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ABSTRACT Lithium‐ and manganese‐rich layered oxides (LMR) stand out as next‐generation lithium‐ion cathode chemistries, which harness both transition‐metal and lattice‐oxygen redox processes to deliver exceptional capacity and energy density. However, their full potential is hindered by intrinsic oxygen instability and structural degradation, resulting in pronounced voltage fade and capacity decay. Here, we present a complex‐concentrated anion‐doping paradigm in which multiple anions, F, Br, and S, are incorporated into the oxygen sublattice to enhance oxygen‐redox and structural stability. X‐ray absorption spectroscopy and aberration‐corrected scanning transmission electron microscopy confirm ultra‐stable local oxygen coordination environments during long‐term cycling, with detrimental phase transformations and oxygen‐loss‐induced cavitation dramatically inhibited. Notably, we show that the characteristic LiTM6transition metal (TM) honeycomb ordering is preserved even after electrochemical cycling. Concurrently, this strategy yields an unprecedented volume change of only 0.63% upon charging to 4.8 V vs. Li+/Li, achieving the first zero‐strain LMR cathode. The resulting LMR cathode delivers ultralow voltage fade (1 mV per cycle during the first 100 cycles and becomes negligible in subsequent cycles) and outstanding energy retention (93% after 200 cycles) in a pouch cell configuration. Our complex‐concentrated anion‐doping concept establishes a broadly applicable strategy for resolving chemo‐mechanical failure mechanisms in ceramic intercalation electrodes for next‐generation energy storage.
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Metal-free polypeptide redox flow batteries
Non-aqueous organic redox flow batteries (NAORFBs) are considered emerging large-scale energy storage systems due to their larger voltage window as compared to aqueous systems and their metal-free nature. However, low solubility, sustainability, and crossover of redox materials remain major challenges for the development of NAORFBs. Here, we report the use of redox active α-helical polypeptides suitable for NAORFBs. The polypeptides exhibit less crossover than small molecule analogs for both Daramic 175 separator and FAPQ 375 PP membrane, with FAPQ 375 PP preventing crossover most effectivley. Polypeptide NAORFBs assembled with a TEMPO-based polypeptide catholyte and viologen-based polypeptide anolyte exhibit low capacity fade ( ca. 0.1% per cycle over 500 cycles) and high coulombic efficiency (>99.5%). The polypeptide NAORFBs exhibit an output voltage of 1.1 V with a maximum capacity of 0.53 A h L −1 (39% of the theoretical capacity). After 500 charge–discharge cycles, 60% of the initial capacity was retained. Post cycling analysis using spectral and electrochemical methods demonstrate that the polypeptide backbone and the ester side chain linkages are stable during electrochemical cycling. Taken together, these polypeptides offer naturally-derived, deconstructable platforms for addressing the needs of metal-free energy storage.
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- PAR ID:
- 10349356
- Date Published:
- Journal Name:
- Materials Advances
- Volume:
- 3
- Issue:
- 16
- ISSN:
- 2633-5409
- Page Range / eLocation ID:
- 6558 to 6565
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1039/d2ma00498d
