Novel Rechargeable Hybrid Redox Flow Battery Based on Particle-Stabilised Emulsions and H2 carriers

Since 2010, the global energy system has experienced drastic changes. Indeed, rapid decrease in the cost of eolian and solar power generation has made renewable power plants competitive with conventional fossil alternatives. This has driven the need for investment in flexible energy storage technologies (i.e., batteries) to manage the variable output from generation sources. Lithium-ion batteries (LIBs) are ubiquitous and dominate the actual power market due to their high volumetric and gravimetric energy densities. However, the high maintenance costs and safety restrictions of LIBs (i.e., high ignition risk), combined with the limited availability and sustainability of lithium/cobalt elements and their reduced life cycles (<10,000), are encouraging other technologies for large-scale stationary energy storage. Redox Flow Batteries (RFBs), with modular design, low maintenance costs, safer chemistry, and long-life cycles (>25,000), emerge as alternative candidates to LIBs for sustainable energy storage/generation in eolian park and solar farms. RFBs will charge from those power generation plants to provide on-demand power to the local grid while helping to decarbonise global electricity systems.

Despite the benefits of RFBs, current technologies are today limited by low current/power densities due to low solubility/reversibility of anodic/cathodic electroactive molecules (e.g., vanadium ions). To increase the current/power
densities of RFBs, current research programs focus on the design of soluble, reversible anodic/cathodic electroactive molecules, as well as organic solvents & inorganic acids, with negative effect on the green footprint of the batteries.

The aim of this project is to explore a radically different strategy, impacting the efficiency & green footprint of RFBs, allowing a circular resource-flow. It will design a hybrid RFB, employing an organic H2 carrier couple (AH2/A) in a particle stabilised oil-in-water emulsion as anodic element (generation mode), and air at the cathode. To meet this aim, there are 3 objectives:

O1. Preparation of amphiphilic particles with defined sizes, hydrophilic-lipophilic balance, acidity and catalytic functions (i.e. metal centres);

O2. Generation of particle-stabilized oil-in-water emulsions with high level of particle recycling and reuse, and survey of the ionic conductivity and emulsion-electrode electron transfer;

O3. Engineering a lab-scale hybrid RFB prototype based on particle-stabilised emulsions with high current/power density rechargeability and durability.

The present project will design unprecedented rechargeable RFBs with high cell voltage and power density for stationary energy storage/generation, as alternative to poorly sustainable LIBs and state-of-the-art RFBs, without toxic salts,
expensive solvents, inorganic acids or surfactants. Moreover, it will address circular economy by employing reversible H2 carriers, that can be regenerated using green H2. It will promote among others deployment of electric personal and public vehicles and will then help to save in average 4.6 tons of CO2 per vehicle and per year.