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Abstract Li2MnO3has been contemplated as a high‐capacity cathode candidate for Li‐ion batteries; however, it evolves oxygen during battery charging under ambient conditions, which hinders a reversible reaction. However, it is unclear if this irreversible process still holds under subambient conditions. Here, the low‐temperature electrochemical properties of Li2MnO3in an aqueous LiCl electrolyte are evaluated and a reversible discharge capacity of 302 mAh g−1at a potential of 1.0 V versus Ag/AgCl at −78 °C with good rate capability and stable cycling performance, in sharp contrast to the findings in a typical Li2MnO3cell cycled at room temperature, is observed. However, the results reveal that the capacity does not originate from the reversible oxygen oxidation in Li2MnO3but the reversible Cl2(l)/Cl−(aq.) redox from the electrolyte. The results demonstrate the good catalytic properties of Li2MnO3to promote the Cl2/Cl−redox at low temperatures.
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Block Copolymer‐Derived Porous Carbon Fibers Enable High MnO 2 Loading and Fast Charging in Aqueous Zinc‐Ion Battery
Abstract Rechargeable aqueous Zn−MnO2batteries are promising for stationary energy storage because of their high energy density, safety, environmental benignity, and low cost. Conventional gravel MnO2cathodes have low electrical conductivity, slow ion (de‐)insertion, and poor cycle stability, resulting in poor recharging performance and severe capacity fading. To improve the rechargeability of MnO2, strategies have been devised such as depositing micrometer‐thick MnO2on carbon cloth and blending nanostructured MnO2with additives and binders. The low electrical conductivity of binders and sluggish ion (de‐)insertion in micrometer‐thick MnO2, however, still limit the fast‐charging performance. Herein, we have prepared porous carbon fiber (PCF) supported MnO2cathodes (PCF@MnO2), comprised of nanometer‐thick MnO2uniformly deposited on electrospun block copolymer‐derived PCF that have abundant uniform mesopores. The high electrical conductivity of PCF, fast electrochemical reactions in nanometer‐thick MnO2,and fast ion transport through porous nonwoven fibers contribute to a high rate capability at high loadings. PCF@MnO2, at a MnO2loading of 59.1 wt %, achieves a MnO2‐based specific capacity of 326 and 184 mAh g−1at a current density of 0.1 and 1.0 A g−1, respectively. Our approach of block copolymer‐based PCF as a support for zinc‐ion cathode inspires future designs of fast‐charging electrodes with other active materials.
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- Award ID(s):
- 1752611
- PAR ID:
- 10365183
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Batteries & Supercaps
- Volume:
- 5
- Issue:
- 4
- ISSN:
- 2566-6223
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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