Performance Of Lithium-sulfur Batteries Research Articles

2D Ultrathin Titanium Nitride Nanosheets as Separator Coatings for Li-S Batteries.

Transition metal nitrides (TMNs) are affirmed to be an appealing candidate for boosting the performance of lithium-sulfur (Li-S) batteries due to their excellent conductivity, strong interaction with sulfur species, and the effective catalytic ability for conversion of polysulfides. However, the traditional bulk TMNs are difficult to achieve large active surface area and fast transport channels for electrons/ions simultaneously. Here, a 2D ultrathin geometry of titanium nitride (TiN) is realized by a facile topochemical conversion strategy, which can not only serve as an interconnected conductive platform but also expose abundant catalytic active sites. The ultrathin TiN nanosheets are coated on a commercial separator, serving as a multifunctional interlayer in Li-S batteries for hindering the polysulfide shuttle effect by strong capture and fast conversion of polysulfides, achieving a high initial capacity of 1357mAhg-1 at 0.1C and demonstrating a low capacity decay of only 0.046% per cycle over 1000 cycles at 1C.

Preparation and properties of protein-derived carbon-modified CoS2 applied to high-performance lithium-sulfur battery

In this study, we utilized egg white as a carbon source and sublimated sulfur as a source to synthesize the carrier material with carbon nanosheet framework-modified CoS2 nanoparticles (CoS2@C) through a one-step method. We investigated the effect of temperature on the material's structure and chemical composition and the impact of the carrier material on the electrochemical performance of lithium-sulfur batteries. The results reveal that CoS2@C-600 synthesized at 600 °C exhibits an exceptional three-dimensional carbon nanosheet structure with well-defined crystallinity for CoS2. The three-dimensional carbon sheet framework possesses abundant porous structures and high conductivity, providing ample space for sulfur accommodation and physically inhibiting the dissolution of polysulfides. Additionally, electrochemical tests demonstrate that the material exhibits remarkable rate capability and cycling performance. At a current density of 0.5 A/g, the initial discharge-specific capacity reaches 1407 mAh/g, and after 100 cycles, the specific capacity remains at 824 mAh/g. Even under high current conditions of 5 A/g, the specific capacity is maintained at 256 mAh/g. The carrier material, possessing a well-designed structure and an efficient lithium polysulfide electrocatalyst, effectively improves the cycling stability and enhances the rate performance of lithium-sulfur batteries.

Unleashing the power: Superior properties of fluorographene-derived materials for energy storage applications

Fluorographene exhibits a rich chemistry and a wide range of applications in energy storage devices. This review, which is based on our lab results acquired in the last decade, explores the synthesis, properties, and performance of fluorographene-based materials in supercapacitors and batteries. Fluorographene can be prepared through mechanical or chemical delamination of graphite fluoride, allowing for scalable synthesis and further chemical processing. The chemical versatility of fluorographene enables a wide portfolio of chemical reactions, leading to a new class of graphene derivatives. Graphene acid, a product of fluorographene chemistry, exhibits excellent specific capacitance, cycling stability, and rate capability. Hybridizing graphene acid with metal-organic frameworks can achieve even higher energy and power densities. Furthermore, nitrogen-doped graphene derived from fluorographene demonstrates remarkable capacitive behavior, making it an efficient electrode material for supercapacitors. Additionally, fluorographene-based materials, such as graphene acid, graphene-sulfur hybrids, and graphene-based anodes, have exhibited outstanding performance in lithium-ion and lithium-sulfur batteries. The scalable synthesis, high performance, and versatility of fluorographene-derived materials render them attractive for practical energy storage applications. The unique properties and wide range of chemistries offered by fluorographene chemistry open new possibilities for improving advanced energy storage devices.

Effect of activated Ketjen black and nano-size sulfur particles on electrochemical performance of lithium-sulfur battery

The sulfur-activated Ketjen black nanostructure (S@KB), as the cathode in lithium-sulfur (Li-S) battery, was synthesized using the sulfur-amine chemistry technique. The nano-sized sulfur particles expedite the electrical conductivity, and strengthen the sulfur utilization. Moreover, the sulfur nanoparticles compensate for its massive volume expansion driven by the lithiation process. The activation of KB can cultivate the electrochemical properties of the cathodic composition for protracted cycling by intensifying the available surface area. The sulfur mass loading was about 1 mg cm−2. The premier specific capacity was acquired 1190.63 mAh g−1 at 0.1 C, which was stabilized to 671.32 mAh g−1 after 200 cycles. The accomplished characterizations substantiate the suitable incorporation of sulfur into the activated KB (AKB) structure and the splendid interaction between them. It was educed that the S@KB cathode can relieve the penetration of polysulfides toward the anode and, as a result subdue the shuttle effect. It was determined a notable reversible capacity of 1002.81 mAh g−1 after 40 cycles at varied current rates.

Modulation of Potential-Limiting Steps in Lithium-Sulfur Batteries by Catalyst Synergy.

Electrocatalysis is considered to be an effective method to solve the sluggish kinetics of lithium-sulfur batteries. However, a single catalyst cannot simultaneously catalyze multi-step sulfur reductions. And once the catalyst surface is covered by the initially deposited solid products, the subsequent catalytic activity will significantly deteriorate. Here, microporous ZIF-67 and its derivative nano-metallic Co0 are used as dual-catalyst aiming to address these drawbacks. The dual catalytic center effectively cooperates the adsorption and electron transfer for multi-steps of sulfur reductions, transforming the potential-limited step (Li2S4→Li2S2/Li2S) into a thermodynamic spontaneous reaction. ZIF-67 first adsorbs soluble Li2S4 to form a coordination structure of ZIF-Li2S4. Then nano-metallic Co0 attracts uncoordinated S atoms in ZIF-Li2S4 and facilitates the breaking of S-S bonds to form transient reductive ZIF-Li2S2 and Co-S2 via. spontaneous electron transfer. These intermediates facilitate continuous conversion to Li2S with reduced formation energy, which is beneficial to the regeneration of the catalyst. As a result, the cathode with ZIF@CNTs/Co@CNFs synergetic catalyst achieves initial areal capacity of 4.7mAhcm-2 and maintains 3.5mAhcm-2 at low electrolyte/sulfur ratio (E/S) of 5µLmg-1. This study provides valuable guidance for improving the electrochemical performance of lithium-sulfur batteries through catalyst synergistic strategies for multi-step reactions.

Cherry blossom derived micron carbon sheets loaded with Co based particles served as sulfur host for lithium sulfur batteries

In order to effectively alleviate the shuttle effect in lithium-sulfur batteries (LSBs), cherry blossom-derived micron carbon sheets loaded with a small amount of Co-based nano-particles are synthesized in this work. After the thermal decomposition of ZIF-67, the composite shows a high specific surface area (2768.2 m² g−1) and pore volume (1.63 cm³ g−1), which can enhance the physical adsorption of polysulfides. Moreover, the Co-N and Co nano-particles obtained by ZIF-67 have strong catalytic and polar adsorption abilities. Not only can they accelerate the electrochemical reaction, but also effectively inhibit the shuttle effect of polysulfides, which in turn improves the electrochemical performance of lithium-sulfur batteries. Thus, the initial discharge capacity of the Co-PB@S electrodes reached 933 mAh g−1, with a remaining capacity of 550 mAh g−1 after 500 cycles at 0.5 C. This work may provide a practical way for the application of LSBs and the field of electrocatalysis.

Enhancing lithium-sulfur battery performance through electronic/ionic co-conductive multi-walled carbon nanotubes/lithium lanthanum titanium oxide separator modification

As one of the most promising energy storage devices, lithium-sulfur batteries (LSBs or Li-S batteries) are still facing obstacles due to the notorious shuttling of soluble polysulfide intermediates, accompanied by low S utilization, corrosion of the lithium anode, and rapid capacity fading, leading to a short cycling life. To overcome these issues and achieve high-performance LSBs, we introduce a modified separator composed of multi-walled carbon nanotubes/lithium lanthanum titanium oxide (MWCNTs/LLTO). The proposed MWCNTs/LLTO-modified separator improves the redox reaction kinetics from soluble higher-order lithium polysulfides to insoluble lower-order ones and ultimately to Li2S, thereby reducing the polysulfides dissolved in the electrolyte. It also serves as a physical barrier to adsorb polysulfides, efficiently preventing their diffusion from the cathode to the anode. LSBs adopting the MWCNTs/LLTO-modified separator exhibit higher ionic and electronic conductivity than their un-modified counterparts, leading to an initial specific capacity of 1496 mA/h/g (∼90% of the theoretical capacity) at 0.1 C, excellent rate capability performance, and a remarkable capacity retention of 80% after 200 cycles. Furthermore, the cells with S loading reaching up to 4.18 mg/cm2 further confirmed the beneficial impact of the MWCNTs/LLTO-modified separator.

Faradaic impedance and discharge reactions in lithium sulfur battery with sparingly solvating electrolyte

Lithium-sulfur batteries promote next-generation secondary batteries. Elucidating their electrochemical reactions, such as sulfur reduction reactions, particularly their kinetics, is crucial for further improvement of lithium-sulfur batteries. Therefore, experimental knowledge of their reaction rates is required. In this study, we applied in situ electrochemical impedance spectroscopy to a lithium-sulfur battery using a sulfolane-based super-concentrated electrolyte solution to obtain insights into sulfur reduction reaction kinetics. The Faradaic impedance of a sulfur-positive electrode yielded inductive and capacitive semicircles at first and second plateau voltages, respectively, in a low-frequency range. This impedance behavior under a low-frequency range was derived from multistep reactions. The impedance behavior suggests that the reaction rate constant of the second step was greater than that of the first step at the first plateau, whereas at the second plateau, the reaction rate constant of the second step was smaller than that of the first step. A Faradaic impedance simulation was performed to estimate the reaction rate constants of the sulfur reduction reactions. The simulation well reproduced the experimental data. Furthermore, the simulation showed that the internal resistance of the battery decreased as the rate constant of each reaction changed, suggesting that Faradaic impedance analysis is useful not only for investigating reaction kinetics but also for improving lithium-sulfur battery performance.

Carbon nanotubes integrated with multiphasic molybdenum diselenide nanosheets as hybrid membrane accomplish highly efficient electrocatalysts for lithium-sulfur batteries

Lithium sulfur (Li-S) batteries are considered a promising application device due to their high theoretical capacity and energy density. However, the commercialization of Li-S batteries is hindered by the rapid capacity fading caused by the shuttle effect of lithium polysulfide (LiPSs) and the sluggish redox reaction of sulfur cathodes. To address these issues, the hybrid membrane with combination of multiphasic molybdenum diselenide nanosheets (MMS) modified carbon nanotubes (MMS@CNTs) and utilized Li2S6 catholyte for Li-S batteries. The conductivity CNTs facilitate fast electronic/ionic transport, while the polarity of MMS has a strong affinity for LiPSs, effectively anchoring them, facilitating the redox conversion of lithium polysulfides, and effectively diminishing reaction barriers. The cell with MMS@CNTs displays an initial discharge capacity of 1036.2 mAh g−1 and maintains 810.5 mAh g−1 after 300 cycles at 0.2 C with 5.4 mg sulfur loading. Remarkably, even at 10.8 mg sulfur loading, the MMS@CNTs membrane displays high capacity of 8.1 mAh and maintains 6.7 mAh over 100 cycles. The results show that the efficient chemical anchoring polysulfides and catalyzing redox reaction by multifunctional MMS@CNTs hybrid composites is promising for assembling with a high sulfur loading electrode, which exhibits a superior electrochemical performance in Li-S batteries.

Synergistic improvements on capacity and Coulombic efficiency of lithium-sulfur batteries with NiSe-Ni2P/C modification on PP separators

Lithium-sulfur batteries (LSBs) emerge as promising energy storage devices due to their high theoretical energy density. So far, there are constrained issues that need to be urgently addressed, such as the shuttle effect of lithium polysulfides (LiPS) and the sluggish kinetics of redox reactions. Herein, NiSe-Ni2P/C composite was synthesized and casted on the cathode side of polypropylene (PP) separator. This investigation reveals that the adsorption-catalysis synergistic effect of NiSe-Ni2P/C composite, accelerates the reduction of LiPS to lithium sulfide (Li2S) as well as the oxidation of Li2S. The synergistic effect effectively mitigates the shuttle effect of LiPS, reduces concentration polarization, and improves Coulombic efficiency (CE) throughout the entire lifespan. At a current density of 0.05 C, LSBs with NiSe-Ni2P/C modified PP separators exhibit a remarkable high initial CE of 97.0% and a substantial discharge specific capacity of 1205.4 mAh gs−1. Even under conditions of a high sulfur loading (4.3 mg cm−2) and a limited electrolyte dosage (10 μL mgs−1), the LSBs maintained a reversible specific capacity of 804 mAh gs−1, a CE of 94%, and an energy density of 1232.1 Wh kgs−1 after 720 h of continuous cycling at 0.05 C. This work provides a solution for achieving long-time, high-capacity, and high-CE electrochemical performance in LSBs with a high sulfur loading and a limited electrolyte dosage.

Synergistic Effect of CNT-TiO2 Catalyst and 3D Electrode Architecture for Electrochemical Performance in Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) are a potential electrochemical storage system for the future with high capacity (1675 mAh g−1) and energy density (∼2600 Wh kg−1). The poor conductivity of sulfur, polysulfide shuttle effect, and volume expansion of the sulfur cathode are the main hurdles to their commercialization. To mitigate these issues, this work represents a rational composite of hybrid multiwalled carbon nanotubes (MWCNT) -TiO2 high surface area carbon-sulfur composite (CTHS) onto a 3D carbon fiber (CF) based free-standing electrode (CTHS@CF) architecture. TiO2 can effectively anchor the polysulfides by chemical bonding and improve cyclability. MWCNTs and CFs are the effective electron transport materials that accelerate the redox kinetics of polysulfides. The electrochemistry of CTHS@CF reveals an excellent discharge capacity of 910 mAh g−1 (1st cycle) at 100 mA g−1 compared to the conventional aluminum-coated (CTHS@Al) of 532 mAh g−1. The CTHS@CF (at 300 mA g−1) displays 514 mAh g−1 (initial discharge) capacity with 83% capacity retention up to 100 cycles, whereas CTHS@Al shows 394 mAh g−1 with 44% capacity retention. Combining 3D electrode architecture with the metal oxide (TiO2) plays a vital role in the electrochemistry of LSBs by improving the stability of the battery’s cycle life and overall energy density.

Application of sulfur-based composite materials in the positive electrode of lithium-sulfur batteries

Traditional lithium-ion batteries are no longer able to keep up with the growing need for energy storage efficiency in areas like electric cars and renewable energy storage. Because of their great energy density, affordability, and environmental friendliness, lithium-sulfur batteries are regarded as a very promising solution for secondary battery systems. Sulfur-based compounds are an essential part of lithium-sulfur batteries and have a direct impact on the battery’s energy density and performance. However, sulfur-based compounds are easily soluble in electrolytes and have low conductivity, which shortens battery cycle life and energy efficiency. Sulfur dissolution can be successfully inhibited and capacitance may be enhanced by optimizing the structure and characteristics of sulfur-based materials, which will improve the overall performance of lithium-sulfur batteries. To enhance the performance of lithium-sulfur batteries, this article suggests three modification techniques for sulfur-based materials. These techniques mostly include compounding sulfur with carbon compounds, metal oxides, and polymers. This article also outlines the shortcomings of the present lithium-sulfur battery research and looks forward to the future development direction.

Revisiting the unified principle for the single-atom electrocatalysts in sulfur reduction reaction: from liquid to solid-state electrolytes

The conversion of lithium-polysulfides (LPSs) through the sulfur reduction reaction (SRR) is a crucial process for improving the electrochemical performance of lithium-sulfur (Li-S) batteries. However, the microscopic mechanism of SRR...

Discharge characteristic analysis of lithium-sulfur batteries considering the discontinuous deposit and transport-limited effects

The modeling research plays a crucial role in grasping the reaction mechanisms and forecasting the performance of lithium-sulfur (Li–S) batteries. A transient Li–S battery model including continuity, transportation, and reaction kinetics by simultaneously considering the discontinuous deposit of discharge product Li2S and the transport limitation in the concentrated electrolyte, is developed to reveal the discharge phenomena. The effects of operating conditions and electrolyte and electrode properties on the discharge behaviors including voltage-capacity curve, energy density, profiles of solid product (ɛLi2S) and porosity (ɛ) at the cathode are quantitatively studied. It is found that low discharge rate is beneficial to the discharge capacity and utilization of cathode sulfur. Enhancing precipitate (S8) solubility Ksp, S8 and ionic diffusivity Di improves voltage plateau and specific energy to varying degrees; the promotion of voltage plateau will be inconspicuous as electrode conductivity σ is enlarged over 0.1 S/m. With the rise of ɛ from 0.5 to 0.9, the specific capacity and the specific energy are expanded by around 5 times. When lengthening Lca from 20 μm to 60 μm, the specific capacity ascends from 944.5 to 991.5 mAh/g-S, whereas the growth rate of specific capacity and specific energy decreases gradually; the practical total energy almost increases linearly with thickness, yielding a 218.75% enhancement. With a certain period of relaxation, the recovered cell capacity after the high discharge rate is higher than that after the low discharge rate. This work may guide in designing electrodes and electrolytes and provide performance regulation strategies for Li–S batteries.

Theoretical investigation of synergistically boosting the anchoring and electrochemical performance of lithiophilic/sulfiphilic transition metal carbides for lithium-sulfur batteries.

Lithium-sulfur (Li-S) battery is one of the most promising next-generation energy-storage systems with a high energy density and low cost. However, their commercial applications face several challenges, such as the shuttle effect caused by the soluble lithium polysulfide (LiPSs) intermediates and the sluggish sulfur redox reaction. In this article, we systematically investigated the anchoring and electrochemical performance of a series of transition metal carbides (TMCs: TiC, VC, ZrC, NbC, HfC, TaC) as cathode materials for Li-S batteries by theoretical calculations. The lithiophilic/sulfiphilic non-polar (001) surfaces of TMCs can offer moderate binding strength with LiPS intermediates, ensuring good performance of sulfur immobilization. These TMCs can also facilitate lithium diffusion, indicating the good rate performance of Li-S batteries. We also demonstrated that the studied TMCs can be classified into two classes according to their catalytic activity for Li2S decomposition which originated from their different electronic structural features. Furthermore, TiC, ZrC, and HfC exhibited excellent bifunctional electrochemical activity through reducing the Gibbs free energy for sulfur reduction reactions (SRRs) and lowering the barrier for Li2S decomposition which facilitates accelerating electrode kinetics and elevating utilization of sulfur. Our results offer a systematic approach to designing and screening non-polar materials for high-performance Li-S batteries, based on the rational electronic structure and lattice match strategy.

APPLICATION OF SULFUR RADICAL ANIONS IN ORGANIC SYNTHESIS. DETERMINATION OF FORMS OF SULFUR

The study of reactions involving sulfur anion radicals in organic synthesis has become an area of active research in the last few years. The role of polysulfide radicals in the electrochemical processes of lithium-sulfur (Li-S) batteries has been particularly discussed. Understanding the pathways of the electrochemical reactions is crucial for improving the performance of Li-S batteries. In order to summarize and analyze the most relevant literature data, the review presents information on the application and study of sulfur anion radicals in organic synthesis and methods for the determination of sulfur forms. We have classified and discussed in detail the spectra of various forms of sulfur in the ultraviolet and visible ranges. The article describes the choice of solvent, the correlation between the properties of solvents, the influence of the nature of the solvent on the absorption band shift of sulfur particles and on the stability of the anion radical, the identification of sulfur forms in the ultraviolet and visible spectrum regions, and the possibility of stabilizing anion radicals by complexation with crown ethers. The absorption bands for S22-, S32-, S52-, S72- strongly overlap with other particles while having lower intensities, leading to different conclusions regarding the distribution of polysulfides and different forms of sulfur in aqueous media. The data presented in the review have an applied meaning, contribute to the understanding of the application of sulfur anion radicals in organic synthesis and can be used for the choice of method for the determination of sulfur forms and solvent. This review article may be of interest to specialists in the field and will help to plan studies on the study of sulfur forms and the interpretation of spectra of different sulfur forms.

Theoretical study of highly efficient VS2-based single-atom catalysts for lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries have become a research hotspot due to their high energy density. However, they also have certain disadvantages and limitations. To enhance the performance of Li-S batteries, this study focuses on the utilization of transition metal (TM)-embedded vanadium disulfide (VS2) materials as cathode catalysts. Using density functional theory (DFT), comprehensive calculations and atomic-level screening of ten TM atoms were conducted to understand the underlying mechanisms and explore the potential of TM@VS2 catalysts for enhancing battery performance. The computational results indicate that five selected catalysts possess sufficient bonding strength towards high-order lithium polysulfide intermediates by the formation of a significant covalent bond between S atoms in Li2Sn and TM atoms, thereby effectively suppressing the shuttle effect. The Ni@VS2 catalyst can effectively decrease the decomposition energy barrier of Li2S in the charge reaction and can have an optimal Gibbs free energy at the rate-determining step among TM@VS2 catalysts for the discharge reaction. This study elucidates the mechanism of VS2-based transition-metal single-atom catalysts and provides an effective reference for the anchoring of TM atoms on other materials.

Sulfonic groups modified carbon nanotubes: the decorative strategy for enhancing the performance of lithium-sulfur batteries

Porous carbon nanotubes can not only provide a large surface area for anchoring sulfur and restraining polysulfides, but also provide continuous conductive networks to facilitate ion transport in lithium-sulfur batteries...

A zinc coordination supramolecular network synergized manganese dioxide achieves high-rate lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have attracted large attention due to their high capacity and energy density, however, the electrochemical performance of LSBs limited by the difficult conversion of lithium polysulfides (LiPSs)....

CoFe2O4 nanoparticles modified amidation of N-doped carbon nanofibers hybrid catalysts to accelerate electrochemical kinetics of Li-S batteries with high sulfur loading

Lithium-sulfur battery have been considered as promising energy storage devices because of its superiority in energy density. However, the low active material utilization, low sulfur loading, shuttle effect and torpid kinetics of polysulfides, and poor cycling stability limit its commercial applications. Herein, the functionalized nitrogen doped carbon nanofibers containing amide groups were designed by electrospun and polyamidoamine dendrimer (PAMAM) solution impregnation techniques. The obtained amide groups modified nitrogen-doped carbon nanofibers (ANF) were combined with spinel CoFe2O4 (CFO) nanoparticles (CFOANF) via hydrothermal method to design as membrane electrode containing Li2S6 catholyte for lithium-sulfur batteries. The introduction of nitrogen doped and amide groups modified ANF can increase fibers polarity, which have chemical adsorption capability toward lithium polysulfides. CFO nanoparticles can further absorb the soluble polysulfides by strong chemical interaction due to its intrinsic polarity and also serve as a catalyst to promote the redox kinetics of polysulfides conversion. Benefiting from the synergism of the physical confinement, polar chemical adsorption, and catalytic conversion, the as-prepared CFOANF delivers excellent electrochemical performances at high sulfur loading. The as-prepared CFOANF membrane with 6.3 mg cm−2 sulfur loading delivers a high initial capacity of 940 mAh g−1 and excellent long-term cycling stability up to 450 cycles with a low decay rate 0.059 % per cycle at 0.2C. Remarkably, even at 12.6 mg cm−2 and 16.4 mg cm−2 sulfur loading, the CFOANF membrane electrodes show high capacity of 9.7 mAh cm−2 and 11.8 mAh cm−2, respectively. The results show that the chemically anchoring polysulfides and catalyzing redox reaction by multifunctional CFOANF hybrid composite is promising for assembling with a high sulfur loading electrode, which exhibits a superior electrochemical performance in lithium-sulfur batteries.