POLY(ETHYLENE OXIDE)-B-POLY (4-VINYLBENZYLMETHOXYTRIS-OXYETHYLENE ETHER) DIBLOCK COPOLYMER ELECTROLYTES FOR LITHIUM BATTERIES

摘要

Polymer electrolytes are of great interests in the applications of high power density lithium batteries due to their safety advantage over the volatile, flammable and toxic small molecule electrolytes. Dry polymer electrolytes in lithium batteries are often made of mixing polymers with a lithium salt. The polymer materials used in the electrolytes are able to solvate lithium ion to keep high ion conductivity without sacrificing the mechanical strength for electrode separation. Poly(ethylene oxide) (PEO) has been the most widely studied and used polymer in electrolytes due to its high ionic conductivities at temperature above its melting point. However, the low modulus of the amorphous PEO fails to prevent the dendrite growth, which eventually short circuits the battery.2 Many recent work has been done to develop polymers to enhance the lithium ion solvating and retain the mechanical properties, including diblock copolymer consists of an ionic conductive block and a rubbery block. The PEO-b-polystyrene(PS) diblock copolymers as polymer electrolytes have been extensively studied by Balsara's group. Nevertheless, the non-conducting PS block has negative impact on the ion conductivity of the polymer electrolytes. Here we address this issue by introducing oligo(ethylene oxide) side chains to the nonconducting block. The poly(ethylene oxide)-b-poly(4-vinylbenzyl methoxytris-oxyethylene ether) (PEO-b-PTEGSt) diblock copolymer were synthesized by atom transfer radical polymerization (ATRP) and evaluated as electrolytes in lithium battery.