Elucidating Metal and Ligand Redox Activities of Copper-Benzoquinoid Coordination Polymer as Cathode for Lithium-Ion Batteries
Cheng-Han Chang, An-Che Li, Ilja Popovs, Watchareeya Kaveevivitchai, Jeng-Lung Chen, Kai-Chun Chou, Ting-Shen Kuo and Teng-Hao Chen
Abstract
A novel redox-active quinone-based organic building block 1,4-dicyano-2,3,5,6-tetrahydroxybenzene (LH4) has been synthesized, and used as a bridging ligand to form a new 1D copper-benzoquinoid coordination polymer [CuL(DMF)2]n. The compound is able to deliver an initial capacity as high as 240 mA h g–1 at 20 mA g–1 (~C/3) when used as cathode in Li batteries. Ex situ XPS and FT-IR reveal the involvement of both Cu and the organic moieties in the multi-electron redox reaction. Cu K-edge XANES and EXAFS measurements confirm the change in the oxidation state and coordination environment of Cu during discharge-charge process. In situ generated metallic nanoparticles have been observed by TEM. The obtained mechanistic understanding of the metal-organic electrode materials for Li-based batteries may pave the way for the design of next-generation energy-storage systems.