Crown Ethers as Electrolyte Additives To Modulate the Electrochemical Potential of Lithium Organic Batteries

Organic batteries have attracted much attention because of their flexibility, high-power densities, and highly designable structures of electrode-active materials. The electrochemical potential of the batteries can be modulated using different organic redox species or by structural modification of the redox unit centers. In this study, the electrochemical potential of lithium organic radical batteries is modulated, without the structural modification of the redox unit centers. Two different crown ethers, 12-crown-4 (12C4) and 15-crown-5 (15C5), served as electrolyte additives to increase the electrochemical potential of the batteries. An average discharge voltage can be increased to 3.90 V through the electrolyte system using various concentrations of the electrolyte salt and crown ethers. The addition of 1 equiv of 12C4 to the Li|0.25 M LiClO4-ethylene carbonate/diethyl carbonate (= 1/1, v/v|poly(2,2,6,6-tetramethylpiperidin-1-oxy-4-yl methacrylate) cells significantly improved the capacity retention up to 21% after 300 cycles at a current rate of 3C. Furthermore, the structures and system energies of the lithium–crown ether complexes are investigated using density functional theory calculations.