A sulphur/boron-doped reduced graphene oxide (S/B-rGO) composite was prepared using a facile hydrothermal method. The two-dimensional stacked nanosheet structure of the S/B-rGO composite provides an ...effective electron-conduction path and traps soluble polysulphide intermediates via the introduction of boron doping. The electrochemical performance delivers a relatively high reversible discharge capacity of 521.9 mAh g-1 after 100 cycles at 0.1 C with a boron-doped reduced graphene oxide composite lithium/sulphur battery.
Although numerous research efforts have been made for the last two decades, the chronic problems of lithium-sulphur batteries (LSBs), i.e., polysulfide shuttling of active sulphur material and ...surface passivation of the lithium metal anode, still impede their practical application. In order to mitigate these issues, we utilized polyimide functionalized glass microfibers (PI-GF) as a functional separator. The water-soluble precursor enabled the formation of a homogenous thin coating on the surface of the glass microfiber (GF) membrane with the potential to scale and fine-tune: the PI-GF was prepared by simple dipping of commercial GF into an aqueous solution of poly(amic acid), (PAA), followed by thermal imidization. We found that a tiny amount of polyimide (PI) of 0.5 wt.% is more than enough to endow the GF separator with useful capabilities, both retarding polysulfide migration. Combined with a free-standing microporous carbon cloth-sulphur composite cathode, the PI-GF-based LSB cell exhibits a stable cycling over 120 cycles at a current density of 1 mA/cm
and an areal sulphur loading of 2 mgS/cm
with only a marginal capacity loss of 0.099%/cycle. This corresponds to an improvement in cycle stability by 200%, specific capacity by 16.4%, and capacity loss per cycle by 45% as compared to those of the cell without PI coating. Our study revealed that a simple but synergistic combination of porous carbon supporting material and functional separator enabled us to achieve high-performance LSBs, but could also pave the way for the development of practical LSBs using the commercially viable method without using complicated synthesis or harmful and expensive chemicals.
A modified 4-electrode Swagelok cell is proposed as an in situ analytical tool for the detection of soluble polysulphides in the electrolyte during lithium sulphur battery operation. Besides the ...standard Swagelok configuration, this cell has two additional perpendicular electrodes (wires) placed between two separators. Soluble polysulphides in the electrolyte are reduced on the nickel wire and the cumulative charge in the potential range between 2.25V and 1.5V versus platinum is used for the quantitative analysis. The proposed cell can be used as an effective and a reliable in situ analytical tool which can significantly help in studying how different solvents, salts, additives and electrode architectures impact the stability of the lithium–sulphur battery, hence the set up of foundation to design better electrolytes and/or additives.
Lithium sulphur technology for energy storage is considered to be one of the most promising of emerging technologies due to its high theoretical capacity, but the performance of these batteries is ...limited by problems such as dissolution of polysulphide species in electrolyte, lithium dendrite formation. Previously we demonstrated the capability of Li6PS5Cl, Li6PS6Br and Li10GeP2S12 anode-protecting solid electrolyte membranes to mitigate these problems. To further enhance the stability of these solid electrolyte membranes, here we demonstrate that atomic layer deposition of a thin conformal coating of lithium tantalate leads to lithium polysulphide semi-flow batteries with superior performance.
•Lithium tantalate is successfully coated on Li6PS5Cl, Li6PS5Br, Li10GeP2S12 solid electrolytes using Atomic Layer Deposition.•Demonstrated enhance met of stability of semi-flow lithium sulphur battery using lithium tantalate coated membrane•Demonstrated possible use of semi-flow lithium sulphur battery for portable applications
A novel approach is developed to synthesize microporous carbon spheres with pore size ranges from 5 to 11 Å from hyper-cross-linked polymer β-cyclodextrin. Sulphur is incorporated in the micropores ...by solution impregnation followed by melt infusion. The resultant carbon sulphur (C/S) composite is wrapped in reduced graphene oxide (rGO) to provide conductive pathways to access the sulphur in micropores and to protect the surface-adhered sulphur. The cathode material obtained from rGO wrapping delivers initial discharge capacity of 1103 mA h g
−1
at 0.1 C, maintaining a capacity of 626 mA h g
−1
at 0.2 C with capacity loss of 0.2% per cycle for more than 100 cycles. In another cell configuration using carbon paper as an interlayer, discharge capacity has raised to 850 mA h g
−1
at 0.2 C and maintained 86% of its capacity for 100 cycles with excellent rate capability and high Coulombic efficiency. The good performance may be referred to excellent conductive networks, porous architecture of carbon spheres and adsorption of catholyte by fibrous interlayer that can effectively reduce the polysulfide shuttling.
In this study a binder-free activated carbon cloth-sulphur (ACC-S) composite cathode is presented. Such a cathode was obtained using the impregnating technique of microporous activated carbon cloth ...with elemental melted sulphur. The surface morphology of an activated carbon cloth-sulphur electrode was studied using a scanning electron microscope (SEM), which was equipped with an EDX spectroscopy attachment. Electrochemical properties of the ACC-S composite cathode was tested in an ionic liquid electrolyte consisting of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide (EtMeImNTf2) and bis(trifluoromethanesulphonyl)imide (LiNTf sub(2)). The ACC-sulphur cathode working together with lithium anode was tested with the use of cyclic voltammetry (CV), galvanostatic charge/discharge cycles and electrochemical impedance spectroscopy (EIS). The capacity and cyclic stability of the ACC-S composite cathode were much better than those for the sulphur cathode (a mixture of sulphur from graphene nanoplatelets and carbon black) tested in the same ionic liquid electrolyte. The ACC-sulphur cathode showed good cyclability and coulombic efficiency (99%) with the ionic liquid electrolyte. The reversible capacity of the ACC-S|electrolyte|Li cell was ca. 830 mAh g super(-1) after 50 cycles.
Here we report on a Li-S battery with cathode, based on a S powder obtained from bulk amorphous S, by cryogenic grinding. The cathode was prepared from a slurry, wherein the content of cryo-ground S ...powder was equal to 80 wt % (corresponds to ≈ 2.26 mg cm−2). Other slurry components included carbon Super P, and polyvinylidene fluoride, dispersed in N-methylpyrrolidone. The electrochemical performance of the as-prepared battery was compared to a battery based on an identically prepared paste, but containing reference S powder (with the orthorhombic structure). A longer life cycle, and enhanced capacity per gram, as well as per cm2 of electrode was revealed for the cryo-ground S-based cathode. The electrochemical results show that the loss in capacity of the cryo-ground S powder cathode was just 3% after 50 cycles, which suggests on a higher stability of S inside the cathode during cycling.
•The novel method of sulphur cathode preparation for Li-S batteries was developed.•Cryo-ground sulphur cathode provides better characteristics at high current load.•Cryo-ground sulphur cathode shows very high stability also with high sulphur loading.
Lithium-sulphur accumulators are, thanks to their high theoretical energy density and good availability of sulphur, one of the most promising concepts of the new generation of accumulators. In this ...paper, we present a 3D structured cathode formed on a natural basis. A sea sponge
Spongia officinalis
served as a template for the electrode structure. This 3D electrode provides enough space for sulphur. Thus, it allows high sulphur loading. This electrode structure also immobilizes polysulphides inside the cathode and improves stability during cycling. The resultant new cathode configuration allows reaching very high sulphur area loading of 4.9 mg/cm
2
which is almost four times more than in the case of a standard coated electrode. Despite the high sulphur loading, the electrode maintains high stability during cycling in comparison with a standard electrode and it also reaches much higher square capacity, exceeding 3.0 mAh/cm
2
.
Graphene is used as a barrier film to suppress the “shuttle effect” and to improve the performance of activated carbon-sulphur hybrid cathode materials in a lithium-sulphur battery by forming a ...core-shell structure. Graphene wraps around the activated carbon-sulphur hybrid to form a core-shell structure, in which the porous carbon framework stores most of the sulphur and the graphene layer suppresses the movement of the soluble polysulfide in the electrolyte during charge-discharge, resulting in an improvement of capacity and cyclic stability during long-term cycling. Such a core-shell structure is formed by changing the hydrophilicity of graphene oxide during reduction, in which the hydrophobic graphene closely wraps around the hydrophobic carbon surface.
The lithium-sulphur (Li-S) system is one of the most promising candidates for high energy density applications. Sulphur has several drawbacks such as poor conductivity, large volumetric expansion ...upon lithiation, dissolution of the intermediate polysulfides during charge-discharge processes. The objective of the present work is to prepare a ternary composite of MWCNT/S/conducting polymer system with unique characteristics to be used as a cathode material for lithium sulphur batteries. The synthesis has been carried out in two steps. Sulphur is introduced onto the surface of MWCNT by the chemical reaction between sodium thiosulphate and hydrochloric acid. In the second step, polyindole is produced by insitu reaction from indole monomer by using FeCl3 as oxidising agent. The MWCNT and conducting polymer help to improve the conductivity of sulphur. The composite material is characterised by TGA, FTIR, SEM-EDS and XRD analysis. The polyindole formation is confirmed by using FTIR and SEM-EDS. Electrochemical studies have been performed to demonstrate MWCNT/sulphur/polymer composites as a cathode material for rechargeable lithium –sulphur batteries.
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