Shuttling Effect Research Articles

Tailoring eco-friendly siloxane-based electrolytes for high-performance lithium–sulfur batteries

Lithium–sulfur batteries (LSBs), with their ultra-high theoretical energy density (2600 Wh kg−1), are considered one of the most attractive high-energy batteries. However, the “shuttling effect” of polysulfides and the uncontrolled growth of lithium (Li) dendrites pose significant challenges to the practical implementation of LSBs. Herein, a lightweight and eco-friendly diethoxydimethylsilane (DEMS) is chosen as a multi-functional solvent for LSBs. The low polarity of DEMS promotes the “solid–solid” conversion of sulfurized polyacrylonitrile (SPAN) during charge–discharge processes, eliminating the shuttle effect of polysulfides. Moreover, the DEMS-based electrolyte enables highly reversible Li plating/stripping processes across a wide temperature range spanning from −20 to 60 °C. As a result, the Li/SPAN batteries using the DEMS electrolyte exhibit excellent cyclic stability at 0.2 C with retainable capacities of 524.4 mAh/g after 200 cycles, 598.8 mAh/g after 100 cycles, and 318.6 mAh/g after 50 cycles at 26, 60 and −20 °C, respectively. This study aims to identify low-cost and highly stable electrolytes through solvent screening to enhance the electrochemical performance of LSBs.

Single-Atom Cobalt Catalyst with Boron and Nitrogen Codoped Graphene (Co-BN-G) Enables Adsorption and Catalytic Conversion of Polysulfides for High-Performance Lithium-Sulfur Batteries.

In lithium-sulfur batteries, the shuttling effect and sluggish redox conversion of soluble polysulfides lead to unsatisfactory sulfur utilization and capacity retention. In this research, we used a one-pot hydrothermal method to prepare graphene with single-atom Co and B, N codoped as a sulfur host in Li-S batteries, thereby suppressing the shuttling effect and facilitating the redox conversion of lithium polysulfides (LiPSs). A series of characterizations demonstrated that dual doping of B and N introduces more lattice defects and structural deformations in graphene oxide, thus enhancing its adsorption of polysulfides. Simultaneously, single-atom cobalt can also polarize adsorption and accelerate the conversion reaction of LiPSs. The Li-S cell with the as-prepared Co-BN-G sulfur host materials exhibited an excellent capacity of 1034 mAh g-1 at 0.5 C and satisfactory cycle performance (retention of 69% over 500 cycles). Even at a rate of 2 C, a discharge capacity of 851 mAh g-1 is achieved. The results show that the Co-BN-G configuration efficiently captures LiPSs and enhances their rate conversion kinetics in redox reactions, demonstrating significant practical potential.

Insight into the polysulfides conversion kinetics and its activation energy relationship on ultrafine V8C7 in Li-S batteries

Catalytic conversion of lithium polysulfides (LiPSs) is regarded as an effective approach to boosting kinetics and suppressing shuttling effect in lithium-sulfur (Li-S) batteries, but developing efficient catalysts and understanding of its catalytic mechanism still remain challenges. Herein, the ultrafine V8C7 nanocrystals embedded into the porous N-doped carbon frameworks (V8C7/NC) was designed for accelerating the LiPSs catalytic-conversion kinetics toward high-performance Li-S batteries. We propose that the ultrafine V8C7 nanocrystals with abundant unsaturated coordination atoms increase the active sites for catalytic-conversion of LiPSs and also accelerate the corresponding kinetics by reducing its reaction activation energy, meanwhile the interlinked nano-channels of V8C7/NC can effectively confine LiPSs and also promote electron/ion transfer. These attributes enable the Li-S cell equipped with V8C7/NC to deliver a large discharge capacity of 1393.3 mAh g−1 at 0.2 C, excellent rate capability (496.0 mAh g−1 at 10 C), and robust cycling stability (1000 cycles with a negligible capacity decay rate of 0.019 % per cycle even at 5 C). The innovative concept of ultrafine V8C7 nanocrystals embedded into the porous carbon toward improved LiPSs catalytic-conversion kinetics could be extended to develop other electrocatalytic hosts for high-performance Li-S batteries.

A 3D network-structured gel polymer electrolyte with soluble starch for enhanced quasi-solid-state lithium-sulfur batteries

The polysulfide shuttling effect and safety concerns associated with liquid electrolytes impede the commercialization of lithium-sulfur (Li-S) batteries. We report a novel gel polymer electrolyte (GPE) denoted as "PTPHS" prepared via facile ultraviolet polymerization of pentaerythritol tetrakis (3-mercaptopropionate) (PETT) and pentaerythritol tetraacrylate (PETEA) with poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the polymer matrix. Soluble starch (SST) is incorporated as an interacting filler to construct a 3D network structure with intermolecular hydrogen bonds. This unique architecture not only ensures high ionic conductivity and mechanical robustness but also effectively mitigates the polysulfide shuttling effect, thereby improving cycling stability. The PTPHS-based Li-S cell exhibits stable cycling over 150 cycles at 0.2 C with 87.6 % capacity retention. This strategy provides insights into material development and structural design of GPEs for high-performance quasi-solid-state Li-S batteries.

Polymorph interface strategy presents avenues for kinetics-enhanced and dendrite-free lithium sulfur batteries

Shuttle effect and slow kinetic property are the challenges for the practical application of lithium-sulfur (Li-S) batteries. As an effective strategy, the polymorph effect is applied to rationally design multifunctional catalysts. Herein, the unique polymorph interface was constructed by different CoSe2 crystalline phases, and the systematic investigation on the sulfur cathodes and lithium anode is reported. Carbon nanofiber (CNF) derived from bacterial cellulose (BC) is used as a scaffold for disperse CoSe2 catalysts to construct electrically conductive highways. According to the experimental and calculation results, orthorhombic CoSe2 exhibits superior adsorption capacity and catalytic activity towards LiPSs, while cubic CoSe2 shows better electronic conductivity. Mixed phase CoSe2 not only balances the advantages of both, but also showcases impressive performance due to its unique polymorph interface structure. Besides, uniform lithium deposition can be also achieved. Consequently, the modified separators endow Li-S batteries with a high reversible discharge capacity (700 cycles at 1 C with only 0.063 % capacity decay per cycle) and excellent rate performance (702 mAh g−1 is maintained at 5 C). The pouch cell with separator modifications on both sides was assembled and exhibits a high discharge capacity. This work provides a polymorph interface strategy for the rational design of catalysts.

Inhibiting Shuttle Effect and Dendrite Growth in Sodium-Sulfur Batteries Enabled by Applying External Acoustic Field.

The room-temperature sodium-sulfur (RT Na-S) battery is a promising alternative to traditional lithium-ion batteries owing to its abundant material availability and high specific energy density. However, the sodium polysulfide shuttle effect and dendritic growth pose significant challenges to their practical applications. In this study, we apply diverse disciplinary backgrounds to introduce a novel method to stimulate polarized BaTiO3 (BTO) nanoparticles on the separator. This approach generates more charges due to the piezoelectric effect under stronger driving forces produced by applying a controllable acoustic field at the outer edge of the cell. The acoustically stimulated BTO attracts more polysulfides, thus reducing the shuttling effect from the cathode to the anode and ultimately enhancing the battery performance. Meanwhile, the acoustic waves create additional streaming flows, improving the uniformity of the sodium ion dispersion, enhancing the sodium ion transport and reducing the possibility of sodium dendrite development. We believe that this work offers a new strategy for the development of high-performance Na-S batteries.

Investigating PEDOT:PSS Binder as an Energy Extender in Sulfur Cathodes for Li-S Batteries.

Although lithium-sulfur (Li-S) batteries offer a high theoretical energy density, shuttling of dissolved sulfur and polysulfides is a major factor limiting the specific capacity, energy density, and cyclability of Li-S batteries with a liquid electrolyte. Cathode host materials with a microstructure to restrict the migration of active material may not totally eliminate the shuttling effect or may create additional problems that limit the full dissolution and redox conversion of all active cathode materials. Selecting a cathode coating binder with a multifunctional role offers a universal solution suitable for various cathode hosts. PEDOT:PSS is investigated as such a binder in this study via experimental testing and material characterization as well as multiscale modeling. The study is based on Li-S cells with a sulfur cathode in hollow porous particles as the cathode host and the 10 wt % PEDOT:PSS binder and electrolyte 1 M LiTFSI in 1:1 DOL:DME 1:1 v/v. A reference supercapacitor cell with the same electrolyte and electrodes comprising a coating of the same hollow porous particles and 10 wt % PEDOT:PSS revealed the pseudocapacitive effect of PEDOT:PSS following a surface redox mechanism that dominates the charge phase, which is equivalent to the discharge phase of the Li-S battery cell. A multipore continuum model for supercapacitors and Li-S cells is extended to incorporate the pseudocapacitive effects of PEDOT:PSS with the Li+ ions and the adsorption effects of PEDOT:PSS with respect to sulfur and lithium sulfides in Li-S cells, with the adsorption energies determined via molecular and ab initio simulations in this study. Experimental data and predictions of multiscale simulations concluded a 7-9% extension of the specific capacity of Li-S battery cells due to the surface redox effect of PEDOT:PSS and elimination of lithium sulfides from the anode by slowing down their migration and shuttling via their adsorption by the PEDOT:PSS binder.

Activation of the Radical‐Mediated Pathway and Facilitation of the Li2S Conversion by N‐Doped Carbon‐Embedded Ti1–xCoxN Nanowires as a Multifunctional Separator with a High Donor‐Number Solvent toward Advanced Lithium–Sulfur Batteries

Electrolyte modification with a high donor‐number solvent is necessary to increase sulfur utilization, but it also presents poor compatibility with lithium metal. The amount of the solvent should be optimized to maximize sulfur utilization at the cathode and minimize side reactions with Li metal at the anode. An electrolyte solution comprising 1 vol% N,N‐dimethylacetamide (DMA) in a 1,2‐dimethoxyethane (DME)/1,3‐dioxolane (DOL) co‐solvent demonstrated increased discharge capacity and reduced overpotential compared to DME/DOL and DMA/DOL. In addition to electrolyte, modification that creates radical‐mediated pathways from a high donor‐number solvent, long‐cycle performance is achieved by effectively mitigating the shuttling effect and enhancing reaction kinetics with an efficient electrocatalyst. Cobalt doping into TiN introduced an upshift of the d‐band center with ferromagnetic properties that suppressed the shuttling effect, activated radical‐mediated pathways, and facilitated the Li2S conversion. A multifunctional separator fabricated with N‐doped carbon‐embedded cobalt‐doped titanium nitride nanowires (NC‐Ti0.95Co0.05N NWs) under 1 vol% DMA electrolyte achieved a discharge capacity of 464.4 mA h g−1 even after 200 cycles at a decay rate of 0.093% per cycle through the synergistic effects of electrolyte and electrocatalyst modifications. This work highlights the importance of ferromagnetic catalysts with a high donor‐number solvent for lithium–sulfur (Li–S) batteries.

Capitalizing on the Iodometric Reaction for Energetic Aqueous Energy Storage.

Iodometric and iodimetric titrations represent a prevailing technique to determine the concentration of Cu2+ ions in aqueous solutions; However, their utilization in electrochemical energy storage has been overlooked due to the poor reversibility between CuI and Cu2+ related to the shuttling effect of I3- species. In this work, we developed a 4A zeolite separator capable of suppressing the free shuttling of I3- ions, thus achieving a record-high capacity retention of 95.7% upon 600 cycles. Theoretical and experimental studies reveal that the negatively charged zeolite can effectively impede the approach and penetration of I3- ions, as a result of electrostatic interaction between them. To explore the practical potential, a hybrid cell of Zn∥I2 consisting of Cu2+ redox agent has been assembled with a discharge capacity of 356 mA h g-1. The cell affords a specific energy of 443 W h kg-1 based on I2, or 193 W h kg-1 based on both electrodes. This work offers insight on the energy utilization of the iodometric reactions and advocates a Cu2+-mediated cell design that could potentially double the capacity and energy of conventional aqueous battery systems.

Mechanistic Understanding of the Role of Bis(4-nitrophenyl) Carbonate (BNC) As Additive on the Solvation Structure and Polysulfides Shuttling Effect Towards Capacity Improvement in Lithium-Sulfur Batteries

The lithium-sulfur (Li-S) batteries are considered as one of the most promising devices for next-generation energy storage applications, owing to its exceptional theoretical capacity and energy density. However, persistent challenges have hampered its performance, notably the sluggish polysulfides conversion kinetics and the polysulfides shuttling phenomenon. These issues lead to irreversible active material loss, rapid capacity decay, low coulombic efficiency, and a limited cycle life. This study demonstrates that bis(4-nitrophenyl) carbonate (BNC) can serve as an effective agent in anchoring dissolved polysulfides, thereby preventing their migration to the anode. Furthermore, this investigation indicates that BNC has the capability to modify the solvation structure of polysulfides in the electrolyte. The presence of 0.01M BNC induces a downfield shift in the 7Li NMR spectrum, signifying a strengthened solvation structure on Li-ion. This solvation modification results in altered kinetics, specifically a reduced Li2S2/Li2S conversion without sacrificing capacity, as confirmed by operando X-ray absorption spectroscopy (XAS). Operando Raman spectroscopy reveals the suppression of long-chain polysulfides (at 400 cm-1) and intermediate polysulfides (at 453 cm-1) with 0.01M BNC, mitigating sulfur shuttling to the anode. This observation is corroborated by X-ray fluorescence (XRF) mapping. Analysis of the corresponding X-ray absorption near-edge structure (XANES) demonstrates that both anodes and cathodes with 0.01M BNC exhibit lower levels of unconverted polysulfides over extended cycles. This improvement is attributed to the kinetic consequences resulting from solvation structure alteration. However, this investigation cautions against an indiscriminate increase in BNC concentration, as higher concentrations may lead to the over-conversion of soluble polysulfides. This nuanced understanding of the solvation structure's intrinsic mechanism, coupled with chemical reactions, provides valuable insights for practical design of Li-S batteries Figure 1

Multimodal X-Ray Measurements for Sulfur and Sulfide Related Electrochemical Energy Storage

Sulfur and sulfide are very promising candidates for electrochemical energy storage in electric vehicles and grid-scale storage due to their high theoretical capacity, low cost, and abundance. Although tremendous efforts have been devoted to sulfur and sulfide related batteries in recent years, they are still facing several challenges that need to be addressed before they can be widely adopted. Challenges including polysulfide shuttling effect in metal-sulfur batteries and electrochemical/interphase stabilities in sulfide solid-state electrolytes hindered their practical applications. Various techniques and strategies have been developed to address the above-mentioned challenges. However, revealing a next-level understanding of sulfur species interactions and speciation, using multimodal X-ray measurements to study the interaction temporally and spatially is still lacking. Here, we employed multimodal X-ray measurements including in situ sulfur K-edgeX-ray absorption spectroscopy, X-ray diffraction, and transmission X-ray microscopy to reveal electronic structure, crystal structure, morphology of sulfur species during battery cycling. Specifically, using operando sulfur K-edge X-ray absorption and X-ray diffraction, we obtained real-time and chemical information of sulfur species occurring at the sulfur cathode during lithium-sulfur battery operation. In the case of sulfide solid-state electrolytes, we explored the capacity loss mechanism in LiNi0.8Mn0.1Co0.1O2 cathodes when using argyrodite Li6PS5Cl sulfide solid electrolytes. Nickel K-edge X-ray absorption spectroscopy and transmission X-ray microscopy showed the cracking formation and heterogeneity in oxidation states for LiNi0.8Mn0.1Co0.1O2 cathodes using Li6PS5Cl solid-state electrolytes. In summary, we elucidated the dynamic changes in sulfur and provide insights on designing next-generation sulfur and sulfide related batteries.

Nano-anticoagulant based on carrier-free low molecular weight heparin and octadecylamine with an albumin shuttling effect

Low-molecular-weight heparin (LMWH), derived from unfractionated heparin (UFH), has enhanced anticoagulant efficacy, long duration of action, and extended half-life. Patients receiving LMWH for preventive therapies would strongly benefit from its long-term effects, however, achieving this is challenging. Here, we design and evaluate a nanoengineered LMWH and octadecylamine conjugate (LMHO) that can act for a long time while maintaining close to 97 ± 3% of LMWH activity via end-specific conjugation of the reducing end of LMWH. LMHO can self-assemble into nanoparticles with an average size of 105 ± 1.7 nm in water without any nanocarrier and can be combined with serum albumin, resulting in a lipid-based albumin shuttling effect. Such molecules can circulate in the bloodstream for 4–5 days. We corroborate the self-assembly capability of LMHO and its interaction with albumin through molecular dynamics (MD) simulations and transmission electron microscopy (TEM) analysis. This innovative approach to carrier-free polysaccharide delivery, enhanced by nanoengineered albumin shuttling, represents a promising platform to address limitations in conventional therapies.

Integrating CoP/Co heterojunction into nitrogen-doped carbon polyhedrons as electrocatalysts to promote polysulfides conversion in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have garnered extensive research interest as one of the most promising energy storage devices due to their ultra-high theoretical energy density. However, the sluggish reaction kinetics, abominable shuttling effect and inferior cycling stability severely restrict its practical application. Herein, a multifunctional CoP/Co@NC/CNT heterostructure host material was elaborately designed and synthesized by integrating CoP/Co heterojunction, N-doped carbon hollow polyhedrons (NC) and carbon nanotubes (CNTs). Specifically, the CoP/Co heterojunction can reconfigure the local electronic structure, resulting in a synergistic effect that enhances adsorption capacity and catalytic activity compared to CoP and Co alone. Furthermore, the CNTs-grafted NC not only provides multi-dimensional pathways for rapid electron transport and ion diffusion, but also physically restricts the diffusion of polysulfides during charge-discharge processes. Owing to these advantages, the battery assembled with the CoP/Co@NC/CNT/S cathode yields an impressive discharge specific capacity of 1479.9 mAh g−1 at 0.1C, and excellent capacity retention of 793.7 mAh g−1 over 500 cycles at 2C (∼85.5 % of initial capacity). The rational integration of multifunctional heterostructures could provide an effective strategy for designing high-efficiency nanocomposite electrocatalysts to promote sulfur redox kinetics in Li-S batteries.

Confining Iodine into Metal-Organic Framework Derived Metal-Nitrogen-Carbon for Long-Life Aqueous Zinc-Iodine Batteries.

Aqueous zinc-iodine batteries (AZIBs) are highly appealing for energy requirements owing to their safety, cost-effectiveness, and scalability. However, the inadequate redox kinetics and severe shuttling effect of polyiodide ions impede their commercial viability. Herein, several Zn-MOF-derived porous carbon materials are designed, and the further preparation of iron-doped porous carbon (Fe-N-C, M9) with varied Fe doping contents is optimized based on a facile self-assembly/carbonization approach. M9, with atomic Fe coordinated to nitrogen atoms, is employed as an efficient cathode host for AZIBs. Functional modifications of porous carbon hosts involving the doping species and levels are investigated. The adsorption tests, in situ Raman spectroscopy, and in situ UV-vis results demonstrate the adsorption capability and charge-discharge mechanism for the iodine species. Furthermore, experimental findings and theoretical analyses have proven that the redox conversion of iodine is enhanced through a physicochemical confinement effect. This study offers basic principles for the strategic design of single-atom dispersed carbon as an iodine host for high-performance AZIBs. Flexible soft-pack battery and wearable microbattery applications also have implications for future long-life aqueous battery designs.

The study on the reason why ZnS catalyst cannot suppress the shuttle effect of polysulfides in lithium-sulfur (Li–S) battery

The catalytic effect of zinc sulfide (ZnS) on the transformation of polysulfides (Li2S8) to lithium sulfide (Li2S) has been proven by the enhancement in the rate performance of lithium-sulfur (Li–S) batteries incorporating ZnS particles into the cathode. Accordingly, the shuttling effect of polysulfide should also be suppressed. However, the expected phenomenon is not found in the Li–S batteries with ZnS particles being added in the cathodes. In order to find the intrinsic mechanism of this phenomenon, detailed catalytic effects of ZnS particles on different polysulfide molecules are investigated. It is shown that ZnS can only enhance the reaction from Li2S4 to Li2S and it has almost no catalytic effect on the reaction from Li2S6 to Li2S4. This is why the shuttle effect of Li2S6 cannot be effectively prohibited. This mechanism is further verified via combining ZnS particles with S–C@PVA yolk-shell particles containing sulfur (S) and carbon black (C) as the core and PVA as the shell. Although the reaction from Li2S6 to Li2S4 cannot be directly catalysed by ZnS particles, it can still be enhanced when ZnS particles are distributed within the S–C@PVA yolk-shell structure (S–C–ZnS@PVA) because the reaction speed from the Li2S4 to Li2S is accelerated. The fast consumption of Li2S4 will result in the enhancement of the reaction from Li2S6 to Li2S4, which will largely reduce the diffusion of Li2S6 out of the PVA shell. While if ZnS particles are located outside the S–C@PVA yolk-shell structure (S–C@PVA-ZnS), large amount of Li2S6 can still diffuse out of the PVA shell and enter into the electrolyte since the transformation from is Li2S6 to Li2S4 relatively low. Both the rate performance and cycle stability of the batteries with S–C–ZnS@PVA cathodes are higher than those with S–C@PVA-ZnS ones. These results will give a guidance for the preparation of Li–S battery with high performance.

Enabling Efficient Anchoring‐Conversion Interface by Fabricating Double‐Layer Functionalized Separator for Suppressing Shuttle Effect

Lithium‐sulfur batteries (LiSBs) with high energy density still face challenges on sluggish conversion kinetics, severe shuttle effects of lithium polysulfides (LiPSs), and low blocking feature of ordinary separators to LiPSs. To tackle these, a novel double‐layer strategy to functionalize separators is proposed, which consists of Co with atomically dispersed CoN4 decorated on Ketjen black (Co/CoN4@KB) layer and an ultrathin 2D Ti3C2Tx MXene layer. The theoretical calculations and experimental results jointly demonstrate metallic Co sites provide efficient adsorption and catalytic capability for long‐chain LiPSs, while CoN4 active sites facilitate the absorption of short‐chain LiPSs and promote the conversion to Li2S. The stacking MXene layer serves as a microscopic barrier to further physically block and chemically anchor leaked LiPSs from the pores and gaps of the Co/CoN4@KB layer, thus preserving LiPSs within efficient anchoring‐conversion reaction interfaces to balance the accumulation of “dead S” and Li2S. Consequently, with an ultralight loading of Co/CoN4@KB‐MXene, the LiSBs exhibit amazing electrochemical performance even under high sulfur loading and lean electrolyte, and the outperforming performance for lithium‐selenium batteries (LiSeBs) can also be achieved. This work exploits a universal and effective strategy of a double‐layer functionalized separator to regulate the equilibrium adsorption‐catalytic interface, enabling high‐energy and long‐cycle LiSBs/LiSeBs.

Enabling Efficient Anchoring-Conversion Interface by Fabricating Double-Layer Functionalized Separator for Suppressing Shuttle Effect.

Lithium-sulfur batteries (LiSBs) with high energy density still face challenges on sluggish conversion kinetics, severe shuttle effects of lithium polysulfides (LiPSs), and low blocking feature of ordinary separators to LiPSs. To tackle these, a novel double-layer strategy to functionalize separators is proposed, which consists of Co with atomically dispersed CoN4 decorated on Ketjen black (Co/CoN4@KB) layer and an ultrathin 2D Ti3C2Tx MXene layer. The theoretical calculations and experimental results jointly demonstrate metallic Co sites provide efficient adsorption and catalytic capability for long-chain LiPSs, while CoN4 active sites facilitate the absorption of short-chain LiPSs and promote the conversion to Li2S. The stacking MXene layer serves as a microscopic barrier to further physically block and chemically anchor the leaked LiPSs from the pores and gaps of the Co/CoN4@KB layer, thus preserving LiPSs within efficient anchoring-conversion reaction interfaces to balance the accumulation of "dead S" and Li2S. Consequently, with an ultralight loading of Co/CoN4@KB-MXene, the LiSBs exhibit amazing electrochemical performance even under high sulfur loading and lean electrolyte, and the outperforming performance for lithium-selenium batteries (LiSeBs) can also be achieved. This work exploits a universal and effective strategy of a double-layer functionalized separator to regulate the equilibrium adsorption-catalytic interface, enabling high-energy and long-cycle LiSBs/LiSeBs.

Boron-Doped Dinickel Phosphide to Enhance Polysulfide Conversion and Suppress Shuttling in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are promising for next-generation high-energy energy storage systems. However, the slow reaction kinetics render mobile polysulfides hardly controlled, yielding shuttling effects and eventually damaging Li metal anodes. To improve the cyclability of Li-S batteries, high-efficiency catalysts are desired to accelerate polysulfide conversion and suppress the shuttling effect. Herein, we studied a doping system with Ni2P and Ni2B as the end members and found a B-doped Ni2P catalyst that demonstrates high activity for Li-S batteries. As anionic dopants, B demonstrates an interesting reverse electron transfer to P and tunes the electronic structure of Ni2P dramatically. The resultant B-doped Ni2P exhibits short Ni-B bonds and strong Ni-S interaction, and the electron donation of B to P further enhances the adsorption of polysulfide on catalysts. The S-S bonds of polysulfides were activated appropriately, therefore decreasing a low energy barrier for conversion reactions.

Nickel-doped CNTs composite as cathode by sulfur vapor deposition for high-performance all-solid-state lithium‑sulfur batteries

Shuttle effect of polysulfide in the cathode and the safety issues arising from dendrite formation at Li metal anode are the main challenges of traditional liquid lithium‑sulfur batteries. In order to solve the shuttle effect and prevent short circuit, the all-solid-state lithium‑sulfur battery (ASSLSB) is proposed. However, the huge volume expansion of sulfur and the improvement of sulfur conversion efficiency during charge and discharge, which could lead to the limitation of electrochemical performance. Herein, a homogeneous Ni-doped carbon-nanotubes (H-Ni-SVD@CNT) composite cathode of ASSLSB is prepared by sulfur vapor deposition to confine sulfur and promote the conversion of sulfur and Li2S. In this work, SVD-5-S@CNT composite cathode demonstrates high reversible discharge capacity of 1001.1 mAh g−1 after 127 cycles and capacity retention rate of 78.6 % at the rate of 0.1C and 60 °C. Moreover, H-Ni-SVD@CNT composite cathode exhibits superior electrochemical performance, displaying the discharge specific capacity of 1519.3 mAh g−1 at 0.1C and 60 °C. Meanwhile, the discharge specific capacity of H-Ni-SVD@CNT composite cathode is 1060.9 mAh g−1 at room temperature. The synergistic effect of physical confinement and chemical catalysis improves the electrochemical performance of the all-solid-state lithium‑sulfur battery. This work proposes a new strategy for the cathode structure design of the all-solid-state lithium‑sulfur battery.

Suppressing the Shuttle Effect via Polypyrrole-Coated Te Nanotubes for Advanced Na-Te Batteries.

There is a growing demand for research and development of advanced energy storage devices with high energy density utilizing earth-abundant metal anodes such as sodium metal. Tellurium, a member of the chalcogen group, stands out as a promising cathode material due to its remarkable volumetric capacity, comparable to sulfur, and significantly high electrical conductivity. However, critical issues arise from soluble sodium polytellurides, leading to the shuttle effect. This phenomenon can result in the loss of active materials, self-discharge, and anode instability. Here, we introduce polypyrrole-coated tellurium nanotubes as the cathode materials, where polypyrrole plays a crucial role in preventing the dissolution of polytellurides, as confirmed through operando optical microscopy. The polypyrrole-coated tellurium nanotubes exhibited an outstanding rate performance and long cycle stability in sodium-tellurium batteries. These research findings are anticipated to bolster the viability of polypyrrole-coated tellurium nanotubes as promising cathode materials, making a substantial contribution to the commercialization of sodium-ion battery technology.