*2.4. Preparation of the Electrodes*

Electrodes were prepared using the mesoporous carbon PICACTIF from PICA (BP10) as reported in [8] and described in Figure S1a. BP10 featured a Brunauer, Emmett and Teller (BET) specific surface >2000 m<sup>2</sup> g−<sup>1</sup> and a pores size distribution centered at 2.7 nm [8]. Two water processable formulations have been studied. A first one with 70% BP10, 10% Carbon black, 20% pullulan-glycerol (1:1 wt) and low mass loading (3.6–4.6 mg cm<sup>−</sup>2) is referred in the following text as high binder low mass electrode (HBLME). A second one with 85% BP10, 5% Carbon black, 10% pullulan-glycerol and higher mass loading is labelled as low binder high mass electrode (LBHME). Electrodes have been obtained by casting on pre-cut nickel foams (diameter 0.9 cm) a slurry containing 23.5 mg of BP10, 3.5 mg of carbon black (as conducting additive), 6.7 mg of pullulan (P0978, TCI) and glycerol in 0.8 g of MilliQ water for HBLME. For LBHME the ink was composed of 40.2 mg of BP10, 2.3 mg of carbon black (as conducting additive), 4.7 mg of pullulan and glycerol in 0.57 g of MilliQ water. The electrodes were then dried in an oven (under vacuum) overnight at room temperature (Büchi glass oven B-585). The composite electrode loadings (excluding the nickel foam mass) are reported in Table 1.

**Table 1.** Composition and mass loading of High Binder Low Mass Electrode (HBLME) and Low Binder High Mass Electrode (LBHME).


\* single electrodes mass loading.
