Abstract: A battery for oilfield applications which may include: a housing and an electrolytic cell disposed in the housing. The electrolytic cell may include: a cathode, an anode, and a polymeric separator disposed between the cathode and anode. The cathode may include a cathode composite material coated on a substrate. The cathode composite material may include: a polymeric continuous phase; an active material; a carbon source; and; a first lithium salt. The anode may comprise lithium. The polymeric separator may include: a first polymer crosslinked by a photoinitiator; and a second lithium salt.

Abstract: A laterally compressed envelope of solid electrolyte material is provided for use as an electrode holder in an electrochemical cell. It has two opposed major faces sealed together along at least part of the periphery of the envelope, each major face being provided by a sheet of said solid electrolyte material. Each sheet is provided on its inner surface with a plurality of ribs or corrugations extending alongside one another, each rib or corrugation of each said sheet crossing over a plurality of the ribs or corrugations of the other said sheet. The envelope has an internal volume, between the sheets, defined at least in part by grooves or valleys between the ribs or crests of the corrugations. Each part of said internal volume is in communication with each other part of said internal volume. The invention also provides a method of making the envelope, and an electrochemical cell in which the envelope forms an electrode holder.