June 3, 2020

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Breakthrough in lithium-sulfur batteries

Battery charge status set, accumulator indicator image

Battery charge status set, accumulator indicator image

Australian and German researchers have developed a battery that gives cars a range of 1,000 kilometers and more. It is also inexpensive to manufacture and does not require any toxic elements such as lithium-ion batteries.

With a new battery that is the same size as a block of lithium-ion batteries used today, electric cars have a range of 1,000 kilometers and more. Researchers from Monash University in Melbourne (Australia) the Fraunhofer Institute for Material and Beam Technology (IMS) and the Chair of Inorganic Chemistry at the Technical University of Dresden have developed the sensational electricity storage system.

The battery already manages 200 charging cycles

Dresden has been the most important center for the development of this new type of battery for years. Previous prototypes, however, had too short a lifespan. After a few charge and discharge cycles, the cathodes were destroyed. The current model, which was manufactured in Dresden, has at least 200 cycles without losing any significant capacity. In practice, this is still too little, but an encouraging step, especially since this battery does not need the toxic cobalt.

The cathodes consist of 70% sulfur, 20% carbon and 10% lithium carboxymethyl cellulose (CMC). These components are mixed with water to a paste and smoothed out. After drying, the cathode is finished. CMC is a binder that reduces the consequences of “breathing” the cathodes. This means their extreme extent during unloading, which is reversed when loading. This leads to rapid destruction of the electrodes.

Mahdokht Shaibani from the Faculty of Mechanical and Aerospace Engineering at Monash University led the international team of researchers who came up with the idea of ​​using CMC. When the battery is discharged, lithium ions migrate from the anode to the cathode, where they form lithium-sulfur compounds. This process was reversed when loading. The CMC does not completely prevent “breathing”. However, it ensures that the remaining components of the cathodes always remain connected. To a certain extent, CMC forms flexible bridges. This was shown when taking pictures with the scanning electron microscope. In the language of the scientists, it sounds like this: “Inspired by the classic approaches in particle agglomeration theory, we have found an approach in which minimal amounts of a high-modulus binder are placed between neighboring particles, leaving more space for material expansion and ion diffusion.”