Advanced Lithium Sulfur Batteries Research Articles

Rational design and superfast production of biomimetic, calendering-compatible, catalytic, sulfur-rich secondary particles for advanced lithium-sulfur batteries

Scalable fabrication of thick sulfur electrodes with high-energy-density and good calendering-compatibility is a prerequisite for the practical success of lithium-sulfur batteries. However, this task turns out extremely challenging due to the lack of scalable production of rationally designed sulfur-rich particles, as well as fundamental understanding of the main issues of thick electrodes. Here, we develop a hail-inspired sulfur nanostorm (HSN) technology to efficiently produce calendering-compatible sulfur-rich secondary particles with customizable composition and material functions. To dig out the fundamental links between sulfur-rich particles properties and their electrochemical performance, an electro-mechanical method is proposed to evaluate the sulfur-rich particles properties (calendering-compatibility and conductivity). Meanwhile, the role of active material calendering-compatibility in controlling its electrochemical performance is discussed by a “healthy” microenvironment model as learned from cell biology. Consequently, a high areal capacity of 12 mAh cm−2 @ 1 mA cm−2 is realized in coin-cell. Furthermore, a pouch cell with a high specific capacitance of 1294 mAh g−1 in a quasi-lean electrolyte is successfully demonstrated. In a nutshell, this study may provide guidelines for the design, fabrication and characterization of high-quality of thick sulfur cathode for Li-S batteries.

Core–Shell Structure S@PPy/CB with High Electroconductibility to Effective Confinement Polysulfide Shuttle Effect for Advanced Lithium–Sulfur Batteries

Core–Shell Structure S@PPy/CB with High Electroconductibility to Effective Confinement Polysulfide Shuttle Effect for Advanced Lithium–Sulfur Batteries

Hierarchical Porous Graphene Bubbles as Host Materials for Advanced Lithium Sulfur Battery Cathode.

The serious shuttle effect, low conductivity, and large volume expansion have been regarded as persistent obstacles for lithium sulfur (Li-S) batteries in its practical application. Carbon materials, such as graphene, are considered as promising cathode hosts to alleviate those critical defects and be possibly coupled with other reinforcement methods to further improve the battery performance. However, the open structure of graphene and the weak interaction with sulfur species restrict its further development for hosting sulfur. Herein, a rational geometrical design of hierarchical porous graphene-like bubbles (PGBs) as a cathode host of the Li-S system was prepared by employing magnesium oxide (MgO) nanoparticles as templates for carbonization, potassium hydroxide (KOH) as activation agent, and car tal pitch as a carbon source. The synthesized PGBs owns a very thin carbon layer around 5 nm that can be comparable to graphite nanosheets. Its high content of mesoporous and interconnected curved structure can effectively entrap sulfur species and impose restrictions on their diffusion and shuttle effect, leading to a much stable electrochemical performance. The reversible capacity of PGBs@S 0.3 C still can be maintained at 831 mAh g−1 after 100 cycles and 512 mAh g−1 after 500 cycles.

Two Competing Reactions of Sulfurized Polyacrylonitrile Produce High-Performance Lithium-Sulfur Batteries.

Sulfurized polyacrylonitrile (SPAN) is an attractive cathode candidate for the advanced lithium-sulfur (Li-S) batteries owing to its outstanding cyclic stability. Nevertheless, SPAN suffers from inadequate initial Coulombic efficiency (CE) induced by the sluggish reaction kinetics, which is primarily ascribed to the low Li-ion diffusivity and high electronic resistivity of the Li2S product. In this work, an optimal trace amount of soluble lithium polysulfide of Li2S8 is introduced as a redox mediator for a freestanding fibrous SPAN cathode to enhance the reversible oxidation efficiency of Li2S. During the delithiation process, the chemical interactions between Li2S and Li2S8 additive facilitate the electrochemical oxidation of Li2S, resulting in the transformation of not only C-S/S-S bonds in SPAN but also elemental sulfur. Benefiting from the synergistic effect of the two competing reactions, a high initial CE of 82.9% could be achieved at a current density of 200 mA g-1. Moreover, a superior capacity retention along with a high capacity of 1170 mAh g-1 up to the 400th cycle is available at 1000 mA g-1. The study offers a feasible approach for Li-S batteries toward the practical applications of SPAN.

Nitrogen, phosphorus co-doped porous carbon originated from egg white for advanced lithium-sulfur battery

N, P co-doped micro-/meso-/macroporous carbon originated from egg white using freeze drying followed by carbonization method. The porous carbon derived from protein provides moderate nitrogen and phosphorus doping in carbon matrix. When used for sulfur host and the cathode with a sulfur loading of 0.57 mg cm−2 demonstrates brilliant battery performance with a first capacity of 1635 mAh g−1 at 0.1 A g−1 and kept at 762 mAh g−1 after 100 cycles, remarkable rate capabilities of 1352, 1017, 961 and 701 mAh g−1 at 0.1, 0.2, 0.5 and 1.0 A g−1. The excellent stability and rate performance are due to the N, P co-dopants and porous structure, which have strong adsorption effect to the soluble polysulphides.

In Situ Construction of Mo2 C Quantum Dots-Decorated CNT Networks as a Multifunctional Electrocatalyst for Advanced Lithium-Sulfur Batteries.

The slow redox kinetics during cycling process and the serious shuttle effect caused by the solubility of lithium polysulfides (LiPSs) dramatically hinder the practical application of Li-S batteries. Herein, a facile and scalable spray-drying strategy is presented to construct conductive polar Mo2 C quantum dots-decorated carbon nanotube (CNT) networks (MCN) as an efficient absorbent and electrocatalyst for Li-S batteries. The results reveal that the MCN/S electrode exhibits a high specific capacity of 1303.3 mAh g-1 at 0.2 C, and ultrastable cycling stability with decay of 0.019% per cycle even at 1 C. Theoretical simulation uncovers that Mo2 C exhibits much stronger binding energies for S8 and Li2 Sn . The energy barrier for the conversion between Li2 S4 and Li2 S2 decreases from 1.02 to 0.72eV when hybriding with Mo2 C. Furthermore, in situ discharge/charge-dependent Raman spectroscopy shows that long-chain Li2 S8 configuration is generated via S8 ring opening near the first plateaus at ≈2.36V versus Li/Li+ and the S6 2- configuration in CNT/S electrode is maintained below the potential of ≈2.30V versus Li/Li+ , indicating that the shuttle of soluble LiPSs happens during the whole discharge process. This work provides deep insights into the polar nanoarchitecture design and scalable fabrication for advanced Li-S batteries.

SnS2 monolayer and SnS2/graphene heterostructure as promising anchoring materials for lithium-sulfur batteries: A computational study

• Interactions between polysulfides and SnS 2 were studied by DFT calculations. • SnS 2 /G heterostructure was considered to improve electrical conductivity. • Both SnS 2 and SnS 2 /G are promising anchoring materials for Li-S batteries. Lithium-sulfur (Li-S) batteries have attracted widespread attention as high energy storage systems. However, the shuttle of intermediate polysulfides is still one of the unresolved obstacles for their practical application. In this work, the potential of SnS 2 monolayer as polysulfides anchoring material for suppressing the “shuttle effect” were investigated through density functional theory (DFT) calculations. We found that SnS 2 monolayer can immobilize polysulfides with moderate binding strength and preserve their structural integrity well. The low diffusion barriers of long-chain polysulfides on SnS 2 surface suggest the improved electrode reaction efficiency. Furthermore, SnS 2 /graphene heterostructure with improved electrical conductivity was selected to analyze the applicability, which also shows outstanding anchoring performance and good diffusion property for polysulfides. Combined with the small reduction free energies of S 8 to Li 2 S and low decomposition barriers of Li 2 S during the discharge/charge process, we can conclude that SnS 2 -based composites are promising anchoring materials for advanced Li-S batteries.

Rational design of NiCo2S4@MoS2 ball-in-ball heterostructure nanospheres for advanced lithium-sulfur batteries

Lithium sulfur battery has a theoretical specific capacity of up to 1600 mA h g−1, which has a significant prospect. However, the shuttle effect of polysulfide, the low conductivity of sulfur and the serious volume change during charging and discharging process hinder the commercial application of lithium-sulfur batteries (LSBs). Here, the flower-like ball-in-ball NiCo2S4@MoS2 heterojunction composites were fabricated as the effective sulfur host in LSBs, which exhibited high specific capacity and durable cyclic life. The NiCo2S4 made up ball-in-ball structure offering more chemisorption sites to limit lithium polysulfide (LiPS) dissolution, and the MoS2 nanosheets grow in the surface of NiCo2S4 sphere to form three dimensional flower structure for accelerating the kinetics of LSBs redox reaction. Additionally, the specific hollow structure also availably alleviated the volume change during charging and discharging. Based on these merits, the NiCo2S4@MoS2 electrode with a sulfur content of 74% possessed an initial specific capacity of 1118 mAh g−1 at 0.1 C, and still had a reversible capacity of 865 mAh g−1 after 300 cycles. Even at a high rate of 5 C, the capacity of 467 mAh g−1 could still be achieved after 500 cycles.

Highly Effective Trapping-Conversion Interface Based on Nickel-Modified Versatile Carbon Skeleton Enabled High-Performance Li-S Battery.

The development of comprehension in the mechanism of lithium-sulfur (Li-S) batteries creates more opportunities and potential for the application of interlayer. However, the viable design of versatile interlayer to retard the shuttling effects and improve the sluggish kinetics is still a focus and paramount challenge. Herein, we present a tentacles-like metallic nickel-modified and nitrogen-doped carbon skeleton (NCS) to serve as adsorbent and catalyst in the lithium-sulfur battery (LSBs). The carbonized skeleton and derived carbon tubes jointly construct conductive networks and adequate ion pathways. Meanwhile, abundant metallic nickel nanoparticles synergistically build a multifunctional interface with polar networks for the fixation and conversion of polysulfides, giving rise to significant improvement of cyclic stability and reaction kinetics of LSBs. As a result, the Li-S batteries using NCS as an interlayer could possess superior electrochemical performance including cyclic stability, high specific capacity (1204.8 mAh g-1 at 0.2C, 998.7 mAh g-1 at 1C), and good Coulombic efficiency. More importantly, even with the areal sulfur loading of up to 6.1 and 7.5 mg cm-2, it still demonstrates superior electrochemical performance with the areal capacity of 4.2 and 5.9 mAh cm-2 with steady cycling, respectively. In conclusion, we confirm this work provides a promising way to explore and expand the application of metal nanoparticles in interlayers for advanced Li-S batteries.

Integration of nickel phosphide nanodot-enriched 3D graphene-like carbon with carbon fibers as self-supported sulfur hosts for advanced lithium sulfur batteries

Lithium-sulfur batteries are spotlighted as the promising next-generation batteries because of their high energy density and low-cost. Nevertheless, intrinsic low conductivity, notorious shuttle effect, and sluggish redox kinetics of sulfur cathode greatly impede their commercialization. Herein, we design and demonstrate a powerful combined strategy to build a novel hybrid architecture for hosting sulfur, which are achieved by growing Ni2P nanodot-enriched 3D graphene-like carbon onto carbon fiber paper (NP-3DGC@CFP) via a facile one-step carbonization approach. In the integrated NP-3DGC@CFP/S electrode: micro-mesoporous 3DGC provides abundant space and complicated pore structures to accommodate sulfur and physically confine polysulfide species; polar Ni2P nanodots chemically immobilize the lithium polysulfides and accelerate electrochemical reaction kinetics; flexible CFP serves as mechanical scaffold to support the electrode and avoids binder-related limitations. As a result, self-supported NP-3DGC@CFP/S cathode demonstrates an excellent combination of capacity, rate, cycling endurance (1409.4 mAh g−1 at 0.1 C, 538.2 mAh g−1 at 5 C, 786.3 mAh g−1 with 72.7% retention at 0.5 C for 300 cycles) and anti-self-discharge capability. Significantly, such cathode also shows satisfied cycling stability at a high sulfur loading of 6.5 mg cm−2 or at a high rate of 2 C, demonstrating its bright perspective for practical application.

Synergistic regulation of polysulfides immobilization and conversion by MOF-derived CoP-HNC nanocages for high-performance lithium-sulfur batteries

Abstract Lithium-sulfur (Li-S) batteries have drawn intense attention in the realm of electrochemical energy storage owing to their high theoretical energy density, as well as the natural abundance of sulfur and low cost. However, the severe shutting of polysulfides and sluggish reaction kinetics hinder the practical application of Li-S batteries. To solve these problems, MOF (ZIF-67) derived in-situ N-doped carbon nanocage embedded with CoP (CoP-HNC) as an efficient sulfur host for advanced Li-S batteries is proposed here. With the abundant porosity and cavity, hollow polar heteroatom N-doped carbon architecture can effectively alleviate volume expansion, buffer electrolyte and trap polysulfides. More importantly, the embedded polar CoP nanoparticles acted as an effective electrocatalyst not only anchor polysulfide intermediates, but also promote the redox kinetics toward polysulfides conversion remarkably, which is clearly proved by experimental results and DFT calculations. Benefiting from above advantages, Li-S batteries assembled with CoP-HNC electrode achieve a significantly enhanced sulfur utilization (about 800 mAh g−1 at 5 C), improved cycling stability and ultralow capacity decay rate of 0.02% per cycle after 1000 cycles. Even at high sulfur loading of 3.0 mg cm−2, the S/CoP-HNC electrode still delivers a high initial capacity of 866 mAh g−1 at 0.5 C. This work has guiding synergistically combining desired design and electrocatalysis in sulfur cathode for Li-S batteries.

Titanium Glycolate Nanorods with Unsaturated Sites as Multifunctional Layers for Advanced Lithium–Sulfur Batteries

The troublesome shuttle effects and the slow electrochemical reaction kinetics restrict the practical application of Li–S batteries. Herein, a titanium glycolate nanorod (TGN) with unsaturated site...

Suppressed shuttling effect of polysulfides using three-dimensional nickel hydroxide polyhedrons for advanced lithium-sulfur batteries

In this work, controlled-size hollow polyhedron assembled by crumpled nickel hydroxide (Ni(OH)2) nanosheets from silicon dioxide (SiO2)-covered zeolitic imidazole framework-67 (ZIF-67@SiO2) is prepared via a template-sacrificed method. It is found that SiO2 plays an essential role in keeping intact polyhedrons and suppressing particle growth. Benefiting from structural and compositional advantages, the Ni(OH)2@S electrode exhibits high specific capacity, excellent rate performance, and stable cycle life at 1C with a small capacity decay of 0.067% per cycle. The Ni(OH)2 hollow polyhedrons can accommodate the volume expansion to maintain the integrity of the electrode and suppress the shuttling effect of polysulfides via abundant hydroxyl groups. Hence, this strategy is beneficial to anticipate the material for large-scale applications.

Improved polysulfide adsorption by using honeycomb-like titanium dioxide boxes as efficient sulfur hosts for advanced lithium-sulfur batteries

Despite the fact that lithium-sulfur batteries are considered promising energy storage system due to their high specific capacity and energy density, however, there is no doubt that the severe polysulfide migration greatly hindered the practical employment of the lithium-sulfur batteries. In our work, novel honeycomb-like TiO2 boxes were designed as host materials for sulfur in the lithium-sulfur batteries. Owing to the strong chemical adsorption ability for polysulfide and superior electronic transportation, the polysulfide migration could be efficiently inhibited and the electronic conductivity is greatly improved. As a result, the as-prepared honeycomb-like TiO2/S (HLTO/S) composite electrode delivers high specific capacity of 1268 mAh g−1 at 0.1 C. Moreover, the specific capacity could remain at 712 mAh g−1 after 100 cycles at 0.5 C, demonstrating excellent cycling stability. This work provides a new strategy to develop the host materials for sulfur in the lithium-sulfur batteries.

N-doped hollow carbon nanoparticles encapsulated fibers derived from ZIF-8 self-sacrificed template for advanced lithium–sulfur batteries

Abstract The facile synthesis of sulfur scaffold with high electrical conductivity and strong polysulfide immobilization capability plays an important role in developing high-performance lithium sulfur batteries. Here a new type of porous N-doped carbon fiber consisting of hollow carbon nanoparticles (9 wt%-CF) is designed as sulfur scaffold through electrospinning and carbonization processes with ZIF-8 and polyacrylonitrile as precursors. The carbon fiber skeleton can provide high electrical conductivity, and interconnected hollow particles provide ample space to host active materials and to immobilize polysulfides. Moreover, the N-doping further improves the interaction between 9 wt%-CF and polysulfides. Consequently, the as-prepared 9 wt%-CF/S cathode delivers an initial discharge capacity of 1524 mAh g−1 at 0.1 C and high capacity retention of 83% after 200 cycles charge/discharge at 0.5 C with a sulfur loading of 1.9 mg cm−2.

Cobalt sulfide quantum dot embedded in nitrogen/sulfur-doped carbon nanosheets as a polysulfide barrier in Li-S batteries

Abstract Lithium-sulfur (Li-S) batteries are considered to be one of the most promising next-generation energy storage systems, due to their low cost and high theoretical energy density (2600 W h kg −1). However, the shuttle effect seriously limits the practical use of Li-S batteries. In this work, we demonstrate cobalt sulfide quantum dot embedded nitrogen/sulfur-doped carbon nanosheets composite material (CoSx QD-NSC) as coating material for commercial polypropylene (PP) separator (celgard 2400) in Li-S batteries. It is able to act as an efficient barrier for the blocking of polysulfides in Li-S batteries. The cell with modified separator, at the sulfur loading of 1.6 mg cm−2, can exhibit a high initial specific capacity of 1250 mAh g −1 at 500 mA g−1, with a capacity retention of 73.6% after 100 cycles. When cycled at 1 C (1675 mA g−1), the cell can deliver a high initial specific capacity of 874 mAh g−1 and a reversible specific capacity of nearly 500 mAh g −1 after 1000 cycles, exhibiting an average capacity fading of only 0.05% per cycle. The excellent performance is ascribed to the efficient adsorption of the CoSx QD-NSC to polysulfides, which inhibits the shuttle effect in Li-S batteries. The CoSx QD-NSC modified separator in this work provides new insights and opportunities for the development of advanced Li-S batteries.

A short review on dissolved lithium polysulfide catholytes for advanced lithium-sulfur batteries

Lithium-sulfur battery (LSB) technology has drawn enormous attention during the last decade. Benefitting from the high theoretical specific discharge capacity (1,675 mAh g−1) and energy density (2,600 Wh kg−1), LSBs have proved to be a suitable candidate for electric vehicles and large-scale power grid electrical energy storage systems. However, the commercialization of LSB is hindered by various barriers, which include the high insulating nature of sulfur and its discharge products, severe polysulfide shuttling phenomenon, extreme volume expansion during charging/discharging, and poor stability of Li metal anodes. Additionally, LSB technology faces considerable battery design challenges, which allows high sulfur content and/or sulfur-loading while simultaneously maintaining a low electrolyte/sulfur ratio. Therefore, in this review, we highlight recent effective strategies that lead to more practical and commercial LSBs. We restrict ourselves to various cathode architectures designed specifically to absorb dissolved polysulfide catholyte. The integration of dissolved lithium polysulfide catholyte with specially designed cathode substrates efficiently allows ultra-high sulfur loading and/or sulfur-content with low electrolyte/sulfur ratio while still exhibiting reasonable electrochemical performance and cycling stability. The effect of concentration variation of dissolved lithium polysulfide catholyte on the cell performance is also discussed in detail. Therefore, the present review encapsulates feasible strategies with practical parameters to address the problems associated with LSBs.

Bifunctional polyvinylpyrrolidone generates sulfur-rich copolymer and acts as “residence” of polysulfide for advanced lithium-sulfur battery

Sulfur-rich copolymer is considered as a promising cathode in lithium-sulfur battery due to its superior chemical confinement for polysulfides on the molecular level, but the sulfur-rich copolymer with low cost and physiological inert is reported rarely. Here, a novel sulfur-polyvinylpyrrolidone (PVPS) copolymer is synthesized by one-step thermal polymerization. The break and recombination of CO lead to the formation of PVPS, which is proved by various characterizations. Due to the strong chemical confinement of C–S bond, the excellent polysulfides adsorption ability of PVP with abundant polar bonds (such as C–O and C–N) and the improved charge transfer of PVPS, 20PVPS combining with PVP-modified separator as “residence” of polysulfides delivers the high reversible capacity of 1079 and 729 mAh g−1 at 0.1 and 2 C and a slow capacity fading rate of 0.093% over 500 cycles at 1 C. These findings provide a reference for the synthesis of low-cost, biocompatible and high-performance sulfur-rich copolymer in lithium-sulfur battery.

NiCo2S4 nanoparticles embedded in nitrogen-doped carbon nanotubes networks as effective sulfur carriers for advanced Lithium–Sulfur batteries

Abstract To enhance the electrochemical performance of Li–S battery, a composite sulfur cathode was designed by doping sulfur onto N-doped carbon nanotubes with metal sulfide particles attached to their surface. This designing approach allowed performing high sulfur loading in the cathode, while maintaining prominent stability and good charge/discharge capacity. The results showed that at a sulfur loading of 2.1 mg cm−2, the cell with S/NiCo2S4/N-CNT cathode delivered an average discharge capacity of 998 mA h g−1 at 0.1C, and preserved an excellent discharge capacity of 713 mA h g−1 at a high current density of 1 C. At the same time, the cell demonstrated high stability and reversibility delivering a capacity of 950 mA h g-l when current density reduced back again to 0.1C. Furthermore, the S/NiCo2S4/N-CNT cathode showed a steady capacity of 915 mA h g−1 at 0.2C over 100 cycles.

CoS2 Nanospheres Anchored on 3D N-Doped Carbon Skeleton Derived from Bacterial Cellulose for Lithium-Sulfur Batteries

To address sluggish sulfur redox kinetic and the “shuttling behavior” of polysulfides in lithium-sulfur batteries (LSBs), CoS2 hollow nanospheres tightly anchored on three-dimensional (3D) N-doped biological carbon nanofibers skeleton (CoS2/N-CNFs) are successfully designed as highly-efficient sulfur hosts. The carbon nanofibers obtained by carbonization of bacterial cellulose are interweaved with each other, and can provide a firm 3D conductive skeleton for the low-conductive sulfur cathode. And the N-doping carbon nanofibers skeleton with polar CoS2 can achieve synergetic physical/chemical adsorption of polysulfides and effective catalytic conversion, which are contributed to enhance sulfur redox kinetic and effectively suppress the shuttling effect. Moreover, the skeleton with abundant −OH functional groups achieve strong chemisorption to CoS2, greatly maintaining structural stability during cycling process. Benefitting from the above-mentioned merits, CoS2/N-CNFs@S electrode with high sulfur loading of 74.4% exhibits superior reversible capacity of 497.3 mAh g−1 at 0.2 C after 100 cycles with an improved coulombic efficiency of approximately 100%, and the electrode has excellent cycle life with 73% capacity retention over 300 cycles at 0.5 C. This synthesis strategy makes a leading exploration for the application of biological carbon materials in advanced LSBs.