"Neutral-Ph" Aqueous Zinc Ion Battery for Utility Energy Storage

Abstract

Solar and wind are the key to meet US National Academies requirement of replacing fossil fuel by renewable energy sources: 30% in 2030 and 50% in 2040. While the intermittent and seasonal nature of solar/wind energy generation will require unusually large-scale energy storage capacity for wide durations of 4-10 hours or longer. As today’s dominant grid energy storage technology, Li ion battery has high energy density and long durability but fire hazards and supply chain concerns. For the utility-scale energy storage applications, fundamentally different electrochemistry with intrinsic safety is required based on earth-abundant elements (e.g., Na, K, Zn, Mg, Ca, Al, Fe, Mn) to avoid the competing demands of LIBs for mobile and EV battery applications. Among emerging beyond LIB chemistries, aqueous zinc ion battery (AZIB) utilizing Zn, Mn, close to neutral-PH aqueous electrolyte is a promising candidate due to raw materials abundance, low cost, nonflammability, low corrosion, high durability, etc. Even though water stability leads to lower operating voltage of AZIB than LIB (1.7 V vs. 4 V), the overall theoretical energy densities are comparable to high ends of LIBs (300 Wh/kg and 500 Wh/L). With further research and development for performance improvements, neutral-PH AZIB could be a very competitive solution for utility energy storage. In this presentation, we show recent efforts from Hunt Energy Enterprises (HEE) to commercialize this class of AZIB system. With the optimized electrolyte control, the system reveals high potential to achieve durability for at least 5,000 cycles under practical current rate. The fundamental and development challenges for this system will be discussed.