Fig. 4: Schematic representation of the charging and discharging behaviour of Ni3(HITP)2 MOF electrodes with aqueous 1 M NaTFSI electrolyte. | Nature Communications

Fig. 4: Schematic representation of the charging and discharging behaviour of Ni3(HITP)2 MOF electrodes with aqueous 1 M NaTFSI electrolyte.

From: Selective Anion Anchoring in MOF-Based Supercapacitors Revealed with Operando Small-Angle X-Ray Scattering

Fig. 4

The schematic highlights immobilised TFSI- ions near the pore walls, even in the absence of an applied external cell voltage, likely due to hydrogen bond interactions between the fluorine atoms (yellow-green) of TFSI- and the NH groups (blue and light grey) of the MOF linker. Charge balancing is cation-dominated, with co-ion expulsion of Na+ at positive cell voltage and counter-ion adsorption of Na+ at negative cell voltage. The dashed circles in the pore at 0 V indicate the pore diameter (1.39 nm) and the boundary of the TFSI--rich layer (0.9 nm) from the form factor.

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