A tert-butyl functionalized quinone as active material for rechargeable aqueous zinc-ion batteries exhibiting high round-trip efficiency

The implementation of renewable electricity into the grid requires efficient grid-energy storage systems for balancing supply and demand. Rechargeable zinc-ion batteries (ZIBs) are a low-cost, safe option for grid energy storage; however, challenges pertaining to energy storage capacity, round-trip efficiency, stability, and reliance on critical minerals still need to be addressed. Herein, 3,5-di-tert-butyl-ortho-benzoquinone (TBOBQ) was evaluated as an organic cathode material for ZIBs, achieving a maximum theoretical specific capacity of 246 mAh/g at 40 mA/g (C/4) with a 1 to 1 mass ratio of TBOBQ-to-acetylene black. The observed charge and discharge curves presented a voltage hysteresis of only 100 mV, resulting in a round-trip efficiency of 90 %. Degradation of the TBOBQ cathode was attributed to fractional dimerization and dissolution during discharge, as observed by nuclear magnetic resonance, mass spectroscopy, and rotating ring disk electrode. This work sets the stage for the development of organic ZIB cathodes based on TBOBQ with high discharge capacities and energy efficiency.