TiO2-decorated porous carbon nanofiber interlayer for Li–S batteries

Lithium–sulfur (Li–S) batteries are the most promising energy storage systems owing to their high energy density. However, shuttling of polysulfides detracts the electrochemical performance of Li–S batteries and thus prevents the commercialization of Li–S batteries. Here, TiO₂@porous carbon nanofibers (TiO₂@PCNFs) are fabricated via combining electrospinning and electrospraying techniques and the resultant TiO₂@PCNFs are evaluated for use as an interlayer in Li–S batteries. TiO₂ nanoparticles on PCNFs are observed from SEM and TEM images. A high initial discharge capacity of 1510 mA h g⁻¹ is achieved owing to the novel approach of electrospinning the carbon precursor and electrospraying TiO₂ nanoparticles simultaneously. In this approach TiO₂ nanoparticles capture polysulfides with strong interaction and the PCNFs with high conductivity recycle and re-use the adsorbed polysulfides, thus leading to high reversible capacity and stable cycling performance. A high reversible capacity of 967 mA h g⁻¹ is reached after 200 cycles at 0.2C. The cell with the TiO₂@PCNF interlayer also delivers a reversible capacity of around 1100 mA h g⁻¹ at 1C, while the cell without the interlayer exhibits a lower capacity of 400 mA h g⁻¹. Therefore, this work presents a novel approach for designing interlayer materials with exceptional electrochemical performance for high performance Li–S batteries.

Lithium–sulfur (Li–S) batteries are the most promising energy storage systems owing to their high energy density.     

Ultradispersed titanium dioxide nanoparticles embedded in a three-dimensional graphene aerogel for high performance sulfur cathodes

Lithium–sulfur (Li–S) batteries are regarded as one of the most promising energy storage technologies, however, their practical application is greatly limited by a series of sulfur cathode challenges such as the notorious “shuttle effect”, low conductivity and large volume change. Here, we develop a facile hydrothermal method for the large scale synthesis of sulfur hosts consisting of three-dimensional graphene aerogel with tiny TiO₂ nanoparticles (5–10 nm) uniformly dispersed on the graphene sheet (GA–TiO₂). The obtained GA–TiO₂ composites have a high surface area of ∼360 m² g⁻¹ and a hierarchical porous structure, which facilitates the encapsulation of sulfur in the carbon matrix. The resultant GA–TiO₂/S composites exhibit a high initial discharge capacity of 810 mA h g⁻¹ with an ultralow capacity fading of 0.054% per cycle over 700 cycles at 2C, and a high rate (5C) performance (396 mA h g⁻¹). Such architecture design paves a new way to synthesize well-defined sulfur hosts to tackle the challenges for high performance Li–S batteries.

GA–TiO₂ composites as a cathode material realize an excellent electrochemical performance in Li–S batteries.     

Sb nanosheet modified separator for Li–S batteries with excellent electrochemical performance

An air-stable antimony (Sb) nanosheet modified separator (SbNs/separator) has been prepared by coating exfoliated Sb nanosheets (SbNs) successfully onto a pristine separator through a vacuum infiltration method. The as-prepared Li–S batteries using SbNs/separators exhibit much improved electrochemical performance compared to the ones using commercial separators. The coulombic efficiency (CE) of the Li–S battery using the SbNs/separator after the initial cycle is close to 100% at a current density of 0.1 A g⁻¹, and 660 mA h g⁻¹ capacity retained after 100 cycles. The rate capability of Li–S battery using SbNs/separator delivers a reversible capacity of 425 mA h g⁻¹ when the current density increases to 1 A g⁻¹. The improved electrochemical performance is mainly attributed to the following reasons. Firstly, the combination of physical adsorption and chemical bonding between SbNs and lithium polysulfides (LiPSs), which efficiently inhibits the shuttle phenomena of LiPSs. Secondly, the good electronic conductivity of SbNs improves the utilization of the adsorbed LiPSs, which benefits the capacity release of active materials. Lastly, the fast conversion kinetics of intermediate LiPSs caused by the catalytic effect from SbNs further suppresses the shuttle effect of LiPSs. The SbNs/separators exhibit a great potential for the future high-performance Li–S batteries.

Antimony nanosheet modified separator is prepared for high performance Li–S batteries for the first time.     

Interaction between functionalized graphene and sulfur compounds in a lithium–sulfur battery – a density functional theory investigation

Lithium–sulfur (Li–S) batteries are emerging as one of the promising candidates for next generation rechargeable batteries. However, dissolution of lithium polysulfides in the liquid electrolyte, low electrical conductivity of sulfur and large volume change during electrochemical cycling are the main technical challenges for practical applications. In this study, a systematic first-principles density functional theory calculation is adopted to understand the interactions between graphene and graphene with oxygen containing functional groups (hydroxyl, epoxy and carboxyl groups) and sulphur (S₈) and long chain lithium polysulfides (Li₂S₈ and Li₂S₄). We find the adsorption is dominated by different mechanisms in sulphur and lithium polysulfides, i.e. van der Waals attraction and formation of coordinate covalent Li–O bonds. The adsorption strength is dependent on the inter-layer distance and electron rich functional groups. Through these mechanisms, sulphur and lithium polysulfides can be successfully retained in porous graphene, leading to improved conductivity and charge transfer in the cathode of Li–S batteries.

Functionalized graphene can successfully anchor sulfur compounds via moderate interactions, leading to improved conductivity and charge transfer in the cathode of Li–S batteries.     

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.

Design of two-dimensional graphene with dispersed Co–N catalysts as a multifunctional S holding material in Li–S batteries to improve the retention of LiPSs and accelerate the reaction kinetics.     

ZnO quantum dot-modified rGO with enhanced electrochemical performance for lithium–sulfur batteries

Lithium–sulfur batteries are considered the most promising next-generation energy storage devices. However, problems like sluggish reaction kinetics and severe shuttle effect need to be solved before the commercialization of Li–S batteries. Here, we successfully prepared ZnO quantum dot-modified reduced graphene oxide (rGO@ZnO QDs), and first introduced it into Li–S cathodes (rGO@ZnO QDs/S). Due to its merits of a catalysis effect and enhancing the reaction kinetics, low surface impedance, and efficient adsorption of polysulfide, rGO@ZnO QDs/S presented excellent rate capacity with clear discharge plateaus even at a high rate of 4C, and superb cycle performance. An initial discharge capacity of 998.8 mA h g⁻¹ was delivered, of which 73.3% was retained after 400 cycles at a high rate of 1C. This work provides a new concept to introduce quantum dots into lithium–sulfur cathodes to realize better electrochemical performance.

ZnO quantum dot-modified rGO was first introduced into lithium–sulfur cathodes, realizing better reaction kinetics and enhanced electrochemical performance.     

A defective MOF architecture threaded by interlaced carbon nanotubes for high-cycling lithium–sulfur batteries

Metal organic frameworks (MOFs) have been deemed among the most promising sulfur hosts for lithium–sulfur (Li–S) batteries owing to their high specific surface areas, novel pore structures and open metal sites. However, their highly coordinated, electronically insulating and structurally unstable nature overshadows the merits of MOFs to a great extent. In this work, a novel UiO-66/carbon nanotube (UC) composite was initially synthesized via a facile one-pot synthesis strategy, in which abundant linker-missing defects were caused by introduced competitive coordination. Meanwhile, flexible and interlaced carbon nanotubes (CNTs) throughout mechanically stable UiO-66 nanoparticles constructed a reliable conductive network. Because of its superior structural stability, high electronic conductivity and strong polysulfide chemisorption, the UC architecture as the sulfur cathode in Li–S batteries shows stable cycling, delivering an initial capacity of 925 mA h g⁻¹ at 0.5 A g⁻¹ and a very low fading rate over 800 cycles of 0.071% per cycle at 1 A g⁻¹. A strong chemical affinity between coordination defects and LiPSs was revealed by first principles calculations and apparent absorption, which indicates significant entrapment of soluble polysulfides by the UC composite, thus leading to the outstanding cycling performance of S@UC electrodes.

Abundant artificial linker-missing defects as active sites display superior chemisorption of LiPSs, which contribute to outstanding cycling performance in Li–S cells.     

Effect of Ti3C2Tx–PEDOT:PSS modified-separators on the electrochemical performance of Li–S batteries

Lithium–sulfur (Li–S) batteries have attracted much attention due to their high theoretical energy density, environmental friendliness, and low cost. However, the practical application of Li–S batteries is impeded by a severe shuttle effect. Using polar and conductive materials to prepare a modified separator as the second collector is an effective strategy to solve the shuttle effect. Herein, a Ti₃C₂T_x–PEDOT:PSS hybrid for modifying PP separators is successfully fabricated. In this hybrid, PEDOT:PSS can effectively prevent Ti₃C₂T_x nanosheets from restacking and enhance the electrical conductivity of Li–S batteries, thereby promoting fast Li⁺/electron transport and improving the sulfur utilization. Meanwhile, the introduction of Ti₃C₂T_x–PEDOT:PSS makes Ti₃C₂T_x nanosheets effectively anchor polysulfide, thus inhibiting the shuttle effect. As a result, Li–S cells with Ti₃C₂T_x–PEDOT:PSS modified-separators exhibit superior performances, including a high discharge capacity of 1241.4 mA h g⁻¹ at 0.2C, a long cycling stability, and a low decay rate of 0.030% per cycle at 0.5C for 1000 cycles.

Lithium–sulfur (Li–S) batteries have attracted much attention due to their high theoretical energy density, environmental friendliness, and low cost.     

Prussian blue coated with reduced graphene oxide as high-performance cathode for lithium–Sulfur batteries

Lithium–sulfur (Li–S) batteries with their outstanding theoretical energy density are strongly considered to take over the post-lithium ion battery era; however, they are limited by sluggish reaction kinetics and the severe shuttling of soluble lithium polysulfides. Prussian blue analogues (PBs) have demonstrated their efficiency in hindering the shuttle effects as host materials of sulfur; unfortunately, they show an inferior electronic conductivity, exhibiting considerable lifespan but poor rate performance. Herein, we rationally designed a PB@reduced graphene oxide as the host material for sulfur (S@PB@rGO) hybrids via a facile liquid diffusion and physical absorption method, in which the sulfur was integrated into Na₂Co[Fe(CN)₆] and rGO framework. When employed as a cathode, the as-prepared hybrid exhibited excellent rate ability (719 mA h g⁻¹ at 1C) and cycle stability (918 mA h g⁻¹ at 0.5C after 100 cycles). The improved electrochemical performance was attributed to the synergetic effect of PB and conductive rGO, which not only enhanced the physisorption of polysulfides but also provided a conductive skeleton to ensure rapid charge transfer kinetics, achieving high energy/power outputs and considerable lifespan simultaneously. This study may offer a new method manufacturing high performance Li–S batteries.

Lithium–sulfur batteries with high theoretical energy density are strongly considered to take over the post-lithium ion battery era; however, they are limited by sluggish reaction kinetics and the severe shuttling of soluble lithium polysulfides.     

The phase transfer effect of sulfur in lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries are considered to be among the most promising energy storage technologies owing to their high theoretical capacity (1675 mA h g⁻¹). At present, however, discharge mechanisms are complicated and remain a controversial issue. In this work, elemental sulfur, used as an electrical insulator for the cathode, was introduced into batteries for its potential chemical reactions in the electrolyte. A film, prepared by loading elemental sulfur onto glass fiber, was introduced as an interlayer in a Li–S battery. The results demonstrate that elemental sulfur may be reduced to polysulfides even when it functions as an electrical insulator for the cathode. Furthermore, it can improve the overall capacity of the Li–S battery and cycle life. This was verified by simulating the phase equilibrium of the chemical system in Li–S batteries using HSC Chemistry software. We hypothesize that the insulating elemental sulfur could be reduced by polysulfides generated on the cathode, after which they are dissolved in the electrolyte and participate in cathode reactions. This phase transfer effect of sulfur in Li–S batteries revealed a chemical equilibrium in the electrolyte of the Li–S battery, which may form a chemical path embedded into the discharge process of Li–S batteries.

The insulating elemental sulfur in a Li–S battery could be reduced to high-grade polysulfides by low-grade polysulfides from the cathode, after which they could participate in the discharging process of the Li–S battery.     

Three-dimensional ordered macroporous ZIF-8 nanoparticle-derived nitrogen-doped hierarchical porous carbons for high-performance lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have attracted considerable attention due to their ultra-high specific capacity and energy density. However, there are still problems to be resolved such as poor conductivity of sulfur cathodes and dissolution of polysulfides in organic electrolytes. Herein, a novel ZIF-8-derived nitrogen-doped connected ordered macro–microporous carbon (COM-MPC) was developed by a dual solvent-assisted in situ crystallization method within a face-centered cubic stacking sphere template, which acts as an advanced sulfur host for enhanced Li–S battery performance. Compared with the conventional predominant microporous C-ZIF-8, the unique hierarchical macro–microporous structure with nitrogen doping not only renders polysulfide intermediates enhanced entrapment by confining the effect of micropores and chemisorption of doping N atoms, but also facilitates electrolyte accessibility and efficient ion transport owing to the ordered macroporous structure. Benefitting from this, the COM-MPC@S cathode delivers a high initial specific capacity of 1498.5 mA h g⁻¹ and a reversible specific capacity of 1118.9 mA h g⁻¹. Moreover, the COM-MPC@S cathode exhibits 82.3% of capacity retention within 10th to 50th cycle at 0.5C and a large capacity of 608.5 mA h g⁻¹ after 50 cycles at a higher rate of 1C, and this enhanced cycling stability and rate capability demonstrate great practical application potential in Li–S battery systems.

Lithium–sulfur (Li–S) batteries have attracted considerable attention due to their ultra-high specific capacity and energy density.     

Conducting polymer-coated MIL-101/S composite with scale-like shell structure for improving Li–S batteries

Lithium–sulfur batteries are regarded as a promising energy storage system. However, they are plagued by rapid capacity decay, low coulombic efficiency, a severe shuttle effect and low sulfur loading in cathodes. To address these problems, effective carriers are highly demanded to encapsulate sulfur in order to extend the cycle life. Herein, we introduced a doped-PEDOT:PSS-coated MIL-101/S multi-core–shell structured composite. The unique structure of MIL-101, large specific area and conductive shell ensure high dispersion of sulfur in the composite and minimize the loss of polysulfides to the electrolyte. The doped-PEDOT:PSS-coated sulfur electrodes exhibited an increase in initial capacity and an improvement in rate characteristics. After 192 cycles at the current density of 0.1C, a doped-PEDOT:PSS-coated MIL-101/S electrode maintained a capacity of 606.62 mA h g⁻¹, while the MIL-101/S@PEDOT:PSS electrode delivered a capacity of 456.69 mA h g⁻¹. The EIS measurement revealed that the surface modification with the conducting polymer provided a lower resistance to the sulfur electrode, which resulted in better electrochemical behaviors in Li–S battery applications. Test results indicate that the MIL-101/S@doped-PEDOT:PSS is a promising host material for the sulfur cathode in the lithium–sulfur battery applications.

Lithium–sulfur batteries are regarded as a promising energy storage system.     

Self-supporting S@GO–FWCNTs composite films as positive electrodes for high-performance lithium–sulfur batteries

Although lithium–sulfur (Li–S) batteries are a promising secondary power source, it still faces many technical challenges, such as rapid capacity decay and low sulfur utilization. The loading of sulfur and the weight percentage of sulfur in the cathode usually have a significant influence on the energy density. Herein, we report an easy synthesis of a self-supporting sulfur@graphene oxide-few-wall carbon nanotube (S@GO–FWCNT) composite cathode film, wherein an aluminum foil current collector is replaced by FWCNTs and sulfur particles are uniformly wrapped by graphene oxide along with FWCNTs. The 10 wt% FWCNT matrix through ultrasonication not only provided self-supporting properties without the aid of metallic foil, but also increased the electrical conductivity. The resulting S@GO–FWCNT composite electrode showed high rate performance and cycle stability up to ∼385.7 mA h g_electrode⁻¹ after 500 cycles and close to ∼0.04% specific capacity degradation per cycle, which was better than a S@GO composite electrode (353.1 mA h g_electrode⁻¹). This S@GO–FWCNT composite self-supporting film is a promising cathode material for high energy density rechargeable Li–S batteries.

We report a synthesis of a self-supporting composite cathode film, wherein aluminum foil current collector is replaced by FWCNTs and sulfur particles are uniformly wrapped by graphene oxide along with FWCNTs.     

Reduced graphene oxide/TiO2(B) nanocomposite-modified separator as an efficient inhibitor of polysulfide shuttling in Li–S batteries

The shutting effect in lithium–sulfur (Li–S) batteries hinders their widespread application, which can be restrained effectively by a modified separator. In this work, a composite of reduced graphene oxide and beta-phase TiO₂ nanoparticles (RGO/TiO₂(B)) is designed as a separator modification material for improving the electrochemical behavior of Li–S batteries. The TiO₂(B) nanoparticles are in situ prepared and tightly adhere to the RGO layer. A series of examinations demonstrated that the RGO/TiO₂(B)-coated separator efficiently inhibits the polysulfide shuttling phenomenon by the cooperative effect of physical adsorption and chemical binding. Specifically, as modified separators, a comparison between TiO₂(B) and anatase TiO₂(A) each composited with RGO has been conducted. The TiO₂(B) sample not only exhibits a superior blocking character of migrating polysulfides, but also enhances battery electrochemical kinetics by fast Li ion diffusion.

Beta-phase TiO₂ nanoparticles were adhered onto RGO in situ to fabricate a multi-functional separator for high-performance lithium–sulfur (Li–S) batteries.     

A new metallic π-conjugated carbon sheet used for the cathode of Li–S batteries

Lithium–sulfur (Li–S) batteries are considered as the most promising next generation high density energy storage devices. However, the commercialization of Li–S batteries is hindered by the shuttle effect of polysulfides, the low electronic conductivity of the sulfur cathode and a large volume expansion during lithiation. Herein, we predict a new two dimensional sp² hybridized carbon allotrope (PHE-graphene) and prove its thermodynamic and kinetic stability. If it is utilized to encapsulate the cathode of Li–S batteries, not only will the shuttle effect be avoided but also the electronic conductivity of the sulfur cathode will be improved significantly owing to its metallic electronic band structure. The thermal conductivity of PHE-graphene was found to be very high and even comparable with graphene, which is helpful for the heat dissipation of cathodes. In addition, PHE-graphene also exhibited superior mechanical properties including ideal tensile strength and in-plane stiffness.

A metallic carbon sheet was used for the cathode of Li–S batteries to eliminate the shuttle effect and improve cathode electric conductivity.     

Transition metal decorated phthalocyanine as a potential host material for lithium polysulfides: a first-principles study

The shuttle effect caused by the soluble long-chain lithium polysulfides greatly hinders the practical application of lithium–sulfur (Li–S) batteries. Therefore, the introduction of suitable anchoring materials is more effective to mitigate this problem. Transition metal phthalocyanines (TMPc) are regarded as a new class of sulfur host materials. Here, 4d transition metal (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd) decorated phthalocyanines are designed and systematically researched for the performance analysis of anchoring S₈/LiPSs by first-principles calculations. The results reveal that the bonding strength of LiPSs can be well adjusted by introducing suitable 4d transition metals into the phthalocyanine structure. The electronic structure analysis indicates the formation of TM–S bonds between the TMPc substrate materials and the LiPSs, which is essential to weaken the Li–S bonds and hence slow down the shuttle effect of LiPSs. ZrPc and NbPc both exhibit excellent potential and thermal stability for facilitating the conversion of LiPSs, as well as a better promoting effect for the sulfur reduction reactions (SRR) with a reduced Gibbs free energy in the rate-determining step (*Li₂S₂ → *Li₂S) during the discharge reaction process. These findings in our work may encourage further experimental and theoretical research for anchoring LiPSs with TMPc as a host material.

DFT calculations reveal that TMPc, especially ZrPc and NbPc exhibit the best anchoring and catalytic effects for lithium polysulfides.     

Bagasse as a carbon structure with high sulfur content for lithium–sulfur batteries

A bagasse-based 3D carbon matrix (BC) with high specific surface area and high conductivity was obtained by carbonization and pore-forming processes with bagasse as the carbon precursor and K₂FeO₄ as the pore-former. The microporous structure and nitrogenous functional groups were determined in the prepared carbon matrix, which could allow high sulfur loading and improve the polysulfide absorption capacity during cycling. After sulfur infusion, the S/BC composite with 68.8% sulfur content was obtained. The lithium–sulfur (Li–S) battery with the S/BC cathode shows high specific capacity and good cycling performance. It delivers a specific capacity of 1360 mA h g⁻¹ at 0.2C and remains at 790 mA h g⁻¹ after 200 cycles. At 1C, the Li–S with this composite cathode exhibits 601 mA h g⁻¹ after 150 cycles. This work offers a new kind of green material and a new method for Li–S batteries.

Bagasse-based carbon matrix with microporous structure and nitrogenous functional groups could have high sulfur loading and excellent polysulfide absorption capacity.     

Enhanced performance of lithium–sulfur batteries based on single-sided chemical tailoring,and organosiloxane grafted PP separator

Even after a decade of research and rapid development of lithium–sulfur (Li–S) batteries, the infamous shuttle effect of lithium polysulfide is still the major challenge hindering the commercialization of Li–S batteries. In order to further address this issue, a functionalized PP separator is obtained through selective single-sided chemical tailoring, and then organosiloxane fumigation grafting. During the charge–discharge process, the grafted functional groups can effectively block the transportation of the dissolved polysulfides through strong chemical anchoring, inhibit the shuttle effect and greatly enhance the cycle stability of the Li–S battery. Interestingly, the specially designed single-sided enlarged channel structure formed by chemical tailoring can well accommodate the deposition with intermediate polysulfides on the separator surface toward the cathode chamber, resulting in enhanced initial discharge capacity and rate performance. Compared to the battery assembled with PP, the Li–S battery employing the separator grafted with a 3-ureidopropyltrimethoxysilane (PP–O^x−–U) displays better electrochemical performance. Even at 2C, it can still deliver a high capacity of 786 mA h g⁻¹, and retain a capacity of 410 mA h g⁻¹ with a low capacity fading of 0.095% per cycle over 500 cycles. This work provides a very promising and feasible strategy for the development of a special functionalization PP separator for Li–S batteries with high electrochemical performance.

Even after a decade of research and rapid development of lithium–sulfur (Li–S) batteries, the infamous shuttle effect of lithium polysulfide is still the major challenge hindering the commercialization of Li–S batteries.     

A LiAlO2/nitrogen-doped hollow carbon spheres (NdHCSs) modified separator for advanced lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have gained significant attention due to their ultrahigh theoretical specific capacity and energy density. However, their practical commercialization is still facing many intractable problems, of which the most difficult is the shuttle effect of dissolved polysulfides. To restrict the shuttle of polysulfides, herein, a novel double-layer lithium aluminate/nitrogen-doped hollow carbon sphere (LiAlO₂/NdHCSs)-modified separator was designed. The upper NdHCSs layer on the separator works as the first barrier to physically and chemically adsorb polysulfides, whereas the bottom LiAlO₂ layer acts as the second barrier to physically block the polysulfides without restricting the Li⁺ transport due to the high ionic conductivity of LiAlO₂. Cells with the LiAlO₂/NdHCSs-modified separator showed an initial discharge capacity of 1500 mA h g⁻¹ at 0.2C, and a discharge capacity of 543.3 mA h g⁻¹ was obtained after 500 cycles at 2C. Especially, when the areal density of the active material was increased to 4.5 mg cm⁻², the cells retained a discharge capacity of 538.6 mA h g⁻¹ after 100 cycles at 0.5C. The outstanding electrochemical performance of Li–S cells with the LiAlO₂/NdHCSs-modified separators show a new approach for the applications of Li–S batteries.

LiAlO₂/nitrogen-doped hollow carbon spheres (NdHCSs)-modified separators restrict the shuttle of the polysulfides.     

Stabilizing cathode structure via the binder material with high resilience for lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have been considered as one of the most promising next-generation energy storage systems with high-energy density. The huge volumetric change of sulfur (ca. 80% increase in volume) in the cathode during discharge is one of the factors affecting the battery performance, which can be remedied with a binder. Herein, a self-crosslinking polyacrylate latex (PAL) is synthesized and used as a binder for the sulfur cathode of a Li–S battery to keep the cathode structure stable. The synthesized PAL has nano-sized latex particles and a low glass transition temperature (T_g), which will ensure a uniform dispersion and good adhesion in the cathode. This crosslinking structure can provide fine elasticity to recover from the deformation due to volumetric change. The stable cathode structure, stemming from the fine elasticity of the PAL binder, can facilitate ion migration and diffusion to decrease the polarization. Therefore, the Li–S batteries with the PAL binder can function well with excellent cycling stability and superior C-rate performance.

A self-crosslinking polyacrylate binder with fine elasticity stabilizing the sulfur cathode and endowing Li–S batteries with excellent performance.