Representative embodiments provide a composition for printing a liquid or gel separator utilized to separate and space apart first and second conductors or electrodes of an energy storage device, such as a battery or a supercapacitor. A representative composition comprises a plurality of particles, typically having a size (in any dimension) between about 0.5 to about 50 microns; a first, ionic liquid electrolyte; and a polymer or polymeric precursor. In another representative embodiment, the plurality of particles comprise diatoms, diatomaceous frustules, and/or diatomaceous fragments or remains. Another representative embodiment further comprises a second electrolyte different from the first electrolyte; the plurality of particles are comprised of silicate glass; the first and second electrolytes comprise zinc tetrafluoroborate salt in 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid; and the polymer comprises polyvinyl alcohol (“PVA”) or polyvinylidene fluoride (“PVFD”). Additional components, such as additional electrolytes and solvents, may also be included.