The worldwide demand of lithium-ion batteries for use in laptop computers is 150 million units per year, but this batteries cannot support requirements of electric cars, so Li and Ni-MH (nickel-metal hydride) batteries have to fulfil new requirements. With the status of 1999 latest achievements in the performance of Li batteries are described in this article. Among the options for improving Li cells are changing the processing and the composition of electrolytes. Today Li cells use liquid-organic, dry-polymer or gel-polymer electrolytes (GPE). With reducing manufacturing costs and improving cell packages, GPE cells can compete in the portable-device market. Cell designs can be optimized by computer modeling. Optimizing the electrode surface allows Li batteries with 100 Wh/kg. Goals of a development program for advanced Li-ion solid-polymer-electrolyte are: 200 - 250 Wh/kg specific energy, 350 - 400 Wh/l energy density and cycle life of 2000 (100 % discharge) and 35000 (25 % discharge). New development tools are systems engineering and modeling. In a micro-macro coupled model, equations of the electrochemical processes are entered. Evaluating of data is effectively done with fuzzy logic. Low-temperature performance and loss of carbon is discussed for the Li batteries, also improved materials for the cathodes. The low-temperature performance will be a focal point for spacecraft and interplanetary spacecraft; requirements for the Mars 2001 lander are described. An important application for Li-batteries are geosynchronous satellites where their lifetime must be nine years. Alternatives to Li batteries are batteries with Ni-MH, especially for telecommunications systems. Requirements are a supplying power for 3 h at -20 to +60 deg C plus standby life of 15 years at 30 deg C. Additives reduce degradation from overcharge; improved Ni-MH batteries can last 2.5 years at 25 deg C.
Advances in lithium and nickel-metal hydride battery performance
MRS Bulletin ; 24 , 11 ; 33-39
1999
7 Seiten, 6 Bilder, 1 Tabelle, 20 Quellen
Article (Journal)
English
galvanische Batterie , Lithium , Nickel-Metallhydrid-Batterie , Stand der Technik , Leistungsabgabe , Betriebstemperatur , Festelektrolyt , Gel , Polymer , Energiedichte , Fertigungstechnik , mathematisches Modell , Fuzzy-Logik , Entwicklung (Tendenz) , Raumfahrt , Telekommunikation , geosynchroner Satellit
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