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Volume 30 (2003)
- Issue 5 Pages 224-
- Issue 4 Pages 154-
- Issue 3 Pages 98-
- Issue 2 Pages 54-
- Issue 1 Pages 2-
Volume 30, Issue 1
Displaying 1-7 of 7 articles from this issue
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M. Kamimoto2003 Volume 30 Issue 1 Pages 2
Published: January 25, 2003
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (199K) -
Jun-ichi Yamaki2003 Volume 30 Issue 1 Pages 3-8
Published: January 25, 2003
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSLithium-ion (abbreviated as Li-ion) cells are widely used as power sources for portable electric devices. Recently, the study of the utilization of the high-performance Li-ion cells as power sources of electric vehicles (EV) and other large-sized equipments has been undertaken by many corporations and laboratories. However large-sized Li-ion cells are not used practically, primarily due to safety considerations. Organic compounds are used as electrolytes of Li-ion cells, and these compounds are flammable. Therefore the generation of heat by chemical decomposition and the chemical reactions in the cells is an important factor to be considered. It is not easy to measure the thermal stability of electrolytes because of their low boiling points. Although, it would be quite interesting to evaluate the stability in a closed sample case such as a cell case, there has been no previous report of such investigations. Therefore, we used DSC to measure the thermal stability of electrolytes as well as the influence of Li metal, C6Li and cathode (Li0.49CoO2) addition on the thermal behavior of these electrolytes under air tight conditions. This report reviews recent studies on thermal stability of materials in Li-Ion cells including our study.View full abstractDownload PDF (1211K) -
Yasushi Idemoto2003 Volume 30 Issue 1 Pages 9-13
Published: January 25, 2003
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSWe investigated the relation between the thermodynamic stability and cathode performance of lithium manganese spinels as cathode active materials for the lithium secondary batteries. The heat of dissolution of these samples was measured by the solution calorimetry method. The standard enthalpy of formation, ΔfH0, the enthalpy change of reaction, ΔH, and the enthalpy change per mole of atoms for the formation reaction, ΔHR, were calculated from the heat of dissolution. The larger |ΔH| or |ΔHR| means a thermodynamically more stable sample. A more thermodynamically stable sample makes a stable crystal structure and leads to a good cycle performance.View full abstractDownload PDF (1279K) -
Jun Aragane2003 Volume 30 Issue 1 Pages 14-17
Published: January 25, 2003
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSFor the evaluation of the chemical properties of the anode active materials for the lithium ion battery, the immersion heat analysis method was studied. The immersion heat is detected when the anode active material like graphite is immersed in organic solvent. The heat value depends on the graphite structure. It was found that the anode active materials were separated in the point of immersion heat.View full abstractDownload PDF (725K) -
Yoshiyasu Saito2003 Volume 30 Issue 1 Pages 18-24
Published: January 25, 2003
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSCalorimetry of lithium-ion cells that were commercially available was carried out to characterize the thermal behavior of the cells during charge and discharge. The generated heat was mainly caused by the entropy change of the cell reaction and the electrochemical polarization. However, in the cell using non-graphitizable carbon material as the anode, complicated heat generation behavior was observed with hysteresis in charging and discharging voltage. Thermal behaviors due to crystal phase transition of the cathode active materials and due to variation of stage structure of graphitic carbon as the anode materials were also observed. Temperature dependency of the crystal phase transition of the cathode active materials was also discussed. Calorimetry could be one of effective methods to characterize the performance of lithium-ion cells.View full abstractDownload PDF (1581K) -
Kenji Tsutsumi, Yo Kobayashi, Seiichi Hagiwara, Michihiro Miyake2003 Volume 30 Issue 1 Pages 25-30
Published: January 25, 2003
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSThe basic examination has been made for the development of a calorimeter detecting a nano-watt output voltage and an efficiency of a newly constructed calorimeter has been tested.
The representative improvements of the calorimeter are as follows; (1) improvement of the thermomodule for the exclusion of temperature noise incident to atmospheric pressure change, (2) improvement of a circuit regulating the sensibility of the thermomodule for the reduction of the base-line drift, (3) temperature stabilization of a water bath immersing the calorimeter, and (4) elimination for the electrostatic and electromagnetic coupling noise. The precision of the calorimeter was less than 0.02μV 4K-124h-1 (0.18μW) for the base line drift in a long time and 0.016μV (0.144μW) for the noise-level of the base line.
The linear relation of the thermal detection to the step-wise supply of the electric energy by about 1μW has been found in the devised calorimeter. As an efficiency test of the calorimeter, calorimetric measurement of a Zn/O2 coin-type cell at low generating power has been carried out, resulting in good effect.View full abstractDownload PDF (1477K) -
2003 Volume 30 Issue 1 Pages 31
Published: January 25, 2003
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (125K)
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