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A novel polymer lithium - sulfur battery was developed by combining theory with experiment

- Dec 24, 2018 -

The researchers found that after more than 100 charging cycles, the capacity of the new li-sulfur battery was still double that of the traditional li-sulfur battery.

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This figure shows the formation of complex ion clusters during the cycle of li-sulfur battery cells. These clusters consist of cationic polymer adhesives, battery electrolytes, and anionic sulfur active materials.

Lithium-sulphur batteries are a promising alternative to conventional lithium-ion batteries in electric cars, because they are cheaper, lighter and can store nearly twice as much energy for the same mass. However, over time, li-sulfur batteries become unstable and their electrodes deteriorate, limiting their widespread use.

Recently, a research team led by scientists at Lawrence Berkeley national laboratory of the us department of energy found that compared with traditional li-sulfur batteries, the capacity of the new li-sulfur battery modules doubles and the charging cycle at high current density exceeds 100 times, which is a key performance indicator used in electric vehicles (EV) and aviation. They designed a new polymer binder to actively regulate key ion transport processes in lithium-sulphur batteries and showed how it works at the molecular level.

Brett Helms, a scientist at Lawrence Berkeley laboratory's molecular foundry institute, said:New polymer is like a wall in the main body in the pore of carbon, sulphur load and the polymer sealing, due to the chemical reaction of sulfur in the battery, stop the negatively charged polymer sulfur compounds are free to go out, and then produced the next generation of electric cars when lithium sulfur batteries to store and release energy, chemical reaction to produce mobile sulfur molecules, disconnected and electrode, decomposition and eventually lead to reduce the capacity of the battery in order that the battery is more stable, the researchers have been trying to develop for the protection of the electrode coating, and the development of new polymer adhesive will battery components togetherThese traditional adhesive to control or reduce the expansion of the electrode and cracking, the new adhesive is further from the Lawrence Berkeley laboratory of the centre for the study of molecular foundry, the researchers designed a kind of polymer by selectively combined sulfur molecules, sulfur will keep in close to the position of the electrode, offset the tendency of the next step is to understand the migration in the process of charging and discharging, as well as the possibility of dynamic structure under different charging status changes, the guiding theory of casting facilities facilities project scientist David Prendergast and theory of TodPascal developed a hypothesis to simulate testing polymer behavior Prendergast said:We can now reliably and efficiently in the adhesive curing learning model, based on the dissolved from the sulfur product detailed simulation of quantum mechanics in Lawrence Berkeley laboratory of national energy research scientific computing center (NERSC) super computing resources on a large scale molecular dynamics simulation, confirmed that the affinity of the polymer is combined with mobile sulfur molecules, and also predicts the polymer can be used in battery charging condition of different sulfur material using Lawrence BerkeleyLaboratory of advanced light source and the argonne national laboratory in electrochemistry lab experiments confirmed the prediction research group to further study the performance of the new polymer adhesive preparation of lithium sulfur batteries through a series of experiments, they can analyze and quantify the polymer of the sulfur cathode how to influence the chemical reaction rate, which is to achieve these batteries with high current density and high power key through long-term circulation increase battery capacity nearly doubled, new type of polymer to improve the capacity of the lithium battery and powerThe U.S. department of energy's joint center for energy storage and research (JCESR) 's comprehensive understanding of the synthesis, theory and properties of the new polymer makes it a key component of the prototype lithium-sulfur battery