skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Nanostructured Conductive Metal Organic Frameworks for Sustainable Low Charge Overpotentials in Li-Air Batteries
Lithium-oxygen batteries are among the most attractive alternatives for the future electrified transportation. However, the practical application of these batteries is hindered by many obstacles. Due to insulating nature of Li2O2 product and the slow kinetics of reactions, attaining sustainable low charge overpotentials at high rates becomes a major challenge resulting in battery's early failure and low round trip efficiency. Herein, we discovered outstanding characteristics of a conductive metal organic framework (c-MOF) that promotes the growth of nanocrystalline Li2O2 products with amorphous regions. This provides a novel platform for the continuous growth of Li2O2 units away from framework enabling a fast discharge at high current rates. Moreover, the Li2O2 structure works in an excellent synergy with the redox mediator (RM) in the electrolyte. The conductivity of the amorphous Li2O2 structure allows the RM to act directly on the Li2O2 surface instead of catalyst edges and then transport through the electrolyte to the Li2O2 surface. This direct charge transfer enables a small charge potential of <3.7 V under high current densities (1-2 A/g) sustained for a long cycle life (100-300 cycles) for large capacities (1000-2000 mAh/g). These results open a new direction for utilizing c-MOFs towards advanced energy storage systems.  more » « less
Award ID(s):
1729420
PAR ID:
10301710
Author(s) / Creator(s):
Date Published:
Journal Name:
Small
ISSN:
1613-6829
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. (, ACS applied materials interfaces)
    null (Ed.)
    Redox mediators (RMs) are solution-based additives that have been extensively used to reduce the charge potential and increase the energy efficiency of Li–oxygen (Li–O2) batteries. However, in the presence of RMs, achieving a long cycle-life operation of Li–O2 batteries at a high current rate is still a major challenge. In this study, we discover a novel synergy among InX3 (X = I and Br) bifunctional RMs, molybdenum disulfide (MoS2) nanoflakes as the air electrode, dimethyl sulfoxide/ionic liquid hybrid electrolyte, and LiTFSI as a salt to achieve long cycle-life operations of Li–O2 batteries in a dry air environment at high charge–discharge rates. Our results indicate that batteries with InI3 operate up to 450 cycles with a current density of 0.5 A g–1 and 217 cycles with a current density of 1 A g–1 at a fixed capacity of 1 A h g–1. Batteries with InBr3 operate up to 600 cycles with a current density of 1 A g–1. These batteries can also operate at a higher charge rate of 2 A g–1 up to 200 cycles (for InBr3) and 160 cycles (for InI3). Our experimental and computational results reveal that while X3– is the source of the redox mediator, LiX at the MoS2 cathode, In3+ reacts on the lithium anode side to form a protective layer on the surface, thus acting as an effective bifunctional RM in a dry air environment. This evidence for a simultaneous improvement in the current rates and cycle life of a battery in a dry air atmosphere opens a new direction for research for advanced energy storage systems. 
    more » « less
  2. ; (, Journal of Materials Chemistry A)
    Current commercial batteries are mainly metal based, with metal elements in charge carriers and/or electrode materials, which poses potential economic and environmental concerns due to the heavy use of nonrenewable metals. Thus, metal-free batteries present a unique opportunity as sustainable energy storage devices, though the relevant research is still in its infancy. Herein, we present an all-organic metal-free NH 4 + ion full battery that can operate at a low temperature of 0 °C, by using polypyrrole (PPy) as the cathode, polyaniline (PANI) as the anode, and 19 m ammonium acetate aqueous solution as electrolyte. For the first time, PPy is demonstrated as a high-capacity host material for both NH 4 + and K + storage, when cycled in water in salt electrolytes (WiSEs). When tested in a three-electrode cell containing 25 m NH 4 CH 3 COO electrolyte, PPy exhibits an impressive capacity of 125 mA h g −1 at a specific current of 1 A g −1 and retains 43.61 mA h g −1 at 25 A g −1 . Additionally, a full battery is assembled using the PPy cathode and PANI anode coupled with 19 m NH 4 CH 3 COO WiSE. This battery is found to deliver a capacity of 78.405 mA h g −1 at 25 °C and 49.083 mA h g −1 at 0 °C with a capacity retention of 71.83% after 200 cycles, demonstrating its potential for operations at low temperatures. Additionally, the physiochemical properties of NH 4 + -based WiSEs are examined by Raman and nuclear magnetic resonance (NMR) spectroscopies, to explore their electrochemical behaviors and the fundamental effect of salt concentration on the electrolyte characteristics. This study presents the first non-metal battery with potential for low-temperature applications and opens the door to future metal-free electronics that would generate long-term benefits to the environment. 
    more » « less
  3. ; ; ; ; ; ; ; (, Proceedings of the National Academy of Sciences)
    Flexible and low-cost poly(ethylene oxide) (PEO)-based electrolytes are promising for all-solid-state Li-metal batteries because of their compatibility with a metallic lithium anode. However, the low room-temperature Li-ion conductivity of PEO solid electrolytes and severe lithium-dendrite growth limit their application in high-energy Li-metal batteries. Here we prepared a PEO/perovskite Li 3/8 Sr 7/16 Ta 3/4 Zr 1/4 O 3 composite electrolyte with a Li-ion conductivity of 5.4 × 10 −5 and 3.5 × 10 −4 S cm −1 at 25 and 45 °C, respectively; the strong interaction between the F − of TFSI − (bis-trifluoromethanesulfonimide) and the surface Ta 5+ of the perovskite improves the Li-ion transport at the PEO/perovskite interface. A symmetric Li/composite electrolyte/Li cell shows an excellent cyclability at a high current density up to 0.6 mA cm −2 . A solid electrolyte interphase layer formed in situ between the metallic lithium anode and the composite electrolyte suppresses lithium-dendrite formation and growth. All-solid-state Li|LiFePO 4 and high-voltage Li|LiNi 0.8 Mn 0.1 Co 0.1 O 2 batteries with the composite electrolyte have an impressive performance with high Coulombic efficiencies, small overpotentials, and good cycling stability. 
    more » « less
  4. ; ; ; ; ; (, Small)
    Abstract Porous carbon plays a significant role in all‐solid‐state lithium‐sulfur batteries (ASSLSBs) to enhance the electronic conductivity of sulfur. However, the conventional porous carbon used in cell with liquid electrolyte exhibits low efficiency in ASSLSBs because the immobile solid electrolyte (SE) cannot reach sulfur confined in the deep pores. The structure and distribution of pores in carbon highly impact the electrochemical performance of ASSLSBs. Herein, a N‐doped carbon fiber with micropores located only at the surface with an ultrahigh surface area of 1519 m2 g–1is designed. As the porous layer is only on the surface, the sulfur hosted in the pores can effectively contact SE; meanwhile the dense core provides excellent electrical conductivity. Therefore, this structurally designed carbon fiber enhances both electron and ion accessibilities, promotes charge transfer, and thus dramatically improves the reaction kinetic in the ASSLSBs and boosts sulfur utilization. Compared to the vapor grown carbon fibers, the ASSLSBs using PAN‐derived porous carbon fibers exhibit three times enhancement in the initial capacity of 1166 mAh g–1at C/20. An exceedingly cycling stability of 710 mAh g–1is maintained after 220 cycles at C/10, and satisfactory rate capability of 889 mAh g–1at C/2 is achieved. 
    more » « less
  5. ; ; ; (, Journal of The Electrochemical Society)
    Sodium metal batteries (SMBs) are cost-effective and environmentally sustainable alternative to lithium batteries. However, at present, limitations such as poor compatibility, low coulombic efficiency (CE), and high electrolyte cost hinder their widespread application. Herein, we propose a non-flammable, low-concentration electrolyte composed of 0.3 M NaPF6in propylene carbonate (PC), fluoroethylene carbonate (FEC), and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE). This low-concentration electrolyte not only reduces cost but also delivers rapid ion diffusion and superior wetting properties. While the Na||FePO4system with this electrolyte demonstrates slightly reduced performance at room temperature compared to standard-concentration formulations (S-PFT), it excels at both high (55 °C) and low (−20 °C) temperatures, showcasing its balanced performance. At 0.5 C (charge)/1 C (discharge), capacity retention reaches 92.8% at room temperature and 98.5% at elevated temperature, with CE values surpassing 99% and 99.63%, respectively, and significant performance sustained at −20 °C at 0.2 C. This electrolyte development thus offers a well-rounded, economically viable path to high-performance SMBs for diverse environmental applications. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email