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Scientists discover how to make safer lithium batteries

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Lithium-based batteries' tendency to overheat and catch fire has been keeping back the development of promising new technologies. In particular, it's been affecting R&D of lithium-sulfur and lithium-air batteries, both of which are much lighter than current options and can store 10 times more energy. Thankfully, a group of Stanford researchers has discovered a way to make them a lot safer. See, batteries based on the metal usually short out or randomly burst into flames due to dendrites or finger-like growths of lithium. These dendrites start forming once the electrode starts to break down, elongating more and more as time goes by, until they pierce the barrier separating the anode from the cathode (as pictured above.)

So, in order to make next-gen batteries that don't spontaneously combust, the researchers looked for a way to keep dendrites from forming. They added two kinds of chemicals to the electrolytes of coin cell batteries during their experiments. One is lithium nitrate, which is already a known additive that improves battery life, and the other is lithium polysulfide, which has the capability to break down lithium electrode. After running tests using different concentrations, they found that the right mixture led to the formation of harmless pancake-like growths (see top right) instead of dendrites.

Further, adding both chemicals made the batteries more resilient, as they continued to operate at 99 percent efficiency even after 300 charge-discharge cycles. Those that were only treated with lithium nitrate started becoming less efficient after 150 cycles. "This does not completely solve all the problems associated with lithium metal batteries," Fiona Li, one of the paper's authors, said, "but it's an important step." After all, lithium-sulfur and lithium-air batteries could lead to EVs with much longer ranges and gadgets that last for days without being recharged.

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