Excellent Effect of Betaine in Dilute Electrolytes and Application to High Performance Aqueous Li‐Ion Batteries

The energy density and operating voltage of aqueous batteries are limited by the narrow electrochemical stability window side reactions traditional electrolytes. Considering that optimization electrolyte composition can effectively improve performance batteries, it has advantages simple easy large-scale preparation, betaine with rich polar groups zwitterions is added to as a functional material reduce binding degree water molecules adsorbed in electrolyte-electrode interface prevent contact interface. A wide (2.91 V) low salt concentration (2 M) were achieved electrolyte. interactions between molecules, lithium salts explored ATR-FITR, NMR Raman spectroscopy. Aqueous TiO2/LiFePO4 full cells stable specific energies 69 Wh kg−1 demonstrated over 500 cycles on such non-fluorinated