402030 polymer battery.Researchers use graphene aerogel to help lithium-sulfur battery breakthrough

　　Swedish researchers use a porous, sponge-like aerogel made of reduced graphene oxide as an independent electrode of the battery, thereby improving the utilization rate of lithium-sulfur batteries. According to foreign media reports, in order to adapt to the future needs of electrification, new battery technologies need to be developed. One of the options is lithium-sulfur batteries. Compared with lithium-ion batteries, theoretically, the energy density of such batteries is five times higher. Recently, researchers at Chalmers University of Technology in Sweden achieved a breakthrough in the development of such batteries using catholyte with the help of graphene sponges. The researchers' idea is very novel, using a porous, sponge-like aerogel made of reduced graphene oxide as an independent electrode of the battery to better utilize sulfur and increase utilization rate. A traditional battery consists of four parts. First, there are two supporting electrodes that cover the active material, the anode and the cathode. Between them is an electrolyte, usually a liquid, that allows ions to be transferred back and forth. The fourth part is the separator, which acts as a physical The barrier prevents contact between the two electrodes while allowing ion transfer. Previously, researchers have tried to combine the cathode and electrolyte into a "cathode electrolyte." The concept helps reduce battery weight while enabling faster charging and greater power delivery. Now, thanks to the development of graphene aerogels, the concept is proven to be effective and promising. First, the researchers injected a thin layer of porous graphene aerogel into a standard battery box. Carmen Cavallo, from the Department of Physics at Chalmers University of Technology and lead researcher on the study, said: "The aerogel is a long, thin cylinder, which is sliced like a salami and then the slices are squeezed into the battery. Then Then you take a sulfur-rich solution, the catholyte, and add it to the battery. The porous aerogel acts as a support and absorbs the solution like a sponge." "Graphene's porous structure is key, allowing it to absorb large amounts of cathode electrolyte to obtain enough sulfur, thereby enabling the concept of catholyte to be realized. This type of semi-liquid catholyte is very necessary to avoid losing any sulfur during the sulfur cycle. Since sulfur has been dissolved in the catholyte, Therefore there is no loss through dissolution”. In order for the catholyte to perform its role as an electrolyte, part of the catholyte is also added to the separator, which also maximizes the sulfur content of the battery. At present, most commercial batteries are lithium-ion batteries, but the development of such batteries is approaching its limit. In order to meet higher requirements, it becomes more important to find new chemical methods. Lithium-sulfur batteries have several advantages, such as higher energy density. Currently, the best lithium-ion battery on the market has an operating efficiency of 300 Wh/kg, and theoretically, it can reach a maximum of 350/kg. Theoretically, the energy density of lithium-sulfur batteries is about 1000 to 1500 Wh/kg. Aleksandar Matic, professor in the Department of Physics at Chalmers University of Technology and leader of the research, said: "In addition, sulfur is cheap, abundant and more environmentally friendly. In addition, lithium-ion batteries generally contain fluorine, which is harmful to the environment, while lithium-sulfur batteries No." So far, the problem with lithium-sulfur batteries is that they are not stable enough, resulting in short cycle life. But when researchers at Chalmers University of Technology tested a new battery prototype, they found that the new battery still maintained 85% of its capacity after 350 cycles. The new design avoids two major problems in the degradation process of sulfur lithium batteries. One is the loss of sulfur by dissolving into the electrolyte, and the other is the "shuttle effect" in which sulfur molecules migrate from the cathode to the anode. In this design, the impact of such problems is greatly reduced. However, researchers point out that there is still a long way to go before the technology can reach its full market potential. AleksandarMatic said: “Because the production method of this kind of battery is different from that of most normal batteries, new production processes need to be developed to commercialize this battery.”

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