Advanced Lithium Sulfur Batteries Research Articles

Electrochemically Active MoO3/TiN Sulfur Host Inducing Dynamically Reinforced Built-in Electric Field for Advanced Lithium-Sulfur Batteries.

Although various electrocatalysts have been developed to ameliorate the shuttle effect and sluggish Li-S conversion kinetics, their electrochemical inertness limits the sufficient performance improvement of lithium-sulfur batteries (LSBs). In this work, an electrochemically active MoO3/TiN-based heterostructure (MOTN) is designed as an efficient sulfur host that can improve the overall electrochemical properties of LSBs via prominent lithiation behaviors. By accommodating Li ions into MoO3 nanoplates, the MOTN host can contribute its own capacity. Furthermore, the Li intercalation process dynamically affects the electronic interaction between MoO3 and TiN and thus significantly reinforces the built-in electric field, which further improves the comprehensive electrocatalytic abilities of the MOTN host. Because of these merits, the MOTN host-based sulfur cathode delivers an exceptional specific capacity of 2520mA h g-1 at 0.1 C. Furthermore, the cathode exhibits superior rate capability (564mA h g-1 at 5 C), excellent cycling stability (capacity fade rate of 0.034% per cycle for 1200 cycles at 2 C), and satisfactory areal capacity (6.6mA h cm-2) under a high sulfur loading of 8.3mg cm-2. This study provides a novel strategy to develop electrochemically active heterostructured electrocatalysts and rationally manipulate the built-in electric field for achieving high-performance LSBs.

MOF derived phosphorus doped cerium dioxide nanorods modified separator as efficient polysulfide barrier for advanced lithium-sulfur batteries

MOF derived phosphorus doped cerium dioxide nanorods modified separator as efficient polysulfide barrier for advanced lithium-sulfur batteries

Dual-function hollow MoS2 nanocages decorated on graphene sheets as efficient sulfur hosts for advanced lithium-sulfur batteries

Due to the presence of polysulfitabde shuttling, serious electrode expansion, and the low electrical conductivity of sulfur materials at room temperature, the commercialization of Li-S batteries is still not feasible. In this study, we have synthesized unique hollow molybdenum disulfide nanocages/reduced graphene oxide (H-MoS2/rGO) composites to be employed as highly effective cathodes for Li-S batteries. In this well-designed structure, the hollow MoS2 nanocages are tightly bound by C-O-Mo bonds and uniformly distributed across the graphene sheets. The dual-function MoS2 nanocages can adsorb polysulfides by Mo-S bond and accelerate the conversion reaction of S8 and Li2S. Moreover, the 3D rGO network with abundant pores effectively reduces the diffusion path and enhances the rapid transport of electrons and ions. The hybrid H-MoS2/rGO cathodes with these advantages exhibit a remarkable initial discharge capacity of 801.7 mAh g−1 at 1 C, as well as a high specific discharge capacity of 533.2 mAh g−1 is remained over 500 cycles.

A Nitrogen/Oxygen Dual-Doped Porous Carbon with High Catalytic Conversion Ability toward Polysulfides for Advanced Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) have attracted widespread attention due to their high theoretical energy density and low cost. However, their development has been constrained by the shuttle effect of lithium polysulfides and their slow reaction kinetics. In this work, a nitrogen/oxygen dual-doped porous carbon (N/O-PC) was synthesized by annealing the precursor of zeolitic imidazolate framework-8 grown in situ on MWCNTs (ZIF-8/MWCNTs). Then, the N/O-PC composite served as an efficient host for LSBs through chemical adsorption and providing catalytic conversion sites of polysulfides. Moreover, the interconnected porous carbon-based structure facilitates electron and ion transfer. Thus, the S/N/O-PC cathode exhibits high cycling stability (a stable capacity of 685.9 mA h g−1 at 0.2 C after 100 cycles). It also demonstrates excellent rate performance with discharge capacities of 1018.2, 890.2, 775.1, 722.7, 640.4, and 579.6 mAh g−1 at 0.2, 0.5, 1.0, 2.0, 3.0, and 5.0 C, respectively. This work provides an effective strategy for designing and developing high energy density, long cycle life LSBs.

Enhancement of Overall Kinetics by Se-Br Chemistry in Rechargeable Li-S Batteries.

The sluggish kinetics of lithium-sulfur (Li-S) batteries severely impedes the application in extreme conditions. Bridging the sulfur cathode and lithium anode, the electrolyte plays a crucial role in regulating kinetic behaviors of Li-S batteries. Herein, we report a multifunctional electrolyte additive of phenyl selenium bromide (PhSeBr) to simultaneously exert positive influences on both electrodes and the electrolyte. For the cathode, an ideal conversion routine with lower energy barrier can be attained by the redox mediator and homogeneous catalyst derived from PhSeBr, thus improving the reaction kinetics and utilization of sulfur. Meanwhile, the presence of Se-Br bond helps to reconstruct a loose solvation sheath of lithium ions and a robust bilayer SEI with excellent ionic conductivity, which contributes to reducing the de-solvation energy and simultaneously enhancing the interfacial kinetics. The Li-S battery with PhSeBr displays superior long cycling stability with a reversible capacity of 1164.7 mAh g-1 after 300 cycles at 0.5 C rate. And the pouch cell exhibits a maximum capacity of 845.3 mAh and a capacity retention of 94.8 % after 50 cycles. Excellent electrochemical properties are also obtained in extreme conditions of high sulfur loadings and low temperature of -20 °C. This work demonstrates the versatility and practicability of the special additive, striking out an efficient but simple method to design advanced Li-S batteries.

Hollow CoP-FeP cubes decorating carbon nanotubes heterostructural electrocatalyst for enhancing the bidirectional conversion of polysulfides in advanced lithium-sulfur batteries

The sluggish redox reaction kinetics and “shuttle effect” of lithium polysulfides (LPSs) impede the advancement of high-performance lithium-sulfur batteries (LSBs). Transition metal phosphides exhibit distinctive polarity, metallic properties, and tunable electron configuration, thereby demonstrating enhanced adsorption and electrocatalytic capabilities towards LPSs. Consequently, they are regarded as exceptional sulfur hosts for LSBs. Moreover, the introduction of a heterogeneous structure can enhance reaction kinetics and expedite the transport of electrons/ions. In this study, a composite of hollow CoP-FeP cubes with heterostructure modified carbon nanotube (CoFeP-CNTs) was fabricated and utilized as sulfur host in advanced LSBs. The presence of carbon nanotubes (CNTs) facilitates enhanced electron and Li+ transport. Meanwhile, the active sites within the heterogeneous interface of CoP-FeP suppress the “shuttle effect” and enhance the conversion kinetics of LPSs. Therefore, the CoFeP-CNTs/S electrode exhibited exceptional cycling stability and demonstrated a capacity attenuation of merely 0.051 % per cycle over 600 cycles at 1C. This study presents a highly effective tactic for synthesizing dual-acting transition metal phosphides with heterostructure, which will play a pivotal role in advancing the development of efficient LSBs.

Versatile Separators Toward Advanced Lithium-Sulfur Batteries: Status, Recent Progress, Challenges and Perspective.

Lithium-sulfur batteries (LSBs) have recently gained extensive attention due to their high energy density, low cost, and environmental friendliness. However, serious shuttle effect and uncontrolled growth of lithium dendrites restrict them from further commercial applications. As "the third electrode", functional separators are of equal significance as both anodes and cathodes in LSBs. The challenges mentioned above are effectively addressed with rational design and optimization in separators, thereby enhancing their reversible capacities and cycle stability. The review discusses the status/operation mechanism of functional separators, then primarily focuses on recent research progress in versatile separators with purposeful modifications for LSBs, and summarizes the methods and characteristics of separator modification, including heterojunction engineering, single atoms, quantum dots, and defect engineering. From the perspective of the anodes, distinct methods to inhibit the growth of lithium dendrites by modifying the separator are discussed. Modifying the separators with flame retardant materials or choosing a solid electrolyte is expected to improve the safety of LSBs. Besides, in-situ techniques and theoretical simulation calculations are proposed to advance LSBs. Finally, future challenges and prospects of separator modifications for next-generation LSBs are highlighted. We believe that the review will be enormously essential to the practical development of advanced LSBs.

Geometric design of carbon-based interlayer for advanced lithium-sulfur batteries

Interlayer engineering is considered as an innovative and efficient approach to constrain the shuttle effect of polysulfides while elevating sluggish redox reaction kinetics in lithium‑sulfur (LiS) batteries. However, the principles for functional interlayer design have not been scientifically established yet, as very few works have focused on the investigation of parameters (e.g., geometrical structure) that affect the electrochemical performance of interlayer. In this study, interlayers with identical chemical compositions but different micromorphologies are fabricated by polyacrylonitrile, including nanofiber, short stick, and powder. Multiphysics simulation and experimental results reveal that the distinctions in the microcrystalline interlayers lead to completely different suppression effects on polysulfides. Notably, the 3D carbon nanofiber-modified interlayer (NF) prepared from electrospinning technology forms a higher specific area and continuous electron access compared to short sticks and powder. Accordingly, the NF-based LiS battery exhibited excellent cycling performance at 1.0 C, with a reversible capacity of 660 mAh g−1 after 300 cycles and a decay rate of about 0.10 %. Even at a high sulfur loading of 8.2 mg cm−2, it achieves a high areal capacity of 5.1 mAh cm−2 after 100 cycles at 0.2 C. This study clearly elucidates a design strategy for high-performance interlayer in LiS batteries from a mesoscale perspective.

Pristine MOF Materials for Separator Application in Lithium-Sulfur Battery.

Lithium-sulfur (Li-S) batteries have attracted significant attention in the realm of electronic energy storage and conversion owing to their remarkable theoretical energy density and cost-effectiveness. However, Li-S batteries continue to face significant challenges, primarily the severe polysulfides shuttle effect and sluggish sulfur redox kinetics, which are inherent obstacles to their practical application. Metal-organic frameworks (MOFs), known for their porous structure, high adsorption capacity, structural flexibility, and easy synthesis, have emerged as ideal materials for separator modification. Efficient polysulfides interception/conversion ability and rapid lithium-ion conduction enabled by MOFs modified layers are demonstrated in Li-S batteries. In this perspective, the objective is to present an overview of recent advancements in utilizing pristine MOF materials as modification layers for separators in Li-S batteries. The mechanisms behind the enhanced electrochemical performance resulting from each design strategy are explained. The viewpoints and crucial challenges requiring resolution are also concluded for pristine MOFs separator in Li-S batteries. Moreover, some promising materials and concepts based on MOFs are proposed to enhance electrochemical performance and investigate polysulfides adsorption/conversion mechanisms. These efforts are expected to contribute to the future advancement of MOFs in advanced Li-S batteries.

Perspectives on Advanced Lithium-Sulfur Batteries for Electric Vehicles and Grid-Scale Energy Storage.

Intensive increases in electrical energy storage are being driven by electric vehicles (EVs), smart grids, intermittent renewable energy, and decarbonization of the energy economy. Advanced lithium-sulfur batteries (LSBs) are among the most promising candidates, especially for EVs and grid-scale energy storage applications. In this topical review, the recent progress and perspectives of practical LSBs are reviewed and discussed; the challenges and solutions for these LSBs are analyzed and proposed for future practical and large-scale energy storage applications. Major challenges for the shuttle effect, reaction kinetics, and anodes are specifically addressed, and solutions are provided on the basis of recent progress in electrodes, electrolytes, binders, interlayers, conductivity, electrocatalysis, artificial SEI layers, etc. The characterization strategies (including in situ ones) and practical parameters (e.g., cost-effectiveness, battery management/modeling, environmental adaptability) are assessed for crucial automotive/stationary large-scale energy storage applications (i.e., EVs and grid energy storage). This topical review will give insights into the future development of promising Li-S batteries toward practical applications, including EVs and grid storage.

Ingenious separator architecture: Revealing the versatile 3D heterostructured MXene-hydrogen titanate electrocatalysts for advanced lithium-sulfur battery

Lithium-sulfur batteries (LSBs) with high theoretical energy density and cost-effectiveness have great promise as alternative energy storage systems to traditional lithium-ion batteries. Nevertheless, their practical application is severely hindered due to a myriad of shortcomings such as “shuttling effect” of lithium polysulfides (LiPSs), sluggish conversion kinetics of sulfur (S) species, low electrical conductivity of S and discharged products, and intractable lithium dendrite growth. Herein, a novel 3D-heterostructured electrocatalyst consisting of the in-situ grown H2Ti3O7 (HTO) nano-whiskers on a Ti3C2Tx (MXene) substrate (M-HTO-0.5) is designed using a MXene-derived hydrothermal process combined with following ion exchange between Na+ and H+, wherein the hydrothermal reaction time regulation (0.5 h) mainly induces the balanced co-existence of HTO and MXene in the microstructure of M-HTO-0.5. Benefiting from the synergistic effect between M-HTO-0.5 (strong LiPS chemisorption, outstanding catalytic activity with abundant active sites, and boosted Li+ ion migration) and carbon nanotubes (CNTs) (construction of ion/electron transport network), the ingenious design of multi-functional separators (M-HTO-0.5-C) effectively restricts LiPS shuttling and dendritic Li growth simultaneously. Consequently, LSBs with M-HTO-0.5-C separators achieve remarkable rate capability, and stable long-term cyclability even at 5.0 C. This study opens an innovative avenue for developing high-performance LSB configurations.

All-purpose redox-active metal-organic frameworks as both cathodic and anodic host materials for advanced lithium-sulfur batteries

All-purpose redox-active metal-organic frameworks as both cathodic and anodic host materials for advanced lithium-sulfur batteries

Achieving High-Performance Lithium-Sulfur Batteries by Modulating Li+ Desolvation Barrier with Liquid Crystal Polymers.

Lithium-sulfur (Li-S) batteries offer high theoretical capacity but are hindered by poor rate capability and cycling stability due to sluggish Li2S precipitation kinetics. Here a sulfonate-group-rich liquid crystal polymer (poly-2,2'-disulfonyl-4,4'-benzidine terephthalamide, PBDT) is designed and fabricated to accelerate Li2S precipitation by promoting the desolvation of Li+ from electrolyte. PBDT-modified separators are employed to assemble Li-S batteries, which deliver a remarkable rate capacity (761 mAh g-1 at 4 C) and cycling stability (500 cycles with an average decay rate of 0.088% per cycle at 0.5 C). A PBDT-based pouch cell even delivers an exceptional capacity of ≈1400 mAh g-1 and an areal capacity of ≈11 mAh cm-2 under lean-electrolyte and high-sulfur-loading condition, demonstrating promise for practical applications. Results of Raman spectra, molecular dynamic (MD) and density functional theory (DFT) calculations reveal that the abundant anionic sulfonate groups of PBDT aid in Li+ desolvation by attenuating Li+-solvent interactions and lowering the desolvation energy barrier. Plus, the polysulfide adsorption/catalysis is also excluded via electrostatic repulsion. This work elucidates the critical impact of Li+ desolvation on Li-S batteries and provides a new design direction for advanced Li-S batteries.

Mxene quantum dots decorated reduced graphene oxide networks as multifunctional electrocatalyst for advanced lithium–sulfur batteries

Lithium sulfur (Li-S) battery has shown great potential as an attractive rechargeable energy storage devices, but the shuttle behavior and slow conversion kinetics of the intermediate lithium polysulfides (LiPSs) are the main obstacles to the practical application of Li-S battery. Herein, a simple and scalable spray drying strategy was used to construct conductive polar Ti3C2 MXene quantum dots (QDs)-decorated reduced graphene oxide (rGO) microsphere (rGO@Ti3C2 QDs) as efficient electrocatalyst and absorbent for Li-S battery. Firstly, the DFT results show that Ti3C2 QDs can effectively adsorb and catalyze LiPSs conversion. This ability can be attributed to the Ti3C2 QDs can provide a large number of LiPSs catalytic active sites. In addition, the rGO provides physical LiPSs constraint and a flexible substrate to prevent QDs from aggregating. Moreover, both parts are conductive, effectively improving the electron/charge transfer. Therefore, this unique structure and composition show high LiPSs adsorption and catalysis, while allowing rapid Li+/electron transfer. As a result, the S/rGO@Ti3C2 QDs electrode provides high initial capacity (1185 mAh/g at 0.2C), good rate capability (758 mAh/g at 3C), and excellent long-term cyclability (500 cycles at 1C with low attenuation of 0.07% per cycle), as well as an excellent electrochemical performance even at high sulfur loading. Meanwhile, the Li-S pouch cell based on S/rGO@Ti3C2 QDs also achieved a high initial energy density of 230.9 Wh kg−1. This work may provide a promising strategy to obtain better electrochemical performance by introducing quantum dots into Li-S cathodes.

Boron doped MXenes as redox catalyst for highly efficient and reversible polysulfide conversion

Due to the accumulation of soluble polysulfides during the process reaction process, the shuttle effect emerges and significantly impacts the electrochemical performance. The development of novel efficient catalysts and adsorbents is a very popular way to fabricate the sulfur host materials. MXene as one of the most novel and popular materials have been wildly used in electrochemical energy storage. While the limited catalytic activity and adsorption capacity hindering its application in lithium sulfur batteries. Here, we introduced boron atoms as dopants in a creative modification of MXene (B-MXene). The introduced B atoms can effectively mitigate the “shuttle effect” through chemical adsorption, owing to their electron-deficient nature. Furthermore, the introduction of boron atoms and vacancy can modify the electronic structure, enhancing the catalytic activity of MXene by providing empty perpendicular-orientation orbitals. As a result, B-MXene exhibited excellent electrochemical performance, maintaining at 943 mA h g−1 at a current density of 1.0C, after 500cycles, with a corresponding decay rate as low as 0.046 %. This work proposes an efficient strategy to fabricate highly efficient electrocatalysts for advanced lithium-sulfur batteries (Li-S batteries).

Dual-ultrasmall Sb and Sb6O13 nanodots co-anchored MXene with manipulable structural chemistry modulating bidirectional kinetics toward advanced lithium-sulfur batteries

Exfoliation and modulation of intercalated layered transition metal carbides and/or nitrides (MAX) into their derivatives (MXenes) featured with manipulable structural chemistry by remain enormous challenges toward practical applications. Herein, an extraordinary low-dimensional MXenes modulated by dual-ultrasmall Sb and Sb6O13 nanodots via in situ structural editing protocol using Lewis-basic fluorides in organic molten salts. Their original internal non-van der Waals bonds and physicochemical natures are simultaneously mediated by manipulating fluorine anions and antimony cations as chemical scissors generating into zero- and one-dimensional MXenes (MFNCTS-Z, MFNCTS-O) encapsulated by hierarchical porous N-doped carbon. Experimental and theoretical results manifest MFNCTSs as alternative dual-functional hosts toward both sulfur (S) cathode and lithium (Li) anode modulating bidirectional kinetics originated from their synergistic effect of physical confinement and chemical anchor effect accelerating polysulfides redox chemistry, and homogeneous lithium deposition. As a result, the assembled lithium-sulfur full batteries offer impressive electrochemical performances. This work paves a new avenue for developing low-dimensional MXenes by controllable structural editing strategy toward practical energy conversion and storage fields.

Heteroatom doping carbon film derived from hyphae as a self-supporting cathode for advanced lithium sulfur batteries

Much attention has been paid to lithium sulfur battery due to its high energy density. However, low S loading and poor cycling stability have hindered their commercialization. In this work, a porous carbon film with rich heteroatom doping was prepared from the Penicillium chrysogenum hyphae film by freezing drying and high-temperature carbonization. Then the carbon film loaded polysulfide solution was utilized as a self-supporting cathode for Li-S batteries. The self-supporting cathode exhibited good rate performance (513.1 mAh/g at 1C) and improved cycling stability (more than 400 cycles) under a high current density (0.5C). This is mainly attributed to the abundant heteroatoms that provided active sites with superior adsorption ability for lithium polysulfide, which not only enhanced the cycling stability but also facilitated the conversion kinetics. Besides, the fibrous network morphology with affluent porous structures inherited from hyphae provided a large specific surface area and sufficient space for accommodating active substances. This work shows the great potential of hyphae derived porous carbon electrodes for high-performance energy storage applications.

Advanced Lithium-sulfur batteries enabled by a flexible electrocatalytic membrane of TiO2 and SiO2 co-decorated necklace-like carbon nanofibers

Lithium-sulfur (Li-S) batteries are regarded as new energy storage systems due to their low cost and high specific energy density; however, their commercial prospects are hindered by the shuttle effect of lithium polysulfides (LiPSs). Herein, the fabricating necklace-like carbon nanofibers membrane co-decorated by TiO2 and SiO2 (TiO2@SiO2/CNF) is prepared by the electrospinning technique as an interlayer to catalyze the conversion of LiPSs in Li-S batteries. The necklace-like nanofibers provide a three-dimensional conductive network, enabling SiO2 synergy with TiO2 to accelerate the redox kinetics of LiPSs through an enhanced interfacial effect. The Li-S batteries based on TiO2@SiO2/CNF interlayers exhibit an impressive specific capacity of 658 mAh g−1 at 3.0C, and their performances are decayed only 0.05 % per cycle at 1.0C within 500cycles. Our study reveals that the shuttle effect addition of LiPSs can be significantly improved by rational structural design, thus enhancing the electrochemical performance of Li-S batteries. The synthesis of necklace-like TiO2@SiO2/CNF presents a promising strategy for designing functional interlayers for advanced Li-S batteries.

Synergistically accelerating capture and catalytic conversion of polysulfides by Co@NCNT-MoSe2 nanocomposite modified separator for advanced Lithium-Sulfur batteries

Lithium-sulfur (Li-S) battery with a high theoretical energy density (2600 Wh·kg−1) is considered as a promising energy storage system. However, the shuttle effect and the sluggish redox kinetics of lithium polysulfides (LiPSs) lead to low sulfur utilization. A multifunctional layer modified on separator, as a collaborator of capturer-catalyst-conductor, is be regarded as an effective strategy to solve these problems. Herein, the Co@NCNT-MoSe2 nanocomposite as a modified layer is synthesized with a mesoporous structure by the hydrothermal reaction, in which a large number of transparent MoSe2 nanosheets grow outside NCNT embedded with Co nanoparticles, forming a flower-like outer walls of tube. The modified layer displays the significant features of capturing and catalytic conversion toward LiPSs, attributing to strong adsorption abilities, abundant catalytic active sites, and efficient transferring pathway of electron/Li+. Benefitting from these alluring properties, the results demonstrate that the modified separator offers a high discharge capacity of 983.2 mAh·g−1 at 0.2C after 200 cycles. Even at 2C, after long-term 1000 cycles, it still shows a superb capacity of 725 mAh·g−1 accompanied by a low capacity fading of 0.042 % per cycle. More notably, at 0.2C, the modified separator can realize an ideal areal capacity of 5.24 mAh·cm−2 under high S load (5 mg·cm−2) and poor electrolyte (7.5 μL·mg−1). Therefore, this work will provide a new insight on the development of multifunctional separators to achieve a long-life battery with high sulfur utilization by restraining shuttle effect and accelerate redox kinetics of LiPSs.

Organic Electrolyte Additive: Dual Functions Toward Fast Sulfur Conversion and Stable Li Deposition for Advanced Li-S Batteries.

Lithium-sulfur (Li-S) battery is of great potential for the next generation energy storage device due to the high specific capacity energy density. However, the sluggish kinetics of S redox and the dendrite Li growth are the main challenges to hinder its commercial application. Herein, an organic electrolyte additive, i.e., benzyl chloride (BzCl), is applied as the remedy to address the two issues. In detail, BzCl can split into Bz· radical to react with the polysulfides, forming a Bz-S-Bz intermediate, which changes the conversion path of S and improves the kinetics by accelerating the S splitting. Meanwhile, a tight and robust solid electrolyte interphase (SEI) rich in inorganic ingredients namely LiCl, LiF, and Li2O, is formed on the surface of Li metal, accelerating the ion conductivity and blocking the decomposition of the solvent and lithium polysulfides. Therefore, the Li-S battery with BzCl as the additive remains high capacity of 693.2mAhg-1 after 220 cycles at 0.5C with a low decay rate of 0.11%. This work provides a novel strategy to boost the electrochemical performances in both cathode and anode and gives a guide on the electrolyte design toward high-performance Li-S batteries.