Voltage Regulation of Conjugated Coordination Polymer Electrodes via 3d Orbital Electron Control in Metal Ions

The application of metal–organic conjugated coordination polymers (CCPs) in lithium-ion batteries has garnered significant attention. However, studies on the regulation of their charge–discharge voltage remain limited. This work demonstrates the regulation of discharge potentials for M-DHBQ (M = Mg, Mn, Fe, Ni, Zn, DHBQ = 2,5-dihydroxy-1,4-benzoquinone) through the optimization of coordination center metal ions. Both experimental and theoretical calculations reveal that the lithium storage potential of different transition metal ions in M-DHBQ correlates closely with the corresponding metal oxides. Ultimately, Fe-DHBQ was identified as the optimal candidate. Fe-DHBQ exhibited a smaller average potential and electrochemical polarization. Experimental results further confirmed that Fe-DHBQ exhibited consistent electrochemical reaction processes, achieving a specific capacity involving a 9-electron transfer. This study provides valuable insights into the design and optimization of CCP-based lithium-ion battery materials and establishes Fe-DHBQ as an electrode candidate for Li-ion batteries.