In meeting the cost and safety demand of grid storage and electric vehicles, new battery technologies are being developed to transition from the nonaqueous organic electrolytes used in today’s lithium-ion batteries to nonflammable and nonvolatile alternatives such as aqueous and all-solid-state electrolytes. However, today’s best electrode active materials are not optimized for these systems, and the observed specific energy and especially cycle life are less than satisfactory. For example, aqueous electrolytes’ aggressive nature and limited stability window have limited the choice of anode materials to a handful of conversion-type materials such as metallic lead and mischmetal hydrides, which do not have the necessary structural stability to survive prolonged (&gt;1000 cycles) cycling. In another instance, solid superionic conductors based on sulfides have lower anodic decomposition potentials than those of virtually all existing Li-/Na-intercalation cathode materials, making sulfide-based all-solid-state batteries thermodynamically unstable systems. Here we show our efforts on tailoring organic redox materials for these emerging electrolyte systems. In particular, we focus on organic carbonyl compounds which are resource abundant and highly versatile electroactive materials. Our function-oriented molecular design has led to reduction potentials well matching the stability window of each desired aqueous/solid-state electrolyte. Further equipped with sufficiently low solubility (in aqueous electrolytes), chemical inertness, electrochemical/structural reversibility, and adequate electronic/ionic conductivity, these organic redox materials have enabled several examples of long-cycle-life and high-energy aqueous/all-solid-state batteries.

Electrolyte-dictated organic redox material design for beyond-lithium-ion batteries

256th National Meeting (2018)

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