Both CV and GCD three-electrode experiments reveal exciting insights into the cation sizeperformance behaviour of Cu 3 (HHTP) 2 . Firstly, an overall decrease in capacity for both positive and negative charging was observed as the solvated electrolyte cation size approaches and then exceeds the electrode pore size of approximately 14 Å (Fig. ), with TEA + having the highest capacity for both positive and negative charging. This result demonstrates that smaller electrolyte ions lead to higher energy storage performances in MOF-based supercapacitors, and represents the first time that the impact of ion size on the performances of triphenylene-based conductive layered MOFs has been uncovered. One potential explanation for this cation size-performance behaviour is that the nitrogen charge centre of the smaller TAA + cations can get closer to the pore walls of Cu 3 (HHTP) 2 , resulting in smaller charge separation distances and higher capacities. These results confirm, as expected, that electrolytes with smaller ion sizes should be employed in conductive layered MOF supercapacitors in the future to optimise their energy storage performances.