Encouraged by the good reversibility and high utilisation of non-exfoliated DAAQ-TFP-COF, we decided to extend the study to COF performance in Mg-based batteries. Given the strong tendency of Mg metal to passivate, only handful of salt/solvent combinations are available that enable reversible Mg plating and stripping. In this case, we opted for two electrolytes -one containing chloride species (0.6 M MgTFSI 2 -1.2 M MgCl 2 in DME) and another containing weakly coordinating anions (0.2 M Mg(B(hfip) 4 ) 2 in DME). Given the high surface area of the chosen COF, we have subjected cathodes to electrochemically assisted swelling, to maximise capacity utilisation. Comparison of the galvanostatic curves obtained in two different electrolytes revealed significant differences: COF in non-chlorinated electrolyte exhibited higher overpotential accompanied by a lower average discharge potential (Figs. 4a and S16, ESI). Notably, the COF exhibited good stability in both electrolytes, which is a consequence of its robust structure. This stands in stark contrast to linear anthraquinone-based polymers reported in Mg electrolytes. However, in the case of the chlorinated electrolyte, Coulombic efficiency surpasses 100% during cycling, likely indicative of side reactions or an inadequate voltage window. The rate capability (Fig. ) was performed only in chlorinated electrolyte, considering the relatively low capacities achieved at low current density in the non-chlorinated electrolyte. The rate performance was substantially poorer compared to that in lithium-based counterpart. This discrepancy suggests that kinetic limitations become more pronounced when Mg species are involved in the electrochemical reaction.