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HANNOVER MESSE 2019, 01 - 05 April
Homepage>Exhibitors & Products >Strong polymers for stronger accumulator

Strong polymers for stronger accumulator

Separator can lengthen the life of lithium-ion accumulators.

Logo Karlsruher Institut für Technologie

Exhibitor

Karlsruher Institut für Technologie

Exhibitor details
Exhibitor details
Logo Strong polymers for stronger accumulator

Product description

Thanks to their high energy density, lithium-ion accumulators are suitable for use in portable devices such as smartphones. Nowadays, they are also applied in other areas, for example to store energy in electrically powered cars. Properties such as charge time, efficiency, voltage and service life of the accumulator can be modified with the use of selected materials and then be adapted according to where it is used. In charging and discharging an accumulator, lithium ions move between the electrodes through the electrolyte in the electro-chemical cell. The electrodes are spatially and electrically isolated by a separator which has to be permeable for ions. Often, micro-porous polymer membranes are used for this purpose. But if the cells are overcharged or exposed to high temperatures, the polymer separators become deformed. In this process, strong changes in their shape may result in the electrodes coming into direct contact with one another, or even in fires. Scientists at the KIT have developed a novel separator membrane for lithium-ion accumulators consisting of water-soluble polymers and inorganic particles: HTSep - High Temperature Stable Separator for lithium-ion batteries. To make these separators, guaran, or guar gum, a polysaccharide gained from the guar bean, is dissolved in water, and silicon dioxide is subsequently added. In several stages, heat is used to draw water from the suspension that is thus created.The suspension is then transformed into micrometre-thin membranes that are both mechanically and thermally more stable than separators in use so far. Even in the event of overcharging and the development of temperatures of up to 180 degrees Celsius, contact between the electrodes is prevented. In addition, the separator demonstrates good connecting properties vis-à-vis liquid electrolytes. All in all, this results in lithium-ion cells with a high cycle stability and an improved service life.

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Hall 27, Stand K51

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