Dendrite–free and Ultra–High energy lithium sulfur battery enabled by dimethyl polysulfide intermediates

Abstract

Although lithium sulfur batteries made a lot of progress over decades, they are still faced with low energy and fragile stability. Herein, we report a new strategy to achieve extremely high energy lithium sulfur battery with dimethyl polysulfide intermediates, which can greatly increase the specific capacity to 1497.3 mAh g−1 at 0.1C, and dendrite–free lithium anode so as to ensure a long lifespan with 500 cycles. The brilliant performance is attributed to the radical exchange between sulfur and dimethyl polysulfide intermediates rather than lithium polysufides. Density functional theory calculations and nuclear magnetic resonance spectroscopy verify the existence of dimethyl polysulfide intermediates and in–situ UV/Vis spectroscopy confirms that mechanism for exchange reaction of radicals can boost the capacity of sulfur cathodes by eliminating complications, such as shuttle effect associated with formation and transformation of lithium polysulfides in the electrolyte. This study develops a new avenue for the innovative discharge intermediate design that helps increase capacity and stability for the practical application of lithium sulfur batteries.