Design of Organic-Based Coordination Architectures as Electrode Materials for Metal-Ion Batteries
Hristo Rasheev, Yanislav Danchovski, Daniel Dinev, Radostina Stoyanova, Alia Tadjer
Abstract: Batteries have been in the focus of scientists’ attention ever since they were discovered but this century sees more aspects of their application than mankind ever imagined. This invokes a zealous competition for their upgrading and diversification in two directions – search of new electrochemical workhorses and search of new materials outperforming the established ones. Unquestionably, the Liion batteries are the most successful current technology but any improvement in terms of efficiency, price and safety is appreciated avidly.
Traditionally, the electrodes in metal-ion batteries are inorganic oxygen-containing compounds of one or more transition metals. In the redox process participate mainly the metals and only in special cases the oxygen comes into play. In the quest for novel electrode materials, various classes of organic redox-active compounds have been suggested but they feature an intermediate potential (low for cathodes and high for anodes), low cycling stability and are usually soluble in the electrolyte. Here we suggest constructs, in which organic redox-active molecules are locked in coordination
architectures of different dimensionality, thus taking advantage of the reversible redox properties of
both the transition metal and the organic ligands.
The structures are assembled of Ni in two of its oxidation states (II, IV) and functionalized benzoquinones as ligands. With these building blocks are constructed complexes (0D), coordination
polymers (1D), and a 3D metal-organic framework, while in the 2D architecture the coordination
complexes are covalently anchored on graphene. Stepwise addition of charge carriers (Li, Na, Mg) is
executed to assess the profile of the electrode potential and the structural and electronic changes
ensued. DFT within the GGA level is the method of choice for both the single complexes (Gaussian)
and the periodic structures (VASP). The theoretical capacity and energy density of the constructs
reveal that they could be successfully used as novel hybrid electrode materials.
The authors from CARiM’s Research Team are bolded.
VIHREN-CARiM 2019 