Most rechargeable batteries that power portable devices, similar to toys, handheld vacuums and e-bikes, use lithium-ion technology. But these batteries can have short lifetimes and will catch fire when damaged. To deal with stability and questions of safety, researchers reporting in ACS Energy Letters have designed a lithium-sulfur (Li-S) battery that features an improved iron sulfide cathode. One prototype stays highly stable over 300 charge-discharge cycles, and one other provides power even after being folded or cut.
Sulfur has been suggested as a cloth for lithium-ion batteries due to its low price and potential to carry more energy than lithium-metal oxides and other materials utilized in traditional ion-based versions. To make Li-S batteries stable at high temperatures, researchers have previously proposed using a carbonate-based electrolyte to separate the 2 electrodes (an iron sulfide cathode and a lithium metal-containing anode). Nevertheless, because the sulfide within the cathode dissolves into the electrolyte, it forms an impenetrable precipitate, causing the cell to quickly lose capability. Liping Wang and colleagues wondered if they may add a layer between the cathode and electrolyte to cut back this corrosion without reducing functionality and rechargeability.
The team coated iron sulfide cathodes in several polymers and located in initial electrochemical performance tests that polyacrylic acid (PAA) performed best, retaining the electrode’s discharge capability after 300 charge-discharge cycles. Next, the researchers incorporated a PAA-coated iron sulfide cathode right into a prototype battery design, which also included a carbonate-based electrolyte, a lithium metal foil as an ion source, and a graphite-based anode. They produced after which tested each pouch cell and coin cell battery prototypes.
After greater than 100 charge-discharge cycles, Wang and colleagues observed no substantial capability decay within the pouch cell. Additional experiments showed that the pouch cell still worked after being folded and cut in half. The coin cell retained 72% of its capability after 300 charge-discharge cycles. They next applied the polymer coating to cathodes created from other metals, creating lithium-molybdenum and lithium-vanadium batteries. These cells also had stable capability over 300 charge-discharge cycles. Overall, the outcomes indicate that coated cathodes could produce not only safer Li-S batteries with long lifespans, but in addition efficient batteries with other metal sulfides, based on Wang’s team.
The authors acknowledge funding from the National Natural Science Foundation of China; the Natural Science Foundation of Sichuan, China; and the Beijing National Laboratory for Condensed Matter Physics.
