Electrocatalysts are key for renewable energy technologies and other important industrial processes. Currently, noble metals and metal oxides are the most widely used catalysts for electrocatalysis. ...However, metal‐based catalysts often suffer from multiple disadvantages, including high cost, low selectivity, poor durability, impurity poisoning and fuel crossover effects, and detrimental effects on the environment. Therefore, carbon‐based metal‐free catalysts have received increasing interest as promising electrocatalysts for advanced energy conversion and storage. Recently, tremendous progress has been achieved in the development of low‐cost, efficient carbon‐based metal‐free catalysts for renewable energy technologies and beyond. Here, a concise, but comprehensive and critical, review of recent advances in the field of carbon‐based metal‐free catalysts is provided. A brief overview of various reactions involved in renewable energy conversion and storage, including the oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, and bifunctional/multifunctional electrocatalysis, along with some challenges and opportunities, is presented.
The emerging carbon‐based metal‐free catalysts have been demonstrated to be promising alternatives to noble metal/metal oxide catalysts for various reactions, including the oxygen reduction reaction, the hydrogen evolution reaction, the oxygen evolution reaction, the carbon dioxide reduction reaction, and the nitrogen reduction reaction, and for bi/multifunctional electrocatalysis. A concise, but comprehensive and critical overview of this field, including preparation strategies, mechanisms, and applications, along with some challenges and perspectives, is presented.
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Lithium‐ion capacitors (LICs) are a game‐changer for high‐performance electrochemical energy storage technologies. Despite the many recent reviews on the materials development for LICs, the design ...principles for the LICs configuration, the possible development roadmap from academy to industry has not been adequately discussed. Systematic understanding of device development is the foundation to more efficient utilization of advanced LICs materials. This review focuses on the principle of the recent configurations of LICs, the device design rationales, and new prelithiation techniques that are an integral part in LIC design. The authors also comment on the new generation multifunctional LICs that are capable of meeting the emerging applications in flexible electronics and other modern technologies. Finally, the status of LICs is presented and several key take‐home messages about minimizing the gaps between academic and industry requirements are proposed.
Lithium‐ion capacitors (LICs) are powerful competitors to supercapacitors and batteries due to their high energy‐power performance and long lifespan. The design rationale and device configuration of LICs are introduced, followed by the prelithiation methods and fabrication of multifunctional LICs. Finally, the status of commercial LICs and a possible roadmap of advanced LICs from laboratory to industry are discussed.
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With its earth abundance and two-electron-transfer reaction mechanism, sulfur has been driving the rapid growth of metal-sulfur batteries. The practical performance of metal-sulfur batteries, ...however, is restricted by the notorious electrode processes of sulfur (such as low conductivity, intermediate loss, mass crossover,
etc.
). Sulfur conversion reactions can be stabilized and promoted through a surface immobilization strategy
via
physical confinement and chemical adsorption effects. As an emerging method in the field, covalent-bonding sulfur materials have demonstrated promise for metal-sulfur batteries. The covalent fixing of sulfur reinforces the molecular interactions between sulfur and the cathode matrix at the bulk level. In this review, we attempt to address the covalent fixing concept on the basis of the emerging studies related to covalent sulfur-containing compounds and composites in various rechargeable metal-sulfur batteries. Firstly, we briefly discuss the classification of sulfur fixing strategies and identify the uniqueness of covalently stabilized sulfur for metal-sulfur batteries. Secondly, we summarize the state-of-the-art covalent sulfur-based materials as well as their synthetic chemistry. Thirdly, we focus on lithium-sulfur batteries that feature cathodes with covalent sulfur active materials, including reaction mechanisms and material innovations. Advances in alternative alkaline metal-sulfur battery systems (sodium-sulfur and potassium-sulfur) involving covalent fixing of sulfur are also discussed. Finally, the prospective opportunities of applying the covalent fixing strategy to optimize the sulfur redox process are commented on. This contribution is anticipated to place the covalent fixing of sulfur into the spotlight and to encourage more efforts in this challenging cross-disciplinary area of organic/polymer chemistry, materials science, electrochemistry and energy technologies.
This review proposes the concept of covalent fixing as a new research strategy for sulfur electrochemistry in advanced metal-sulfur batteries.
Lithium‐sulfur (Li‐S) batteries have attracted tremendous interest because of their high theoretical energy density and cost effectiveness. The target of Li‐S battery research is to produce batteries ...with a high useful energy density that at least outperforms state‐of‐the‐art lithium‐ion batteries. However, due to an intrinsic gap between fundamental research and practical applications, the outstanding electrochemical results obtained in most Li‐S battery studies indeed correspond to low useful energy densities and are not really suitable for practical requirements. The Li‐S battery is a complex device and its useful energy density is determined by a number of design parameters, most of which are often ignored, leading to the failure to meet commercial requirements. The purpose of this review is to discuss how to pave the way for reliable Li‐S batteries. First, the current research status of Li‐S batteries is briefly reviewed based on statistical information obtained from literature. This includes an analysis of how the various parameters influence the useful energy density and a summary of existing problems in the current Li‐S battery research. Possible solutions and some concerns regarding the construction of reliable Li‐S batteries are comprehensively discussed. Finally, insights are offered on the future directions and prospects in Li‐S battery field.
The research status of Li‐S batteries is briefly reviewed based on statistical analysis results. A summary of existing problems in the current Li‐S battery research is concluded with possible solutions and some concerns comprehensively discussed. Perspectives are proposed with respect to more reliable lithium‐sulfur batteries with rationally improved performance.
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Multipartite entangled states are crucial for numerous applications in quantum information science. However, the generation and verification of multipartite entanglement on fully controllable and ...scalable quantum platforms remains an outstanding challenge. We report the deterministic generation of an 18-qubit Greenberger-Horne-Zeilinger (GHZ) state and multicomponent atomic Schrödinger cat states of up to 20 qubits on a quantum processor, which features 20 superconducting qubits, also referred to as artificial atoms, interconnected by a bus resonator. By engineering a one-axis twisting Hamiltonian, the system of qubits, once initialized, coherently evolves to multicomponent atomic Schrödinger cat states-that is, superpositions of atomic coherent states including the GHZ state-at specific time intervals as expected. Our approach on a solid-state platform should not only stimulate interest in exploring the fundamental physics of quantum many-body systems, but also enable the development of applications in practical quantum metrology and quantum information processing.
The properties of the electrolyte are the dominant factors for the overall performance and safety of electrical energy storage devices. Highly concentrated “water in salt” (WIS) electrolytes are ...inherently non-flammable, moisture-tolerant, and exhibit wide electrochemical stability windows, making them promising electrolytes for high-performance energy storage devices. However, WIS electrolytes possess intrinsically low conductivity and high viscosity, which usually impair the high-rate performance of many energy storage devices, especially supercapacitors (SCs). Additionally, the inevitable salt precipitation at low temperature for WIS electrolytes narrows down their applicable temperature range. Here, we introduce acetonitrile as a co-solvent to a typical “water in salt” electrolyte to formulate an “acetonitrile/water in salt” (AWIS) hybrid electrolyte that provides significantly improved conductivity, reduced viscosity and an expanded applicable temperature range while maintaining the aforementioned important physicochemical properties of WIS electrolytes. Using the AWIS electrolyte for a model SC remarkably enhances the high-rate performance, accompanied by a 2.4 times capacitance increase at 10 A g −1 with respect to the original WIS electrolyte. This AWIS electrolyte also enables a stable long-term cycling capability of the model SC for over 14 000 cycles at a high operation voltage of 2.2 V.
Their chemical stability, high specific surface area, and electric conductivity enable porous carbon materials to be the most commonly used electrode materials for electrochemical capacitors (also ...known as supercapacitors). To further increase the energy and power density, engineering of the pore structures with a higher electrochemical accessible surface area, faster ion‐transport path and a more‐robust interface with the electrolyte is widely investigated. Compared with traditional porous carbons, two‐dimensional (2D) porous carbon sheets with an interlinked hierarchical porous structure are a good candidate for supercapacitors due to their advantages in high aspect ratio for electrode packing and electron transport, hierarchical pore structures for ion transport, and short ion‐transport length. Recent progress on the synthesis of 2D porous carbons is reported here, along with the improved electrochemical behavior due to enhanced ion transport. Challenges for the controlled preparation of 2D porous carbons with desired properties are also discussed; these require precise tuning of the hierarchical structure and a clarification of the formation mechanisms.
Two‐dimensional (2D) porous carbon sheets, which can be synthesized by templating approaches, biomass carbonization, biomass carbonization–activation, in situ activation, etc, are good candidates for supercapacitors due to their advantages in their short ion‐transport length and high aspect ratio for electrode packing and electron transport.
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Sodium‐ion batteries (SIBs) have the potential to be practically applied in large‐scale energy storage markets. The rapid progress of SIBs research is primarily focused on electrodes, while ...electrolytes attract less attention. Indeed, the improvement of electrode performance is arguably correlated with the electrolyte optimization. In conventional lithium‐ion batteries (LIBs), ether‐based electrolytes are historically less practical owing to the insufficient passivation of both anodes and cathodes. As an important class of aprotic electrolytes, ethers have revived with the emerging lithium‐sulfur and lithium‐oxygen batteries in recent years, and are even booming in the wave of SIBs. Ether‐based electrolytes are unique to enabling these new battery chemistries in terms of producing stable ternary graphite intercalation compounds, modifying anode solid electrolyte interphases, reducing the solubility of intermediates, and decreasing polarization. Better still, ether‐based electrolytes are compatible with specific inorganic cathodes and could catalyze the assembly of full SIBs prototypes. This Research News article aims to summarize the recent critical reports on ether‐based electrolytes in sodium‐based batteries, to unveil the uniqueness of ether‐based electrolytes to advancing diverse electrode materials, and to shed light on the viability and challenges of ether‐based electrolytes in future sodium‐based battery chemistries.
In this Research News article, the unique advantages of ether‐based electrolytes in enabling new sodium‐based battery chemistries are highlighted in depth. Full sodium‐based battery prototypes based on ether‐based electrolytes are also summarized. Moreover, the future feasibility as well as challenges of ether‐based electrolytes in sodium‐based batteries are discussed in detail.
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Tackling the huge volume expansion of silicon (Si) anode desires a stable solid electrolyte interphase (SEI) to prohibit the interfacial side reactions. Here, a layered conductive polyaniline (LCP) ...coating is built on Si nanoparticles to achieve high areal capacity and long lifespan. The conformal LCP coating stores electrolyte in interlamination spaces and directs an in situ formation of LCP‐integrated hybrid SEI skin with uniform distribution of organic and inorganic components, enhancing the flexibility of the SEI to buffer the volume changes and maintaining homogeneous ion transport during cycling. As a result, the Si anode shows a remarkable cycling stability under high areal capacity (≈3 mAh cm−2) after 150 cycles and good rate performance of 942 mAh g−1 at 5 A g−1. This work demonstrates the great potential of regulating the SEI properties by a layered polymer‐directing SEI formation for the mechanical and electrochemical stabilization of Si anodes.
A layered conductive polyaniline (LCP) coating is built from a bottom‐up polymer design strategy for Si anodes. The in situ formation of LCP‐integrated solid electrolyte interphase (SEI) with uniform structure and flexible mechanical property enhances the stability of the electrode–electrolyte interface.
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Carbon materials are usually used as the sulfur host in rechargeable lithium–sulfur (Li–S) batteries that are considered as promising electrochemical energy storage systems. However, the “shuttling” ...caused by the soluble lithium polysulfides (LiPSs) formed by the reaction of Li and sulfur causes rapid capacity fade and low sulfur utilization, greatly hindering their practical use. The carbon materials can also be tailored to prevent LiPS shuttling because of their abundant porosity and controllable surface chemical properties, which are divided into four specific functions: confining, trapping, blocking, and breaking up. Confinement means physically confining the LiPSs in pores in the carbon while trapping refers to chemical adsorption on the carbon surface to restrict their diffusion and promote their transformation to insoluble Li2S2/Li2S. Blocking means placing a barrier in the cells to inhibit LiPS diffusion to the anode, while breaking up means decreasing the size of the sulfur moiety to increase its affinity with carbons. The advantages and disadvantages of functional carbons in relation to these four functions are summarized and the specific ways to achieve them are highlighted. The design of advanced carbons with synergistic functions is discussed and some perspectives on the future development of carbons in Li–S batteries are given.
Functional carbon materials are widely used in lithium–sulfur batteries to remedy the shuttling of lithium polysulfides, which can be generalized into four different functions: confining, trapping, blocking, and breaking up. Research advances for the design of carbons with different roles and the corresponding performance improvement are discussed in detail. The perspectives on the challenges and solutions for future applications are proposed.
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