed for determining the oxygen stoichiometry of LizMnlOp and the average oxidation state of the manganese.
Characterization of lithiated natural graphite before and after mild oxidation
99102583
Menachem, C. et al. J. Power Sources, 1998, 76, (2), 180-185. Partial oxidation of natural graphite utilized in lithium ion batteries was found to increase its reversible capacity, while decreasing the irreversible capacity. Several chemically distinct Li sites in lithiated graphite were identified by solid state Li nuclear magnetic resonance (NMR): intercalated Li and Li chemically bonded within the surface passivation layer or solid electrolyte interface (SEl). The partially oxidized graphite exhibited a third site, attributed to Li bonded to armchair, zigzag or other edge sites in the carbon. In addition, the NMR signal from the SE1 in the partially oxidized graphite is consistent with earlier work suggesting that oxidation lays the foundation for a chemically bonded SE1 that is implicated in improved electrochemical performance. Electron paramagnetic resonance (EPR) signals observed in lithiated graphite are attributed to conduction electrons, as noted by other authors. EPR in unlithiated graphite, however, failed to detect a correlation between possible radical sites to which Li could bond and excess Li capacity in the partially oxidized graphite.
Determination of conductance activation energy 99102584 and phase transition entropy of solid Agl
Wang, X. and Li, X. Liaoning Shifan Dame Xuebao. Ziran Kexueban, 1998, 21, (l), 65-66. (In Chinese) The DTA method was used to measure conductance activation energy and phase transition entropy of solid electrolyte AgI. This method is straightforward and quick, making data processing simple and easy. 99102585
Development
of a 1 kW phosphoric acid fuel cell
stack
Ghouse, M. ef al. Applied Energy, 1998, 60, (3), 153-167. Components developed ‘in-house’ at the Energy Research Institute (ERI), King Abdulaziz City for Science and Technology (KACST) were used to design, fabricate and assemble a 1 kW phosphoric acid fuel cell (PAFC) stack with an effective electrode area of 400 cm2. The stack was operated at 180°C for 250 h without any degradation, using commercial Hz/C02 gas and air at 1 bar. The electrical output power generated by the stack was 1 kW (20.5 V x 50 A). Data such as individual cell voltages, stack voltage, stack current, stack temperatures, stack power, stack resistance and flow rates of hydrogen and carbon dioxide gases, and air were recorded during the operation of the stack using a data acquisition and control system. The results of the stack operation show that the stack was stable and that the heat generated in the stack was sufficient to sustain its temperature of 180°C without any external heating. Three cooling plates were used to cool the stack, and it was insulated to maintain a more uniform temperature.
270
Fuel and Energy Abstracts
July 1999
Narukawa, S. ef al. J. Power Sources, 1998, 76, (2), 186-189. Light weight prismatic lithium-ion cells for cellular phones have been developed using an aluminum alloy case. Various kinds of aluminum alloys have been examined from the view point of the electrochemical stability, mechanical strength, the ability to be laser-welded and easy formation into a casing. An aluminum alloy with 1.1 wt% manganese was the best candidate for the casing. The energy density of the lithium-ion cell with the aluminum alloy casing was improved by about 30% compared to the conventional steel casing.
Dynamic characteristics of phosphoric-acid cell stack cooling system
99102587
fuel-
Mikia, H. and Shimizu, A. Applied Energy, 1998, 61, (l), 41-56. In power generation systems, the phosphoric-acid fuel-cell has advanced with relatively small outputs from thousands to millions of watts and several commercial plants are expected to be built in the near future. In such a system, the temperature in the cells must be kept within a certain range by a cooling system. The cooling system, employing water, would be preferable in order to obtain a uniform temperature-distribution, thereby saving the power of auxiliary machines and utilizing the exhaust heat for other processes requiring heat. In this paper, the results of the numerical simulation of dynamic characteristics of this cooling system and the fuzzy approach to control the cooling system are reported. The fuzzy control system with strategies self-tuned during operation could be superior to a conventional PID control, which is difficult to tune via three parameters for a complex system.
Effects of barium and cobalt on electrochemical performance of nickel hydroxide with chemically co-precipitated zinc 99102580
Shaoan, C. et al. J. Power Sources, 1998, 76, (2), 215-217. The effects of Ba(OH), and Co(OH)z on electrochemical performance of nickel hydroxide prepared with chemically co-precipitated zinc in a nickelmetal hydride battery _ (Ni-MH) are studied. The results show that the oxygen-generation potential and the discharge depth of the nickel electrode are improved by the combined addition of Ba(OH)l and Co(OH)z compared with only Co(OH) 2. The capacity of the Ni-MH battery is also enhanced due to increase in the utilization of the active material of the positive electrode.
Electrical resistivity of liquid carbon 99102589 Korobenko, V. N. et al. High Temp., 1998, 36, (5), 701-707. In this study the first results of experiments in rapid (~1 mcs) heating of graphite of perfect structure by an electric current pulse are presented. The specific enthalpy and specific heat capacity of the solid and liquid phases during melting and the heat of melting were both measured. The electric resistivity of liquid carbon was recorded during heating of cylindrical graphite samples in sapphire capillary tubes. Initial data for the heat capacity of liquid carbon up to -10,000 K are given. Electrochemical characteristics of a carbon electrode with gel polymer electrolyte for lithium-ion polymer batteries
99102590
Kim, D.-W. J. Power Sources, 1998, 76, (2), 175-179. A study of the electrochemical performance of a carbon electrode prepared with mesocarbon microbeads is carried out in a new polymer electrolyte for application as the negative electrode in rechargeable lithium-ion polymer batteries. The polymer electrolyte is prepared by solution casting from a homogeneous mixture containing 18 wt% acrylonitrile-methyl methacrylate-styrene (AMS) terpolymer, 73 wt% 1 M LiC104 in ethylene carbonate (EC)/dimethyl carbonate (DMC) and 9 wt% silica. The lithium/polymer electrolyte/carbon half cell has a reversible capacity of 305 mA h-’ g in the voltage range 0.01 to 1.5 V at the C/10 rate and shows an attractive coulombic efficiency which is higher than 99% after the first three cycles. Good cycling performance of a lithium-ion polymer cell which comprises a carbon anode, an AMS-based polymer electrolyte and a lithium intercalation cathode (LiNi~.X~Co0.170~) has been achieved.
Electrochemical intercalation of cationic and anio99102591 nic species from a lithium perchlorate-propylene carbonate system - a rocking-chair type of dual-intercalation system
Santhanam, R. and Noel, M. J. Power Sources, 1998, 76, (2). 147-152. The reductive and oxidative intercalation of ionic species of lithium perchlorate (LiCIOI) in propylene carbonate (PC) medium are carried out to develop a dual-intercalation battery system. Cyclic voltammetry (CV), potentiostatic transients (i-t), galvanostatic charging, thermogravimetry (TG) and differential thermal analysis (DTA) are performed to establish the intercalation behaviour of both lithium and perchlorate ionic species. A polypropylene graphite composite electrode material containing- 20 wt% polypropylene as a binder is found to be a suitable host material for dual intercalation studies. The intercalation/de-intercalation efficiency (IDE)
Electrical power supply and utilization (scientific, technical)
the polarization potential is built up at the interface. The high dielectric constant of ferroelectric films also enhances dipole polarization, substantially improving the Hz gas-induced polarization potential. The results obtained from this experiment reveal the possibility of fabricating largescale, silicon-based ferroelectric thin film gas sensors and related electronic devices, even though research is still in its early stages.
The water formed during stack operation was collected through the outlet of the hydrogen gas and air manifolds. Since the temperature at the centre of the stack was slightly higher than desired, it is recommended that two more cooling plates be added to achieve a more uniform temperature and better stack performance.
Development of prismatic lithium-ion cells using aluminum alloy casing
99102586
Bipolar MIM nonlinear electric components, manufacturing and crystal display panels using thereof 99lO2580
Inoue. T. et al.
Jpn. Kokai Tokkyo Koho, JP 10 270,778 [98 270.7781, (Cl. 9 Ott 1998, Appl. 97/90,312, 25 March, 1997, 15 pp. (In
HOlL49/02), Japanese) The MIM non-linear components described comprise a first conductor film (made from tantalum or tantalum alloy prepared by anodization), a watercontaining insulator film and a second conductor film successively laminated on a substrate. The distribution of the water concentration in the insulator film decreases along the depth towards the first conductor film, reaching a maximum peak near the surface of the second conductor film according to caesium secondary ion SIMS analysis on hydrogen spectra for the water. The maximum peak in thermal desorption spectra occurs in the temperature range 220°C ? 5°C. The insulator films, for example tantalum oxide films, give the components a large non-linearity coefficient, which generates a steep increase in the voltage-current relationship.
Carbon powders for secondary 99lO2581 anodes and their manufacture
lithium battery
Yekoyama, A. et al. Jpn. Kokai Tokkyo Koho JP 10 289,719 [98 289,719], (Cl. HOlM4/58), 27 Ott 1998, Appl. 971110,132, 11 Apr 1997, 6 pp. (In Japanese) Amorphous coal- or petroleumtype pitch is non-graphitized and infusibilized using crvstalization (arauhitiziation) inhibitors. Carbonization then produces the titie carbon poGde;s which lIa;e average particle sizes of S-30 p.m, crystal lattice size dclll,2 of 3.70-3.85 A and less than 0.1% content of elements such as sulfur an d halogens. The carbon powders produce secondary lithium battery anodes with a ~400 mAh/g capacity and good cycling performance.
Characterization of Li2Mn409 cathode material by thermogravimetry
99102582
Dallek, S. Proc. Power Sources Conf., 1998, 38, 378-381. Thermogravimetry (TG) was used to characterize spine1 Li2Mn409 cathode material-for rechargeable lithium batteries. In this paper, a new TG method was developed for determining the oxygen stoichiometry of LizMnlOp and the average oxidation state of the manganese.
Characterization of lithiated natural graphite before and after mild oxidation
99102583
Menachem, C. et al. J. Power Sources, 1998, 76, (2), 180-185. Partial oxidation of natural graphite utilized in lithium ion batteries was found to increase its reversible capacity, while decreasing the irreversible capacity. Several chemically distinct Li sites in lithiated graphite were identified by solid state Li nuclear magnetic resonance (NMR): intercalated Li and Li chemically bonded within the surface passivation layer or solid electrolyte interface (SEl). The partially oxidized graphite exhibited a third site, attributed to Li bonded to armchair, zigzag or other edge sites in the carbon. In addition, the NMR signal from the SE1 in the partially oxidized graphite is consistent with earlier work suggesting that oxidation lays the foundation for a chemically bonded SE1 that is implicated in improved electrochemical performance. Electron paramagnetic resonance (EPR) signals observed in lithiated graphite are attributed to conduction electrons, as noted by other authors. EPR in unlithiated graphite, however, failed to detect a correlation between possible radical sites to which Li could bond and excess Li capacity in the partially oxidized graphite.
Determination of conductance activation energy 99102584 and phase transition entropy of solid Agl
Wang, X. and Li, X. Liaoning Shifan Dame Xuebao. Ziran Kexueban, 1998, 21, (l), 65-66. (In Chinese) The DTA method was used to measure conductance activation energy and phase transition entropy of solid electrolyte AgI. This method is straightforward and quick, making data processing simple and easy. 99102585
Development
of a 1 kW phosphoric acid fuel cell
stack
Ghouse, M. ef al. Applied Energy, 1998, 60, (3), 153-167. Components developed ‘in-house’ at the Energy Research Institute (ERI), King Abdulaziz City for Science and Technology (KACST) were used to design, fabricate and assemble a 1 kW phosphoric acid fuel cell (PAFC) stack with an effective electrode area of 400 cm2. The stack was operated at 180°C for 250 h without any degradation, using commercial Hz/C02 gas and air at 1 bar. The electrical output power generated by the stack was 1 kW (20.5 V x 50 A). Data such as individual cell voltages, stack voltage, stack current, stack temperatures, stack power, stack resistance and flow rates of hydrogen and carbon dioxide gases, and air were recorded during the operation of the stack using a data acquisition and control system. The results of the stack operation show that the stack was stable and that the heat generated in the stack was sufficient to sustain its temperature of 180°C without any external heating. Three cooling plates were used to cool the stack, and it was insulated to maintain a more uniform temperature.
270
Fuel and Energy Abstracts
July 1999
Narukawa, S. ef al. J. Power Sources, 1998, 76, (2), 186-189. Light weight prismatic lithium-ion cells for cellular phones have been developed using an aluminum alloy case. Various kinds of aluminum alloys have been examined from the view point of the electrochemical stability, mechanical strength, the ability to be laser-welded and easy formation into a casing. An aluminum alloy with 1.1 wt% manganese was the best candidate for the casing. The energy density of the lithium-ion cell with the aluminum alloy casing was improved by about 30% compared to the conventional steel casing.
Dynamic characteristics of phosphoric-acid cell stack cooling system
99102587
fuel-
Mikia, H. and Shimizu, A. Applied Energy, 1998, 61, (l), 41-56. In power generation systems, the phosphoric-acid fuel-cell has advanced with relatively small outputs from thousands to millions of watts and several commercial plants are expected to be built in the near future. In such a system, the temperature in the cells must be kept within a certain range by a cooling system. The cooling system, employing water, would be preferable in order to obtain a uniform temperature-distribution, thereby saving the power of auxiliary machines and utilizing the exhaust heat for other processes requiring heat. In this paper, the results of the numerical simulation of dynamic characteristics of this cooling system and the fuzzy approach to control the cooling system are reported. The fuzzy control system with strategies self-tuned during operation could be superior to a conventional PID control, which is difficult to tune via three parameters for a complex system.
Effects of barium and cobalt on electrochemical performance of nickel hydroxide with chemically co-precipitated zinc 99102580
Shaoan, C. et al. J. Power Sources, 1998, 76, (2), 215-217. The effects of Ba(OH), and Co(OH)z on electrochemical performance of nickel hydroxide prepared with chemically co-precipitated zinc in a nickelmetal hydride battery _ (Ni-MH) are studied. The results show that the oxygen-generation potential and the discharge depth of the nickel electrode are improved by the combined addition of Ba(OH)l and Co(OH)z compared with only Co(OH) 2. The capacity of the Ni-MH battery is also enhanced due to increase in the utilization of the active material of the positive electrode.
Electrical resistivity of liquid carbon 99102589 Korobenko, V. N. et al. High Temp., 1998, 36, (5), 701-707. In this study the first results of experiments in rapid (~1 mcs) heating of graphite of perfect structure by an electric current pulse are presented. The specific enthalpy and specific heat capacity of the solid and liquid phases during melting and the heat of melting were both measured. The electric resistivity of liquid carbon was recorded during heating of cylindrical graphite samples in sapphire capillary tubes. Initial data for the heat capacity of liquid carbon up to -10,000 K are given. Electrochemical characteristics of a carbon electrode with gel polymer electrolyte for lithium-ion polymer batteries
99102590
Kim, D.-W. J. Power Sources, 1998, 76, (2), 175-179. A study of the electrochemical performance of a carbon electrode prepared with mesocarbon microbeads is carried out in a new polymer electrolyte for application as the negative electrode in rechargeable lithium-ion polymer batteries. The polymer electrolyte is prepared by solution casting from a homogeneous mixture containing 18 wt% acrylonitrile-methyl methacrylate-styrene (AMS) terpolymer, 73 wt% 1 M LiC104 in ethylene carbonate (EC)/dimethyl carbonate (DMC) and 9 wt% silica. The lithium/polymer electrolyte/carbon half cell has a reversible capacity of 305 mA h-’ g in the voltage range 0.01 to 1.5 V at the C/10 rate and shows an attractive coulombic efficiency which is higher than 99% after the first three cycles. Good cycling performance of a lithium-ion polymer cell which comprises a carbon anode, an AMS-based polymer electrolyte and a lithium intercalation cathode (LiNi~.X~Co0.170~) has been achieved.
Electrochemical intercalation of cationic and anio99102591 nic species from a lithium perchlorate-propylene carbonate system - a rocking-chair type of dual-intercalation system
Santhanam, R. and Noel, M. J. Power Sources, 1998, 76, (2). 147-152. The reductive and oxidative intercalation of ionic species of lithium perchlorate (LiCIOI) in propylene carbonate (PC) medium are carried out to develop a dual-intercalation battery system. Cyclic voltammetry (CV), potentiostatic transients (i-t), galvanostatic charging, thermogravimetry (TG) and differential thermal analysis (DTA) are performed to establish the intercalation behaviour of both lithium and perchlorate ionic species. A polypropylene graphite composite electrode material containing- 20 wt% polypropylene as a binder is found to be a suitable host material for dual intercalation studies. The intercalation/de-intercalation efficiency (IDE)