What is advanced battery technology

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Plastics for the battery technologies of tomorrow

 

The mobile electrification of our living and working worlds is reflected today, for example, in smartphones, cordless screwdrivers, robotic lawnmowers and electric cars. And a further increase in mobile electrical solutions is to be expected. Such a wide distribution z. B. of modern consumer electronics is inconceivable without advanced energy storage technologies such as rechargeable batteries. But they are also indispensable for storing electrical energy from alternative energy sources such as photovoltaics and wind power, in order to guarantee a constant power supply even under unfavorable weather conditions. Plastics have long played an important role in such batteries as electrolytes, electrode components, separators or coatings. Corresponding polymer materials, also with new functionalities, can be used in existing battery systems on the one hand to optimize the battery parameters, but on the other hand they could also enable new effective chemical compositions and thus new battery types. In this way, they could also be important pioneers for very high energy densities. Lithium-ion and lithium-sulfur batteries, in which polymer materials can make a decisive contribution to further development, are currently of particular interest.

Elastic and self-healing polymers can, for example, help stabilize and protect silicon anodes, which theoretically can improve battery performance ten times over graphite anodes in lithium-ion batteries. This is because the large volume changes occurring in such anodes can lead to the formation of cracks and thus the destruction of the anode during the charging and discharging processes in silicon anodes. Sulfur cathodes in lithium-sulfur batteries also show large changes in volume. In particular, electrically conductive polymers such as polyaniline, polypyrrole or poly-3,4-ethylenedioxythiophene (PEDOT) can serve as matrix material. Furthermore, polymer solid electrolytes or special polymer coatings can be used to control the dendrite formation in lithium anodes, so that the formation of tree-like or bush-like outgrowths from the anode into the electrolyte is prevented during the charging process. Since the ion conductivity of such polymeric solid electrolytes is currently still insufficient, there is still a great need for research. Thin polymer coatings of lithium anodes are also a solution to prevent the formation of lithium dendrites. However, a fundamental understanding of how the most effective coatings can be designed or modified is still lacking.

However, polymer electrolytes are also being further developed for other batteries. They can be divided into solid electrolytes and gel electrolytes. Both types of polymer electrolytes can be produced comparatively cheaply and easily, as well as being adapted to existing battery systems. In order to further optimize polymer electrolytes for effective lithium-ion transport, the aim is to reduce the so-called glass transition temperature of various polymer systems, but also (further) developing organic lithium salts that are suitable as electrolytes. The transport of lithium ions in such electrolytes can take place on the one hand through the solid polymer chains and in gel electrolytes also through the liquid or gelled areas.

Polymer materials for batteries will continue to play an important role because their properties can help improve the safety of batteries. Their flame-retardant and thermoresponsive properties can, for example, prevent uncontrollable thermal runaway. Solid polymer electrolytes with good mechanical properties are also seen as a prerequisite for the integration of energy storage functions in structural components. The manufacturing costs of batteries can also be reduced with the help of polymers, whereby the processability of the materials used is of particular importance. The further development of lithium-ion and lithium-sulfur batteries will also depend on the future development of suitable polymer materials for electrodes and electrolytes.

 

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