► Binder in sulfur electrodes does influence the cycling behavior and stability. ► Coating with Nafion improves the properties of the electrodes. ► Excellent electrochemistry achieved for very simple ...and cheap electrode setups.
The specific capacity and cycling stability of lithium sulfur batteries have been investigated with respect to the chemical composition and fabrication process of the sulfur electrode. Three different kinds of electrode compositions (containing Nafion, polyacrylonitrile/carboxymethylcellulose, and Teflon, respectively, as binder materials) have been tested. For the electrodes containing Nafion as the binder material, an additional Nafion coating has been deposited on top of the electrodes to enhance the sulfur retention and to suppress the polysulfide shuttle. Both SEM images before cycling and post mortem are presented in order to shed light on the influence of the composition of the electrode on its electrochemical performance. Good cycling performance can be attained based on relatively simple and therefore cost-effective electrode setups and production methods.
All-solid-state Na/S cells with high safety, capacity, and low material costs are desirable for smart grid systems. We report sulfur composite electrodes prepared by the mechanical milling of sulfur, ...Ketjen black, and P2S5 or Na3PS4 for high-capacity cells. A cell using P2S5, which is not ion conductive, in the sulfur electrode exhibits a high reversible capacity of 340mAh (g‑sulfur electrode)−1 at 0.04C rate at 25°C, which is much larger than that (37.3mAh (g‑sulfur electrode)−1) obtained in a conventional cell using a high ion-conductive Na3PS4 electrolyte. To investigate the reaction mechanism of the sulfur composite electrode containing P2S5, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) measurements and scanning and transmission electron microscopy (SEM/TEM) observations of the electrodes were conducted. The results indicate that a crystalline Na3PS4 component is automatically produced by the electrochemical reaction with Na in the amorphous S-P2S5 electrode and it mixing with the sulfur redox parts at the nanoscale. The mixing degree is higher than that at microscale in the conventional S-Na3PS4 electrode, which results in the high capacity of the cells containing the S-P2S5 electrode. Partial substitution of P2S5 for SiS2 in the sulfur electrode suppresses the nanocrystallization and further increases the reversible capacity up to 390mAh (g‑sulfur electrode)−1 under 0.04C rate, which is the highest in reported all-solid-state Na batteries to date.
•All-solid-state Na/S cells with S-KB-P2S5 nanocomposites are fabricated.•Reaction mechanism of S electrodes is analyzed by XPS, SEM and TEM.•Ion conduction channel is automatically formed by Na+ ion insertion.•The highest reversible capacity is achieved in solid-state Na batteries.
In this paper, a nation coated electrode is prepared to improve the performance of lithium sulfur batteries. It is demonstrated from a series of measurements that the nafion layer is quite effective ...in reducing shuttle effect and enhancing the stability and the reversibility of the electrode. When measured under the rate of 0.2 C, the initial discharge capacity of the nafion coated electrode can reach 1084 mAh g super(-1), with a Columbic efficiency of about 100%. After 100 charge/discharge cycles, this electrode can also deliver a reversible capacity of as high as 879 mAh g super(-1). Significantly, the charge-transfer resistance of the electrode tends to be reducing after coated with an appropriate thickness of nafion film. The cation conductivity as well as anion inconductivity is considered to be the dominant factor for the superior electrochemical properties.
► A sodium/sulfur cell using tetra ethylene glycol dimethyl ether (TEGDME) liquid electrolyte at room temperature has 538
mAh
g
−1 sulfur of the first discharge capacity and decreases to 240
mAh
g
−1 ...after ten cycles. The mechanism of the battery is 2Na
+
nS
→
Na
2S
n
(4
>
n
≥
2) at discharge and Na
2S
n
(4
>
n
≥
2)
→
x (2Na
+
nS)
+
(1
−
x)Na
2S
n
(5
>
n
>
2) at charge. The decrease in discharge capacity is due to a decrease in active material by dissolution of sulfur or sodium polysulfides into the electrolyte and the irreversible reduction from sodium sulfides to elemental sulfur at full charge.
The first discharge curve of a sodium–sulfur cell using a tetra ethylene glycol dimethyl ether liquid electrolyte at room temperature shows two different regions: a sloping region and a plateau region of 1.66
V. The first discharge capacity is 538
mAh
g
−1 sulfur and then decreases with repeated charge–discharge cycling to give 240
mAh
g
−1 after ten cycles. Elemental sulfur of the cathode changes to sodium polysulfides Na
2S
2 and Na
2S
3, during full discharge. The sodium polysulfides, however, do not reduce completely to elemental sulfur after full charging. In summary, the mechanism of the battery with liquid electrolyte is 2Na
+
nS
→
Na
2S
n
(4
>
n
≥
2) on discharge and Na
2S
n
(4
>
n
≥
2)
→
x(2Na
+
nS)
+
(1
−
x)Na
2S
n
(5
>
n
>
2) on charge.
A high-capacity type of all solid-state battery was developed using sulfur electrode and the thio-LISICON electrolyte. New nano-composite of sulfur and acetylene black (AB) with an average particle ...size of 1–10
nm was fabricated by gas-phase mixing and showed a reversible capacity of 900
mAh
g
−1 at a current density of 0.013
mA
cm
−2.
Inspired by the hail formation in nature, a sulfur-based nanostorm technology is reported to realize scalable production of core–shell S/C active materials via micro-adhesion guided self-assembly ...mechanism.
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The demand on low-carbon emission fabrication technologies for energy storage materials is increasing dramatically with the global interest on carbon neutrality. As a promising active material for metal-sulfur batteries, sulfur is of great interest due to its high-energy-density and abundance. However, there is a lack of industry-friendly and low-carbon fabrication strategies for high-performance sulfur-based active particles, which, however, is in critical need by their practical success. Herein, based on a hail-inspired sulfur nano-storm (HSN) technology developed in our lab, we report an energy-saving, solvent-free strategy for producing core–shell sulfur/carbon electrode particles (CNT@AC-S) in minutes. The fabrication of the CNT@AC-S electrode particles only involves low-cost sulfur blocks, commercial carbon nanotubes (CNT) and activated carbon (AC) micro-particles with high specific surface area. Based on the above core–shell CNT@AC-S particles, sulfur cathode with a high sulfur-loading of 9.2 mg cm−2 delivers a stable area capacity of 6.6 mAh cm−2 over 100 cycles. Furthermore, even for sulfur cathode with a super-high sulfur content (72 wt% over the whole electrode), it still delivers a high area capacity of 9 mAh cm−2 over 50 cycles in a quasi-lean electrolyte condition. In a nutshell, this study brings a green and industry-friendly fabrication strategy for cost-effective production of rationally designed S-rich electrode particles.
The research on room-temperature sodium-sulfur batteries is gathering significant attention over the past ten years. This battery technology is a competitive candidate for upcoming grid scale ...stationary storage units where cost gains precedence over the energy density in market feasibility for applications. Despite the high theoretical capacity of the sodium-sulfur battery, its acceptance is obstructed by serious challenges. The key challenge includes its accelerated shuttle effect and little sulfur electroactivity, which lead to inferior accessible discharge capacity and faster decay.This paper summarizes major benefits, challenges, and operating principle of Na-S battery technology at room-temperature. The conventional and recent strategies for performance improvements of these batteries by tailoring sulfur cathode have been discussed. The broad guidelines for future advancement of these batteries are also summarized and critically explained. Understanding the cell chemistry using in-situ characterization techniques and optimization of each compartment i.e. cathode/anode/electrolyte of room temperature sodium-sulfur batteries, are essential for their further advancement as a feasible technology for energy storage. Keywords: Composite sulfur electrode, Sodium-sulfur battery, Polysulfide shuttle, Energy storage
Lithium–sulfur batteries suffer from severe self-discharge due to polysulfide dissolution into electrolytes. In this work, a chemically anchored polymer-coated (CAPC) sulfur electrode was prepared, ...through chemical bonding by coordinated Cu ions and cross-linking, to improve cyclability for Li/S batteries. This electrode retained specific capacities greater than 665 mAh g–1 at high current density of 3.35 A g–1 (2C rate) after 100 cycles with an excellent Coulombic efficiency of 100%.
Lithium-sulfur batteries possess high theoretical energy density. They are promising in future application. Practical electrochemical performance of lithium-sulfur batteries need to be improved. In ...this study, a facile approach has been proposed to improve electrochemical properties of lithium-sulfur batteries. Lamellar graphite coatings with different thickness have been prepared on the surface of sulfur electrodes. Morphology of materials has been characterized and electrochemical properties for batteries have been tested. Results indicate that there are cracks on the surface of sulfur electrodes. Lamellar graphite coatings with thickness of 6 μm and 12 μm have uniformly covered surface of sulfur electrodes. Graphite coatings effectively hinder the dissolution of lithium polysulfides and contribute to increase in discharge capacity and retention rate. Thickness of graphite coating affects electrochemical properties of lithium-sulfur batteries. Electrode with 12 μm graphite coating possesses higher discharge capacity and cycle stability than that with 6 μm graphite coating. After 150 cycles, discharge capacity of electrodes with 6 μm and 12 μm graphite coating is 693 mAh g
−1
and 821 mAh g
−1
respectively.
The investigation focused on sulfur chemistry and application to the development of rechargeable batteries with energy density exceeding 250 W h/kg, a rate capability comparable to or exceeding ...water-based electrolyte systems, and operation at temperatures up to −60 °C. The study addressed sulfur electrochemical utilization limits, low-temperature performance process limits, and rate capability limits.
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