A new discovery! Discarded plastic could improve the life of lithium-sulphur batteries

Engineers at PurdueUniversity in the us have come up with a solution to the world's perennial problem of plastic waste, while improving the life of lithium-sulphur batteries.

The theoretical energy density of lithium-sulfur batteries is 3 to 5 times higher than that of lithium-ion batteries, up to 2,600Whkg, which is an important condition for electric vehicles and laptop batteries. Therefore, it is called the next generation technology of lithium-ion batteries, but the battery only has a short charging cycle of 100 times.

Purdue university team to find a way to kill two birds with one stone, can solve the problem of plastic recycling and battery life at the same time, according to the research in the ACSAppliedMaterialsandInterfaces, first of all, such as a transparent plastic bags will no ink plastic soaking in sulfur solution, then the microwave and bracket of the carbon batteries, lithium sulfur batteries cycle can be promoted to 200 times.

VilasPol, an assistant professor of chemical engineering at purdue university, said that no matter how many times the plastic is recycled, it will always be there in the world, and the team just came up with a way to increase its value.

Low-density polyethylene, often used in plastics and packaging, is the main culprit of plastic pollution, but it turns out to be the key to solving the long-term problem of lithium-sulphur batteries in experiments. The disorder is called polysulphide shuttle effect (polysulfideshuttlingeffect), to cause a decline in the battery capacity and life.

Lithium sulfur sulfur, just as its name implies is to use lithium battery when electric current passes through, the lithium ions migrate to the sulfur and produces chemical reaction, which produce lithium sulfide (lithiumsulfide), however, the reaction by-products polysulphide easily return to lithium electrode, and prevents the lithium ions move, which will reduce the battery charge capacity and life.

PatrickKim, a chemical engineering researcher at purdue university, says the easiest way to block polysulfides is to create a physical barrier between lithium and sulfur.

Previous studies have looked at this approach, using biomass energy, such as banana peels and pistachio shells, to capture polysulfides from the pores in biomass derived carbon. Pol says each material has its own benefits, but biomass is easier to preserve and better suited for other USES, while waste plastics are really just useless, heavy materials.

So the researchers wanted to incorporate plastic into the carbon scaffolding of the battery, and past studies have shown that low-density polyethylene plastic can also produce carbon when combined with the sulfonatedgroup.

By immersing plastic bags in a sulfur-containing solvent and microwaving them, the researchers can raise the temperature in a cheap and efficient way and turn the plastic into low-density polyethylene. The heat energy can also promote the sulfonation and carbonization of the plastic, making the pores denser and capturing more sulfide.

According to Kim, the plastic derived carbon and sulfonated group produced by this method will have a negative charge, which is also the characteristic of polysulfide. Therefore, the sulfonated low-density polyethylene is made into a carbon scaffold, which USES similar chemical properties to block polysulfide. Pol notes that this is the first step in increasing the capacity of lithium-sulphur batteries, and the next step is to use the concept to make larger batteries.

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