Effect In Lithium-sulfur Batteries Research Articles

N-doped vanadium pentoxide materials for inhibiting shuttle effect in lithium-sulfur batteries

N-doped vanadium pentoxide materials for inhibiting shuttle effect in lithium-sulfur batteries

Two-dimensional SnP3 monolayer for inhibiting the shuttle effect in lithium-sulfur batteries: A first-principles study

The problems of the shuttle effect and sluggish transformation kinetics of lithium polysulfides (LiPSs) severely inhibit the practical application of Li-S batteries. Exploring anchoring materials with catalytic properties is an effective way to overcome these obstacles. In this paper, the electrochemical performance of SnP3 monolayer as an anchoring material is explored by using first-principles calculations. SnP3 monolayer can effectively anchor soluble LiPSs under vacuum and solvent conditions, and provides abundant adsorption sites for anchoring multiple LiPSs. Importantly, the rate-limiting step has changed to the conversion of Li2S8 to Li2S6, suggesting that the monolayer can facilitate the conversion of LiPSs and inhibit their accumulation in the electrolyte. Furthermore, lower decomposition and diffusion barriers of Li2S effectively inhibit the volume expansion of Li-S batteries. Thus, SnP3 monolayer becomes a promising anchoring material with suitable catalytic properties. This work demonstrates the feasibility of SnP3 monolayer as an anchoring material and expands the membership of phosphide family for applications in the field of Li-S batteries.

ARGET-ATRP-Mediated Grafting of Bifunctional Polymers onto Silica Nanoparticles Fillers for Boosting the Performance of High-Capacity All-Solid-State Lithium-Sulfur Batteries with Polymer Solid Electrolytes.

The shuttle effect in lithium-sulfur batteries, which leads to rapid capacity decay, can be effectively suppressed by solid polymer electrolytes. However, the lithium-ion conductivity of polyethylene oxide-based solid electrolytes is relatively low, resulting in low reversible capacity and poor cycling stability of the batteries. In this study, we employed the activator generated through electron transfer atom transfer radical polymerization to graft modify the surface of silica nanoparticles with a bifunctional monomer, 2-acrylamide-2-methylpropanesulfonate, which possesses sulfonic acid groups with low dissociation energy for facilitating Li+ migration and transfer, as well as amide groups capable of forming hydrogen bonds with polyethylene oxide chains. Subsequently, the modified nanoparticles were blended with polyethylene oxide to prepare a solid polymer electrolyte with low crystallinity and high ion conductivity. The resulting electrolyte demonstrated excellent and stable electrochemical performance, with a discharge-specific capacity maintained at 875.2 mAh g-1 after 200 cycles.

N doped carbon supported cobalt/tungsten nitride Mott−Schottky heterojunction as an efficient electrocatalyst to enhance adsorption and conversion of lithium polysulfides for high-performance lithium–sulfur batteries

Lithium–sulfur batteries (LSBs) suffer from the dissolution of lithium polysulfides (LiPSs) which leading to capacity degradation and poor cycling stability. Hence, weʼve developed the Co/W3N4@NC Mott–Schottky heterostructures with built in electric field (BIF) are prepared as catalyst model to generate a built-in electric field to enhance the electrocatalytic effect on sulfur electrochemistry. Theoretical and experimental results have jointly demonstrated that the redistribution of charge and the presence of a built-in electric field at the Co/W3N4@NC heterointerface can promote the redox reaction within lithium sulfur battery during the discharge and charge processes, respectively. Experimental tests have confirmed its outstanding reversibility, achieving a capacity of 793.2 mAh·g−1 over 500 cycles at 1 C. It also shows excellent cycling performance with only 0.05 % attenuation per cycle over 800 cycles at 2 C for LSBs. Furthermore, even with a high sulfur loading of 5.5 mg·cm−2, the S@ Co/W3N4@NC cathode maintains favorable sulfur-related electrochemistry and delivers a high areal capacity of 3.61 mAh·cm−2 as well as maintaining considerable stability. This synthetic Mott–Schottky heterostructure not only amplifies the electrocatalytic effect in LSBs, but also advances the design of catalysts for advanced high-energy-density batteries.

Modified electron structure of CNT-CoSe2 (vs. CoSe2) with more Co2+ for improving catalytic effect in lithium sulfur batteries

Currently, the great challenge of lithium sulfur (Li-S) batteries is the sluggish redox kinetics and the ineludible shuttle effect, which induce the rapid capacity fading. Regulating the electron structure of metal-based catalysts is regarded as a significant strategy to improve the catalytic effect of Li-S batteries, for accelerating the redox kinetics and enhancing the cathode performance. In this work, the valence of Co in CoSe2 is regulated by introducing carbon nanotube (CNT) during the preparation of ZIF-67. Compared with CoSe2, the ratio of Co2+/Co3+ increases, which boost the catalytic activity of CNT-CoSe2 both in discharging and charging process. Furthermore, the ratio of Co2+/Co3+ is reduced after discharging due to the electron transfer to sulfur species, and the ratio is increased again due to the inverse electron transfer. As a result, the CNT-CoSe2 with better catalytic properties endows the corresponding Li-S batteries more stable cycling performance, especially at high current density or high sulfur loading. The CNT-CoSe2 modified separator can endow Li-S batteries with a discharge capacity of 735.49 mAh g−1 at 2 C, and a retention ratio of 72.28% for 200 cycles at 0.1 C with sulfur loading of 4.60 mg cm−2.

Synergetic catalytic regulation of nitrogen doped NiS2/CoS2 heterostructure for polysulfide immobilization in Li-S batteries

The sluggish kinetics of sulfur species conversion and the shuttle effect in lithium-sulfur batteries are severely hindered in practical applications. Herein, we propose nitrogen doped NiS2/CoS2 heterostructure supported on CNT (N-NiS2/CoS2/CNT) by simple thiourea pyrolysis served as electrocatalyst functionalized on PP separator. The new formed M-N bonds on N-NiS2/CoS2/CNT motivate the catalytic activity of metal active centers strengthening the chemical anchoring towards polysulfides and Li2S electrodeposition behavior. The N,S dual doping on CNT support synergistically affords the electrochemical active sites for polysulfides conversion kinetics and increases the electrical conductivity of the whole catalyst. In Li-S batteries, the initial capacity of the battery with N-NiS2/CoS2/CNT functionalized separators reaches 1317.3 mAh g−1 at 0.2 C, and after 200 cycles, the capacity reaches 939.5 mAh g−1 with a capacity retention rate of 59.8%. Even at a large multiplicity rate of 2 C, the capacity can still be maintained at 552.2 mAh g−1 with a low-capacity decay of 0.068% after 500 cycles.

Mn and N-doped RGO as a sulfur hosting accelerate electron transfer and redox reactions for Li–S batteries

The notorious polysulfides shuttling and slow redox reaction kinetics largely limit the Li–S battery commercial application as an effective energy storage system. In this report, Mn/N catalysts were co-doped on a high specific surface area reduced graphene oxide (RGO) scaffold by a simple formamide media-assisted method to develop the sulfur holding material for Li–S battery. The N-doped RGO with conductive layer structure not only facilitates the ion and electron transfer, but also provides superb reservoir space for sulfur volume expansion and intermediate polysulfides. Moreover, the introduction of Mn metal catalysts both paly the roles of chemical trappers and electrocatalysts to chemically anchor the polysulfides and accelerate the redox kinetics. It is a promising holding material to improve the reutilization of the polysulfides and suppression of the shuttle effect in lithium-sulfur batteries. As a result, the high initial discharge capacity for the Mn-NG modified Li–S battery is about 1124.7 mAh g−1 at 0.2 C, which can still reach to 914.3 mAh g−1 after 100 cycles, with a retention rate up to 81%. We believe that our method offers a significant approach to prepare multi-functional sulfur hosts for high performance Li–S batteries.

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.

Preparation and application of carbon nanotubes loaded atomic-level Ni–N4 catalyst for lithium-sulfur battery

Lithium-sulfur batteries (LSBs) are promising candidates as next-generation secondary batteries due to their advantages with respect to cost and energy density. However, their practical application is hindered by their slow kinetics and the shuttle behavior of soluble polysulfide ions. Herein, we successfully prepared a three-dimensional porous conductive catalyst material with an atomic-level Ni–N4 structure. The results showed that a strong adsorption of lithium polysulfides (LiPSs) by the Ni–N4 catalytic active sites and a strong catalytic effect on the conversion of LiPSs in the sulfur reduction reaction (SRR) as well as the lithium sulfide oxidation reaction (SOR) were achieved, effectively inhibiting the shuttle effect of polysulfide ions and promoting the sulfur cathode kinetics process. Thus, the LSBs exhibited an excellent performance with a specific capacity of 829.8 mAh g–1 and an average coulombic efficiency of 98.8 % after 420 cycles at a high rate of 1 C. Our work provides new insights and novel efforts to solve the shuttle effect in LSBs.

Mechanism and Solution of Overcharge Effect in Lithium-Sulfur Batteries.

Increasing the sulfur cathode load is an important method for promoting the commercialization of lithium-sulfur batteries. However, there is a common problem of overcharging in high-loading experiments, which is rarely reported. In this work,it isbelieved that an insulating layer of S8 forms on the current collector surface, hindering electron exchange with polysulfides. Continuous external current input during layer formation can cause irreversible electrode changes and overcharging. The general solution is to provide nucleation centers with adsorption sites to promote the 3D growth of the insulated S8 , thus avoiding overcharging. In this work, a solution isproposed by providing nucleation centers by gallium nitrate, by regulating the 3D growth of S8 away from the surface of the current collector to avoid overcharging and by improving battery performance.

Combining in situ electrochemistry, operando FTIR and post-mortem analyses to understand Co-Mn-Al spinels on mitigating shuttle effect in lithium-sulfur battery

The spinel oxide Co2Mn0.5Al0.5O4 (CMA) was investigated as an additive onto the cathode of lithium-sulfur batteries. We demonstrate the polysulfide adsorption onto CMA, mitigating the shuttle effect, a well-known failure mechanism. The in situ electrochemical impedance spectroscopy and cyclic voltammetry tests evidenced that CMA facilitates the conversion of short-chain lithium polysulfides (LPS). The CMA reduced the maximum voltammetric current by approximately 20% compared to the AC/S cathode and facilitates the conversion of LPS into solid-liquid-solid species. High conversion efficiencies were verified after 315 cycles, resulting in 89% of capacity retention. Low CMA concentrations of up to 10 wt.% increased battery capacity and showed that CMA has high ionic conductivity, while moderate concentrations of approximately 50 wt.% improved cyclability but increased cell’s resistivity. This improvement in cyclability is related to LPS trapped at CMA which is demonstrated by micrographs, X-ray energy dispersive and photoelectron spectra of post-mortem samples. The byproducts formed after cycling until failure, were identified by Raman spectra and diffraction patterns. Fourier transform infrared spectroscopy operando analyses suggested electrolyte decomposition as a relevant cell failure mechanism. In conclusion, we demonstrated how CMA can trap LPS and enhanced initial capacity to 1000 mA h g-1sulfur cm-2 and improved cyclability for more than ∼360 cycles.

The Voltage-Adaptive Effect in Lithium-Sulfur Batteries Integrated with an Electron-Conductive Interlayer.

Lithium-sulfur (Li-S) batteries are considered as one of the top competitors to go beyond Li-ion batteries. However, the shuttle effect triggered by soluble lithium polysulfides (LPSs) brings great troubles for understanding the solid-liquid-solid conversion process of the sulfur cathode. Herein, a new characterization technique is developed to deepen the understanding of such soluble LPSs shuttling, by integrating an electron-conductive interlayer. The voltage of the interlayer exhibits a voltage-adaptive effect to the cathode, indicating the true dependence of the open-circuit voltages on the LPSs instead of on the solid cathodes. Furthermore, a quantitative method can be introduced to monitor the shuttling LPSs by such interlayer design, and it shows great potential to be a new standard technique, providing direct comparison of the shuttle effect between different studies. The newly developed interlayer design paves an avenue to gain new insight into the reaction process and improve the performance of Li-S batteries.

Modification of interlayers with YCl3 for the suppression of shuttle effects in lithium-sulfur batteries

To reinforce the electrochemical properties of next-generation lithium-sulfur batteries (LSBs), modified interlayers emerge as a promising approach to suppress the polysulfide shuttling effect and improve cycle stability. This work presents a straightforward approach to produce a YCl3-doped carbonized cellulose paper (YCl3-CCP) as an interlayer, which has been demonstrated to significantly suppress the shuttle effect in LSBs. The synergistic effect of graphite and Y2O3 of the interlayer of YCl3-CCP can capture lithium polysulfides through strong absorption, thereby improving both cycle stability and coulombic efficiency. Herein, our results indicate that LSBs with interlayers of YCl3-CCP achieve a discharge capacity of 903 m Ah g−1 at 2 C, with a capacity retention of 77.3% over 500 cycles and an average capacity fading rate of 0.045% per cycle. Overall, this work provides a promising strategy for addressing the polysulfide shuttling effect in LSBs and opens up new avenues for further research in this area.

Polyoxometalate-cyclodextrin-based Cluster-Organic Supramolecular Framework for Polysulfide Conversion and Guest-host Recognition in Lithium-sulfur Batteries.

Developing polyoxometalate-cyclodextrin cluster-organic supramolecular framework (POM-CD-COSF) still remains challenging due to an extremely difficult task in rationally interconnecting two dissimilar building blocks. Here we report an unprecedented POM-CD-based framework crystalline structure produced through the self-assembly process of a Krebs-type polyoxometalate, [Zn2(WO2)2(SbW9O33)2]10-, and two β-cyclodextrin units (β-CD). For the first time, we present the exploration of new application forms of POM-CD-COSF materials in Lithium-sulfur (Li-S) batteries. The as-prepared POM-CD-COSF-based battery separator can be applied as a lightweight barrier (approximately 0.3 mg cm-2) to mitigate the fundamental polysulfide shuttle effect in Lithium-sulfur chemistry. The designed Li-S batteries equipped with the POM-CD-COSF modified separator exhibit remarkable electrochemical performance, attributed to fast Li+ diffusion through the supramolecular channel of β-CD, efficient polysulfide-capture ability by the dynamic host-guest interaction of β-CD, and improved sulfur redox kinetics by the bidirectional catalysis of POM cluster. This research provides a broad perspective for the development of multifunctional supramolecular POM frameworks and their applications in Li-S batteries.

Thin-walled hollow MoS2 microspheres as sulfur hosts for high-performance lithium sulfur batteries

The thin-walled hollow MoS2 microsphere was synthesized by a facile released online NH3-blowing during the reduction of ammonium tetrathiomolybdate ((NH4)2MoS4) in N-methylpyrrolidone (NMP) solvent by hydrazine hydrate at 80℃and investigated electrochemically as sulfur host for lithium sulfur battery. The results show that the as-prepared MoS2 @S electrode delivers an initial specific capacity of as high as 1801 mAh g−1, albeit partly due to the formation of SEI membrane, indicating the modulation of MoS2 on the electrochemical reaction of sulfur when compared with bare sulfur electrode. Moreover, the as-prepared MoS2 @S electrode exhibits excellent cycling stability and good rate capability, corroborating the interaction of MoS2 with lithium polysulfides (LiPSs) due to the severe shuttling effect in lithium sulfur battery, which is further authenticated by cyclic voltammetry, Tafel plot and electrochemical impedance spectroscopy techniques. This is anticipated to be a straightforward strategy for the practical implementation of lithium sulfur battery as an alternative to the state-of -the-art lithium ion battery.

Perovskite lead zirconate titanate (PbZr0.52Ti0.48O3) nanofibers for inhibiting polysulfide shuttle effect in lithium-sulfur batteries

Rapid capacity fade and untimely failure caused by the infamous “shuttle effect” prevents the commercialization of Lithium-sulfur batteries (LSB). In this work, lead zirconate titanate (PZT) nanofibers have been employed as polysulfide immobilizer in LSB. Ferroelectric materials possess a unique domain structure where each individual domain carries a dipole moment. The dipole-dipole interaction between the domains of the ferroelectric PZT nanofibers and polysulfides inhibits the diffusion of polysulfides from the cathode. In addition to electrostatic interactions, the 1-dimensional nanofibers with large specific surface area are accompanied by lithiophilic and sulfiphilic heteroatoms which act as anchoring points for chemically binding the polysulfides. Moreover, the enhanced wettability of the electrode arising from the favorable affinity of PZT nanofibers towards the electrolyte along with lithiophilic heteroatoms aids the diffusion of Lithium-ions. Briefly, the synergy of physical and chemical interaction of PZT nanofibers towards the polysulfide species is found to mitigate the shuttle effect and improve electrochemical performance of LSB. Further, a promising long-term cycling over 200 cycles for LSB cell with PZT interlayer is observed with 98% Coulombic efficiency and slow fade rate of 0.08% per cycle.

Multifunctional α-MoO3 Nanobelt Interlayer with the Capacity Compensation Effect for High-Energy Lithium-Sulfur Batteries.

Spatial hindrance of lithium polysulfide (LiPS) diffusion by inserting a barrier interlayer has been deemed as an effective strategy to restrict the shuttle effect in lithium-sulfur batteries (LSBs). However, the extra interlayer without reversible capacity production inevitably reduces the actual energy density of the battery. Herein, a freestanding α-MoO3 nanobelt interlayer with the decoration of TiN nanoparticles and carbon nanotubes (denoted as MCT) is established. To investigate the capacity compensation effect of the MCT during cell operations, X-ray absorption near-edge spectrometry is conducted. It is revealed that MoO3 can sustain a reversible Li intercalation/deintercalation in a voltage range of 1.8-2.8 V, providing 180 mAh g-1 of extra capacity for compensating sulfur cathode. In addition, the adsorption of the lithiated α-MoO3 toward LiPSs is further evaluated. By matching a high-loading sulfur cathode (3.0 mg cm-2), a superior capacity of 713.3 mAh g-1 can be retained after 100 cycles under the MCT assistance.

Tuning Fe-spin state of FeN4 structure by axial bonds as efficient catalyst in Li-S batteries

In lithium-sulfur (Li-S) batteries, the root-cause solution is to accelerate the polysulfide conversion to their end products by electrocatalysts. Herein, we put forward a molecular spin engineering to break the symmetry of Fe-N-C and achieve the spin modulation for triplet-to-singlet conversion by the ligand field theory. The Fe-N-C shows an 3d-electronic structure of (dxy)2(dxz)2(dyz)2 and dramatically speeds up the LPSs conversion kinetics. According to the density functional theory (DFT), there is an upshift of energy levels after the adsorption of LPSs on Fe center. As a result, the optimized catalyst delivers a capacity fading rate of 0.026% per cycle at 2 C. In addition, a high capacity of 1042 mA h g−1 is achieved with satisfied capacity retention with the sulfur loading of about 4 mg cm−2. This strategy provides a novel route for the regulation of Fe-spin state and the exploration of catalytic effect in Li-S batteries.

Asymmetric N-coordinated iron single-atom catalysts supported on graphitic carbon for polysulfide conversion in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries with extremely high theoretical energy density are expected to be the next-generation energy storage systems. However, the electrochemical performance of Li-S batteries is still restricted by the shuttle effect of lithium polysulfides (LiPSs) resulting from their sluggish conversion kinetics. Herein, we demonstrated a coordination-confinement-pyrolysis strategy to fabricate iron single-atom catalysts (Fe SACs) supported on graphitic carbon nanocapsules (GCNC) by using imine (-RC = N-)-enriched polymer as precursors, aiming at suppressing the shuttle effect in Li-S batteries via simultaneously enhancing LiPSs confinement and catalytic conversion. The in-depth experiment investigations have revealed that the as-obtained N-doped carbon nanocapsules with ample hollow channels and large specific surface area (SSA) enable efficient adsorption and confinement for LiPS intermediates. Further, the isolated Fe SACs anchored on highly conductive graphitic carbon frameworks show an asymmetric N-coordinated active moiety (Fe-N5) that ensures fast redox kinetics of LiPSs and solid Li2S/Li2S2 products. As a result, the Li-S cell with a functional separator modified by the Fe-N5/GCNC exhibits a much-increased specific capacity of 1125 mAh/g at 0.1 C, excellent rate capability of 627 mAh/g at 2 C, and remarkable long-term cycling stability with a low capacity decay of 0.0386 % per cycle upon 1000 cycles. This work presents a useful strategy to fabricate high-activity SACs coupled with hollow graphitic carbon frameworks and to accelerate the catalytic conversion kinetics of LiPS intermediates for high-performance Li-S batteries.

An ultralight electroconductive metal-organic framework membrane for multistep catalytic conversion and molecular sieving in lithium-sulfur batteries

Developing optimal catalysts, with the ability for trapping lithium polysulfides (LiPSs), catalyzing the multistep redox reaction concerning multifarious LiPSs and transferring electrons simultaneously, is vital for overcoming the shuttle effect in lithium-sulfur batteries (LSBs), which however remains a great challenge. Herein, the concept of effectively catalyzing multistep LiPSs conversion with one catalyst was demonstrated by integrating dual catalytic centers (Ni-N4 and quinone) within one metal-organic framework (MOF, Ni-TABQ). Moreover, an ultrathin and ultralight multifunctional electroconductive Ni-TABQ membrane (1.8 μm, 0.075 mg cm−2) were designed and in situ synthesized for tackling shuttle effect. Systematic in/ex situ electrochemical experiments and simulated calculations demonstrate that such MOF membrane enables ions sieving, LiPSs adsorption and multistep catalytic conversion at the same time. The LSB assembled with Ni-TABQ interlayer delivers a high capacity and ultra-low decay rate of 0.198‰ after 1000 cycles at 1 C, a capacity up to 5.59 mAh cm−2 after 100 cycles under high sulfur loading and lean electrolyte, as well as remarkably improved punch cell performances.