Energy Solutions CR2032 SS316 coin cell cases. Film electrodes were cut from freestanding composite f-CMK-3 and YP-80F films with areal mass loadings of f-CMK-3 ranging between 5 -11 mg cm -2 . The minimum weight ratio between the negative (f-CMK-3) and positive (YP80F) electrode was 1: >2.5, respectively. This ensured excess charging capacity on the YP-80F electrode (relative to the f-CMK-3 electrode). Therefore, the potential on the working f-CMK-3 electrode is expected to limit the stable working voltage range for the cell. Whatman glass microfiber filter (GF/A) was used as a separator and dried in vacuo at 100 °C for 24 h prior to use. 1-Butyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide ionic liquid (200 𝜇m) was used as an electrolyte in all experiments. All electrochemical cells were assembled inside a glovebox under an inert nitrogen (N2) atmosphere. Each coin cell contained two SS316 spacer disks and one SS316 spring to ensure sufficient and consistent pressure in the cells. The coin cells were sealed in the glovebox using a Compact Hydraulic Coin Cell Crimper (Cambridge Energy Solutions) before being removed for testing.