Rational Molecular Design Strategy of a Carbonyl Cathode for Better Aluminum Organic Batteries

Thispaper reports SPTCDA cathode for green and sustainablealuminum organic battery. Aluminumbatteries with aluminum as the anode and organic materialsas the cathode have continuously drawn considerable attention becauseof their high theoretical energy density, natural abundance, and environmentallybenign nature. Herein, we have done an elaborate design work on thebasis of & pi;-& pi; conjugated organic molecule PTCDAby a molecular engineering strategy. Introducing a sulfur atom toreplace the H atom in the aromatic ring of the PTCDA molecule to formSPTCDA (sulfurized PTCDA) with p-& pi; conjugated systemcan reduce the energy level of the molecule. In addition, the extensionof the conjugated system makes the electrons more delocalized, whichis beneficial to the improvement of the conductivity of SPTCDA. Experimentalresults show that compared with pristine PTCDA, SPTCDA has a morestable structure and better cycle performance, rate capability, andcoulombic efficiency, as well as a higher discharge voltage plateau.To further understand the electronic structure, operating voltage,and correct redox mechanism, density functional theory (DFT) calculationswere performed for PTCDA and SPTCDA. The diffusion behavior of ionson the electrode surface was also discussed. This work reveals animportant molecular structure design strategy for a carbonyl cathode,in order to break the application limitations of this electrode materialon aluminum organic batteries.