Cathode For Lithium-sulfur Batteries Research Articles

Hard Carbons for Use as Electrodes in Li-S and Li-ion Batteries.

Activated hard carbons, obtained from the pyrolysis of various waste biomasses, were prepared and characterized for use as the active material for the fabrication of battery electrodes. The preparation consisted of a pyrolysis process, followed by an activation with KOH and a further high-temperature thermal process. TG and DTA were used to discriminate the steps of the activation process, while SEM, XRD, and Raman characterization were employed to evaluate the effects of activation. The activated carbons were tested as electrodes in lithium-sulfur and lithium-ion batteries. The carbonaceous materials coming from cherry stones and walnut shells have proved to be particularly suitable as electrode components. When used as anodes in lithium-ion batteries, both carbons exhibited a high first cycle discharge capacity, which was not restored during the next charge. After the first two cycles, in which there was a marked loss of capacity, both electrodes showed good reversibility. When used as cathodes in lithium-sulfur batteries, both carbons exhibited good catalytic activity against the redox reaction involving sulfur species with good cycle stability and satisfactory Coulombic efficiency.

Electrochemical Performance of Carbon-Rich Silicon Carbonitride Ceramic as Support for Sulfur Cathode in Lithium Sulfur Battery

As a promising matrix material for anchoring sulfur in the cathode for lithium-sulfur (Li-S) batteries, porous conducting supports have gained much attention. In this work, sulfur-containing C-rich SiCN composites are processed from silicon carbonitride (SiCN) ceramics, synthesized at temperatures from 800 to 1100 °C. To embed sulfur in the porous SiCN matrix, an easy and scalable procedure, denoted as melting-diffusion method, is applied. Accordingly, sulfur is infiltrated under solvothermal conditions at 155 °C into pores of carbon-rich silicon carbonitride (C-rich SiCN). The impact of the initial porosity and microstructure of the SiCN ceramics on the electrochemical performance of the synthesized SiCN-sulfur (SiCN-S) composites is analysed and discussed. A combination of the mesoporous character of SiCN and presence of a disordered free carbon phase makes the electrochemical performance of the SiCN matrix obtained at 900 °C superior to that of SiCN synthesized at lower and higher temperatures. A capacity value of more than 195 mAh/g over 50 cycles at a high sulfur content of 66 wt.% is achieved.

Synthesis of 2-substituted-Pyrimidine-based porous aromatic frameworks via oxygen involved biginelli multicomponent polymerization: toward high performance Li–S batteries

Facile, general methods for the preparation of functionalized porous aromatic frameworks (PAFs) are necessary. Herein, we describe a new method for the one-step synthesis of functionalized pyrimidine-based PAFs via oxygen involved Biginelli multicomponent polymerization. As first application instance, we constructed a 2-amino-pyrimidine-based PAF (BPAF-1), and followed by employed it as a sulfur host material for lithium-sulfur batteries. Attributed to its 2-amino-pyrimidine structural superiorities, the BPAF-1/S composites demonstrate excellent electrochemical performance as cathode in lithium-sulfur batteries, such as good cyclability with a high capacity retention of 78.1% after 500 cycles and high rate capability up to 5C. Besides, it is convenient to bring various 2-substituted functional groups such as –OH, –SH, methyl, and phenyl functional groups to pyrimidine-based PAFs under similar conditions, which provided its wide applicability.

Tunable vacancy defect chemistry on free-standing carbon cathode for lithium-sulfur batteries

The defect chemistry is successfully modulated on free-standing and binder-free carbon cathodes for highly efficient Li–S redox reactions. Such rationally regulated defect engineering realizes the synchronization of ion/electron-conductive and defect-rich networks on the three-dimension carbon cathode, leading to its tunable activity for both relieving the shuttle phenomenon and accelerating the sulfur redox reaction kinetics. As expected, the defective carbon cathode harvests a high rate capacity of 1217.8 mAh g−1 at 0.2 C and a superior capacity retention of 61.7% at 2 C after 500 cycles. Even under the sulfur mass loading of 11.1 mg cm−2, the defective cathode still holds a remarkable areal capacity of 8.5 mAh cm−2.

A reign of bio-mass derived carbon with the synergy of energy storage and biomedical applications

The high specific surface area and suitable pore size distribution of carbon based electrodes significantly improves the energy and power density of energy storage devices. The present study details the development of eco-friendly and low-cost carbon material containing fluorine (F) atoms prepared from biomass Ipomoea carnea flower (IC). The favourably developed carbon material is used as electrode for lithium‑sulfur batteries (LSBs), supercapacitors and biomedical application of the same is explored. Owing to its high theoretical specific capacity, high energy density and low production cost, LSBs are recognised as propitious class of energy storage devices. The detriments like fast capacity fading arising due to insulating nature, shuttle effect and volume expansion of sulfur electrode is surmount by employing ternary composite of sulfur/silicon dioxide/IC (SSIC) as cathode for LSBs. The outcome of this work reveals that polysulfides are confined both physically and chemically by highly electronegative F atoms present in IC along with SiO2, thereby alleviating shuttle effect and demonstrates better electrochemical performance. SIC electrode exhibited a coulombic efficiency of 95%, whereas SSIC electrode delivered efficiency of 99.5% after entire cycling life. Here, IC carbon matrix is also employed as electrode material for supercapacitor device which delivered specific capacitance up to 382 F g−1 which is outstanding when compared to capacitances from other reported carbon supercapacitors. The cytotoxicity of IC carbon is analysed by co-culturing IC carbon with human breast cancer cells (MCF-7 cell line). The cell death is observed in the IC50 concentration of 56.23 μg/ mL.

Graphene coated and nitrogen-rich porous carbon composites with sulfur encapusulation as cathode for lithium-sulfur batteries

In this work, a three-dimensional porous composite (S/RGO@NPC) is prepared by graphene (RGO) coated nitrogen-rich porous carbon (NPC) and combined with sulfur.The doping of nitrogen and porous structure can alleviate the shuttling effect through chemical and physical double adsorption of polysulfide, respectively. RGO coating restricts the movement of polysulfide, further alleviates the shuttling effect, and also improves the electrical conductivity.Our results show when the sulfur content is 70% with a loading up to 3 mg/cm2, the Li-S battery with S/RGO@NPC as cathode still shows good capacity (880.8mAh/g at 0.5C), and superior cycle stability (capacity retention of 68.1% after 400 cycles at 0.5C).

Visualized redox reaction guides polysulfide synthesis with electrochemical approach for long-cycle lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are promising next-generation energy storage systems. However, low active material utilization and sluggish reaction kinetics restrict their practical applications. Here, the redox reaction of these batteries was visualized, and their polysulfide component was established with their ultraviolet-visible absorption spectra through in-situ discharge observations. Liquid polysulfides with controllable component and concentration can be obtained by discharging solid sulfur into a determined potential. Fast and timely electrochemical conversion kinetics will occur due to the excellent wettability between polysulfides and carbon nanotube sponges (CNSs). In addition, the robust chemical interaction between liquid polysulfides and oxygen-containing groups inhibit the shuttle effect to a certain extent. Accordingly, the polysulfides-CNSs cathode demonstrates high sulfur utilization that exceeds 60% after 200 cycles. The obtained Li-S battery exhibits remarkably long cycling stability for 1500 cycles at 1 C with nearly 100% coulombic efficiency. This work provides valuable concepts for fabricating cathodes for Li-S batteries and for achieving their high-level services.

A review on theoretical models for lithium–sulfur battery cathodes

AbstractLithium–sulfur (Li–S) batteries have been considered as promising battery systems due to their huge advantages on theoretical energy density and rich resources. However, the shuttle effect and sluggish transformation of soluble lithium polysulfides (LiPSs) hinder the practical application of Li–S batteries. Tremendous sulfur host materials with unique catalytic activity have been exploited to inhibit the shuttle effect and accelerate LiPSs redox reactions, in which theoretical simulations have been widely adopted. This review aims to summarize the fundamentals and applications of theoretical models in sulfur cathodes. Concretely, the integration of theoretical models provides insights into the adsorption and conversion mechanisms of LiPSs and is further utilized in the smart design of catalysts for the exploitation of practical Li–S batteries. Finally, a perspective on the future combination of calculation technology and theoretical models is provided.

A renaissance for lithium-sulfur batteries through low-cost, efficient, and sustainable biomass cathodes

Although lithium-ion batteries face material sustainability issues, one promising alternative—lithium-sulfur (Li-S) batteries—suffers from destructive chemical reactions. Recently in Chem, Hou et al. proposed one viable solution: an encapsulating lithium polysulfide electrolyte. We discuss this advance and the potential role of biomass as an alternative sustainable material for Li-S battery cathodes. Although lithium-ion batteries face material sustainability issues, one promising alternative—lithium-sulfur (Li-S) batteries—suffers from destructive chemical reactions. Recently in Chem, Hou et al. proposed one viable solution: an encapsulating lithium polysulfide electrolyte. We discuss this advance and the potential role of biomass as an alternative sustainable material for Li-S battery cathodes. An encapsulating lithium-polysulfide electrolyte for practical lithium–sulfur batteriesHou et al.ChemJanuary 21, 2022In BriefAn encapsulating LiPS electrolyte (EPSE) is proposed for suppression of parasitic reactions based on a nano-heterogeneous solvation structure design of LiPSs. In the EPSE with di-isopropyl sulfide (DIPS) as a co-solvent, soluble LiPSs are encapsulated into two concentric solvent shells with different solvating power and reduction stability. Reduction-stable DIPS in the outer solvent shell significantly suppresses the parasitic reactions between encapsulated LiPSs and lithium metal. This work opens up new frontiers in electrolyte engineering toward long-cycling lithium–sulfur batteries. Full-Text PDF

Trade-off effect of 3d transition metal doped boron nitride on anchoring polysulfides towards application in lithium-sulfur battery

Sulfur cathodes in lithium-sulfur batteries (LSBs) suffer from the notorious “shuttle effect”, low sulfur use ratio, and tardy transformation of lithium polysulfides (LiPSs), while using two-dimensional (2D) polar anchoring materials combined with single-atom catalysis is one of the promising methods to address these issues. Herein, the 3d transition metal (TM) doped 2D boron nitrides (BN), labeled as TM-BN, are studied for the anchoring and redox kinetics of LiPSs using first principles calculations. From the simulated results, the TM atom and adjacent N atoms are active adsorption sites for binding S atoms in LiPSs/S8 and Li atoms in LiPSs, respectively. A negative d-band center closer to the Fermi level of TM-BN is key for enhancing the binding strength of TM-S and lowering the Li2S decomposition energy barrier, while it deteriorates the activity of adjacent N atoms. Fortunately, the electrolyte environment has little effect on the superiority of the TM-BN for binding polysulfides/S8, guaranteeing the sturdy anchor of polysulfides/S8 in realistic conditions. The trade-off effect on the activities of TM and adjacent N atom sites in TM-BN for binding LiPSs highlights the excellence of Ti/V/Cr-BN as modification materials for LSB.

Controlled synthesis of cube-like ZnSnO3 decorated by nickel-based films and electrochemical applications on lithium-sulfur batteries

ABSTRACT Transition metal oxide was considered as an effective cathode additive to depress ‘shuttle effect’ in lithium-sulfur (Li-S) batteries via forming a strong polar chemical bond with polysulfides. Here, we firstly synthesized unique S@Ni/NiO/ZnSnO3 microcubes as composite cathodes for Li-S batteries, in which Ni/NiO films were deposited onto surface of as-prepared ZnSnO3 microcubes via a hydrothermal reaction and later calcinations process. The S@Ni/NiO/ZnSnO3 composite showed attractive electrochemical performances with a high initial discharge-specific capacity of 1070 mAh g−1. After cycling up to 1000 cycles at 0.5 C, the as-prepared cathode still retained a capacity output of 379 mAh g−1 with approximate 0.063% decay rate per cycle, indicating its excellent capacity retention. The excellent improved electrochemical properties of S@Ni/NiO/ZnSnO3 composite are attributed mainly to the synergistic effect between an accelerating reaction kinetic and a strong polar adsorption for polysulfides, which are derived from the addition of nickel-based materials and ZnSnO3 into cathodes.

Catalytically Active CoSe2 Supported on Nitrogen-Doped Three Dimensional Porous Carbon as a Cathode for Highly Stable Lithium-Sulfur Battery.

Lithium-sulfur batteries are promising secondary energy storage devices that are mainly limited by its unsatisfactory cyclability owing to inefficient reversible conversion of sulfur and lithium sulfide on the cathode during the discharge/charging process. In this study, nitrogen-doped three-dimensional porous carbon material loaded with CoSe2 nanoparticles (CoSe2 -PNC) is developed as a cathode for lithium-sulfur battery. A combination of CoSe2 and nitrogen-doped porous carbon can efficiently improve the cathode activity and its conductivity, resulting in enhanced redox kinetics of the charge/discharge process. The obtained electrode exhibits a high discharge specific capacity of 1139.6 mAh g-1 at a current density of 0.2 C. After 100 cycles, its capacity remained at 865.7 mAh g-1 thus corresponding to a capacity retention of 75.97 %. In a long-term cycling test, discharge specific capacity of 546.7 mAh g-1 was observed after 300 cycles performed at a current density of 1 C.

Boric acid functionalized triazine-based covalent organic frameworks with dual-function for selective adsorption and lithium-sulfur battery cathode

Functional triazine-based covalent organic frameworks (COFs) with boric acid units, COF-Tr-BA, are designed and synthesized via cycloaddition of imine-linked COFs, COF-Tr, with (4-ethynylphenyl) boronic acid. Owing to the chemical interaction between boric acid units and adjacent dihydroxyl groups, COF-Tr-BA is used as the adsorbent for the selective adsorption of genistein isomer 4′6,7-trihydroxyisoflavone, showing an excellent selectivity and great adsorption performance with 5.4 times adsorption capacity (67.5 mg g−1) as high as 4′5,7-trihydroxyisoflavone (12.5 mg g−1). Meanwhile, COF-Tr-BA as the sulfur host for lithium-sulfur (Li-S) battery also exhibits a better electrochemical property, giving an initial discharge capacity up to 1349 mA h g−1 and a substantial capacity of 627 mA h g−1 after 200 cycles at 0.5C. It is attributed to the sulfiphilic interaction between the introduced boric acid groups and polysulfides (PSs), as well as the lithiophilic interaction between N atoms from quinoline and triazine moieties on the backbone of COF-Tr-BA and lithium ions (Li+), thus alleviating the dissolution and reducing the shuttle effect of LiPSs. The boric acid functionalized material COF-Tr-BA with the dual-function for selective adsorption and Li-S battery proposed here lays a significant foundation for multifunctional COFs as a versatile platform in practical application.

Effect of zinc-based active sites on porous carbon and electrochemical properties in lithium-sulfur batteries

Hierarchically porous carbon (HPC) is considered as one of the promising cathodes of lithium-sulfur batteries (LSBs) owing to its appealing merits. However, it is still preventing the shuttle effect poorly due to the weak interaction between nonpolar carbon and polar polysulfide (LiPS). Herein, we report a facile method to prepare polar hierarchically porous carbon by in-situ loading the different amounts of zinc-based active sites (p-HPC-X) onto the HPC materials. The close combination of a carbon interconnected skeleton and ZnS nanoparticles derived zinc-based active sites forms the strong interaction that suppresses the soluble polysulfide shuttle effect and catalyzes the kinetics redox reactions of lithium polysulfide/sulfide. Moreover, the effect of polar sites introduced in situ on the morphology/porosity of carbon materials is also focused on. Crystallization of zinc-based active sites during the freeze-drying process and self-assembly during carbonization allow the pore size distribution of porous carbon to be customized, which offers fast lithium-ion and electron transport channels. Due to the synergistic effect of the hierarchical pore structure and suitable polarity sites, the p-HPC-X exhibits high capacity and good cycling performance. Especially p-HPC-1, it yields a high reversible capacity of 683.7 mAh g−1 and a low fading rate of 0.041% per cycle over 900 cycles at a current density of 1 C. This work offers novel insights into realizing the effect of in-situ loaded active sites on pore structure and electrochemical performance in LSBs.

Molten salt assisted fabrication of ferroelectric BaTiO3 based cathode for high-performance lithium sulfur batteries

As a promising candidate for the next-generation power source with high energy density and low cost, the lithium-sulfur battery is attracting considerable research interests while the development of efficient cathode materials with low shuttle effects of polysulfides still remains a grand challenge. Herein, different from the conventional mechanical mixing methods, we present an effective molten-salt protocol for loading ferroelectrics into the hierarchical porous carbon matrix as the host for the sulfur cathode. As the proof of concept, prototype BaTiO3 is used as the ferroelectric additive. Interestingly, the rationally-fabricated composite structure ensures homogeneous distribution of ferroelectric particles within the carbon framework through the liquid medium and effectively avoids aggregation of ferroelectrics that was always seen in traditional compositing methods. Profiting from the electrochemically active merits including uniform dispersion of ferroelectrics, activated carbonaceous porous structure, enhanced crystallinity of BaTiO3, and high-strength component interactions that were introduced by the molten-salt strategy, the as-prepared cathode presented excellent rate capabilities and outstanding cycling stability. This work marks a step ahead towards the fabrication of high-performance ferroelectric based composites for advanced energy conversion and storage use.

Optimized Preparation of Polyacrylonitrile/Sulfur Composite as Cathode for Lithium Sulfur Batteries

Optimized Preparation of Polyacrylonitrile/Sulfur Composite as Cathode for Lithium Sulfur Batteries

A flexible self-supporting ultralong MnO2 nanowires-expanded graphite nanosheets current collector with enhanced catalytic reaction kinetics for high-loading lithium-sulfur batteries

Owing to the shuttle effect of lithium polysulfides (LiPSs), poor conductivity and low loading mass of active sulfur, and its large volume expansion during cycling, these shortcomings still restrict practical application of high performance lithium-sulfur (Li-S) batteries. Herein, a stable flexible current collector, composed of ultralong MnO 2 nanowires and expanded graphite nanosheets (MnO 2 NW/EG) with high electronic conductivity, is combined with Li 2 S 6 to serve as a self-supporting cathode in Li-S batteries, in which the maximum loading mass of sulfur can be regulated to 7 mg cm −2 , the ultralong MnO 2 nanowires has the ability to accelerate the adsorption and catalytic conversion of LiPSs through the chemical action of the polar active surface and the good mechanical flexibility caused by the introduction of ultralong nanowires and nanosheets can buffer the large volume expansion of sulfur during charging/discharging. Moreover, Li-S batteries with MnO 2 NW/EG current collector still maintain a high capacity of 538 mAh g −1 after 500 cycles at 1 C and the capacity decay is only 1.2 mAh g −1 per cycle, even when the sulfur loading is 7 mg cm −2 , the capacity can be as high as 2.5 mAh cm −2 , indicating a practical application ability. • A stable flexible current collector is applied in Li-S batteries. • The loading mass of sulfur can be regulated to 7 mg cm −2 • The MnO 2 nanowires can accelerate the adsorption and catalytic conversion of LiPSs. • The cathode with high sulfur loading mass exhibits excellent cyclic stability.

Enhanced multiple anchoring and catalytic conversion of polysulfides by SnO2-decorated MoS2 hollow microspheres for high-performance lithium-sulfur batteries

Lithium-Sulfur (Li-S) batteries are very competitive in energy storage equipment due to their high theoretical capacity and low cost of raw materials. However, the serious polysulfide "shuttle effect", volume expansion effect and slow conversion reaction kinetics of Li−S batteries during the charge/discharge cycle process still need to be resolved urgently. Herein, we prepared a novel sulfur host of SnO2-decorated MoS2 hollow microspheres (SnO2-MoS2 HMSs). The unique hollow structure provides enough space to accommodate a large amount of sulfur and effectively adapts to its large volume expansion during charge and discharge process. On the other hand, the SnO2 nanoparticles that attached to the surface of the MoS2 nanosheets will accelerate the catalysis of MoS2 and enhance the bonding strength with the polysulfide intermediates through the S−Sn−O chemical bond, which further inhibits the shuttle effect. The newly synthesized SnO2-MoS2 HMSs cathode has achieved excellent electrochemical performance. The initial discharge specific capacity of 1326.4 mAh g−1 was obtained at 0.2 C, and after 100 cycles, the specific capacity of the SnO2-MoS2 HMSs/S cathode only decreased slightly to 1183.8 mAh g−1, its capacity retention rate reaching as high as 89.2%. We expect the newly synthesized hollow structured MoS2 with SnO2 decoration provides a new strategy for the construction of Li-S battery cathode materials.

Enhancement of the cycling stability of lithium-sulfur batteries by using a reactive additive for blocking dissolution of lithium polysulfides

Hexamethylene diisocyanate was employed as a reactive additive to capture lithium polysulfides formed at the cathode of lithium-sulfur batteries. Unlike other solid additives used to trap polysulfides through physical and chemical interactions, it could effectively capture lithium polysulfides through chemical reaction between hexamethylene diisocyanate and lithium polysulfides at the electrode–electrolyte interface. A small amount of hexamethylene diisocyanate was enough to completely block the dissolution of lithium polysulfides into liquid electrolyte due to its high chemical reactivity, which enhanced the cycling stability of the lithium-sulfur battery while maintaining its high energy density. Our results demonstrate that the addition of hexamethylene diisocyanate to liquid electrolyte can provide an efficient strategy to address dissolution of lithium polysulfides and achieve good cycling stability in the high energy–density lithium-sulfur batteries.

Highly branched amylopectin binder for sulfur cathodes with enhanced performance and longevity.

The sulfur cathode of lithium-sulfur (Li-S) batteries suffers from inherent problems of insufficient mechanical strength and the dissolution of sulfur and polysulfides. Inspired by the extraordinarily resilient and strong binding force of the Great Wall binder, that is, the sticky rice mortar, we extracted highly branched amylopectin (HBA), the effective ingredient, as a low-cost, nontoxic and environmentally benign aqueous binder for the sulfur cathode. The HBA-based cells outperform the Li-S batteries based on the traditional polyvinyldene diflouride (PVDF) binder and a lowly branched polysaccharide binder. The improved electrochemical performance in the HBA-based cell could be attributed to two mechanisms. First, the branched structure of the HBA provides enhanced mechanical and adhesive properties, which allow for a robust electronic and ionic conductive framework to be maintained throughout the cathode after extended cycling. Second, the HBA shows enhanced polysulfide retention due to the polymer's abundant lone-pair rich hydroxyl groups and the formation of C─S bonds between the HBA and polysulfides prohibits the shuttle effect of polysulfides. The improved mechanical properties and polysulfide retention function of the HBA binder facilitate the HBA-based Li-S battery to deliver a long cycle life of 500cycles at 2 C while only displaying a capacity fading of 0.104% per cycle.