It sounds like old-fashioned alchemy with a drop of sulfur, a bit aluminum and some polymerizable ionic liquids to top it off, but the crazy idea fostered in Spain and at DTU Energy have potential to change and vastly improve battery performance.
Some ideas are just too good to put down, even though the ideas may look impossible to achieve. So it is with an idea fostered by Francisco Jose Perez Alonso at the Spanish company Albufera Energy Storage. A former postdoc from the Technical University of Denmark (DTU) he contacted his old colleagues with an idea to a new battery material that might change the world, and his DTU colleagues liked the idea.
The outcome is new research project funded by EU and starting 1 November 2017.
“We have this crazy idea of batteries based on aluminum and sulfur that - if we are successful - will have a great impact on society”, says senior researcher at DTU Energy, Juan Maria Garcia Lastra.
The project “Sulfur-Aluminium Battery with Advanced Polymeric Gel Electrolytes”, abbreviated SALBAGE, will do research and development on a new aluminum-sulfur battery. The new battery is expected to have a high energy density (1000 Wh/kg), significantly higher than existing Li-ion technology. At the same time, the cost is expected to be only about 60% of that of Li-ion batteries.
In comparison, lead batteries have an energy density of 40 Wh/kg, and Li-ion batteries have 160 Wh/kg.
"All three components have been proven, but not together, so this idea of an aluminum-sulfur-battery might be a crazy idea, but I think we have a chance in making it work"
Juan Maria Garcia Lastra, senior researcher, DTU Energy.
Lithium ions, Li1+, are singly charged, whereas Al3+ ions have a charge of three, meaning that you in principle are able to move three times the amount energy when using aluminum as the electrolyte in a battery instead of lithium; at the same time aluminum is much cheaper. The problem is that Al3+ is very difficult to move compared to Li1+ that only carries a single positive charge. This is one of the reasons for lithium to be so widely used in batteries, but a new battery based on zinc–sulfur will enter the market in a few years, and the Salbage-project plan to substitute zinc with aluminum in their even newer electrolyte material.
The focus will be on the synthesis of solid-like electrolytes based on polymerizable ionic liquids and aluminum compounds with a low melting point to obtain polymer-gel electrolytes with an overall ionic conductivity in the range of 1-10 mS/cm at room temperature. At the same time, the aluminum negative electrode will be combined with a sulfur positive electrode to facilitate sulfur reaction kinetics and boost performance. Moreover, the researchers in SALBAGE will take advantage of the flexibility and shapeability of the resulting battery to design a device for a specific application within intelligent transport systems. The project will also test the performance of the SALBAGE battery.
To achieve the objectives a strong consortium has been gathered, with recognized experts in all the relevant fields, such as polymerization (ICTP- CSIC), synthesis and characterization of materials for the aluminum anode (TU Graz) and for the sulfur cathode (Univ. of Southampton) and development of instrument landing system and data encryption (University of Leicester and Scionix Ltd.). The consortium is led by Albufera Energy Storage, expert in development and testing of batteries, and the role of DTU Energy will be computational modelling at which DTU excels.
“There are three different aspects: the polymerizable ionic liquids, the sulfur electrode and the aluminum electrode. All three components have been proven, but not together, so this idea of an aluminum-sulfur-battery might be a crazy idea, but I think we have a chance in making it work. And our job at DTU will be to make models on how to make it work”, explains senior researcher Juan Maria Garcia Lastra from DTU Energy.
In SALBAGE Project, a new secondary Aluminium Sulfur Battery will be developed. The focus will be put in the synthesis of solid-like electrolytes based on polymerizable ionic liquids and Deep Eutectic Solvents in order to obtain polymer-gel electrolytes with an overall ionic conductivity in the range of 1-10 mS/cm at room temperature. At the same time, the aluminium negative electrode will be combined with a sulfur positive electrode including the unprecedented use of redox mediators, to facilitate sulfur reaction kinetics and boost performance. The new battery is expected to have a high energy density (1000Wh/kg) and low price compared with the actual Li-ion technology (-60%). Moreover, we will take advantage of the special features of the resulting battery (flexibility, adaptability, shapeability) to design a new device with the focus put on strategic applications such as transport, aircraft industry or ITs, for which the SALBAGE battery will be specially designed and tested in relevant conditions.