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This past decade has seen extensive research in lithium-sulfur batteries with exemplary works mitigating the notorious polysulfide shuttling. However, these works utilize ether electrolytes that are highly volatile severely hindering their practicality. Here, we stabilize a rare monoclinic γ-sulfur phase within carbon nanofibers that enables successful operation of Lithium-Sulfur (Li-S) batteries in carbonate electrolyte for 4000 cycles. Carbonates are known to adversely react with the intermediate polysulfides and shut down Li-S batteries in first discharge. Through electrochemical characterization andpost-mortemspectroscopy/ microscopy studies on cycled cells, we demonstrate an altered redox mechanism in our cells that reversibly converts monoclinic sulfur to Li₂S without the formation of intermediate polysulfides for the entire range of 4000 cycles. To the best of our knowledge, this is the first study to report the synthesis of stable γ-sulfur and its application in Li-S batteries. We hope that this striking discovery of solid-to-solid reaction will trigger new fundamental and applied research in carbonate electrolyte Li-S batteries.

A new electroanalytical design based on asymmetric interdigitated arrays (IDA) is presented and the effects of asymmetry on the device performance are characterized electrochemically. Varying the collector and generator band widths independently of each other tunes the collection efficiency and redox cycling-induced feedback. These arrays are able to provide low feedback (<10%) while maintaining moderate collection efficiency (25%–40%). Behavior is evaluated experimentally and using a numerical model. The application of the device to detect soluble electrolyte degradation products in nonaqueous lithium-ion and sodium-ion battery electrolytes is demonstrated.