Developing lithium-metal polymer batteries is considered as a long-term solution to provide high-energy power sources that will enable electrical vehicle to perform comparably to conventional vehicles. A promising solid polymer electrolyte should combine high conductivity, chemical/electrochemical stability, and good mechanical properties. Polyether type materials are the most studied polymer matrix for "dissolving" lithium salts. Poly(ethylene oxide) (PEO), a low-cost commercial polymer, has very poor conductivity at ambient temperature due to crystallization. Its conductivity above melting point is acceptable for advanced transportation usage (10~(-3) S/cm at 85deg C). However, the mechanical properties become much decreased at the molten state. Although the mechanical properties of PEO can be improved by increasing molecular weight (increasing "entanglement"), the stress relaxation behavior upon time makes it not a definite solution for the problem. The true solid, rubber-like polymer electrolytes without scarifying conductivity are desired for good battery performance.
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