In the race to achieve a battery that can revolutionize the electric car sector, a technology has been trying to reach prime time for a few years. It’s all about lithium-sulfur chemistry. A great promise for electric mobility due to the high theoretical specific capacity of the sulfur cathode, 8 times greater than that of the materials used in current systems. Its use would reduce the weight of the pack and significantly increase the autonomy of electric vehicles.
Now, after a few years without much news about this system, we have learned that the prestigious Fraunhofer Institute for Materials Technology is working on a new generation of batteries lithium-sulfur within the research project «MaSSiF».
The teams in this project have focused on a combination that includes a solid sulfur-silicon electrolyte, whose objective is the design, construction and evaluation of prototypes of cells based on sulfur. They hope the result will be to develop lightweight batteries, but also at a low cost, with a high capacity for fast charging, and with a high storage capacity.
The use of silicon as anode material should also significantly improve cell life. One of the keys to this chemistry that until now has been very limited due to the low number of cycles.
The Federal Ministry of Education and Research (BMBF), under the leadership of the Fraunhofer Institute for Materials and Beam Technology IWS in Dresden, is financing six industry partners with a total of almost 2.9 million euros. The project was launched in February 2023.
Sulfur-based solid electrolyte batteries are considered a potential successor technology to current lithium batteries. According to the Fraunhofer researchers, the combination with sulfur as the active cathode material is particularly promising. Allow dispense with critical elements such as cobalt and nickelmaintaining high figures of energy density.
However, the short life of these batteries and their poor charge and discharge capacity made them unfeasible for commercialization. The problem with lithium-sulfur batteries is twofold. On the one hand, the sulfur cathode degrades during the charge and discharge processes, forming polysulfites, which dissolve easily in the organic electrolyte. On the other hand, some of the polysulfites can react with lithium and deposit on the anode surface.
As part of the project, the partners rely on develop a material for the anode which has also proven to be a promising alternative in current research work on batteries with solid electrolyte: silicon. In the sulfur combination, a solid electrolyte and silicona prototype will be created that combines low material costs and high energy density.
The goal of the initiative is to create a real test model with a density of 350Wh/kgand that manages to maintain its useful life in a high percentage beyond 300 cycles.
The result will be a base on which to create batteries with a high specific energy, in addition to having important advantages in aspects such as cost thanks to the use of cheaper and more sustainable raw materials and a short local supply chain, which will even allow a production 100% local.