Regulating adsorption ability toward polysulfides in a porous carbon/Cu_(3)P hybrid for an ultrastable high-temperature lithium-sulfur battery

Lithium-sulfur batteries(LSBs)can work at high temperatures,but they suffer from poor cycle life stability due to the“shuttle effect”of polysulfides.In this study,pollen-derived porous carbon/cuprous phosphide(PC/Cu_(3)P)hybrids were rationally synthesized using a one-step carbonization method using pollen as the source material,acting as the sulfur host for LSBs.In the hybrid,polar Cu_(3)P can markedly inhibit the“shuttle effect”by regulating the adsorption ability toward polysulfides,as confirmed by theoretical calculations and experimental tests.As an example,the camellia pollen porous carbon(CPC)/Cu_(3)P/S electrode shows a high capacity of 1205.6 mAh g^(−1) at 0.1 C,an ultralow capacity decay rate of 0.038%per cycle after 1000 cycles at 1 C,and a rather high initial Coulombic efficiency of 98.5%.The CPC/Cu_(3)P LSBs can work well at high temperatures,having a high capacity of 545.9 mAh g^(−1) at 1 C even at 150℃.The strategy of the PC/Cu_(3)P hybrid proposed in this study is expected to be an ideal cathode for ultrastable high-temperature LSBs.We believe that this strategy is universal and worthy of in-depth development for the next generation energy storage devices.

A functional hyperbranched binder enabling ultra-stable sulfur cathode for high-performance lithium-sulfur battery

Binders are of vital importance in stabilizing the cathodes to enhance the cycling stability of lithiumsulfur(Li-S) batteries. However, conventional binders are typically confronted with the drawback of inability for adsorbing lithium polysulfide(Li PS), thus resulting in severe active material losing and rapid capacity fading. Herein, a novel water-soluble hyperbranched poly(amidoamine)(HPAA) binder with controllable hyperbranched molecular structure and abundant amino end groups for Li-S battery is designed and fabricated, which can improve efficient adsorption for Li PS and stability of the sulfur cathodes. Besides, the strong intermolecular hydrogen bonds in HPAA binder can contribute to the structural stability of S cathode and integration of the conductive paths. Therefore, the Li-S battery with this functional binder exhibits excellent cycle performance with a capacity retention of 91% after 200 cycles at 0.1 C.Even at a high sulfur loading of 5.3 mg cm-2, a specific capacity of 601 mA h g-1 can also be achieved.Density functional theory(DFT) calculation further demonstrates that the enhanced electrochemical stability derives from the high binding energy between amino groups and LiP S and the wide electrochemical window(6.87 e V) of HPAA molecule. Based on the above all, this functional polymer will lighten a new species of binders for eco-friendly sulfur cathodes and significantly promote the practical applications of high-performance Li-S batteries.

From non-carbon host toward carbon-free lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries with advantages of high energy densities(2600 Wh·kg^(-1)/2800 Wh·L^(-1))and sulfur abundance are regarded as promising candidates for next-generation high-energy batteries.However,the conventional carbon host used in sulfur cathodes suffers from poor chemical adsorption towards Li-polysulfides(LPS)in liquid electrolyte and sluggish redox kinetics,leading to low capacity and rate capability.Besides,carbon host used in Li metal anode with the intrinsic property of poor lithiophilicity and high Li-nucleation barrier gives rise to uncontrollable dendrite growth and further battery failure.Therefore,non-carbon hosts with chemical adsorption toward LPS and catalytic activity for accelerating LPS redox conversion as well as lithiophilic property for guiding uniform Li deposition are proposed and demonstrated a high efficiency in both sulfur cathodes and Li metal anodes.In this review,the principle and challenges of Li-S batteries are first presented,then recent work using non-carbon hosts in Li-S batteries is summarized comprehensively,and the mechanism of non-carbon host in improving sulfur utilization and stabilizing Li metal anode is discussed in detail.Furthermore,remaining challenges and outlook on the implementation of non-carbon host for practical carbon-free Li-S batteries are also provided.

Decorating Vertically Oriented Graphene Arrays with Co-Doped NiTe_(2)Toward Al-Current-Collector-Free Li-S Batteries

Lithium-sulfur(Li-S)batteries are broadly regarded as one of the most promising energy storage systems owing to their high-energy and low-cost features.Nevertheless,their practical implementation is plagued by the notorious polysulfide shuttling and sluggish reaction kinetics.Transition metal telluride has emerged as a promising electrocatalyst to expedite sulfur redox kinetics,even though its controllable and precise fabrication remains quite elusive.Herein,we propose the employment of a chemical vapor deposition approach to achieve in situ growth of Co-doped NiTe_(2)(Co-NiTe_(2))on vertically oriented graphene coated carbon cloth(VG/CC)substrate,in the pursuit of high-performance sulfur host material(Co-NiTe_(2)@VG/CC)in Li-S realms.Electrokinetic analysis and operando Raman spectroscopy characterization reveal the effective regulation capability of Co-NiTe_(2)@VG/CC with respect to polysulfide capture/conversion and Li2S decomposition.As a result,the Al-currentcollector-free Co-NiTe_(2)@VG/CC-based cathodes with typical sulfur loading exhibit outstanding cycling stability(93.8% capacity retention over 100 cycles at 0.5 C).Moreover,an areal capacity of 4.27 mAh cm^(-2) at 0.2 C can be harvested even at an elevated sulfur loading of 7.2 mg cm^(-2).

Applications of transition-metal sulfides in the cathodes of lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries are considered as one of the most promising candidates for next-generation energy storage systems with high energy density and reliable performance.However,the commercial applications of lithium-sulfur batteries is hindered by several shortcomings like the poor conductivity of sulfur and its reaction products,and the loss of active materials owing to the diffusion of lithium polysulfides(LiPSs)into the electrolyte.Hence,the effective restraining of the LiPSs and the promotion of the sluggish conversion are highly demanded to fulfill the potential of lithium-sulfur batteries.Here,we summarize the applications of transition-metal sulfides(TMSs)in the cathodes over recent years and demonstrate the unique advantages they possess to realize reliable long-life lithium-sulfur batteries.

Exploiting methylated amino resin as a multifunctional binder for high-performance lithium-sulfur batteries

The practical application of Li-S batteries is severely restricted by limited cycle life and low sulfur loading.Here,a common industrial paint,methylated amino resin(MAR),was employed as a novel multifunctional binder to address these issues.The S cathodes by using MAR binder(S@MAR) demonstrate an excellent reversible capacity of 480.9 mA·h·g^(-1) after 400 cycles at a rate of 0.5 C,and the sulfur loading in the electrode could achieve as high as 3.0 mg·cm^(-2).These achievements are ascribed to the superior mechanical property for volume expansion,better adsorption ability toward poly sulfides,and more favorable Li+transportation of MAR,compared to the conventional binders of polyvinylidene difluoride and carboxymethylcellulose.This study paves a new way for obtaining high-energy-density Li-S batteries by the simple application of multifunctional binder that are inherently cost-effective.