an advantage, concern has been raised because the high operating voltage may be outside the stability window of most electrolytes. Rechargeable lithium organic electrolyte cell performance data are limited. The companies involved in the technology and the sizes being manufactured are given in Table II. For evaluation purposes, cells were procured from Moli Energy (Li-MoS2) and AT&T (Faraday Li-NbSe3) and subjected to cycling tests. The results are shown in Figs. 2 and 3. Typical charge and discharge curves are given in 2(a) and 3(a). Capacity to a voltage (1.3 V) vs cycle number is given in Fig. 2(b) for the Moli cells operated at three rates and for three Faraday cells operated at the same rate as the cells in Fig. 3(b). Surprisingly, the Moli cells discharged at C/5 had significantly longer cycle life than those operated at C/2 or C/10. End-of-discharge voltage vs cycle data for the Moli cells at 50% DOD are given in Fig. 2(c). JPL assembled engineering model 5 Ah Li-TiS2 cells were discharged at three rates. Examples of the discharge voltage curves for cells discharged at C/10, C/5 and C/2 are given in Fig. 4(a). The capacity of these cells was found to approach 8 Ah (Fig. 4(b)). The cycle life of these first Li-TiS2 cells is given in Fig. 4(c). A comparison of the three types of cells is given in Table III. The Faraday cell exhibited greater than 100 Wh/kg in a prototype cell. The MoS2 cell was significantly less at 65 Wh/kg and the JPL cell assembled with existing laboratory hardware exhibited 75 Wh/kg. With an optimized design and a larger cell configuration, 100 Wh/kg is considered to be realistic for the Li-TiS2 cell. Polymeric Electrolyte Cells Cells of the polymeric electrolyte type have been under development for the past 10 years [3]. They are still in the experimental stage and are not yet commercially available. Harwell Laboratories and Institute de Recherche d’Hydro Quebec (IREQ) are very active in the development of these cells. The uniqueness of this system resides in the fact that all the components are in the solid state. These cells contain thin electrolyte films (10-100 «m thickness) enclosed in a sealed container. A thin polymer is required to enhance the transport of the lithium ions between electrolytes and to minimize cell resistance. In order to be practical the polymeric electrolytes must have a high area to mass ratio.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==