skip to main content

Attention:

The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Friday, April 12 until 2:00 AM ET on Saturday, April 13 due to maintenance. We apologize for the inconvenience.


Search for: All records

Creators/Authors contains: "Jiang, Heng"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Using elemental selenium as an electrode, the redox-active Cu 2+ /Cu + ion is reversibly hosted via the sequential conversion reactions of Se → CuSe → Cu 3 Se 2 → Cu 2 Se. The four-electron redox process from Se to Cu 2 Se produces a high initial specific capacity of 1233 mA h g −1 based on the mass of selenium alone or 472 mA h g −1 based on the mass of Cu 2 Se, the fully discharged product. 
    more » « less
  2. Abstract

    It remains a challenge to design aqueous electrolytes to secure the complete reversibility of zinc metal anodes. The concentrated water‐in‐salt electrolytes, e.g., 30 m ZnCl2, are promising candidates to address the challenges of the Zn metal anode. However, the pure 30 m ZnCl2electrolyte fails to deliver a smooth surface morphology and a practically relevant Coulombic efficiency. Herein, it is reported that a small concentration of vanillin, 5 mg mLwater−1, added to 30 m ZnCl2transforms the reversibility of Zn metal anode by eliminating dendrites, lowering the Hammett acidity, and forming an effective solid electrolyte interphase. The presence of vanillin in the electrolyte enables the Zn metal anode to exhibit a high Coulombic efficiency of 99.34% at a low current density of 0.2 mA cm−2, at which the impacts of the hydrogen evolution reaction are allowed to play out. Using this new electrolyte, a full cell Zn metal battery with an anode/cathode capacity (N/P) ratio of 2:1 demonstrates no capacity fading over 800 cycles.

     
    more » « less
  3. Abstract

    Dual‐ion batteries that use anions and cations as charge carriers represent a promising energy‐storage technology. However, an uncharted area is to explore transition metals as electrodes to host carbonate in conversion reactions. Here we report the reversible conversion reaction from copper to Cu2CO3(OH)2, where the copper electrode comprising K2CO3and KOH solid is self‐sufficient with anion‐charge carriers. This electrode dissociates and associates K+ions during battery charge and discharge. The copper active mass and the anion‐bearing cathode exhibit a reversible capacity of 664 mAh g−1and 299 mAh g−1, respectively, and relatively stable cycling in a saturated mixture electrolyte of K2CO3and KOH. The results open an avenue to use carbonate as a charge carrier for batteries to serve for the consumption and storage of CO2.

     
    more » « less
  4. Abstract

    Dual‐ion batteries that use anions and cations as charge carriers represent a promising energy‐storage technology. However, an uncharted area is to explore transition metals as electrodes to host carbonate in conversion reactions. Here we report the reversible conversion reaction from copper to Cu2CO3(OH)2, where the copper electrode comprising K2CO3and KOH solid is self‐sufficient with anion‐charge carriers. This electrode dissociates and associates K+ions during battery charge and discharge. The copper active mass and the anion‐bearing cathode exhibit a reversible capacity of 664 mAh g−1and 299 mAh g−1, respectively, and relatively stable cycling in a saturated mixture electrolyte of K2CO3and KOH. The results open an avenue to use carbonate as a charge carrier for batteries to serve for the consumption and storage of CO2.

     
    more » « less
  5. Abstract

    Iron ion batteries using Fe2+as a charge carrier have yet to be widely explored, and they lack high‐performing Fe2+hosting cathode materials to couple with the iron metal anode. Here, it is demonstrated that VOPO4∙2H2O can reversibly host Fe2+with a high specific capacity of 100 mAh g−1and stable cycling performance, where 68% of the initial capacity is retained over 800 cycles. In sharp contrast, VOPO4∙2H2O's capacity of hosting Zn2+fades precipitously over tens of cycles. VOPO4∙2H2O stores Fe2+with a unique mechanism, where upon contacting the electrolyte by the VOPO4∙2H2O electrode, Fe2+ions from the electrolyte get oxidized to Fe3+ions that are inserted and trapped in the VOPO4∙2H2O structure in an electroless redox reaction. The trapped Fe3+ions, thus, bolt the layered structure of VOPO4∙2H2O, which prevents it from dissolution into the electrolyte during (de)insertion of Fe2+. The findings offer a new strategy to use a redox‐active ion charge carrier to stabilize the layered electrode materials.

     
    more » « less
  6. Abstract

    A non‐aqueous proton electrolyte is devised by dissolving H3PO4into acetonitrile. The electrolyte exhibits unique vibrational signatures from stimulated Raman spectroscopy. Such an electrolyte exhibits unique characteristics compared to aqueous acidic electrolytes: 1) higher (de)protonation potential for a lower desolvation energy of protons, 2) better cycling stability by dissolution suppression, and 3) higher Coulombic efficiency owing to the lack of oxygen evolution reaction. Two non‐aqueous proton full cells exhibit better cycling stability, higher Coulombic efficiency, and less self‐discharge compared to the aqueous counterpart.

     
    more » « less
  7. Abstract

    A non‐aqueous proton electrolyte is devised by dissolving H3PO4into acetonitrile. The electrolyte exhibits unique vibrational signatures from stimulated Raman spectroscopy. Such an electrolyte exhibits unique characteristics compared to aqueous acidic electrolytes: 1) higher (de)protonation potential for a lower desolvation energy of protons, 2) better cycling stability by dissolution suppression, and 3) higher Coulombic efficiency owing to the lack of oxygen evolution reaction. Two non‐aqueous proton full cells exhibit better cycling stability, higher Coulombic efficiency, and less self‐discharge compared to the aqueous counterpart.

     
    more » « less
  8. Abstract

    Proton conduction underlies many important electrochemical technologies. A family of new proton electrolytes is reported: acid‐in‐clay electrolyte (AiCE) prepared by integrating fast proton carriers in a natural phyllosilicate clay network, which can be made into thin‐film (tens of micrometers) fluid‐impervious membranes. The chosen example systems (sepiolite–phosphoric acid) rank top among the solid proton conductors in terms of proton conductivities (15 mS cm−1at 25 °C, 0.023 mS cm−1at −82 °C), electrochemical stability window (3.35 V), and reduced chemical reactivity. A proton battery is assembled using AiCE as the solid electrolyte membrane. Benefitting from the wider electrochemical stability window, reduced corrosivity, and excellent ionic selectivity of AiCE, the two main problems (gassing and cyclability) of proton batteries are successfully solved. This work draws attention to the element cross‐over problem in proton batteries and the generic “acid‐in‐clay” solid electrolyte approach with superfast proton transport, outstanding selectivity, and improved stability for room‐ to cryogenic‐temperature protonic applications.

     
    more » « less
  9. Abstract

    Aqueous dual‐ion batteries (DIBs) are promising for large‐scale energy storage due to low cost and inherent safety. However, DIBs are limited by low capacity and poor cycling of cathode materials and the challenge of electrolyte decomposition. In this study, a new cathode material of nitrogen‐doped microcrystalline graphene‐like carbon is investigated in a water‐in‐salt electrolyte of 30 m ZnCl2, where this carbon cathode stores anions reversibly via both electrical double layer adsorption and ion insertion. The (de)insertion of anions in carbon lattice delivers a high‐potential plateau at 1.85 V versus Zn2+/Zn, contributing nearly 1/3 of the capacity of 134 mAh g−1and half of the stored energy. This study shows that both the unique carbon structure and concentrated ZnCl2electrolyte play critical roles in allowing anion storage in carbon cathode for this aqueous DIB.

     
    more » « less