Renewable electricity, coupled with electrochemical energy storage, is a pathway to alleviate our dependence on fossil fuel and enable carbon neutrality. Unfortunately, the cost of storing electricity is still higher than generating electricity. In addition to cost, the current version of lithium-ion batteries is unlikely to meet the requirements of all existing and future applications with different energy-to-power ratios and safety sensitivities. Since 2017, our lab at Georgia Tech has been working on several rechargeable battery technologies that have unique advantages over lithium-ion as well as their own challenges. Targeting those challenges, we designed, fabricated and analyzed new materials and reactors with enhanced reaction and transport properties at the nano- and microscale.
For example, metallic zinc as a rechargeable anode material for aqueous batteries has gained tremendous attention with merits of intrinsic safety, low cost, and high theoretical volumetric capacity (5,854 mAh/cm3). Among zinc-based batteries, Zn-air batteries are promising with the highest theoretical volumetric energy density (4,931 Wh/L). Rechargeable zinc anode has recently achieved progress in neutral electrolytes, yet developed slowly in alkaline electrolytes, which are kinetically favorable for air cathodes. Passivation, dissolution, and hydrogen evolution are three main reasons for irreversibility of zinc anodes in alkaline electrolytes, which limits the rechargeability and usable energy density. We carried out material engineering at the nanoscale to overcome these three challenges of zinc anode. We have also used gas chromatography quantitative analysis and operando microscopy to quantify gas evolution side reaction and visualize the reaction on electrodes during operation, respectively. In this talk, I will present our findings on zinc-based batteries, as well as solid-state batteries and redox flow batteries, which could potentially expand the portfolio of electrochemical energy storage technologies for sustainable energy.