Electrode For Lithium-sulfur Batteries Research Articles

Particle Size Control Influence on the Electrochemical Properties of Sulfur Deposited on Metal Organic Frameworks Host Electrodes

Metal organic frameworks (MOF)-808@sulfur composite electrode materials were prepared by hydrothermal reaction with using organic ligands and metal ions. We tried to find the optimum particle size to obtain the enhanced electrochemical performance to be used as an electrode for lithium sulfur batteries. Various particle sizes (20 nm ~ 700 nm) and shapes were successfully prepared by different amounts of modulator and solvent for preparation of MOF-808. Four kinds of substances were analyzed for composition and electrochemical analysis. Electrochemical characterizations were also conducted by cyclic voltammetry and galvanostatic charge–discharge tests. As a result, MOF-808@S(20), with a particle size of about 180 nm, exhibited the best redox reaction, providing the highest initial specific capacity of 999.4 mAh g−1 at 100 mA g−1. Based on this study, we explain the possibility of commercialization of MOF-808 composite as an electrode material of lithium sulfur batteries, which has advantages of stable host electrode structure and facile particle size control.

A reinforced-concrete-like ultrathick cathode supported by carbonization kapok fibers for high loading lithium sulfur batteries

It’s a focus on high sulfur loading electrode for lithium sulfur batteries (LSBs) to improve the practical energy density. Blade casting method is an ideal method due to its efficiency and convenience that means thick electrode was utilized to increase sulfur loading. However, the weak strength and sluggish kinetics hinder to improve the practical energy density. To overcome issues, carbonization kapok fibers (CKFs) were overlapped to form the percolation network like rebar in the reinforced concrete. The cathode (sulfur loading: 8.22 mg cm−2) exhibits the superior initial capacity (1090mAhg−1 at 0.1C) and cycling performance (728mAhg−1 after 80 cycles).

A 3D stable and highly conductive scaffold with carbon nanotubes/carbon fiber as electrode for lithium sulfur batteries

A freestanding thin-film composite with carbon nanotubes/carbon fiber modified by sulfur (S-CNTs/CF) has been fabricated by chemical vapor deposition (CVD) method as the binder-free cathode for lithium sulfur battery. This porous electronic conductor with 3D structure improved the electrochemical performance of the cathodes by simultaneously increasing porosity of material and changing conductive pathway. Electrochemical test results showed that the discharge specific capacity of S-CNTs/CF positive electrode decreased slightly from initial 1213.6 mAh g−1(Sulfur) to 798.4 mAh g−1(Sulfur) after 55 cycles. Comparing with powder cathode, the electrochemical performance of S-CNTs/CF cell is improved significantly. It proves that establishing a sulfur electrode with stable conductive and high porous structure provide a promising way to improve the cycle life.

Pyrite-based mixtures as composite electrodes for lithium-sulfur batteries

Pyrite-based composite materials (Li/S) were prepared by high-energy ball milling of FeS2 with one or more metal sulfides, Li2S, Cu2S, and CuS, in various molar ratios and under different conditions. Prolonged grinding resulted in the formation of mixed compounds rather than single-phase lithiated chalcopyrite. The composite materials were primarily investigated via XPS, XRD, and TOF-SIMS characterization methods, and performance of the materials as composite cathodes was evaluated via analysis of dQ/dV curves. Evidence of main active phases in the materials was found, including, Cu-doped FeS2 (pyrite) and/or nonstoichiometric chalcopyrite (CuxFeyS2 − z). TOF-SIMS measurements exhibited further evidence of formation of partially lithiated pyrite mixtures. Lithium cells comprising mixed pyrite cathodes demonstrate superior electrochemical performance, namely, 98–100% coulombic efficiency and 300–320 mAh g−1 (per gram of active material) after 150 cycles over a voltage range of 1.2–2.8 V at 0.1 C-rate, whereas pristine FeS2/Li cells exhibit only 220 mAh g−1 at similar operating conditions. Lowering of cut-off discharge voltage from 1.2 to 1.0 V of the FeS2/Li cells with FeS2-rich mixed cathodes is accompanied by about 15% capacity enhancement (350–450 mAh g−1 after 200 cycles). The cells with mixed pyrite composite cathodes exhibit an increase in maximum pulse power capability from 5 to 15 W/g and C-rate from 0.3 to 2.5, which points towards higher electrical conductivity of the active material as compared to the pristine pyrite.

A Sulfur-Limonene-Based Electrode for Lithium-Sulfur Batteries: High-Performance by Self-Protection.

The lithium-sulfur battery is considered as one of the most promising energy storage systems and has received enormous attentions due to its high energy density and low cost. However, polysulfide dissolution and the resulting shuttle effects hinder its practical application unless very costly solutions are considered. Herein, a sulfur-rich polymer termed sulfur-limonene polysulfide is proposed as powerful electroactive material that uniquely combines decisive advantages and leads out of this dilemma. It is amenable to a large-scale synthesis by the abundant, inexpensive, and environmentally benign raw materials sulfur and limonene (from orange and lemon peels). Moreover, owing to self-protection and confinement of lithium sulfide and sulfur, detrimental dissolution and shuttle effects are successfully avoided. The sulfur-limonene-based electrodes (without elaborate synthesis or surface modification) exhibit excellent electrochemical performances characterized by high discharge capacities (≈1000 mA h g-1 at C/2) and remarkable cycle stability (average fading rate as low as 0.008% per cycle during 300 cycles).

Rational design of self-supporting graphene - Polypyrrole/sulfur - Graphene sandwich as structural paper electrode for lithium sulfur batteries

Lithium sulfur batteries have been regarded as next-generation battery technology due to its high energy density, environmental benignity and abundance. However, the poor electric/ionic conductivity of sulfur limits the practical use of sulfur in an electrode. The main problem is the high solubility of long-chain polysulfides, which are the intermediates of the electrochemical processes in the liquid electrolyte. The dissolved polysulfide ions shuttle between the cathode and anode, thus causing precipitation of insulating Li2S2/Li2S on the surface of the electrode. The unavoidable phenomenon results in loss of active materials and fast capacity fading. In this regard, we show one simple method to prepare free-standing paper electrode used as cathode material for lithium sulfur batteries. Binder-free graphene-polypyrrole (PPy)/S-graphene (G-PPy/S-G) paper-like sandwich structural electrode was prepared by using the vacuum filtration method. In this structure, the unique graphene layers of sandwich-like framework not only serve as a conductive film, but also effectively block the diffusion of polysulfides, leading to suppression of the shuttle effect and low self-discharge behaviour. In addition, the middle layer, the PPy nanofibers can limit the diffusion of dissolved polysulfides due to the special bond with sulfur, and furthermore maintain the structural stability of the paper electrode because the nanofibers can serve as elastic springs to accommodate the huge volume changes in charging-discharging processes. When tested as cathode for Li-S batteries, the as-prepared sample G-PPy/S-G exhibits excellent electrochemical performance. We believe that our strategy could provide a useful pathway towards commercial utilizing of sulfur.

Ultrasmall titanium oxide/titanium oxynitride composite nanoparticle-embedded carbon nanofiber mats as high-capacity and free-standing electrodes for lithium sulfur batteries

TiO2/TiOxNynanoparticles loaded CNFs have been synthesized as free-standing electrodes for high performance lithium–sulfur batteries, showing high reversible capacity of 1107 mA h g−1after 100 cycles at 1C with superior capacity retention of 85%.

Edge-functionalized acetylene black anchoring sulfur for high-performance Li–S batteries

To date, most of the research on electrodes for lithium sulfur batteries has been focused on the nanostructured sulfur cathodes and achieves significant success. However, from the viewpoint of manufacturers, the nanostructured sulfur cathodes are not so promising, because of the low volumetric energy density and high cost. In this work, we obtained the low-cost, scalable, eco-friendly mass production of edge-functionalized acetylene black-sulfur (FAB-S) composites by high-energy ball-milling technique for lithium sulfur batteries. The as-prepared FAB-S composite can deliver a high initial discharge capacity of 1304mAh/g and still remain a reversible capacity of 814mAh/g after 200 cycles at a charge-discharge rate of 0.2C in the voltage range of 1.7–2.7V. The observed excellent electrochemical properties demonstrate that the cathodes obtained by the facile high-energy ball-milling method as the cathode for rechargeable Li−S batteries are of great potential because it used the sole conductive additive acetylene black (AB). Such improved properties could be attributed to the partially exfoliation of AB, which not only keeps the AB's inherent advantage, but also increases the specific surface area and forms chemical bonds between carbon and sulfur, resulting in the accumulation of the polysulfides intermediate through both the physical and chemical routes.

Nanoporous Cathodes for High-Energy Li-S Batteries from Gyroid Block Copolymer Templates.

This study reports on a facile approach to the fabrication of nanoporous carbon cathodes for lithium sulfur batteries using gyroid carbon replicas based on use of polystyrene-poly-4-vinylpyridine (PS-P4VP) block copolymers as sacrificial templates. The free-standing gyroid carbon network with a highly ordered and interconnected porous structure has been fabricated by impregnating the carbon precursor solution into the gyroid block copolymer nanotemplates and subsequently carbonizing them. A wide range of analytical tools have been employed to characterize fabricated porous carbon material. Prepared nanostructures are envisioned to have a great potential in myriad areas such as energy storage/conversion devices owing to their fascinating morphology exhibiting high surface area and uniform porosity with interconnected three-dimensional networks. The resulting carbon nanoporous structures infused with elemental sulfur have been found to work as a promising electrode for lithium sulfur batteries demonstrating a high cycling stability over more than 200 cycles.

Assembling sulfur spheres on carbon fiber with graphene coated hybrid bulk electrodes for lithium sulfur batteries

Assembling sulfur spheres on carbon fiber with graphene coated hybrid bulk electrodes for lithium sulfur batteries.