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We describe the synthesis of new chain polymers that contain weakly basic anionic mono-oxalato orthoborate (MOB) moieties in a polyether backbone at controllable anionic separations. The conductivities of these lithium-conducting polymers are found to be high relative to those of most conventional dry salt-in-polymer electrolytes. An ambient conductivity of about 10−5 S cm−1 has been obtained for a solid polymer with 14 ethyleneoxy repeating units. The electrochemical window for these materials is in excess of 4.5 V. These inexpensive benign materials should be very suitable as electrolytes for rechargeable lithium batteries. [Copyright &y& Elsevier]

Poly[lithium-N(4-sulfophenyl) maleimide -co- methoxy oligo-(oxyethylene) methacrylates] [P(LiSMOEn)s] with three different oligoether side chains and different salt concentrations were synthesized. The copolyelectrolytes are essentially random in structure, with blocks of methoxy oligo(oxyethylene) meth-acrylate (MOEnM) recurring sporadically in between the salt units of N(4-sulfophenyl) maleimide. They all show two glass transitions in the temperature range of -100 to 100°C. The first one below -30°C is assigned to the oligo(oxyethylene) side chain (Tg1), while the second one located between 20 and 50°C is attributed to the main chain of the polymer host (Tg2). The maximum ionic conductivity of the copolymer electrolytes, 1.6 × 10-7 S cm-1 at 25°C, occurs at lithium salt concentration [Li+]/[EO] = 2.2 mol%. The ionic conductive behavior of the copolyelectrolytes follows the Vogel-Tammann-Fulcher (VTF) equation. Moreover, a special VTF behavior exists in the copolymers with shorter oligoether side chain and higher salt concentration. Sweep voltammetric results indicate that these copolyelectrolytes have a good electrochemical stability window. [ABSTRACT FROM AUTHOR]