RESUMO
This study investigates a salt design principle for aqueous battery electrolytes by combining chaotropic ions, guanidium cations (Gdm) and bis(trifluoromethanesulfonyl)imide anions (TFSI), forming GdmTFSI. This salt's crystal structure was solved via single-crystal X-ray diffraction and characterized using Fourier-transform infrared spectroscopy. Study reveals that GdmTFSI salt disrupts the hydrogen bonding network of aqueous solutions, impacting water reactivity at electrochemical interfaces.
RESUMO
Aqueous sodium-ion batteries (ASIBs) are aspiring candidates for low environmental impact energy storage, especially when using organic electrodes. In this respect, perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) is a promising anode active material, but it suffers from extensive dissolution in conventional aqueous electrolytes. As a remedy, we here present a novel aqueous electrolyte, which inhibits the PTCDA dissolution and enables their use as all-organic ASIB anodes with high capacity retention and Coulombic efficiencies. Furthermore, the electrolyte is based on two, hence "hybrid", inexpensive and non-fluorinated Na/Mg-salts, it displays favourable physico-chemical properties and an electrochemical stability window >3â V without resorting to the extreme salt concentrations of water-in-salt electrolytes. Altogether, this paves the way for ASIBs with both relatively high energy densities, inexpensive total cell chemistries, long-term sustainability, and improved safety.