Achievement of high performance properties of L[lc]i ion cells for scientific satellites
| Autor: | Yamamoto, Masahiro, Oto, Hiroki, Eguro, Takashi, Tajima, Michio, Hirose, Kazuyuki, Takahashi, Keiji |
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| Jazyk: | japonština |
| Rok vydání: | 2003 |
| Předmět: | |
| Zdroj: | 第22回宇宙エネルギーシンポジウム 平成14年度 = The 22nd ISAS Space Energy Symposium March 12, 2003. :11-15 |
| Popis: | Li ion cells have a higher specific energy than alkaline cells widely used to date and can contribute well enough to the requirement of the weight saving of secondary batteries for space applications. Because of their higher discharge voltage, the number of onboard cells installed in the secondary batteries can be reduced, higher reliability for battery subsystems being achieved. In addition, the Li ion cells are characterized by longer life capability in charge and discharge cycles, operations of the cells in a low earth orbit and a geostationary orbit being expected in the near future. Extensive researches have been conducted on improvement in prismatic Li ion cells with specifically longer life capability since 1996 and capabilities of these cells for space applications have been verified. As a result, for the first time in Japan these Li ion cells were adopted as a battery for a sample return mission spacecraft, MUSES-C to be launched in May 2003. The battery consists of 11 lithium ion cells with a rated capacity of 13.2 Ah, which are connected in series to supply power required to loads at a bus voltage of 50 V during a discharge period. However, there are some problems yet with the Li ion cells for MUSES-C. First of all, a specific energy of 85 Wh/kg is too small for these Li ion cells. Next, the capacity degradation due to a floating charge condition is larger than that of the alkaline cells. To resolve such problems, the active material of the negative electrodes of the Li ion cells, their separator, their electrolytic constituents, and so on have been improved, so that a rated capacity of 23.5 Ah as well as a specific energy of more than 105 Wh/kg has been obtained, achievement of a capacity degradation rate of 5.5 percent/year becoming near at hand by evaluating floating charge test results until 430 days and a subsequently potential decrease in the capacity degradation rate. Researches on longer life capability in the space environment of the improved Li ion cells must be immediately conducted to verify the improved cells as batteries to be installed in planetary exploration spacecraft like MMO (Mercury Magnetospheric Orbiter) and a Venus orbiter. PLANET-C. It is planned to carry out further improvement in the specific energy of the improved cells from now on. 資料番号: AA0045915003 |
| Databáze: | OpenAIRE |
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