Rechargeable lithium-sulfur batteries.

Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields

Lithium-sulfur (Li-S) batteries with high energy density and long cycle life are considered to be one of the most promising next-generation energy-storage systems beyond routine lithium-ion batteries. Various approaches have been proposed to break down technical barriers in Li-S battery systems. The use of nanostructured metal oxides and sulfides for high sulfur utilization and long life span of Li-S batteries is reviewed here. The relationships between the intrinsic properties of metal oxide/sulfide hosts and electrochemical performances of Li-S batteries are discussed. Nanostructured metal oxides/sulfides hosts used in solid sulfur cathodes, separators/interlayers, lithium-metal-anode protection, and lithium polysulfides batteries are discussed respectively. Prospects for the future developments of Li-S batteries with nanostructured metal oxides/sulfides are also discussed.

Nanostructured Metal Oxides and Sulfides for Lithium-Sulfur Batteries

Development of advanced energy-storage systems for portable devices, electric vehicles, and grid storage must fulfill several requirements: low-cost, long life, acceptable safety, high energy, high power, and environmental benignity. With these requirements, lithium-sulfur (Li-S) batteries promise great potential to be the next-generation high-energy system. However, the practicality of Li-S technology is hindered by technical obstacles, such as short shelf and cycle life and low sulfur content/loading, arising from the shuttling of polysulfide intermediates between the cathode and anode and the poor electronic conductivity of S and the discharge product Li2 S. Much progress has been made during the past five years to circumvent these problems by employing sulfur-carbon or sulfur-polymer composite cathodes, novel cell configurations, and lithium-metal anode stabilization. This Progress Report highlights recent developments with special attention toward innovation in sulfur-encapsulation techniques, development of novel materials, and cell-component design. The scientific understanding and engineering concerns are discussed at the end in every developmental stage. The critical research directions needed and the remaining challenges to be addressed are summarized in the Conclusion.

Lithium–Sulfur Batteries: Progress and Prospects

https://iopscience.iop.org/article/10.1088/1468-6996/16/2/023501/pdf

Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications.

Dopamine is an excellent and flexible agent for surface coating of inorganic nanoparticles and contains unusually high concentrations of amine groups. In this study, we demonstrate that through a controlled coating of a thin layer of polydopamine on the surface of α-Fe(2)O(3) in the dopamine aqueous solution, followed by subsequent carbonization, N-doped carbon-encapsulated magnetite has been synthesized and shows excellent electrochemical performance as anode material for lithium-ion batteries. Due to the strong binding affinity to iron oxide and excellent coating capability of this new carbon precursor, the conformal polydopamine derived carbon is continuous and uniform, and its thickness can be tailored. Moreover, due to the high percentage of nitrogen content in the precursor, the resulting carbon layer contains a moderate amount of N species, which can substantially improve the electrochemical performance. The composites synthesized by this facile method exhibit superior electrochemical performance, including remarkably high specific capacity (>800 mA h g(-1) at a current of 500 mA g(-1)), high rate capability (595 and 396 mA h g(-1) at a current of 1000 and 2000 mA g(-1), respectively) and excellent cycle performance (200 cycles with 99% capacity retention), which adds to the potential as promising anodes for the application in lithium-ion batteries.

Dopamine as the coating agent and carbon precursor for the fabrication of N-doped carbon coated Fe3O4 composites as superior lithium ion anodes

Novel multifunctional composites composed of highly dispersed nanosized Fe2O3 particles, a tubular mesoporous carbon host, and a conductive polypyrrole (PPy) sealing layer are hierarchically assembled via two facile processes, including bottom-up introduction of Fe2O3 nanoparticles in tubular mesoporous carbons, followed by in situ surface sealing with the PPy coating. Fe2O3 particles are well-dispersed within the carbon matrix and PPy is spatially and selectively coated onto the external surface and the pore entrances of the Fe2O3@C composite, thereby bridging the composite particles together into a larger unit. As an anode material for Li-ion batteries (LIBs), the PPy-coated Fe2O3@C composite exhibits stable cycle performance. Additionally, the PPy-coated Fe2O3@C composite also possesses fast electrode reaction kinetics, high Fe2O3 use efficiency, and large volumetric capacity. The excellent electrochemical performance is associated with a synergistic effect of the highly porous carbon matrix and the conducting PPy sealing layer. Such multifunctional configuration prevents the aggregation of NPs and maintains the structural integrity of active materials, in addition to effectively enhancing the electronic conductivity and warranting the stability of as-formed solid electrolyte interface (SEI) films. This nanoengineering strategy might open new avenues for the design of other multifunctional composite architectures as electrode materials in order to achieve high-performance LIBs.

Nanoengineered Polypyrrole‐Coated Fe2O3@C Multifunctional Composites with an Improved Cycle Stability as Lithium‐Ion Anodes

Porous carbon materials with large pore volume are crucial in loading insulated sulfur with the purpose of achieving high performance for lithium–sulfur batteries. In our study, peapodlike mesoporous carbon with interconnected pore channels and large pore volume (4.69 cm3 g–1) was synthesized and used as the matrix to fabricate carbon/sulfur (C/S) composite which served as attractive cathodes for lithium–sulfur batteries. Systematic investigation of the C/S composite reveals that the carbon matrix can hold a high but suitable sulfur loading of 84 wt %, which is beneficial for improving the bulk density in practical application. Such controllable sulfur-filling also effectively allows the volume expansion of active sulfur during Li+ insertion. Moreover, the thin carbon walls (3–4 nm) of carbon matrix not only are able to shorten the pathway of Li+ transfer and conduct electron to overcome the poor kinetics of sulfur cathode, but also are flexible to warrant structure stability. Importantly, the peapodlike ...

High Sulfur Loading Cathodes Fabricated Using Peapodlike, Large Pore Volume Mesoporous Carbon for Lithium–Sulfur Battery

An effective strategy is explored for the in situ generation of a Cu2S/tubular mesoporous carbon composite by exploiting the charge–discharge processes of a S/C composite on a copper-foil current collector. By studying the reaction mechanism, we discover that the dissolved polysulfide ions (from the reaction of pristine sulfur) and inserted Li+ are firmly anchored by the copper ions released from the copper foil, which forms insoluble CuxS intermediates in the mesopore channels of the carbon matrix. Moreover, the new electrochemically active CuxS intermediates are gradually converted to the final product, Cu2S, during subsequent cycles. The as-prepared Cu2S nanoparticles are highly dispersed throughout the tubular mesoporous carbon, and the Cu2S/C composite exhibits a high reversible capacity of 270 mAh g−1 at 0.2 C over 300 cycles, with the negligible capacity loss, when used as a cathode material for a lithium-ion battery. Furthermore, the composite shows an outstanding rate capability with a reversible capacity of 225 mAh g−1 under a high rate of 10 C. This work provides a convenient platform for the controlled synthesis of metal sulfides for lithium-storage applications.

In Situ Electrochemical Generation of Mesostructured Cu2S/C Composite for Enhanced Lithium Storage: Mechanism and Material Properties

Porous carbon nanofibers (CNFs) are regarded as essential components of high-performance energy storage devices in the development of renewable and sustainable resources, due to their high surface areas, tunable structures, and good conductivities. Herein, we report new synthesis methods and applications of two types of porous carbon nanofibers, i.e., colloidal mesoporous carbon nanofibers as electrode materials for supercapacitors, and microporous carbon nanofibers as substrate media for lithium–sulfur (Li-S) batteries. These carbon nanofibers can be synthesized either by confined nanospace pyrolysis or conventional pyrolysis of their polymeric precursors. The supercapacitor electrodes which are fabricated via a simple dipping and rinsing approach exhibit a reversible specific capacitance of 206 F g−1 at the current density of 5 A g−1 in 6.0 mol L−1 aqueous KOH electrolyte. Meanwhile, the Li-S batteries composed of microporous carbon nanofiber-encapsulated sulfur structures exhibit unprecedented electrochemical performance with high specific capacity and good cycling stability, i.e., 950 mA h g−1 after 50 cycles of charge–discharge. The excellent electrochemical performance of CNFs is attributed to their high-quality fiber morphology, controlled porous structure, large surface area, and good electrical conductivity. The results show that the carbon nanofibers represent an alternative promising candidate for an efficient electrode material for energy storage and conversion.

Duo Li

Papers

Dopamine as the coating agent and carbon precursor for the fabrication of N-doped carbon coated Fe3O4 composites as superior lithium ion anodes

Nanoengineered Polypyrrole‐Coated Fe2O3@C Multifunctional Composites with an Improved Cycle Stability as Lithium‐Ion Anodes

High Sulfur Loading Cathodes Fabricated Using Peapodlike, Large Pore Volume Mesoporous Carbon for Lithium–Sulfur Battery

In Situ Electrochemical Generation of Mesostructured Cu2S/C Composite for Enhanced Lithium Storage: Mechanism and Material Properties

Synthesis of superior carbon nanofibers with large aspect ratio and tunable porosity for electrochemical energy storage