Plastic lithium ion PLI batteries

This technique ensures good interfacial contact between the layers which in turn leads to low internal resistance (and thus to high rate capability) and to long cycle life. A cyclability of up to 1500 cycles to a cut-off of 80% of initial capacity at the 1 C rate at room temperature, energy densities of the 

Ultralife Batteries Inc. has recently announced the development of their Rechargeable Solid State System based on this technology. A schematic drawing of the cell is shown in Fig. 7.41. Single cells and battery packs are now in production. Energy densities in the ranges 100-125 Wh/kg and 200-300 Wh/dm3, as well as cyclability up to 1200 deep cycles, have been reported. Excellent characteristics are claimed. Cellular telephones, portable computers and camcorders appear to be the most suitable outlets for these PLI batteries. 

The physical properties of lithium metal were given in Table 4.4. Despite its obvious attractions as an electrode material, there are severe practical problems associated with its use in liquid form at high temperatures. These are mainly related to the corrosion of supporting materials and containers, pressure build-up and the consequent safety implications. Such difficulties were experienced in the early development of lithium high temperature cells and led to the replacement of pure lithium by lithium alloys, which despite their lower thermodynamic potential remained solid at the temperature of operation and were thus much easier to use. 

Of the various solid intermetallic lithium compounds which might be used in high temperature cells, the Li-Al system has been most studied. The Li-Al phase diagram is shown in Fig. 8.1. An a phase which consists 

The emf of the lithium-aluminium system versus pure lithium in a Lil-KI-LiCl molten eutectic is shown in Fig. 8.2 as a function of temperature and composition. It can be seen that the emf remains constant (at about 300 mV more negative than pure lithium) in the range of stability of the /3-phase (-7-47 atoms per cent of lithium), thus implying a constant lithium activity in the alloy surface. At concentrations greater than 47 atoms per cent, the lithium activity becomes strongly composition-depen-dent. 

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