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Abstract Lithium-based nonaqueous redox flow batteries (LRFBs) are alternative systems to conventional aqueous redox flow batteries because of their higher operating voltage and theoretical energy density. However, the use of ion-selective membranes limits the large-scale applicability of LRFBs. Here, we report high-voltage membrane-free LRFBs based on an all-organic biphasic system that uses Li metal anode and 2,4,6-tri-(1-cyclohexyloxy-4-imino-2,2,6,6-tetramethylpiperidine)-1,3,5-triazine (Tri-TEMPO), N-propyl phenothiazine (C3-PTZ), and tris(dialkylamino)cyclopropenium (CP) cathodes. Under static conditions, the Li||Tri-TEMPO, Li||C3-PTZ, and Li||CP batteries with 0.5 M redox-active material deliver capacity retentions of 98%, 98%, and 92%, respectively, for 100 cycles over ~55 days at the current density of 1 mA/cm2and a temperature of 27 °C. Moreover, the Li||Tri-TEMPO (0.5 M) flow battery delivers an initial average cell discharge voltage of 3.45 V and an energy density of ~33 Wh/L. This flow battery also demonstrates 81% of capacity for 100 cycles over ~45 days with average Coulombic efficiency of 96% and energy efficiency of 82% at the current density of 1.5 mA/cm2and at a temperature of 27 °C.
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Partially Ion‐Paired Solvation Structure Design for Lithium‐Sulfur Batteries under Extreme Operating Conditions
Abstract Achieving increased energy density under extreme operating conditions remains a major challenge in rechargeable batteries. Herein, we demonstrate an all‐fluorinated ester‐based electrolyte comprising partially fluorinated carboxylate and carbonate esters. This electrolyte exhibits temperature‐resilient physicochemical properties and moderate ion‐paired solvation, leading to a half solvent‐separated and half contact‐ion pair in a sole electrolyte. As a result, facile desolvation and preferential reduction of anions/fluorinated co‐solvents for LiF‐dominated interphases are achieved without compromising ionic conductivity (>1 mS cm−1even at −40 °C). These advantageous features were found to apply to both lithium metal and sulfur‐based electrodes even under extreme operating conditions, allowing stable cycling of Li || sulfurized polyacrylonitrile (SPAN) full cells with high SPAN loading (>3.5 mAh cm−2) and thin Li anode (50 μm) at −40, 23 and 50 °C. This work offers a promising path for designing temperature‐resilient electrolytes to support high energy density Li metal batteries operating in extreme conditions.
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- Award ID(s):
- 2011924
- PAR ID:
- 10481754
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 63
- Issue:
- 5
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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