Performance Of Lithium-sulfur Batteries Research Articles

In situ conversion to construct fast ion transport and high catalytic cathode for high-sulfur loading with lean electrolyte lithium–sulfur battery

The difficulty of lithium ion transport and the slow redox reaction kinetics of polysulfide severely limit the performance of lithium-sulfur batteries under high sulfur loading and lean electrolyte conditions, thus hindering the practical process of lithium-sulfur batteries. Herein, FeF2 @rGO composites were used as sulfur host materials for lithium-sulfur batteries, which is in situ converted into LiF and FeS during the first discharging process, achieving rapid lithium ion transport and high catalytic activity simultaneously. The electrode delivered high discharge capacity and low capacity decay of 0.028% per cycle for 500 cycles. Even under elevated sulfur loading and lean electrolyte conditions, the electrode with FeF2 @rGO can exhibit high areal capacity of 12.3 mAh cm−2(12.7 mg cm−2 and 6 μL mg−1).

Anion-doped CeO2 for high-performance lithium-sulfur batteries

Li-S batteries are potential candidates for next-generation energy storage devices because of their ultra-high theoretical capacity and low cost. However, shuttle effect and slow reaction kinetics hinder further commercialization of Li-S batteries. In the present work, CeO2-xSx was prepared using S-doped CeO2 as a cathode material to address some existing challenges of Li-S batteries. After density function theory calculations, it was found that S doping not only effectively shortens the band gap but also enhances the adsorption capacity of the composite to Li2S6, which has a positive effect on mitigating the shuttle effect. The battery also has a highly reversible cycling capability. The first charge/discharge capacity of the battery at 0.1C reached 1380 mAh/g, while the capacity retention rate of the battery reached 90% after 500 cycles at 1C. This provides a new idea for anion doping to be used to enhance the performance of lithium-sulfur batteries.

Atomic Structure Modification of Fe‒N‒C Catalysts via Morphology Engineering of Graphene for Enhanced Conversion Kinetics of Lithium–Sulfur Batteries

AbstractSingle‐atom M‒N‒C catalysts have attracted tremendous attention for their application to electrocatalysis. Nitrogen‐coordinated mononuclear metal moieties (MNx moities) are bio‐inspired active sites that are analogous to various metal‐porphyrin cofactors. Given that the functions of metal‐porphyrin cofactors are highly dependent on the local coordination environments around the mononuclear active site, engineering MNx active sites in heterogeneous M‒N‒C catalysts would provide an additional degree of freedom for boosting their electrocatalytic activity. This work presents a local coordination structure modification of FeN4 moieties via morphological engineering of graphene support. Introducing highly wrinkled structure in graphene matrix induces nonplanar distortion of FeN4 moieties, resulting in the modification of electronic structure of mononuclear Fe. Electrochemical analysis combined with first‐principles calculations reveal that enhanced electrocatalytic lithium polysulfide conversion, especially the Li2S redox step, is attributed to the local structure modified FeN4 active sites, while increased specific surface area also contributes to improved performance at low C‐rates. Owing to the synergistic combination of atomic‐level modified FeN4 active sites and morphological advantage of graphene support, Fe‒N‒C catalysts with wrinkled graphene morphology show superior lithium–sulfur battery performance at both low and high C‐rates (particularly 915.9 mAh g−1 at 5 C) with promising cycling stability.

Designing a Functional CNT+PB@MXene-Coated Separator for High-Capacity and Long-Life Lithium-Sulfur Batteries.

Separators, as indispensable parts of LSBs (lithium–sulfur batteries), play a cucial role in inhibiting dendrite growth and suppressing the shuttle of lithium polysulfide (LiPSs). Herein, we prepared a functional carbon nanotube (CNT) and Fe-based Prussian blue (PB)@MXene/polypropylene (PP) composite separator using a facile vacuum filtration approach. The CNTs and MXene nanosheets are excellent electronic conductors that can enhance the composite separator electrical conductivity, while Fe-based Prussian blue with a rich pore structure can effectively suppress the migration by providing physical space to anchor soluble LiPSs and retain it as cathode active material. Additionally, MXene nanosheets can be well attached to Fe-based Prussian blue by an electrostatic interaction and contribute to the physical barriers that inhibit the shuttle of long-chain soluble Li2Sn (4 ≤ n ≤ 8). When used as a lithium–sulfur (Li–S) cell membrane with a functional coating layer of CNT+PB@MXene facing the cathode side, the batteries reveal a high initial discharge capacity (1042.6 mAh g−1 at 0.2 C), outstanding rate capability (90% retention of capacity at 1.0 C) and high reversible capacity (674.1 mAh g−1 after 200 cycles at 1.0 V). Of note, separator modification is a feasible method to improve the electrochemical performance of LSBs.

Synergistic improvement of the overall performance of lithium-sulfur batteries

<p indent="0mm">As one of the most promising next generation secondary battery systems, lithium-sulfur battery has the advantages of high energy density, low cost, and environmental friendliness. But its commercial application still faces several challenges, such as the intrinsic insulation of sulfur, the shuttle effect of the intermediate lithium polysulfide, and the growth of lithium dendrites. In recent years, our research group has systematically investigated the electrode materials, performance and mechanism for Li-S batteries. We have realized the solid-solid conversion of sulfur via micropore limitation, and rational cathode-electrolyte interface construction. Different from the conventional solid-liquid-solid cathode process, solid-solid conversion of sulfur can not only avoid the diffusion of the soluble intermediate lithium polysulfide and the “shuttle effect”, but also effectively reduce the electrolyte/sulfur ratio (E/S) and therefore enhance the energy density of battery. In addition, we have also realized high surface capacity of the Li-S battery through structural design, and effectively inhibited the shuttle effect of polysulfide by constructing a functional intermediate layer. For lithium metal anode protection, we have designed and constructed kinds of three-dimensional current collection, which can effectively inhibit the formation of lithium dendrite, and hence comprehensively improve the safety and cyclability. We have also improved the air stability and moisture resistance of lithium metal by artificial solid electrolyte interface construction and interface modification. In addition, due to the low room-temperature conductivity and weak mechanical strength of polymer electrolytes commonly used in solid state electrolytes, we have successfully improved the mechanical property and flame resistance of polymer electrolytes by modification. Finally, we put forward a prospect for promoting the practical application of Li-S batteries with the goal of high energy, high safety and long cycle life.

Synthesis and application of single-atom catalysts in sulfur cathode for high-performance lithium–sulfur batteries

Lithium–sulfur (Li-S) batteries are regarded as one of the most promising energy storage devices because of their low cost, high energy density, and environmental friendliness. However, Li-S batteries suffer from sluggish reaction kinetics and serious “shuttle effect” of lithium polysulfides (LiPSs), which causes rapid decay of battery capacity and prevent their practical application. To address these problems, introducing single-atom catalysts (SACs) is an effective method to improve the electrochemical performance of Li-S batteries, due to their high catalytic efficiency and definite active sites for LiPSs. In this paper, we summarized the latest developments in enhancing the electrochemical performance of cathode for Li-S batteries through introducing different SACs. Furthermore, we briefly introduced the catalytic mechanism of SACs and discussed the strategies of synthesizing SACs, including the spatial confinement strategy and the coordination design strategy. Finally, the challenges and prospects in this field are proposed. We believe that this review would help to design and fabricate high-performance Li-S batteries via introducing SACs and boost their practical application.

Defects on Li2S@graphene cathode improves the performance of lithium-sulfur battery, A theoretical study

Lithium-sulfur (Li−S) batteries are promising next generation large-scale electrical energy storage. One of our authors constructed a novel Li2S@graphene cathode material that exhibits outstanding electrochemical performance (Nat. Energy 2017, 2, 17090) in Li−S batteries, but the underlying mechanism remains unexplored. Herein we performed systematical theoretical study to address the mechanisms. First-principle calculation shows that the defects on graphene directly contributes to the superior electrochemical performance of the Li−S battery in three aspects. First, defects on graphene facilitate the binding of Li2S, thus lowering the decomposition barrier of Li2S during the first charge cycle, leading to the lowered activation voltage in experiment. Second, the followed Li ion diffusion is promoted by defects. Third, in the following discharge/charge cycles S-doped graphene is formed, which improves the conversion of S8 to Li2S during discharge process as well as inhibits the “shuttle effect”. Moreover, if vacancy defects remain on graphene, the above two advantages still hold, supporting the high rate performance observed in experiment. This work provides a theoretical understanding of the improved electrochemical performance of Li2S@graphene as cathode in Li−S battery from the perspective of defects on graphene, and helps the rational design of potential 2D materials as cathode for practical Li−S batteries.

Boosting electrochemical performance of Li-S batteries by cerium-based MOFs coated with polypyrrole

Lithium-sulfur (Li-S) batteries are a promising next-generation energy storage technology due to high theoretical energy density, low cost and abundant reserves. However, the poor electronic conductivity of sulfur and huge volume change hindered their commercial applications. In this paper, selected as a cathode host of Li-S batteries from two Ce-MOFs with dissimilar open metal sites for the first time, Ce-MOF-808 was synthesized and then coated with a Polypyrrole (PPy) layer (Ce-MOF-808@S/PPy). Material characterization and electrochemical performance tests were conducted. Results show that Ce-MOF-808@S/PPy has a high specific surface area of 437.491 m2 g−1, with special micro-mesoporous structures. Ce-MOF-808@S/PPy composite possesses the initial discharge specific capacity of 1612.5 mA h g−1 and discharge specific capacity of 771.9 mA h g−1 at 0.1 C after 100 cycles. Additionally, the battery still maintains a reversible specific capacity above 470 mAh g−1 with 40% capacity retention rate at a rate of 2 C after 200 cycles of charge and discharge. Improved electrochemical performances are mainly attributed to the Ce-MOFs with special micro-mesoporous structures and high specific surface area conducive to inhibiting the shuttle effect and volume expansion through physical adsorption and stable channel structures, the Ce sites with unique adsorption and catalytic effect, and the PPy coating layer adsorbing the polysulfide and acting as charge collectors to enhance conductivity.

Structural Regulation of Metal Organic Framework-derived Hollow Carbon Nanocages and Their Lithium-Sulfur Battery Performance

Structural Regulation of Metal Organic Framework-derived Hollow Carbon Nanocages and Their Lithium-Sulfur Battery Performance

Co,N-co-doped graphene sheet as a sulfur host for high-performance lithium-sulfur batteries.

To improve the performance of lithium-sulfur (Li–S) batteries, herein, based on the idea of designing a material that can adsorb polysulfides and improve the reaction kinetics, a Co,N-co-doped graphene composite (Co–N–G) was prepared. According to the characterization of Co–N–G, there was a homogeneous and dispersed distribution of N and Co active sites embedded in the Co–N–G sample. The 2D sheet-like microstructure and Co, N with a strong binding energy provided significant physical and chemical adsorption functions, which are conducive to the bonding S and suppression of LiPSs. Moreover, the dispersed Co and N as catalysts promoted the reaction kinetics in Li–S batteries via the reutilization of LiPSs and reduced the electrochemical resistance. Thus, the discharge specific capacity in the first cycle for the Co–N–G/S battery reached 1255.7 mA h g−1 at 0.2C. After 100 cycles, it could still reach 803.0 mA h g−1, with a retention rate of about 64%. This phenomenon proves that this type of Co–N–G composite with Co and N catalysts plays an effective role in improving the performance of batteries and can be further studied in Li–S batteries.

Deciphering the role of LiNO3 additives in Li-S batteries.

The ultrahigh theoretical energy density of lithium-sulfur (Li-S) batteries has attracted intensive research interest. However, most of the long-term cycling performance parameters are strongly dependent on the utilization of the electrolyte, which is considered as an indispensable component in Li-S batteries. Over the past few decades, numerous research studies around LiNO3 as an electrolyte additive have been carried out and have been confirmed to significantly upgrade the electrochemical performance of Li-S batteries, but the mechanism of performance improvement is still not well-understood. In this minireview, we revisit the controversial issues surrounding LiNO3 based on recent representative studies, provide a comprehensive understanding of the role of LiNO3 in the Li-S battery system, and specifically discuss what the panoramic view of the solid electrolyte interface film formed by LiNO3 on the surface of Li metal anodes looks like. Finally, we present general conclusions and unique insights into the future development of Li-S batteries. This minireview aims to provide a tutorial reference for researchers who are ready to enter or are active in the field of Li-S batteries.

P-block tin single atom catalyst for improved electrochemistry in a lithium–sulfur battery: a theoretical and experimental study

Main group metals are routinely considered as catalytically inactive. In this work, we for the first time prepared a p-block tin single atom catalyst (SnSA–NC) with Sn–N4 active site for effectively improving the lithium–sulfur battery performance.

Tuning the Structure Characteristic of the Flexible Covalent Organic Framework (Cof) Meets a High Performance for Lithium-Sulfur Batteries

Tuning the Structure Characteristic of the Flexible Covalent Organic Framework (Cof) Meets a High Performance for Lithium-Sulfur Batteries

Lithiated Carboxylated Nitrile Butadiene Rubber with Strong Polysulfide Immobilization Ability as a Binder for Improving Lithium-Sulfur Battery Performance

Lithiated Carboxylated Nitrile Butadiene Rubber with Strong Polysulfide Immobilization Ability as a Binder for Improving Lithium-Sulfur Battery Performance

Engineering a TiNb2O7-Based Electrocatalyst on a Flexible Self-Supporting Sulfur Cathode for Promoting Li-S Battery Performance.

Lithium-sulfur (Li-S) batteries are considered a prospective energy storage system because of their high theoretical specific capacity and high energy density, whereas Li-S batteries still face many serious challenges on the road to commercialization, including the shuttle effect of lithium polysulfides (LiPSs), their insulating nature, the volume change of the active materials during the charge-discharge process, and the tardy sulfur redox kinetics. In this work, double transition metal oxide TiNb2O7 (TNO) nanometer particles are tactfully deposited on the surface of an activated carbon cloth (ACC), activating the surface through a hydrothermal reaction and high-temperature calcination and finally forming the flexible self-supporting architecture as an effective catalyst for sulfur conversion reaction. It has been found that ACC@TNO possesses many catalytic activity sites, which can inhibit the shuttle effect of LiPSs and increase the Coulombic efficiency by boosting the redox reaction kinetics of LiPS transformation reaction. As a consequence, the ACC@TNO/S cathode exhibits an impressive electrochemical performance, including a high initial discharge capacity of 885 mAh g-1 at a high rate of 1 C, a high discharge specific capacity of 825 mAh g-1 after 200 cycles with a prominent capacity retention rate of 93%, and a small decay rate of 0.034% per cycle. Although TNO is extensively used in the fields of lithium ion batteries and other rechargeable batteries, it is first introduced as sulfur host materials to boost the redox reaction kinetics of the LiPS transformation reaction and increase the electrochemical performance of Li-S batteries. Therefore, studies of the synergistic effect on the chemical absorption and catalytic conversion effect of TNO for LiPSs of Li-S batteries provide a good strategy for boosting further the comprehensive electrochemical performances of Li-S batteries.

A Highly Efficient Ion and Electron Conductive Interlayer To Achieve Low Self-Discharge of Lithium-Sulfur Batteries.

The practical use of lithium-sulfur (Li-S) batteries is limited by serious self-discharge, fast capacity loss, and severe lithium anode erosion due to the shuttling of lithium polysulfides (LiPSs). Herein, we developed a highly efficient ion and electron conductive interlayer composed of Ti2(SO4)3/carbon composite layer-coated Li1.3Al0.3Ti1.7(PO4)3 (CLATP) and graphene to effectively block the diffusion of polysulfide anions but allow rapid Li ion transfer, therefore significantly inhibiting the self-discharge and boosting the cyclic stability of Li-S batteries. The Ti2(SO4)3/carbon thin protective layer endows an optimized adsorption ability toward LiPSs and avoids the side reactions between LATP and LiPSs. The high electronic conductivity of graphene and high ionic conductivity of CLATP ensures the hybrid interlayer rapid electron and fast Li ion transport. As a result, the Li-S battery with the hybrid interlayer shows a high discharge capacity of 671 mAh g-1 after 500 cycles with an extremely low capacity fading of 0.022% per cycle at 1 C. Moreover, the battery shows no self-discharge even after rest for 12 days. This work opens up a new way for the design of functional separators to significantly improve the electrochemical performance of Li-S batteries.

In situ TEM studies of electrochemistry of high temperature lithium-selenium all-solid-state batteries

Lithium sulfur (Li-S) battery has very high theoretical specific capacity, which is a potential "beyond lithium" energy storage technology for electrical vehicle and grid energy storage applications. However, the poor electronic conductivity of sulfur has plagued the performance of Li-S battery. This prompts the research in lithium selenium (Li-Se) battery, in which the electronic conductivity of Se is more than 25 orders of magnitude higher than that of S. Herein, we have investigated the electrochemistry of Li-Se all-solid-state batteries (ASSBs) at different temperatures using in situ transmission electron microscopy (TEM) technique equipped with a microelectromechanical systems (MEMS) heating device. We found that different from liquid electrolyte, polyselenides were absent during discharge and charge of Li-Se ASSBs. Moreover, we revealed that the discharge products of Li2Se cannot be decomposed at room temperature. However, Li2Se was decomposed easily at high temperatures because of increased Li+ ion conduction, indicating conclusively that it is the Li+ ion conductivity rather than the electronic conductivity that dictates the performance of Li-Se ASSB. Our studies provide not only new understanding to the Li2Se electrochemistry, but also an important strategy to boost the performance of Li-Se ASSBs for energy storage applications.

Li1+xMn2O4 synthesized by in-situ lithiation for improving sulfur redox kinetics of Li-S batteries

Lithium-sulfur (Li-S) battery is one of the most promising candidates for the next generation energy storage systems. However, the inherent slow redox kinetics of sulfur leads to limited rate performance, low discharge capacity and rapid capacity fading. Herein, the Li1+xMn2O4 material produced by in-situ lithium intercalation of LiMn2O4 before 2.5 V is selected to improve the performances of Li-S batteries. First-principles calculations show that Li1+xMn2O4 can improve electronic conductivity and chemical adsorption. Electrochemical characterizations further confirm that lithiated material provides a fast conversion kinetics for LiPSs and a low barrier of lithium-ion diffusion. As a result, the Li-S battery incorporating Li1+xMn2O4 presents excellent rate performance with a discharge capacity as high as 915 mAh g − 1 at 2 C rate. At the same time, the battery maintains a high reversible capacity of 531 mAh g − 1 after 1000 cycles at 1 C rate, and the average capacity loss per cycle is only 0.047%. This work can improve the redox kinetics of sulfur cathodes and provide a new path for the advancement of high-performance Li-S batteries.

Fe3C@NCNT as a promoter for the sulfur cathode toward high-performance lithium-sulfur batteries

Rechargeable Lithium-Sulfur batteries (LSBs) are widely investigated as one of the most promising electrochemical energy storage devices due to their high energy density, low cost and environmental benignancy. However, poor conductivity, insufficient adsorption strength and sluggish multi-electron redox reactions restrict LSBs performance. Thus rational design of one–dimensional materials with good conductivity for sulfur, strong adsorption and catalytic abilities to lithium polysulfides (LiPSs), is necessary for improving the electrochemical behavior of lithium-sulfur batteries. Herein, we report Fe3C nanorods encapsulated in nitrogen-doped carbon nanotube (Fe3C@NCNT) as a promoter for sulfur cathode, in which CNT acting as a conductive network promotes ionic and electronic transfer, while “lithiophilic” heteroatom N immobilizes LiPSs through strong chemical bonding (Li–N bonds), and Fe3C accelerates the adsorption and conversion of LiPSs derived from its catalytic Fe3C site. Therefore, the Fe3C@NCNT as a promoter prolong the life of LSBs with the help of the synergistic effect of polarized N heteroatoms and catalytic effect of Fe3C. As a result, the composite cathode material delivers an outstanding initial capacity of 950 mAh g−1 at 0.5 C, and a capacity of 870 mAh g−1 after 100 cycles. This work proposes a feasible strategy to immobilize LiPSs and accelerate the conversion of LiPSs in high-performance lithium-sulfur batteries.

Two Birds with One Stone: Interfacial Engineering of Multifunctional Janus Separator for Lithium-Sulfur Batteries.

Li-dendrite growth and unsatisfactory sulfur cathode performance are two core problems that restrict the practical applications of lithium-sulfur batteries (LSBs). Here, an all-in-one design concept for a Janus separator, enabled by the interfacial engineering strategy, is proposed to improve the performance of LSBs. At the interface of the anode/separator, the thin functionalized composite layer contains high-elastic-modulus and high-thermal-conductivity boron nitride nanosheets and oxygen-group-grafted cellulose nanofibers (BNNs@CNFs), by which the formation of "hot spots" can be effectively avoid, the Li-ion flux homogenized, and dendrite growth suppressed. Meanwhile, at the interface between the separator and the cathode, the homogenously exposed single-atom Ru on the surface of reduced graphene oxide (rGO@Ru SAs) can "trap" polysulfides and reduce the activation energy to boost their conversion kinetics. Consequently, the LSBs show a high capacity of 460 mAh g-1 at 5C and ultrastable cycling performance with an ultralow capacity decay rate of 0.046% per cycle over 800 cycles. To further demonstrate the practical prospect of the Janus separator, a lithium-sulfur pouch cell using the Janus separator delivers a cell-level energy density of 310.2Wh kg-1 . This study provides a promising strategy to simultaneously tackle the challenges facing the Li anode and the sulfur cathode in LSBs.