Chemists from the University of Texas developed new organic batteries that offer lightweight energy storage. Unlike similar developments, their new battery does not rely on toxic heavy metals, making it a potential ecologic replacement for current batteries. The new study, conducted by Christopher Bielawski and Jonathan Sessler, tries to improve the way electrons move back and forth between two molecules, since this event creates electricity. Moreover, it may be a necessary step toward making artificial photosynthesis, where fuel might be generated directly from the sun, a lot as plants do.
According to previous studies, the exchange of electrons between molecules frequently form new compounds. In some cases, the electron transfer procedure creates one molecule with a positive charge and one molecule with a negative charge. Molecules with opposite charges are attracted to each other and can combine to form something new.
In this latest study, published in Science, the chemists produced two molecules that could meet and exchange electrons ¡§C but not unite to form a new compound. "These molecules were effectively spring-loaded to push apart following interacting with each other," explained Bielawski. "After electron transfer occurs, two positively charged molecules are formed which are repelled by each other, a lot like magnets held in a certain way will repel each other. We also installed a chemical switch that allowed the electron transfer procedure to proceed in the opposite direction."
The new system gives the capability to produce efficient organic battery. By understanding the electron transfer processes in these molecules, the group could design organic materials for storing electrical energy that could then be retrieved for later use. While similar plans were made in the past, other researchers lacked the capability to manipulate electron flow. "This is the first time that the forward and backward switching of electron flow has been accomplished via a switching procedure at the molecular scale," said Sessler.
The paper defines organic batteries by likening it to regular batteries; nevertheless, rather than heavy metals, organic materials are used. They are lightweight, can be molded into any shape, have the potential to store much more energy than conventional batteries, and are safer and cheaper to produce. Thanks to the development with the molecular switch, the group can ensure the electron movement will produce electricity. "I am excited about the prospect of coupling this kind of electron transfer 'molecular switch' with light harvesting to go following what may be an improved artificial photosynthetic device," says Sessler. "Realizing this dream would represent a big step forward for science."
Aside from improving battery technologies, the research may help develop technologies that mimics plants' capability to harvest light and convert it to energy. With such a technologies, fuel might be produced directly from the sun, rather than through a plant mediator, such as corn.
The most exciting application with the new development, nevertheless, is making smaller, lighter, and much more efficient batteries. "I would love it if my iPhone was thinner and lighter, and the battery lasted a month or even a week rather than a day," says Bielawski. "With an organic battery, it might be possible. We are now starting to get a handle on the fundamental chemistry needed to make this dream a commercial reality."
The group collaborated with a number of scientists from multiple institutions, but they wish to specially credit graduate student Jung Su Park, for his detailed work growing crystals with the two molecules. Their next step is to demonstrate these processes can occur in a condensed phase, like in a film, rather than in solution.
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