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

Abstract

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.

Nitroxide radical cathode material with multiple electron reactions

“…1 (c). TPA-TEMPO has an EPR signal with g = 2.0064, which is equal to the g value of OH-TEMPO, corresponding to the oxygen-centered nitroxide unpaired electron [32]. However, the inherent paramagnetic feature makes TPA-TEMPO impossible for 1 H nulcear magnetic resonance (NMR) characterization directly.…”

Ultrafast Charge/Discharge by a 99.9% Conventional Lithium Iron Phosphate Electrode Containing 0.1% Redox-Active Fluoflavin Polymer

“…Nonconjugated redox-active polymers have exceptionally rapid charge/discharge capability, sometimes over 10 3 C, owing to the fast electrochemical kinetics of the redox-active groups and high adhesion to property conductive carbons. − Chemical structures and electrochemical characteristics of redox-active polymers can be tuned finely by versatile organic synthetic approaches. − By sandwiching the potential of LiFePO 4 (3.4 V), fluoflavin redox polymer P1 is expected to facilitate the electron injection/ejection of the inorganic material catalytically via the mediation effect. ,, The concept was preliminarily examined by hybridizing lithium metal oxides (e.g., LiFePO 4 , LiCoO 2 , and LiMnO 2 ) and redox-active polymers to achieve faster charge/discharge. ,, The fast mediation was also supported by the facile electron transfer between the organic compounds and metal oxides, and a rate constant of 10 –3 cm/s was reported with 1,1′-dibromoferrocene and LiFePO 4 . However, the large amount of polymer (20–50 wt %) that was added to the electrodes ,,, lowered the energy density of the cell, especially the volumetric energy density.…”

Polymer‐Based Batteries—Flexible and Thin Energy Storage Systems

“…Recently, crown ethers have been studied as additives in electrolytes, which lead to an increase in the cell voltage of ORBs based on PTMA and lithium. [ 90 ]…”