A Conductive Molecular Framework Derived Li2S/N,P‐Codoped Carbon Cathode for Advanced Lithium–Sulfur Batteries
TL;DR: Li2S is one of the most promising cathode materials for Li-ion batteries because of its high theoretical capacity and compatibility with Li-metal-free anode materials as mentioned in this paper.
Abstract: Li2S is one of the most promising cathode materials for Li-ion batteries because of its high theoretical capacity and compatibility with Li-metal-free anode materials. However, the poor conductivity and electrochemical reactivity lead to low initial capacity and severe capacity decay. In this communication, a nitrogen and phosphorus codoped carbon (N,P–C) framework derived from phytic acid doped polyaniline hydrogel is designed to support Li2S nanoparticles as a binder-free cathode for Li–S battery. The porous 3D architecture of N and P codoped carbon provides continuous electron pathways and hierarchically porous channels for Li ion transport. Phosphorus doping can also suppress the shuttle effect through strong interaction between sulfur and the carbon framework, resulting in high Coulombic efficiency. Meanwhile, P doping in the carbon framework plays an important role in improving the reaction kinetics, as it may help catalyze the redox reactions of sulfur species to reduce electrochemical polarization, and enhance the ionic conductivity of Li2S. As a result, the Li2S/N,P–C composite electrode delivers a stable capacity of 700 mA h g−1 with average Coulombic efficiency of 99.4% over 100 cycles at 0.1C and an areal capacity as high as 2 mA h cm−2 at 0.5C.
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TL;DR: Recent advances regarding defect engineering in electrode materials for rechargeable batteries are systematically summarized, with a special focus on the application of metal-ion batteries, lithium-sulfur batteries, and metal-air batteries.
Abstract: The reasonable design of electrode materials for rechargeable batteries plays an important role in promoting the development of renewable energy technology. With the in-depth understanding of the mechanisms underlying electrode reactions and the rapid development of advanced technology, the performance of batteries has significantly been optimized through the introduction of defect engineering on electrode materials. A large number of coordination unsaturated sites can be exposed by defect construction in electrode materials, which play a crucial role in electrochemical reactions. Herein, recent advances regarding defect engineering in electrode materials for rechargeable batteries are systematically summarized, with a special focus on the application of metal-ion batteries, lithium-sulfur batteries, and metal-air batteries. The defects can not only effectively promote ion diffusion and charge transfer but also provide more storage/adsorption/active sites for guest ions and intermediate species, thus improving the performance of batteries. Moreover, the existing challenges and future development prospects are forecast, and the electrode materials are further optimized through defect engineering to promote the development of the battery industry.
507 citations
TL;DR: This review highlights the highly tunable synthesis of various hydrogels, involving key synthetic elements such as monomer/polymer building blocks, cross-linkers, and functional additives, and discusses how hydrogles can be employed as precursors and templates for architecting three-dimensional frameworks of electrochemically active materials.
Abstract: Energy and water are of fundamental importance for our modern society, and advanced technologies on sustainable energy storage and conversion as well as water resource management are in the focus of intensive research worldwide. Beyond their traditional biological applications, hydrogels are emerging as an appealing materials platform for energy- and water-related applications owing to their attractive and tailorable physiochemical properties. In this review, we highlight the highly tunable synthesis of various hydrogels, involving key synthetic elements such as monomer/polymer building blocks, cross-linkers, and functional additives, and discuss how hydrogels can be employed as precursors and templates for architecting three-dimensional frameworks of electrochemically active materials. We then present an in-depth discussion of the structure-property relationships of hydrogel materials based on fundamental gelation chemistry, ultimately targeting properties such as enhanced ionic/electronic conductivities, mechanical strength, flexibility, stimuli-responsiveness, and desirable swelling behavior. The unique interconnected porous structures of hydrogels enable fast charge/mass transport while offering large surface areas, and the polymer-water interactions can be regulated to achieve desirable water retention, absorption, and evaporation within hydrogels. Such structure-derived properties are also intimately coordinated to realize multifunctionality and stability for different target devices. The plethora of stimulating examples is expounded with a focus on batteries, supercapacitors, electrocatalysts, solar water purification, and atmospheric water harvesting, which showcase the unprecedented technological potential enabled by hydrogels and hydrogel-derived materials. Finally, we study the challenges and potential ways of tackling them to reveal the underlying mechanisms and transform the current development of hydrogel materials into sustainable energy and water technologies.
485 citations
TL;DR: A 3D nanostructured hydrogel-derived Li0.35 La0.55 TiO3 (LLTO) framework was designed and the systematic percolation study revealed that the pre-percolating structure of LLTO framework improved Li-ion conductivity to 8.8×10-5 S cm-1 at room temperature.
Abstract: Solid-state electrolytes have emerged as a promising alternative to existing liquid electrolytes for next generation Li-ion batteries for better safety and stability. Of various types of solid electrolytes, composite polymer electrolytes exhibit acceptable Li-ion conductivity due to the interaction between nanofillers and polymer. Nevertheless, the agglomeration of nanofillers at high concentration has been a major obstacle for improving Li-ion conductivity. In this study, we designed a three-dimensional (3D) nanostructured hydrogel-derived Li0.35 La0.55 TiO3 (LLTO) framework, which was used as a 3D nanofiller for high-performance composite polymer Li-ion electrolyte. The systematic percolation study revealed that the pre-percolating structure of LLTO framework improved Li-ion conductivity to 8.8×10-5 S cm-1 at room temperature.
440 citations
TL;DR: In this article, the intrinsic modulation essence of the anions of CoP/rGO was decoded and the performance variations mainly originate from the shift of p band centers, which modulates the interfacial electron transfer dynamics.
349 citations
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TL;DR: The battery systems reviewed here include sodium-sulfur batteries that are commercially available for grid applications, redox-flow batteries that offer low cost, and lithium-ion batteries whose development for commercial electronics and electric vehicles is being applied to grid storage.
Abstract: The increasing interest in energy storage for the grid can be attributed to multiple factors, including the capital costs of managing peak demands, the investments needed for grid reliability, and the integration of renewable energy sources. Although existing energy storage is dominated by pumped hydroelectric, there is the recognition that battery systems can offer a number of high-value opportunities, provided that lower costs can be obtained. The battery systems reviewed here include sodium-sulfur batteries that are commercially available for grid applications, redox-flow batteries that offer low cost, and lithium-ion batteries whose development for commercial electronics and electric vehicles is being applied to grid storage.
11,144 citations
TL;DR: The energy that can be stored in Li-air and Li-S cells is compared with Li-ion; the operation of the cells is discussed, as are the significant hurdles that will have to be overcome if such batteries are to succeed.
Abstract: Li-ion batteries have transformed portable electronics and will play a key role in the electrification of transport. However, the highest energy storage possible for Li-ion batteries is insufficient for the long-term needs of society, for example, extended-range electric vehicles. To go beyond the horizon of Li-ion batteries is a formidable challenge; there are few options. Here we consider two: Li-air (O(2)) and Li-S. The energy that can be stored in Li-air (based on aqueous or non-aqueous electrolytes) and Li-S cells is compared with Li-ion; the operation of the cells is discussed, as are the significant hurdles that will have to be overcome if such batteries are to succeed. Fundamental scientific advances in understanding the reactions occurring in the cells as well as new materials are key to overcoming these obstacles. The potential benefits of Li-air and Li-S justify the continued research effort that will be needed.
7,895 citations
TL;DR: In this paper, the authors report the feasibility to approach such capacities by creating highly ordered interwoven composites, where conductive mesoporous carbon framework precisely constrains sulphur nanofiller growth within its channels and generates essential electrical contact to the insulating sulphur.
Abstract: The Li-S battery has been under intense scrutiny for over two decades, as it offers the possibility of high gravimetric capacities and theoretical energy densities ranging up to a factor of five beyond conventional Li-ion systems. Herein, we report the feasibility to approach such capacities by creating highly ordered interwoven composites. The conductive mesoporous carbon framework precisely constrains sulphur nanofiller growth within its channels and generates essential electrical contact to the insulating sulphur. The structure provides access to Li+ ingress/egress for reactivity with the sulphur, and we speculate that the kinetic inhibition to diffusion within the framework and the sorption properties of the carbon aid in trapping the polysulphides formed during redox. Polymer modification of the carbon surface further provides a chemical gradient that retards diffusion of these large anions out of the electrode, thus facilitating more complete reaction. Reversible capacities up to 1,320 mA h g(-1) are attained. The assembly process is simple and broadly applicable, conceptually providing new opportunities for materials scientists for tailored design that can be extended to many different electrode materials.
5,151 citations
3,654 citations
TL;DR: A mesoporous carbon foam co-doped with nitrogen and phosphorus that has a large surface area and good electrocatalytic properties for both ORR and OER and is tested as an air electrode for primary and rechargeable Zn-air batteries.
Abstract: A co-doped carbon material, methods of making such materials, and electrochemical cells and devices comprising such materials are provided. The co-doped carbon material comprises a mesoporous carbon material doped with nitrogen and phoshporous (NPMC). The present NPMC exhibit catalytic activity for both oxygen reduction reaction and oxygen evolution reaction and may be useful as an electrode in an electrochemical cell and particularly as part of a battery. The present NPMC materials may be used as electrodes in primary zinc-air batteries and in rechargeable zinc-air batteries and many other energy systems.
2,425 citations