Highly-efficient conversion of SF6 via an eight-electron transfer process in lithium batteries

Abstract Li-SF6 battery has been proposed as a novel energy conversion device for both reducing greenhouse-effect SF6 and potentially providing large specific energy. However, the real discharge process of SF6 remains ambiguous with fast cathode passivation and large polarization. Here we report that the Li-SF6 chemistry is able to deliver an unprecedented capacity of >20,000 mA h gc−1 with reduced polarization and excellent rate capability by using a low-cost, high-surface-area porous carbon as cathode host. More importantly, by adjusting the SF6 atmosphere, an approximately eight-electron transfer process with predominant products of LiF and Li2S is realized via two voltage steps, whereas previously only a little Li2S could be found with one plateau appearing. The eight-electron process leads to a high energy density about 2,300 W h kg−1 based on the mass of carbon and discharge products, which sheds light on SF6 as a promising high-energy-density cathode.