Alkaline Earth Metal Terephthalates MC8H4O4 (M=Ca, Sr, Ba) as Anodes for Lithium Ion Batteries

Carboxylate-based metal organic frameworks are popular lithium storage electrode materials by using carbonyl groups as redox centers. In this study, alkaline earth metal terephthalates MC8H4O4 (M=Ca, Sr, Ba) are prepared and applied as anodes for lithium ion batteries. The structure differences in terms of crystallography and molecular structures and electrochemical differences resulting from alkaline earth metal ionic radii are explored. It is found that electrostatic interactions between the alkaline metal cations and the terephthalate anions are important to the crystal structure, although these three organic matters consist of alternating layers of terephthalate anions and polyhedrally coordinated metal cations, but do not form iso-structure. Moreover, terephthalate salt with smaller cationic radius is featured with ionic bond behavior, lower discharge potential vs. Li/Li+ and higher discharge capacity with good capacity retention behavior.