High Energy Density Lithium-Air Flow Batteries using Ionic Liquid Electrolytes

DOE ARPA-E PROPEL-1K Project

University of Kansas and Washington University in St. Louis

This project aims to develop a scalable Li-air flow battery empowered by room temperature ionic liquid (ILs) and will experimentally show a specific energy of 1,000 Wh/kg and an energy density of 1,240 Wh/L.  The battery employs a lithium metal electrode and a porous positive electrode circulated by ILs.  This innovative approach integrates modular design for rapid mass and ion transfer, leverages ILs chemical, physical, and thermal stability, employs customized separators to prevent oxygen and moisture crossover to lithium metal, and utilizes positive electrodes with high discharge-charge efficiency.  Room temperature ILs are particularly advantageous due to their minimal vapor pressure, resulting in negligible evaporation, and their high oxygen solubility.  Key deliverables from this project include:

  • A scalable battery de-risking experiment that experimentally shows:
    • Specific energy of ≥ 1,000 Wh/kg and > 1,000 Wh/L
    • 90 seconds of ≥ 0.25 kW/kg peak power capability
    • Reversibility 10 cycles and ≤ 10% energy loss based on comparison of the 10th to 1st cycle
  • Electrochemical and mechanical design for a ≥1 kWh unit that can be constructed to experimentally show ≥ 1000 Wh/kr and ≥ 1000 Wh/L at the packaged level
  • High-level system model for a ≥ 1 MWh system model that includes all sub-systems
  • Bridging plan on how to go from 1 kWh unit to 1 MWh system
schematic diagram illustrating an energy storage and transfer system. On the left, a lithium-based electrochemical cell is depicted with labeled components: a lithium (Li) layer, a separator, and an electrode, with positive and negative terminals. The diagram shows ion movement through an electrolyte labeled 'Ionic.' Fluidic pathways with arrows represent the flow of ions and electrical charge. On the right, two detailed sub-diagrams depict the internal structure of a microfluidic or thermal management system. One section shows a serpentine channel design guiding fluid movement, and the other magnifies the porous structure facilitating transport between 'In' and 'Out' points. Labels and arrows indicate the direction of charge and fluid flow within the system.