The Advances in Cathodes

LiCo02 is used in most of the Li batteries in production, in spite of its limited availability and cost. It gives the highest capacity and cycle numbers. Lithiated Ni oxide is next in capacity and 

Solvated polymers are approaching gels in properties, depending on the mobility of the molecules. In some cases the action of a binder and of a separator are combined. By extraction of one of the components and refilling the voids with a liquid, a two-phase system can be created (Bellcore). There are irreversible and re- 

A great variety of polyolefin separator types are now used in Li ion batteries. They must be stable in the organic electrolytes. Typically they may not be properly wetted by the electrolytes of the optimized composition, e. g., mixtures with PC, PE, and others. Therefore some proprietary treatments are needed to provide hydrophilic behavior. Generally, a micro-porous nonwoven morphology with a large surface gives a good wettability. 

As a safety specialty, polyethylene separators are used to shut down run-away (shorting) Li cells by simply melting and creating a high-resistance barrier. The speed of resistance gains increases, approaching the melting point. Bilayers of polyethylene (PE) and polypropylene (PP) are even faster (Hoechst) (see also Chapter III, Sec. 10). 

Liquid organic eIectroI)des consist of a solvent and a salt propylene carbonate (PC) for carbon electrodes, ethylene carbonate and dimethyl carbonate (EC and DMC) for graphite electrodes. LiPF is the usual conductivity salt. A poorly understood process is the formation of a solid electrolyte interface (SEI) on the anode, starting the intercalation process, probably via Li carbonate. Efficiency losses during the formation depend on the carbons or graphites gas is the result of decomposition reactions. To reduce the hazards of flammability solid polymer electrolytes originally polyethylene oxide —PEO— and doped polymer electrolyte with some plasticizers were introduced. Valence first used irradiation for additional crosslinking. 

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