Polypropylene Separator Research Articles

A Quasi-Solid-State Polymer Lithium-Metal Battery with Minimal Excess Lithium, Ultrathin Separator, and High-Mass Loading NMC811 Cathode.

Solid-state batteries with lithium metal anodes are considered the next major technology leap with respect to today's lithium-ion batteries, as they promise a significant increase in energy density. Expectations for solid-state batteries from the automotive and aviation sectors are high, but their implementation in industrial production remains challenging. Here, we report a solid-state lithium-metal battery enabled by a polymer electrolyte consisting of a poly(DMADAFSI) cationic polymer and LiFSI in Pyr13FSI as plasticizer. The polymer electrolyte is infiltrated and solidified in the pores of a commercial LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode with up to 2.8 mAh cm-2 nominal areal capacity and in the pores of a 25 μm thin commercial polypropylene separator. Cathode and separator are finally laminated into a cell in combination with a commercial 20 μm thin lithium metal anode. Our demonstration of a solid-state polymer battery cycling at full nominal capacity employing exclusively commercially available components available at industrial scale represents a critical step forward toward the commercialization of a competitive all-solid-state battery technology.

Natural Polyphenol‐Reinforced Ion‐Selective Separators for High‐Performance Lithium‐Sulfur Batteries with High Sulfur Loading and Lean Electrolyte

Ion‐selective separators are promising to inhibit soluble intermediates shuttle in practical lithium‐sulfur (Li‐S) batteries. However, designing and fabricating such high‐performance ion‐selective separators using cost‐effective, eco‐friendly, and versatile methods remains a formidable challenge. Here we present ion‐selective separators fabricated via the spontaneous deposition of green tea‐derived polyphenols onto a polypropylene separator, aimed at enhancing the stability of Li‐S batteries. The resulting natural polyphenol‐reinforced ion‐selective (NPRIS24) separators exhibit rapid Li ion transport and high soluble intermediates inhibition capability with an ultralow shuttle rate of 0.67% for Li2S4, 0.19% for Li2S6 and 0.10% for Li2S8. This superior ion‐selectivity arises from the high electronegativity and strong lithiophilic nature of the phenolic compounds. Consequently, we have achieved high‐performance Li‐S batteries that are steadily cyclable under the challenging conditions of an S loading of 5.7 mg cm−2, an electrolyte‐to‐S ratio of 5.1 μL mg−1, and a 50 μm Li foil anode. Furthermore, the NPRIS24 separator enhances the performance of other Li metal batteries utilizing commercial LiFePO4 (5.3 mg cm−2) and LiNi0.5Co0.2Mn0.3O2 (9.9 mg cm−2) cathodes. This work underscores the potential of utilizing natural polyphenols for the design of advanced ion‐selective separators in energy storage systems.

Natural Polyphenol-Reinforced Ion-Selective Separators for High-Performance Lithium-Sulfur Batteries with High Sulfur Loading and Lean Electrolyte.

Ion-selective separators are promising to inhibit soluble intermediates shuttle in practical lithium-sulfur (Li-S) batteries. However, designing and fabricating such high-performance ion-selective separators using cost-effective, eco-friendly, and versatile methods remains a formidable challenge. Here we present ion-selective separators fabricated via the spontaneous deposition of green tea-derived polyphenols onto a polypropylene separator, aimed at enhancing the stability of Li-S batteries. The resulting natural polyphenol-reinforced ion-selective (NPRIS24) separators exhibit rapid Li ion transport and high soluble intermediates inhibition capability with an ultralow shuttle rate of 0.67% for Li2S4, 0.19% for Li2S6 and 0.10% for Li2S8. This superior ion-selectivity arises from the high electronegativity and strong lithiophilic nature of the phenolic compounds. Consequently, we have achieved high-performance Li-S batteries that are steadily cyclable under the challenging conditions of an S loading of 5.7 mg cm-2, an electrolyte-to-S ratio of 5.1 μL mg-1, and a 50 μm Li foil anode. Furthermore, the NPRIS24 separator enhances the performance of other Li metal batteries utilizing commercial LiFePO4 (5.3 mg cm-2) and LiNi0.5Co0.2Mn0.3O2 (9.9 mg cm-2) cathodes. This work underscores the potential of utilizing natural polyphenols for the design of advanced ion-selective separators in energy storage systems.

Anion‐repulsive polyoxometalate@MOF‐modified separators for dendrite‐free and high‐rate lithium batteries

AbstractCommercial polyolefin separators in lithium batteries encounter issues of uncontrolled lithium‐dendrite growth and safety incidents due to their low Li+ transference numbers () and low melting points. To address these challenges, this study proposes an innovative approach by upgrading conventional separators through the incorporation of metal‐organic framework (MOF)‐confined polyoxometalate (POM). The presence of POM restricts anion diffusion through electrostatic repulsion while facilitating Li+ transport within MOF nanochannels through their affinity for lithium ions. Moreover, MOF confinement effectively mitigates the acidification of electrolytes induced by POM. As a proof‐of‐concept, the polypropylene separators decorated with phosphotungstic acid@UIO66 (denoted as PW12@UIO66‐PP) exhibit remarkable lithium‐ion conductivity of 0.78 mS cm−1 with a high of 0.75 at room temperature. The modified separators also display excellent thermal stability, preventing significant shrinkage even at 150°C. Furthermore, Li symmetric cells employing PW12@UIO66‐PP separators exhibit stable cycling for 1000 h, benefiting from rapid Li‐ion transport and uniform deposition. Additionally, the modified separator shows promising adaptability to industrial manufacturing of lithium‐ion batteries, as evidenced by the assembly of a 4 Ah NCM811/graphite pouch cell that retains 97% capacity after 350 cycles at C/3, thus highlighting its potential for practical applications.

Synergistic Interaction of Strongly Polar Zinc Selenide and Highly Conductive Carbon Nanoframeworks Accelerates Redox Kinetics of Polysulfides.

Lithium-sulfur batteries (LSBs) have become strong competitors in secondary battery systems because of their superior theoretical capacity and energy density. However, due to the serious shuttle effect of soluble long-chain lithium polysulfides (LiPSs) and the slow solid-solid reaction kinetics, LSBs face some specific challenges, such as a short cycle life and low rate performance. The introduction of selenide/carbon composites derived from zeolite imidazolate frameworks (ZIFs) into separator coatings is a direct and effective solution to the aforementioned problems. Here, a zinc selenide/carbon catalyst material (ZnSe@C) was constructed and employed to modify commercial polypropylene (PP) separators to accelerate the conversion of intermediates. The highly polar ZnSe effectively fixes the active material on the cathode side by transferring electrons between elements with LiPSs and improves the utilization rate of sulfur. Concurrently, the highly conductive carbon nanoskeleton generated following the pyrolysis of ZIF-8 ensures the rapid transfer of charges during the catalytic reaction. The prepared ZnSe@C has a large specific surface area (250.07 m2 g-1) and mesoporous ratio (78.03%), which not only enhances adsorption and catalysis but also promotes the penetration of the electrolyte and the transport of Li+. Based on this, ZnSe@C/PP separator cells exhibit a low average capacity decay rate of 0.051% per cycle after 500 cycles at 1 C.

Organic-Inorganic Dual-Network Composite Separators for Lithium Metal Batteries.

The suboptimal ionic conductivity of commercial polyolefin separators exacerbates uncontrolled lithium dendrite formation, deteriorating lithium metal battery performance and posing safety hazards. To address this challenge, a novel organic-inorganic composite separator designed is prepared to enhance ion transport and effectively suppress dendrite growth. This separator features a thermally stable, highly porous poly(m-phenylene isophthalamide) (PMIA) electrospun membrane, coated with ultralong hydroxyapatite (HAP) nanowires that promote "ion flow redistribution." The synergistic effects of the nitrogen atoms in PMIA and the hydroxyl groups in HAP hinder anion transport while facilitating efficient Li+ conduction. Meanwhile, the optimized unilateral pore structure ensures uniform ion transport. These results show that the 19µm-thick HAP/PMIA composite separator achieves remarkable ionic conductivity (0.68mS cm-1) and a high lithium-ion transference number (0.51). Lithium symmetric cells using HAP/PMIA separators exhibit a lifespan exceeding 1000h with low polarization, significantly outperforming commercial polypropylene separators. Furthermore, this separator enables LiFePO4||Li cells to achieve an enhanced retention of 97.3% after 200 cycles at 1C and demonstrates impressive rate capability with a discharge capacity of 72.7mAh g-1 at 15C.

On the Use of Recycled PVB to Develop Sustainable Separators for Greener Li‐Ion Batteries

AbstractIn this work, sustainable Li‐based battery separators are prepared starting from a waste material from the glass industry, viz. polyvinyl butyral (PVB) widely used as a sacrificial interlayer in high impact‐resistant windows. First, polymeric membranes are prepared via the phase‐inversion method using commercial PVB as the backbone and 4,4′‐methylenebis(cyclohexylisocyanate) as a crosslinking agent. They are characterized from a physicochemical viewpoint by thermomechanical analysis, infrared spectroscopy, and scanning electron microscopy, and are successfully tested as separators in Li‐metal cells with LP30 electrolyte. Electrical and electrochemical properties are evaluated by impedance spectroscopy and galvanostatic cycling, providing comparable results with commercial Celgard 25 µm monolayer microporous polypropylene separator. As a proof‐of‐concept, for the first time, recycled PVB‐based polymer membranes from wasted car glasses are prepared, adjusting the synthesis protocol to account for the presence of plasticizers and contaminants. They show a dense elastomeric appearance and proved to be compatible with Li metal and stable upon 600 h of Li plating/stripping. The electrochemical window is compatible with the LiFePO4 cathode, as demonstrated by prolonged galvanostatic cycling (250 cycles) in laboratory‐scale cells. Preliminary results are highly encouraging and pave the way to developing novel separators for safe, low‐cost, and sustainable energy storage devices.

Cationic Covalent Organic Framework-Modified Polypropylene Separator for High-Performance Lithium Metal Batteries.

As an important component of lithium batteries, the wettability and thermal stability of the separator play a significant role in cell performance. Despite the availability of numerous commercial separators, issues such as low ion selectivity and poor thermal stability continue to limit the efficiency and reliability of the batteries. Herein, two cationic covalent organic frameworks (Br-COF and TFSI-COF) with abundant imidazole cationic groups were designed to modify commercial polypropylene (PP) separators. The strong lithium-ion affinity of the cationic COF enables the effective dissociation of lithium salt ion clusters, simplifying the solvent structure of lithium ions to promote lithium ions transport. Additionally, solvent anions can be anchored to the cationic COF by electrostatic interactions, reducing side reactions on the lithium metal anode surface to form a favorable SEI layer, which can effectively inhibit the growth of lithium dendrites. The rapid dissociation of anions in lithium salts with some organic solvents and cationic COFs was revealed by a molecular dynamics simulation. A LiF-rich SEI layer on the lithium metal anode surface was formed, which can speed up Li+ transport at interfaces, leading to consistent lithium deposition and outstanding battery performance. The ordered porous structure of the cationic COF provides interconnected and continuous channels, improving the wettability between the liquid electrolyte and separators, which is conducive to ion transport. When paired with a LiFePO4 cathode and electrolyte (1.0 M LiTFSI in DEC: EC: DMC = 1:1:1), the LiFePO4/TFSI-COF@PP/Li cell demonstrates a prominent cycling capacity of 148.0 mAh g-1 at 0.5 C with a Coulombic efficiency of 98.0% in the first cycle, and the capacity retention is 82.0% after 100 cycles, showing good cycling stability. Thus, this investigation provides inspiration for the expansion of cationic COF-modified separators for next-generation lithium metal batteries.

Tailoring Lithium Horizontal Deposition for Long-Lasting High-Loading NCA (≥5 mA h cm-2)||Lithium-Metal Full Cells in Carbonate Electrolytes.

We report a design for a synergistic lithium (Li) metal hosting layer for high-loading Li(Ni,Co,Al)O2 (NCA) (≥5 mA h cm-2)||Li-metal full cells in carbonate electrolytes. Based on density functional theory calculations, the hosting layer was designed as a three-dimensional silver/carbon composite nanofiber (Ag/CNF) network with high Li affinity and a platinum (Pt)-coated polypropylene separator with low Li affinity. This design enabled the tailoring of horizontal Li deposition on the Ag/CNF hosting layer. The Li deposition behavior modulated by the hosting layer was thoroughly examined based on the initial Li deposition and cycling behaviors of the Li||Li symmetric cell configuration. Cryogenic focused-ion beam cross-sectional images of the cycled Li anodes clearly demonstrated that dense lithium deposition was enabled by the synergistic hosting layer high-loading NCA (≥5 mA h cm-2)||Li-metal full cells. When the hosting layer was used, the average cycling performance improved by 78.27% under various cycling conditions. Our work demonstrates that the synergistic hosting layer design is a fruitful pathway to accelerate the commercialization of high-energy-density Li-metal batteries in carbonate electrolytes.

Biomimetic Aramid Nanofiber/β-FeOOH Composite Coating for Polypropylene Separators in Lithium-Sulfur Batteries.

Aramid nanofibers (ANFs), with attractive mechanical and thermal properties, have attracted much attention as key building units for the design of high-performance composite materials. Although great progress has been made, the potential of ANFs as fibrous protein mimetics for controlling the growth of inorganic materials has not been fully revealed, which is critical for avoiding phase separation associated with typical solution blending. In this work, we show that ANFs could template the oriented growth of β-FeOOH nanowhiskers, which enables the synthesis of ANFs/β-FeOOH hybrids as composite coatings for polypropylene (PP) separators in Li-S batteries. The modified PP separator exhibits enhanced mechanical properties, heightened thermal performance, optimized electrolyte wettability, and improved ion conductivity, leading to superior electrochemical properties, including high initial specific capacity, better rate capability, and long cycling stability, which are superior to those of the commercial PP separators. Importantly, the addition of β-FeOOH to ANFs could further contribute to the suppression of lithium polysulfide shuttling by chemical immobilization, inhibition of the growth of lithium dendrites because of the intrinsic high modulus and hardness, and promotion of reaction dynamics due to the catalytic effect. We believe that our work may provide a potent biomimetic pathway for the development of advanced battery separators based on ANFs.

Fabrication of a Multi-Functional Separator Incorporating Crown ether- Polyoxometalate Supramolecular Compound for Lithium-Sulfur Batteries.

Recently, research on polyoxometalates (POMs) has gained significant momentum. Owing to their properties as electronic sponges, POMs catalyst harbor substantial potential in lithium-sulfur battery research. However, POMs undergo a transformation into reduced heteropoly blue (HPB) during electrochemical reactions, which then dissolve into the electrolyte, resulting in catalyst loss. In this research, we amalgamated 18-crown-6 (CR6) with K3PW12O40, (KPW), synthesized a novel POM-based supramolecular compound, and integrated it with graphene oxide (GO) to fabricate a multi-functional composite polypropylene (PP) separator KPW-CR6/GO/PP. The crown ether array was employed to immobilize POM and construct ion transport channels, thereby enhancing the Li+ migration rate and capturing polysulfides. Subsequently, leveraging the stable structure and redox properties of POM, the polysulfide is catalyzed to transform and inhibit the shuttle effect, thereby protecting the Li anode. The lithium-sulfur batteries with the Crown ether-POM supramolecular compound separators, exhibit enhanced capacity and stability (1073.3 mAh g-1 at 1.0 C, and 81.5 % retention rate after 250 cycles). The battery (S loading: 3.2 mg cm-2) presents an initial specific discharge capacity of 543.4 mAh g-1 at 0.5 C, with 89.8 % of the capacity retained after 160 cycles. This underlines the practical application potential of Crown ether-POM supramolecular materials in Li-S batteries.

Reversible Li plating regulation on graphite anode through a barium sulfate nanofibers-based dielectric separator for fast charging and high-safety lithium-ion battery

Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithium-ion batteries with graphite anodes. Herein, a dielectric and fire-resistant separator based on hybrid nanofibers of barium sulfate (BS) and bacterial cellulose (BC) is developed to synchronously enhance the battery’s fast charging and thermal-safety performances. The regulation mechanism of the dielectric BS/BC separator in enhancing the Li+ ion transport and Li plating reversibility is revealed. (1) The Max-Wagner polarization electric field of the dielectric BS/BC separator can accelerate the desolvation of solvated Li+ ions, enhancing their transport kinetics. (2) Moreover, due to the charge balancing effect, the dielectric BS/BC separator homogenizes the electric field/Li+ ion flux at the graphite anode-separator interface, facilitating uniform Li plating and suppressing Li dendrite growth. Consequently, the fast-charge graphite anode with the BS/BC separator shows higher Coulombic efficiency (99.0% vs. 96.9%) and longer cycling lifespan (100 cycles vs. 59 cycles) than that with the polypropylene (PP) separator in the constant-lithiation cycling test at 2 mA cm−2. The high-loading LiFePO4 (15.5 mg cm−2)//graphite (7.5 mg cm−2) full cell with the BS/BC separator exhibits excellent fast charging performance, retaining 70% of its capacity after 500 cycles at a high rate of 2 C, which is significantly better than that of the cell with the PP separator (retaining only 27% of its capacity after 500 cycles). More importantly, the thermally stable BS/BC separator effectively elevates the critical temperature and reduces the heat release rate during thermal runaway, thereby significantly enhancing the battery’s safety.

Nano-necklace Co/β-Mo2C hetero-nanodots encapsulating into carbon nanotubes with strong adsorption and catalytic conversion of polysulfides for lithium‑sulfur batteries separator

Due to their high theoretical capacity and high energy density, Lithium‑sulfur (LiS) batteries become the research hotspot in the field of electrochemical energy storage. However, the serious capacity loss caused by the shuttle effect and the decomposition of polysulfides is the biggest obstacle in the research process and practical application of lithium‑sulfur batteries. Herein, cobalt (Co) and molybdenum carbide (Mo2C) hetero-nanodots wrapping into nitrogen-doped carbon nanotubes (Co-Mo2C@NCNTs) are successfully prepared by direct self-catalysis annealing process. When utilized into the polypropylene (PP) separator modifier, the batteries assembled with Co-Mo2C@NCNTs//PP separator presents high capacity and outstanding rate capability. Specifically, it's worth noting that the cells display a high initial specific capacity of 1463.6mAh g−1 at 0.1C, superior rate capacity of 778.7 mAh g−1 at 3C, and excellent cycle stability with capacity decay rate of only 0.11 % per cycle for 500 cycles at 0.5C. Besides, the outstanding electrochemical performance is also demonstrated under high sulfur loading (3.5 mg cm−2). This work provides a novel guidance direction for high-performance lithium‑sulfur batteries from separator modification.

Hybrid conductive-lithophilic-fluoride triple protection interface engineering: Dendrite-free reverse lithium deposition for high-performance lithium metal batteries

Lithium metal batteries (LMBs) with high energy density are impeded by the instability of solid electrolyte interface (SEI) and the uncontrolled growth of lithium (Li) dendrite. To mitigate these challenges, optimizing the SEI structure and Li deposition behavior is the key to stable LMBs. This study novelty proposes a facile synthesis of MgF2/carbon (C) nanocomposite through the mechanochemical reaction between metallic Mg and polytetrafluoroethylene (PTFE) powders, and its modified polypropylene (PP) separator enhances LMB performance. The in-situ formed highly conductive fluorine-doped C species play a crucial role in facilitating ion/electron transport, thereby accelerating electrochemical kinetics and altering Li deposition direction. During cycling, the in-situ reaction between MgF2 and Li leads to the formation of LiMg alloy, along with a LiF-rich SEI layer, which reduces the nucleation overpotential and reinforces the interphase strength, leading to homogeneous Li deposition with dendrite-free feature. Benefiting from these merits, the Li metal is densely and uniformly deposited on the MgF2/C@PP separator side rather than on the current collector side. Furthermore, the symmetric cell with MgF2/C@PP exhibits superb Li plating/stripping performance over 2800 h at 1 mA cm−2 and 2 mA h cm−2. More importantly, the assembled Li@MgF2/C@PP|LiFePO4 full cell with a low negative/positive ratio of 3.6 delivers an impressive cyclability with 82.7% capacity retention over 1400 cycles at 1 C.

Separator modification with a high-entropy hydroxyphosphate, Co0.29Ni0.15Fe0.33Cu0.16Ca3.9(PO4)3(OH), for high-performance Li-S batteries

The shuttle effect of lithium polysulfides (LiPSs) significantly hinders the practical application of lithium-sulfur batteries (LSBs). Herein, a high-entropy hydroxyphosphate (Co0.29Ni0.15Fe0.33Cu0.16Ca3.9(PO4)3(OH), denoted as HE-CHP), was synthesized by metal cation exchange with calcium hydroxyphosphate (CHP) and then coated on polypropylene (PP) separators to suppress the shuttling of LiPSs. Density functional theory calculations indicated that the various introduced metal cations could effectively modulate the binding strength of soluble polysulfides and enhance the reaction kinetics of LiPSs conversion. As a result, LSBs using the HE-CHP@PP separator exhibited an excellent discharge capacity (1297 mAh g−1 under 0.2 C) and a slow capacity decay during long-term cycling (0.046 % per cycle at 2 C). At a sulfur loading of up to 6.5 mg cm−2, the LSB with HE-CHP@PP separator displayed a discharge capacity of 5.8 mAh cm−2. Notably, the CNT@S||Li Li-S pouch cell with HE-CHP modified separator delivered an initial energy density of 432 Wh kg−1.

One-step pyrolysis route to N, O, S co-doped hierarchical carbon as multi-functional separator for lithium-sulfur batteries

Lithium-sulfur batteries have high theoretical energy density while their practical application is trapped because of severe shuttle effect and sluggish conversion kinetics of polysulfides. Here, a nitrogen, oxygen, and sulfur co-doped porous carbon (NOSAKC) is prepared by one-step pyrolysis of acesulfame potassium, which is employed as an efficient component on polypropylene separators to restrict the shuttle of polysulfides based on Lewis acid-base theory. The NOSAKC exhibits a hierarchical porous structure with high specific surface area and abundant adsorption/catalytic sites. The substantial mesoporous channels are conducive to rapid ion transfer, and the micropores minimize the polysulfide shuttle. The abundant heteroatoms doped in NOSAKC can achieve synergistic constraint and conversion of lithium polysulfides. So the Li-S battery with the NOSAKC separator displays distinguished electrochemical performance with a high discharge capacity of 1598 mAh g-1 at 0.2C and 1012 mAh g-1 at 1C. It maintains 84% of the initial capacity after 500 cycles with a stable coulombic efficiency of 99.8%. Moreover, the Li-S battery achieves a capacity retention of 67% after 200 cycles for a high sulfur loading of 4.33mgcm-2. This work reports a one-step preparation of hierarchical porous carbon with tri-doped heteroatoms for synergistic polysulfide adsorption and conversion.

Waste to wealth: calcium-magnesium mud-coated polypropylene separator for lithium-ion battery

Waste to wealth: calcium-magnesium mud-coated polypropylene separator for lithium-ion battery

H3PO4-Impregnated Covalent Organic Framework Membrane on Separators to Prevent Lithium Metal Anode Dendrite Growth.

Inhibiting the growth of lithium dendrites is crucial for battery safety. For separators, their favorable electrolyte wettability, uniform current density, and high ionic conductivity are beneficial for avoiding Li dendrite growth. In this work, we propose a separator (PA@COF/PP) by modifying a polypropylene separator with H3PO4-functionalized covalent organic frameworks. The uniform channels of the covalent organic frameworks and H3PO4 can homogenize the current and act as ionic conductors for efficient Li+ migration. The synthesized separator effectively suppresses the growth of lithium dendrites and improves the stability of the batteries. A symmetric cell with the PA@COF/PP separator exhibits a stable life span over 4000 hours at a high current density of 5 mA cm-2, compared to the commercial PP separator, which lasts only 159 hours. This work provides an efficient method and novel inspiration for the construction of dendrite-free lithium metal batteries.

Cobalt-doped molybdenum sulfide as an interlayer facilitates polysulfide conversion to obtain high-performance lithium−sulfur batteries

Lithium–sulfur (Li–S) batteries are considered to be a promising energy storage system due to their theoretical specific capacity. However, the “shuttle effect” of polysulfides (LiPSs) and the slow redox kinetics of LiPSs in the conversion reaction have hindered their large−scale application. In this study, the Co-MoS2 is prepared and coated on the polypropylene (PP) separator of Li–S batteries. The Co elements are successful addition and uniform distribution in the Co-MoS2. This coating is designed to provide chemical adsorption and catalysis for LiPSs. Consequently, Li–S batteries with a Co-MoS2 interlayer exhibit outstanding long-cycle and high-rate performance. After 500 cycles at 0.5C, the reversible capacity is found to be 561 mAh g−1, with only a low-capacity reduction of 0.097 % per cycle. Furthermore, 602 mAh g−1 is delivered even at 4C. The results of electrochemical measurements and first principles calculations demonstrate that the high performance of Li–S batteries is attributed to the chemical adsorption and electrocatalysis roles of the Co-MoS2 interlayer, which inhibit the “shuttle effect” and enable fast redox reaction kinetics. In addition, the introduction of cobalt doping results in the formation of the 1T phase of MoS2, which enhances the conductivity of the Co-MoS2. The presence of plentiful cobalt-doped MoS2 defects provides abundant catalytic sites for the electrochemical reaction of LiPSs.

Utilization of CoSe2-loaded carbon nanofibers for enhancing separator performance in lithium-sulfur batteries: Polysulfide immobilization and redox conversion enhancement

Lithium‑sulfur batteries (LSBs) are recognized as promising candidates for the next generation of secondary batteries due to their high energy density, high theoretical capacity, and low environmental impact. However, the poor electrical conductivity of sulfur and Li2S, the “shuttle effect” of polysulfides, and the slow kinetics of redox reactions have significantly hindered the practical application of LSBs. In this work, CoSe2-loaded carbon nanofibers (CoSe2@CNF) derived from metal-organic frameworks were successfully prepared by electrospinning and used as a functional coating on the polypropylene separator. The three-dimensional network structure of CNFs not only improves the electrical conductivity of the material but also provides channels to facilitate ion and electron transport, while the CoSe2 particles distributed on the surface effectively act as adsorption and catalytic active sites for lithium polysulfides. Under the synergistic effect, the CoSe2@CNF-modified separator suppressed the shuttle effect and significantly enhanced the kinetics of redox reactions. The LSBs assembled with CoSe2@CNF-modified separator exhibited excellent electrochemical performance, achieving an initial capacity of 1445.6 mAh g−1 at 0.5C and maintaining a discharge specific capacity of 849.5 mAh g−1 after 275 cycles.