Increasing the energy density of rechargeable lithium batteries is a goal of considerable significance and improvements in all battery components are essential to this. The redox reactions that occur at the electrodes of batteries require the transport of both ions and electrons to the active centers. This requirement brings significant complications since materials that transport ions and electrons are vastly different. We report on the synthesis of a block copolymer (BCP) that exhibits simultaneous electronic and ionic conduction. A combination of ac impedance spectroscopy and dc measurements determined that both ionic and electronic charges were transported simultaneously within the BCP. Electronic conductivities are also measured with applied potentials, showing the intrinsic semiconductor property of the polymer. Lithium battery cathodes were then cast from solution using the BCP as binder-electrolyte and LiFePO4 as active material. Fully solid state lithium batteries were assembled by adding a solid polymer electrolyte as separator and lithium foil as the anode. These batteries showed specific capacities within experimental error of the theoretical capacity.  The ability of the BCP to serve all of the supporting functions required in a lithium battery electrode is thus demonstrated.

Multifunctional binder-electrolyte for use in lithium battery electrodes

247th National Meeting (2014)

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