skip to main content

Attention:

The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 5:00 PM ET until 11:00 PM ET on Friday, June 21 due to maintenance. We apologize for the inconvenience.


Title: Stable cycling of lithium-sulfur batteries by optimizing the cycle condition
Lithium-sulfur (Li-S) batteries suffer from poor utilization of active material and short cycle life due to the complicated multi-step reaction mechanisms. Herein, three conditional cycling methods, i.e. asymmetrical cycling, constant voltage (CV) discharge cycling, and partial cycling are designed in order to increase the cyclability of Li-S batteries. It is found that the solid deposition process that takes place during the lower plateau of discharge is the major limiting step for achieving high discharge capacity and cycle retention, and the cathode surface coverage can be deferred by applying an optimal discharge/charge rate and CV discharge cycling. The asymmetrical cycling renders a specific capacity of ca. 700 mAh g-1 after 200 cycles, 30% higher than that under symmetrical cycling, while applying a CV discharge cycling enables a full retention of target specific capacity of ca. 800 mAh g-1 over 50 cycles. The partial cycling with a low number of phase transformation steps and reduced surface coverage at the end of discharge/charge also enhances cyclability. This work paves the way for understanding and improving the cycling performance of Li-S batteries without increasing the cost of electrode design or changing the configuration of the cell.  more » « less
Award ID(s):
1805288
NSF-PAR ID:
10167524
Author(s) / Creator(s):
Date Published:
Journal Name:
Electrochimica acta
Volume:
326
ISSN:
0013-4686
Page Range / eLocation ID:
134948
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    Rechargeable aqueous batteries with Zn2+as a working‐ion are promising candidates for grid‐scale energy storage because of their intrinsic safety, low‐cost, and high energy‐intensity. However, suitable cathode materials with excellent Zn2+‐storage cyclability must be found in order for Zinc‐ion batteries (ZIBs) to find practical applications. Herein, NaCa0.6V6O16·3H2O (NaCaVO) barnesite nanobelts are reported as an ultra‐stable ZIB cathode material. The original capacity reaches 347 mAh g−1at 0.1 A g−1, and the capacity retention rate is 94% after 2000 cycles at 2 A g−1and 83% after 10 000 cycles at 5 A g−1, respectively. Through a combined theoretical and experimental approach, it is discovered that the unique V3O8layered structure in NaCaVO is energetically favorable for Zn2+diffusion and the structural water situated between V3O8layers promotes a fast charge‐transfer and bulk migration of Zn2+by enlarging gallery spacing and providing more Zn‐ion storage sites. It is also found that Na+and Ca2+alternately suited in V3O8layers are the essential stabilizers for the layered structure, which play a crucial role in retaining long‐term cycling stability.

     
    more » « less
  2. Abstract

    We demonstrate a novel crosslinked disulfide system as a cathode material for Li‐S cells that is designed with the two criteria of having only a single point of S−S scission and maximizing the ratio of S−S to the electrochemically inactive framework. The material therefore maximizes theoretical capacity while inhibiting the formation of polysulfide intermediates that lead to parasitic shuttle. The material we report contains a 1:1 ratio of S:C with a theoretical capacity of 609 mAh g−1. The cell gains capacity through 100 cycles and has 98 % capacity retention thereafter through 200 cycles, demonstrating stable, long‐term cycling. Raman spectroscopy confirms the proposed mechanism of disulfide bonds breaking to form a S−Li thiolate species upon discharge and reforming upon charge. Coulombic efficiencies near 100 % for every cycle, suggesting the suppression of polysulfide shuttle through the molecular design.

     
    more » « less
  3. Abstract

    We demonstrate a novel crosslinked disulfide system as a cathode material for Li‐S cells that is designed with the two criteria of having only a single point of S−S scission and maximizing the ratio of S−S to the electrochemically inactive framework. The material therefore maximizes theoretical capacity while inhibiting the formation of polysulfide intermediates that lead to parasitic shuttle. The material we report contains a 1:1 ratio of S:C with a theoretical capacity of 609 mAh g−1. The cell gains capacity through 100 cycles and has 98 % capacity retention thereafter through 200 cycles, demonstrating stable, long‐term cycling. Raman spectroscopy confirms the proposed mechanism of disulfide bonds breaking to form a S−Li thiolate species upon discharge and reforming upon charge. Coulombic efficiencies near 100 % for every cycle, suggesting the suppression of polysulfide shuttle through the molecular design.

     
    more » « less
  4. Abstract

    The morphology and crystallinity of electrode materials have a major effect on their charge carrier storage properties when applied in rechargeable batteries. While nanosizing electrode particles (with larger surface area) and maintaining electrode integrity are both good for performance enhancement, they seem to contradict each other and are challenging to balanced. Herein, electrode particles consisting of numerous nanograins with uniform crystalline orientation are designed to guarantee both high surface area and high structural integrity, allowing the significant improvement of Li+storage kinetics and performance. Applying this “mesocrystallizing” strategy to an NiCo2O4‐based anode, results in various degrees of pseudocapacitance response, the long‐term cyclability and rate performance of this material are also significantly enhanced. Impressively, the mesocrystalline NiCo2O4electrode exhibits a high specific capacity of 1403 mAh g–1after 200 cycles at 1.6 A g–1(a rate of 1.8 C). The growth mechanism of mesocrystalline materials with different morphologies is identified to be a topotactic structural transition process featuring a gradual edge‐to‐core corrosion process. This work presents an important synthetic clue to balance the morphology and crystallinity of battery electrode materials for their performance optimization and is expected to inspire future structural design for battery materials beyond the one prototyped here.

     
    more » « less
  5. null (Ed.)
    Abstract Ammonium vanadate with bronze structure (NH 4 V 4 O 10 ) is a promising cathode material for zinc-ion batteries due to its high specific capacity and low cost. However, the extraction of $${\text{NH}}_{{4}}^{ + }$$ NH 4 + at a high voltage during charge/discharge processes leads to irreversible reaction and structure degradation. In this work, partial $${\text{NH}}_{{4}}^{ + }$$ NH 4 + ions were pre-removed from NH 4 V 4 O 10 through heat treatment; NH 4 V 4 O 10 nanosheets were directly grown on carbon cloth through hydrothermal method. Deficient NH 4 V 4 O 10 (denoted as NVO), with enlarged interlayer spacing, facilitated fast zinc ions transport and high storage capacity and ensured the highly reversible electrochemical reaction and the good stability of layered structure. The NVO nanosheets delivered a high specific capacity of 457 mAh g −1 at a current density of 100 mA g −1 and a capacity retention of 81% over 1000 cycles at 2 A g −1 . The initial Coulombic efficiency of NVO could reach up to 97% compared to 85% of NH 4 V 4 O 10 and maintain almost 100% during cycling, indicating the high reaction reversibility in NVO electrode. 
    more » « less