An integrated approach to improve the performance of lean–electrolyte lithium–sulfur batteries

While the sulfur conversion reaction kinetics in Li–S batteries is nowadays improved by the use of appropriate electrocatalysts,it remains a challenge for the batteries to perform well under the lean electrolyte condition where polysulfide shuttle,electrode passivation and the loss of electrolyte due to side reactions,are aggravated.These challenges are addressed in this study by the tandem use of a polysulfide conversion catalyst and a redox–targeting mediator in a gel sulfur cathode.Specifical...     

A comparison of sulfur loading method on the electrochemical performance of porous carbon/sulfur cathode material for lithium–sulfur battery

To get a high sulfur loaded porous carbon/sulfur cathode material with an excellent performance, we investigated four different sulfur loading treatments. The samples were analyzed by the Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD) patterns, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). We proved that it is more effective to introduce the sulfur into the pores of porous carbon at 300 °C than at 155 °C. Especially, the porous carbon/sulfur composite heated in a sealed reactor at 300 °C for 8 h presents a fine sulfur load with sulfur content of 78 wt.% and exhibits an excellent electrochemical performance. The discharge capacity is 760, 727, 744, 713, and 575 mAh g^?1 of sulfur at a current density of 80, 160, 320, 800, and 1,600 mA g^?1 based on the sulfur/carbon composite, respectively. What is more, there is almost no decay at the current density of 800 mA g^?1 for 50 cycles and coulombic efficiency remains over 95 %.     

Synthesis and electrochemical performance of sulfur–carbon composite cathode for lithium–sulfur batteries

In this paper, porous carbon was synthesized by an activation method, with phenolic resin as carbon source and nanometer calcium carbonate as activating agent. Sulfur–porous carbon composite material was prepared by thermally treating a mixture of sublimed sulfur and porous carbon. Morphology and electrochemical performance of the carbon and sulfur–carbon composite cathode were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectra (EIS), and galvanostatic charge–discharge test. The composite containing 39 wt.% sulfur obtained an initial discharge capacity of about 1,130 mA?h g^?1 under the current density of 80 mA?g^?1 and presented a long electrochemical stability up to 100 cycles.     

Synthesis and electrochemical performance of TiO2–sulfur composite cathode materials for lithium–sulfur batteries

Titania–sulfur (TiO₂–S) composite cathode materials were synthesized for lithium–sulfur batteries. The composites were characterized and examined by X-ray diffraction, nitrogen adsorption/desorption measurements, scanning electron microscopy, and electrochemical methods, such as cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests. It is found that the mesoporous TiO₂ and sulfur particles are uniformly distributed in the composite after a melt-diffusion process. When evaluating the electrochemical properties of as-prepared TiO₂–S composite as cathode materials in lithium–sulfur batteries, it exhibits much improved cyclical stability and high rate performance. The results showed that an initial discharge specific capacity of 1,460 mAh/g at 0.2 C and capacity retention ratio of 46.6 % over 100 cycles of composite cathode, which are higher than that of pristine sulfur. The improvements of electrochemical performances were due to the good dispersion of sulfur in the pores of TiO₂ particles and the excellent adsorbing effect on polysulfides of TiO₂.     

P_4S_(10) modified lithium anode for enhanced performance of lithium–sulfur batteries

To address the corrosion and dendrite issues of lithium metal anodes, a protective layer was ex-situ constructed by P_4S_(10) modification. It was determined by X-ray photoelectron spectroscopy and Raman spectra that the main constituents of the protective layer were P_4S_(10), Li_3PS_4 and other LixPySztype derivatives. The protective layer was proved to be effective to stabilize the interphase of lithium metal. With the modified Li anodes, symmetric cells could deliver stable Li plating/stripping for 16000 h; Li–S batteries exhibited a specific capacity of 520 m A h g~(-1) after 200 cycles at 1000 m A g~(-1) with average Coulombic efficiency of 97.9%. Therefore, introducing LixPySzbased layer to protect Li anode provides a new strategy for the improvement of Li metal batteries.     

Carbon fiber-incorporated sulfur/carbon ternary cathode for lithium–sulfur batteries with enhanced performance

Journal of Solid State Electrochemistry - Smart construction of advanced sulfur cathodes is indispensable for the development of high performance lithium–sulfur (Li–S) batteries. Hence,...     

Enhancing electrochemical conversion of lithium polysulfide by 1T-rich MoSe2 nanosheets for high performance lithium–sulfur batteries

The sluggish conversion kinetics and shuttle effect of lithium polysulfides (LiPSs) severely hamper the commercialization of lithium–sulfur batteries. Numerous electrocatalysts have been used to address these issues, amongst which, transition metal dichalcogenides have shown excellent catalytic performance in the study of lithium–sulfur batteries. Note that dichalcogenides in different phases have different catalytic properties, and such catalytic materials in different phases have a prominent impact on the performance of lithium–sulfur batteries. Herein, 1T-phase rich MoSe₂ (T-MoSe₂) nanosheets are synthesized and used to catalyze the conversion of LiPSs. Compared with the 2H-phase rich MoSe₂ (H-MoSe₂) nanosheets, the T-MoSe₂ nanosheets significantly accelerate the liquid phase transformation of LiPSs and the nucleation process of Li₂S. In-situ Raman and X-ray photoelectron spectroscopy (XPS) find that T-MoSe₂ effectively captures LiPSs through the formation of Mo-S and Li-Se bonds, and simultaneously achieves fast catalytic conversion of LiPSs. The lithium–sulfur batteries with T-MoSe₂ functionalized separators display a fantastic rate performance of 770.1 mAh/g at 3 C and wonderful cycling stability, with a capacity decay rate as low as 0.065% during 400 cycles at 1 C. This work offers a novel perspective for the rational design of selenide electrocatalysts in lithium–sulfur chemistry.     

Emerging energy chemistry in lithium–sulfur pouch cells

正On pursuing high-energy-density energy storage systems beyond the current lithium-ion battery technique, lithium–sulfur(Li–S) batteries have attracted worldwide attention due to their ultrahigh theoretical energy density up to 500 Wh kg~(-1)[1]. The unique Li–S chemistry based on the conversion reactions between solid sulfur, dissolved lithium polysulfides, and solid lithium sulfide affords thermodynamic advantages including high cathode specific capacity and low anode potential [2]. However,     

Catalytic performance of binary transition metal sulfide FeCoS2/rGO for lithium–sulfur batteries

Journal of Solid State Electrochemistry - The FeCoS2/rGO was synthesized by a one-step hydrothermal method, which has the advantages of environmental friendliness and low cost. Dense and...     

Mechanism of high-concentration electrolyte inhibiting the destructive effect of Mn(Ⅱ)on the performance of lithium-ion batteries

By optimizing electrolyte formulation to inhibit the deposition of transition metal ions(TMIs) on the surface of the graphite anode is an effective way to improve the electrochemical performance of lithium-ion batteries.At present,it is generally believed the formation of an effective interfacial film on the surface of the anode electrode is the leading factor in reducing the dissolution of TMIs and prevent TMIs from being embedded in the electrode.It ignores the influence of the solvation struc...     

Synthesis and application of single-atom catalysts in sulfur cathode for high-performance lithium–sulfur batteries

Lithium–sulfur(Li-S) batteries are regarded as one of the most promising energy storage devices because of their low cost, high energy density, and environmental friendliness. However, Li-S batteries suffer from sluggish reaction kinetics and serious “shuttle effect” of lithium polysulfides(LiPSs), which causes rapid decay of battery capacity and prevent their practical application. To address these problems, introducing single-atom catalysts(SACs) is an effective method to improve the electroch...     

Nitrogen-doped hierarchical porous carbon derived from metal–organic aerogel for high performance lithium–sulfur batteries

Nitrogen-doped three-dimensional(3 D) porous carbon materials have numerous applications due to their highly porous structures, abundant structural nitrogen heteroatom decoration and low densities. Herein,nitrogen doped hierarchical 3 D porous carbons(NHPC) were prepared via a novel metal–organic aerogel(MOA), using hexamethylenetetramine(HMT), 1,3,5-benzenetricarboxylic acid and copper(II) as starting materials. The morphology, porous structure of the building blocks in the NHPC can be tuned readily using different amount of HMT, which makes elongation of the pristine octahedron of HKUST-1 to give rise to different aspect ratio rod-like structures. The as-prepared NHPC with rod-like carbons exhibit high performance in lithium sulfur battery due to the rational ion transfer pathways, high N-doped doping and hierarchical porous structures. As a result, the initial specific capacity of 1341 m A h/g at rate of 0.5 C(1 C = 1675 m A h/g) and high-rate capability of 354 m A h/g at 5 C was achieved. The decay over 500 cycles is 0.08% per cycle at 1 C, highlighting the long-cycle Li–S batteries.     

Insight into demand-driven preparation of single-atomic mediators for lithium–sulfur batteries

Lithium-sulfur(Li-S) batteries have attracted considerable attention as one of the most appealing energy storage systems.Strenuous efforts have been devoted to tackling the tremendous challenges,mainly pertaining to the severe shuttle effect,sluggish redox kinetics and lithium dendritic growth.Single-atomic mediators as promising candidates exhibit impressive performance in addressing these intractable issues.Related research often utilizes a trial-and-error approach,proposing solutions to fabri...     

Investigation on the effect of nanosilica towards corn starch–lithium perchlorate-based polymer electrolytes

Biodegradable corn starch–lithium perchlorate (LiClO₄)-based solid polymer electrolytes with addition of nano-sized fumed silica (SiO₂) were prepared by solution casting technique. Ionic conductivity at ambient temperature was measured by AC impedance spectroscopy. Upon addition of nano-sized SiO₂, the ionic conductivity at room temperature is increased. The optimum ionic conductivity value obtained was 1.23?×?10^?4?S?cm^?1 at 4?wt% SiO₂. This may be attributed to the low crystallinity of the polymer electrolytes resulting from the dispersed nanosilica particles. Fourier–transform infrared spectroscopy studies confirmed the complexation between corn starch, lithium perchlorate, and silica. The thermal properties of the prepared samples were investigated with differential scanning calorimetry and thermogravimetric analysis. The surface morphology of the polymer electrolytes confirmed the agglomeration of particles after excess dispersion of inorganic filler. This was proven in the scanning electron microscopy studies.     

Reduced graphene oxide-encapsulated mesoporous silica as sulfur host for lithium–sulfur battery

Journal of Solid State Electrochemistry - With up to fivefold higher in energy density vs. lithium-ion battery, lithium–sulfur (Li–S) battery is a compelling energy storage system,...     

An odyssey of lithium metal anode in liquid lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries exhibit outstanding energy density and material sustainability. Enormous effects have been devoted to the sulfur cathode to address redox kinetics and polysulfide intermediates shuttle. Recent attentions are gradually turning to the protection of the lithium metal anodes, since electrochemical performances of Li–S batteries are closely linked to the working efficiency of the anode side, especially in pouch cells that adopt stringent test protocols. This Perspective article summarizes critical issues encountered in the lithium metal anode, and outlines possible solutions to achieve efficient working lithium anode in Li–S batteries. The lithium metal anode in Li–S batteries shares the common failure mechanisms of volume fluctuation, nonuniform lithium flux, electrolyte corrosion and lithium pulverization occurring in lithium metal batteries with oxide cathodes, and also experiences unique polysulfide corrosion and massive lithium accumulation. These issues can be partially addressed by developing three-dimensional scaffold, exerting quasi-solid reaction, tailoring native solid electrolyte interphase (SEI) and designing artificial SEI. The practical evaluation of Li–S batteries highlights the importance of pouch cell platform, which is distinguished from coin-type cells in terms of lean electrolyte-to-sulfur ratio, thin lithium foil, as well as sizable total capacity and current that are loaded on pouch cells. This Perspective underlines the development of practically efficient working lithium metal anode in Li–S batteries.     

Effect of cosintering of anode–electrolyte bilayer on the fabrication of anode-supported solid oxide fuel cells

A comparative study is carried out on the effect of cosintering temperature of anode–electrolyte bilayer on the fabrication and cell performance of anode-supported solid oxide fuel cells from commercially available tape casting materials. It was found that the sintering conditions have profound effects on the anode characteristic and cell performance. For low cosintering temperature as low as 1,250 °C, the electrolyte is unable to sinter fully and forms a porous structure which leads to a reduced open-circuit potential and poor cell performance especially under low current output. For further increasing cosintering temperature to 1,350 °C, the cell performance was lower under low current operation. However, the cell performance turns out to be better than that of high-temperature cosintering under high current output. Although at temperature as high as 1,500 °C the cell performs better than that of low temperature cosintering, the trend turn out to be reverse for high current operating due to less anode surface area resulting from overagglomeration of anode layer. An optimal cosintering temperature of 1,350–1,450 °C is recommended for commercially available anode–electrolyte bilayer of anode-supported solid oxide fuel cells.     

Nano-wire networks of sulfur–polypyrrole composite cathode materials for rechargeable lithium batteries

Polypyrrole (PPy) nanowire was synthesized through a surfactant mediated approach. The sulfur–polypyrrole (S–PPy) composite materials were prepared by heating the mixture of element sulfur and polypyrrole nanowire. The materials were characterized by FTIR, SEM. PPy with special morphology serves as conductive additive, distribution agent and absorbing agents, which effectively enhanced the electrochemical performance of sulfur. The initial discharge capacity of the active materials was 1222 mA h g⁻¹ the remaining capacity is 570 mA h g⁻¹ after 20th cycles.