High-rate Lithium-sulfur Batteries Research Articles

Atomic Interlamellar Ion Path in High Sulfur Content Lithium-Montmorillonite Host Enables High-Rate and Stable Lithium-Sulfur Battery.

Fast lithium ion transport with a high current density is critical for thick sulfur cathodes, stemming mainly from the difficulties in creating effective lithium ion pathways in high sulfur content electrodes. To develop a high-rate cathode for lithium-sulfur (Li-S) batteries, extenuation of the lithium ion diffusion barrier in thick electrodes is potentially straightforward. Here, a phyllosilicate material with a large interlamellar distance is demonstrated in high-rate cathodes as high sulfur loading. The interlayer space (≈1.396 nm) incorporated into a low lithium ion diffusion barrier (0.155 eV) significantly facilitates lithium ion diffusion within the entire sulfur cathode, and gives rise to remarkable nearly sulfur loading-independent cell performances. When combined with 80% sulfur contents, the electrodes achieve a high capacity of 865 mAh g-1 at 1 mA cm-2 and a retention of 345 mAh g-1 at a high discharging/charging rate of 15 mA cm-2 , with a sulfur loading up to 4 mg. This strategy represents a major advance in high-rate Li-S batteries via the construction of fast ions transfer paths toward real-life applications, and contributes to the research community for the fundamental mechanism study of loading-independent electrode systems.

An ultrathin and continuous Li4Ti5O12 coated carbon nanofiber interlayer for high rate lithium sulfur battery

Abstract Severe capacity fading and poor high rate performance of lithium sulfur (Li–S) battery caused by “shuttle effect” and low conductivity of sulfur hampers its further developments and applications. Li4Ti5O12 (LTO) possesses high lithium ion conductivity, and it is also can be used as an active adsorbent for polysulfide. Herein, fine LTO particle coated carbon nanofibers (CNF) were prepared and a conductive network both for electron and lithium ion was built, which can greatly promote the electrochemical conversion of polysulfide and improve the rate performance of Li–S batteries. Meanwhile, a quantity of adsorption sites is constructed by defects of the surface of LTO-CNF membrane to effectively immobilize polysulfide. The multifunctional LTO-CNF interlayer could impede the shuttle effect and enhance comprehensive electrochemical performance of Li–S batteries, especially high rate performance. With such LTO-CNF interlayer, the Li–S battery presents a specific capacity of 641.9 mAh/g at 5 C rate. After 400 cycles at 1 C, a capacity of 618.0 mAh/g is retained. This work provides a feasible strategy to achieve high performance of Li–S battery for practical utilization.

Hollow carbon nanofibers with dynamic adjustable pore sizes and closed ends as hosts for high-rate lithium-sulfur battery cathodes

Designing a better carbon framework is critical for harnessing the high theoretical capacity of Li-S batteries and avoiding their drawbacks, such as the insulating nature of sulfur, active material loss, and the polysulfide shuttle reaction. Here, we report an ingenious design of hollow carbon nanofibers with closed ends and protogenetic mesopores in the shell that can be retracted to micropores after sulfur infusion. Such dynamic adjustable pore sizes ensure a high sulfur loading, and more importantly, eliminate excessive contact of sulfur species with the electrolyte. Together, the high aspect ratio and thin carbon shells of the carbon nanofibers facilitate rapid transport of Li+ ions and electrons, and the closed-end structure of the carbon nanofibers further blocks polysulfide dissolution from both ends, which is remarkably different from that for carbon nanotubes with open ends. The obtained sulfur-carbon cathodes exhibit excellent performance marked by high sulfur utilization, superior rate capability (1,170, 1,050, and 860 mA·h·g−1 at 1.0, 2.0, and 4.0 C (1 C = 1.675 A·g−1), respectively), and a stable reversible capacity of 847 mA·h·g−1 after 300 cycles at a high rate of 2.0 C.

A spheres-in-tube carbonaceous nanostructure for high-capacity and high-rate lithium–sulfur batteries

A spheres-in-tube carbonaceous nanostructure has been prepared as an effective sulfur host, exhibiting large reversible capacity and good cycling stability.

Micropores of pure nanographite spheres for long cycle life and high-rate lithium–sulfur batteries

An effective and novel structure of pure hollow nanographite with micropores (∼8 Å) was successfully synthesized, and high-rate and long cycle life lithium–sulfur batteries were obtained.

Entrapping polysulfides by using ultrathin hollow carbon sphere-functionalized separators in high-rate lithium-sulfur batteries

Novel ultrathin hollow carbon spheres with a nonporous shell are employed as polysulfide reservoirs to improve the overall performance of Li-S batteries.

Impregnation of sulfur into a 2D pyrene-based covalent organic framework for high-rate lithium–sulfur batteries

By loading 70 wt% sulfur into a pyrene-based COF (Py-COF), we constructed Li–S batteries with high-rate capacity and long-term stability.

Highly Ordered Mesoporous Sulfurized Polyacrylonitrile Cathode Material for High-Rate Lithium Sulfur Batteries

A highly ordered mesoporous sulfurized polyacrylonitrile (MSPAN) composite has been synthesized via in situ polymerization of polyacrylonitrile (PAN) in an SBA-15 template followed by sulfurization. The synthesized composite possessed high sulfur utilization, high Coulombic efficiency, and excellent cycling stability as a cathode active material for high-rate lithium sulfur (Li–S) batteries. A highly ordered mesoporous structure was observed in the MSPAN composite from transmission electron microscopy. Excellent electrochemical and stable cycling performances of the MSPAN composite were obtained, especially at high C rates. The capacity retention of the MSPAN cell was 755 mAh g–1 after 200 cycles at 1 C and 610 mAh g–1 after 900 cycles at 2 C. Even at a higher rate of 5 C, the composite showed reasonable capacity retention. The superior performance of the MSPAN composite was attributed to its highly porous structure, which could effectively improve the wettability, accessibility, and absorption of electro...

High coulombic efficiency and high-rate capability lithium sulfur batteries with low-solubility lithium polysulfides by using alkylene radicals to covalently connect sulfur

The long-chain lithium polysulfides that are soluble in ether-based electrolyte for lithium sulfur battery are regarded as one of reason for their low Coulumbic efficiency and low rate capability. In this work, we reported a new strategy to stabilize sulfur cathodes with alkylene radicals to covalently connect sulfur through the formation of low-solubility lithium polysulfides, which enables high Coulombic efficiencies of 99.9% at 0.2C, 99.9% at 0.5C, 100% at 1C, 100% at 2C, 100% at 4C, 100% at 6C as well as outstanding rate capability with a high capacity of 702mAhg−1 at 6C. The proposed mechanism was clearly revealed by in-situ UV/vis spectroscopy, demonstrating that short chain polysulfides as discharge products with low solubility are mainly produced during charging and discharging process. Moreover, DFT calculations confirmed that the bond breakage of the linear sulfur chains preferentially takes place in the center of the linear polysulfane, resulting in the formation of short-chain polysulfides, which could effectively avoid the production of soluble long-chain polysulfide and suppress the shuttling effect for high Coulumbic efficiency and high-rate capability lithium sulfur batteries.

High rate lithium-sulfur batteries enabled by mesoporous TiO2 nanotubes prepared by electrospinning

Mesoporous titanium dioxide nanotubes (MTDNTs) were prepared by electrospinning and subsequent thermal treatment. The as-synthesized MTDNTs possess anatase mischcrystal structure, hollow texture morphology, and a relatively high specific surface area of 93.6m2g−1 with a pore volume of 0.2190cm−3g−1. The nanotube walls of MTDNTs act as a host for sulfur and the hollow structure is favorable for the fast transmission of Li+ ions. After sulfur was encapsulated into the pores of nanotube walls of MTDNTs, the MTDNTs/S composite electrode displays a relatively good cycling performance and especially excellent rate performance (about 610mAhg−1 at 8C). The retention capacity can be up to 74.2% when the discharge rate increases from 0.5C to 8.0C.

Ordered SnO nanoparticles in MWCNT as a functional host material for high-rate lithium-sulfur battery cathode

Lithium-sulfur battery has become one of the most promising candidates for next generation batteries, and it is still restricted due to the low sulfur conductivity, large volume expansion and severe polysulfide shuttling. Herein, we present a novel hybrid electrode with a ternary nanomaterial based on sulfur-impregnated multiwalled carbon nanotubes filled with ordered tin-monoxide nanoparticles (MWCNT-SnO/S). Using a dry plasma reduction method, a mechanically robust material is prepared as a cathode host material for lithium-sulfur batteries. The MWCNT-SnO/S electrode exhibits high conductivity, good ability to capture polysulfides, and small volume change during a repeated charge–discharge process. In situ transmission electron microscopy and ultraviolet–visible absorption results indicate that the MWCNT-SnO host efficiently suppresses volume expansion during lithiation and reduces polysulfide dissolution into the electrolyte. Furthermore, the ordered SnO nanoparticles in the MWCNTs facilitate fast ion/electron transfer during the redox reactions by acting as connective links between the walls of the MWCNTs. The MWCNT-SnO/S cathode with a high sulfur content of 70 wt.% exhibits an initial discharge capacity of 1,682.4 mAh·g–1 at 167.5 mA·g–1 (0.1 C rate) and retains a capacity of 530.1 mAh·g–1 at 0.5 C after 1,000 cycles with nearly 100% Coulombic efficiency. Furthermore, the electrode exhibits the high capacity even at a high current rate of 20 C.

Facile and tailored synthesis of ultrahigh-surface-area clews of carbon nanobelts for high-rate lithium–sulfur batteries

Hierarchical clews of carbon nanobelts (CsCNBs) with surface area up to 3445 m2g−1have been synthesized by a template-free method from low cost raw materials.

Facile fabrication of nanoporous graphene powder for high-rate lithium–sulfur batteries

High quality and high quantity nanoporous graphene powder has been successfully prepared for high-rate lithium–sulfur battery applications.

Electrostatic-spraying an ultrathin, multifunctional and compact coating onto a cathode for a long-life and high-rate lithium-sulfur battery

Serious shuttle effect of polysulfides is the main obstacle preventing the practical application of lithium sulfur batteries. Herein, we report an ultrathin yet multifunctional polysulfide blocking layer (MPBL) coated on the cathode to effectively restrain the polysulfides shuttling. This MPBL, which was prepared by a simple, one-step electrostatic spray deposition (ESD) technique, was fully and compactly coated on the electrode with controllable thickness, realizing the full protection of the whole cathode. It is noted that the MPBL can be very thin that guarantees the fast ion diffusion but still keeps a high efficiency of blocking polysulfides due to a combination of physical (from carbon) and chemical confinement (from conductive polymer). In addition, the MPBL with good conductivity can act as the upper current collector to reuse the captured polysulfides, and thus improve the sulfur utilization during cycling. With such multifunctional design, the MPBL-coated carbon-sulfur cathode exhibits long cyclic stability and high rate capability, which has only 0.042% capacity decay per cycle at 1C for 1000 cycles and a capacity of 615mAhg−1 even at a high rate of 3C.

Vulcanized Polyacrylonitrile with Graphene Oxide As an Additive for High-Rate Rechargeable Lithium Sulfur Batteries

Graphene oxide (GO)-vulcanized polyacrylonitrile (SPAN) composite was developed by mixing additive GO powder with SPAN powder by ultrasound. Its performance was evaluated in Li-S battery with ether-based electrolyte. Surprisingly the pure SPAN cathode is unstable in ether-based solvent compared with in carbonated solvent, unless a certain amount of GO is added. Due to its unique layer-structure, GO could function as the barriers, which could limit the agglomeration of SPAN composite and reduce the dissolution of sulfur accompanying the electrochemical reactions. With the additive of GO, the maximum cathode capacity of 275 mA h g-1 is higher than that of either GO or SPAN alone. This composite cathode possesses high capacity even at high current density of 1.5 A g-1. More importantly, the composite cathode is stable for 500 cycles of discharge/recharge.

Ladder-Inspired SnO-Multiwalled Carbon Nanotubes with Sulfur Impregnation as Robust Cathode Material for High-Rate Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) battery has the theoretical potential to surpass lithium-ion batteries in terms of capacity and energy density for applications in electric vehicles and hybrid electric vehicles. However several drawbacks prevent it from practical application, such as (1) the low electrical conductivity of both sulfur (5 × 10–3 S cm–1), (2) the large volume expansion (about 80%) during lithiation, (3) the intermediate lithium polysulfides (Li2Sx, 3 ≤ x ≤ 8). During the cycling process, the soluble lithium polysulfides may migrate to the anode side by the “shuttle effect”, resulting in significant irreversible capacity loss and corrosion on the lithium metal anode [1]. Many strategies have been developed to enhance the conductivity of sulfur and suppress the dissolution of polysulfides. The carbon host materials used in Li-S cathodes, despite their excellent electrical and mechanical performances, still demonstrate drawbacks such as rapid capacity fading under cycling and reduced entrapment of polysulfide, leading to decreased rate capability [2]. Therefore, a hybrid design is required for a robust cathode material with high conductivity and low volume change during lithiation-delithiation process.Here, we present ladder-inspired multi-walled carbon nanotubes (MWCNT) filled with tin monoxide (SnO) nanoparticles as a new host material. The MWCNT-SnO/S electrode exhibited excellent electrochemical performance such as stable cycling performance and high rate capability. In situ transmission electron microscopy results indicate that the ladder-inspired MWCNT-SnO host efficiently suppresses volume expansion during lithiation and reduces polysulfide dissolution. Furthermore, the ordered SnO nanoparticles facilitate fast electron and ion transfers during the redox reactions, due to act as connecting links between the walls of MWCNT. This development approach can also be applied to other energy storage devices, including lithium-ion batteries and hybrid supercapacitors.

High rate lithium-sulfur battery enabled by sandwiched single ion conducting polymer electrolyte.

Lithium-sulfur batteries are highly promising for electric energy storage with high energy density, abundant resources and low cost. However, the battery technologies have often suffered from a short cycle life and poor rate stability arising from the well-known “polysulfide shuttle” effect. Here, we report a novel cell design by sandwiching a sp3 boron based single ion conducting polymer electrolyte film between two carbon films to fabricate a composite separator for lithium-sulfur batteries. The dense negative charges uniformly distributed in the electrolyte membrane inherently prohibit transport of polysulfide anions formed in the cathode inside the polymer matrix and effectively blocks polysulfide shuttling. A battery assembled with the composite separator exhibits a remarkably long cycle life at high charge/discharge rates.

Kinetically-enhanced polysulfide redox reactions by Nb2O5nanocrystals for high-rate lithium–sulfur battery

Rational introduction of electrocatalytically-active nanocrystals into carbon–sulfur enables the accelerated kinetics of sulfur redox reactions, thus achieving an ultra-high-rate and long-life Li–S battery.

Efficient Activation of High-Loading Sulfur by Small CNTs Confined Inside a Large CNT for High-Capacity and High-Rate Lithium-Sulfur Batteries.

Sulfur with a high specific capacity of 1673 mAh g(-1) is yet to be used as commercial cathode for lithium batteries because of its low utilization rate and poor cycle stability. In this work, a tube-in-tube carbon structure is demonstrated to relieve the critical problems with sulfur cathode: poor electrical conductivity, dissolution of lithium polysulfides, and large volume change during cycling. A number of small carbon nanotubes (∼20 nm in diameter) and a high loading amount of 85.2 wt % sulfur are both filled completely inside a large amorphous carbon nanotube (∼200 nm in diameter). Owing to the presence of these electrically conductive, highly flexible and structurally robust small CNTs and a large CNT overlayer, sulfur material exhibits a high utilization rate and delivers a large discharge capacity of 1633 mAh g(-1) (based on the mass of sulfur) at 0.1 C, approaching its theoretical capacity (1673 mAh g(-1)). The obtained S-CNTs@CNT electrode demonstrates superior high-rate cycling performances. Large discharge capacities of ∼1146, 1121, and 954 mAh g(-1) are observed after 150 cycles at large current rates of 1, 2, and 5 C, respectively.

Layered carbide-derived carbon with hierarchically porous structure for high rate lithium-sulfur batteries

Practical applications of lithium-sulfur batteries require not only high specific capacities and long cycle life but also high rate performance. Herein, a layered carbide derived carbon (CDC) with hierarchically porous structure is designed and used as sulfur host for high rate lithium-sulfur batteries for the first time. In the layered CDC, sulfur was mainly infiltrated into the micropores and small mesopores, which could efficiently confine sulfur species and suppress polysulfides shuttling. At the same time, the layered structure and large mesopores would further shorten ion diffusion distance and buffer volume expansion. As a result, the layered CDC/sulfur composite with a sulfur loading of 50wt.% delivered not only a high initial discharge capacity of 1229 mAh g⿿1 at 0.5C, but also a superior reversible capacity of 621 mAh g⿿1 at 5C. Especially, the high rate capability could also be achieved even at a higher sulfur loading (68wt.%). This work suggests that porous carbon combined with layered structure and hierarchical pores could be used as effective matrix to host sulfur for high rate lithium-sulfur batteries.