Cells constructed with B-CuHHTP consistently recorded lower rate capabilities across the same current density range (with Cg retention of 40 ± 4% between 0.025 -1 A g -1 ) than those made of A-CuHHTP (Cg retention of 60 ± 1%) (Fig. ; SI Fig. ). This is consistent with the results from CV experiments above, which have recorded current densities of between 0.3 -0.5 A g -1 , and demonstrates that short charging times lead to poor energy storge in 'rod-like' particles. Consideration of the different pore structures of the two samples can explain this difference in behaviour. For the 'flake-like' particles of A-CuHHTP, the pores run perpendicular to the face of the flakes, resulting in many short pores. This creates an easily accessible pore network with short diffusion paths through the particles. In contrast, the 'rod-like' particles of B-CuHHTP have pores which run parallel along the length of the crystals, resulting in fewer longer pores. This reduces accessibility to the full pore network at short charging times as the diffusion paths through the particles are longer. As a result, lower current densities and longer charging times are needed to allow electrolyte ions to access the entire pore volume in B-CuHHTP. C-CuHHTP also displays a very low rate capability over the same current density range (17 ± 2%), supporting the above conclusion that strong agglomeration of the MOF particles further reduces pore accessibility. To test the above hypothesis, electrochemical impedance spectroscopy (EIS) was performed on the cells (Fig. , SI Fig. ). Typically, the EIS spectra of supercapacitors show three distinct domains.