In the current scenario of energy transition, batteries for large-scale grid storage require low cost, high safety, low maintenance, high cycle and calendar life, and for some services high power. Redox Flow Batteries (RFB) are particularly well suited to meet these requirements since they cover a power/energy range from several kW/kWh up to tens of MW/MWh and they are designed for longer storage periods compared to most other storage technologies.
Zinc is a very interesting anode for hybrid RFB, with low cost, high performance, environmentally friendliness and guaranteed safety. Several zinc-based chemistries have been proposed for flow or hybrid batteries, some of which have been scaled-up into industrial systems. Among them, the zinc-bromine flow battery (ZBFB) is the most investigated and successfully commercialized. It has an energy density of 60─85 Wh/kg and is capable of 100% DoD, but the main drawback of this technology is the toxicity of bromine. Zinc-iodine RFBs also show a very high performance and are potentially low cost, but they also suffer from the toxicity of iodine.
The potential of the hybrid Redox Zinc/Manganate-Permanganate system has been checked and confirmed through proof of concept experiments performed at Sunergy. A cell using a solid zinc negative electrode that was mechanically rechargeable, coupled to a Manganate/Permanganate aqueous compartment and separated by a Nafion® membrane was used. With more than 4000 hours of operation, the first tests demonstrated the chemical stability of both the Nafion® membrane and of the cell materials with respect to oxidation by permanganate. These first trials highlighted the elements of the battery which need to be improved.
we aim at developing this technology further through our participation to research projects.
2021-2025 : REDZIM project with Cergy Paris University and EDF
The REDZIM project is our first ANR project aiming to develop a hybrid Redox Flow Battery (RFB) system that utilizes zinc and manganate-permanganate as the active materials. This system has the potential to reach volumetric energy densities 30% higher than current vanadium-based RFB systems, and is environmentally friendly, low-cost, and safe. The project, led by LPPI/CY Cergy Paris University, Sunergy and EDF, aims to develop key elements including a high-capacity rechargeable porous zinc anode, a stable cathode in an optimized permanganate-based electrolyte, and a tailored ionic exchange membrane to decrease manganese crossover. The elements will be assembled in cells to evaluate energy, power, and lifespan, and two 5V-10Ah 3 cell demonstrators will be built and tested to analyze intra-cell interactions. The completion of these demonstrators evaluated at TRL4 will prepare the way to a demonstration at TRL5 and higher with an enlarged consortium.