Self‐healing ability is an important survival feature in nature, with which living beings can spontaneously repair damage when wounded. Inspired by nature, people have designed and synthesized many ...self‐healing materials by encapsulating healing agents or incorporating reversible covalent bonds or noncovalent interactions into a polymer matrix. Among the noncovalent interactions, the coordination bond is demonstrated to be effective for constructing highly efficient self‐healing polymers. Moreover, with the presence of functional metal ions or ligands and dynamic metal–ligand bonds, self‐healing polymers can show various functions such as dielectrics, luminescence, magnetism, catalysis, stimuli‐responsiveness, and shape‐memory behavior. Herein, the recent developments and achievements made in the field of self‐healing polymers based on coordination bonds are presented. The advantages of coordination bonds in constructing self‐healing polymers are highlighted, the various metal–ligand bonds being utilized in self‐healing polymers are summarized, and examples of functional self‐healing polymers originating from metal–ligand interactions are given. Finally, a perspective is included addressing the promises and challenges for the future development of self‐healing polymers based on coordination bonds.
Coordination bonds have been demonstrated to be effective for constructing self‐healing polymers in recent years. The advantages of coordination bonds in constructing self‐healing polymers are discussed, and the various metal–ligand bonds being utilized in self‐healing polymers along with some examples of functional self‐healing polymers originating from metal–ligand interactions are summarized. A few concerns and future directions in this research field are proposed.
Flexible electrochemical energy storage (FEES) devices have received great attention as a promising power source for the emerging field of flexible and wearable electronic devices. Carbon nanotubes ...(CNTs) and graphene have many excellent properties that make them ideally suited for use in FEES devices. A brief definition of FEES devices is provided, followed by a detailed overview of various structural models for achieving different FEES devices. The latest research developments on the use of CNTs and graphene in FEES devices are summarized. Finally, future prospects and important research directions in the areas of CNT‐ and graphene‐based flexible electrode synthesis and device integration are discussed.
Carbon nanotubes (CNTs) and graphene for flexible electrochemical energy storage are reviewed. A definition of flexible devices, followed by an overview of the various structural models for achieving different flexible devices is provided. The use of CNTs and graphene in flexible devices is summarized. Future prospects and important research directions of flexible electrode are introduced.
Next‐generation batteries based on conversion reactions, including aqueous metal–air batteries, nonaqueous alkali metal‐O2 and ‐CO2 batteries, alkali metal‐chalcogen batteries, and alkali metal‐ion ...batteries have attracted great interest. However, their use is restricted by inefficient reversible conversion of active agents. Developing bifunctional catalysts to accelerate the conversion reaction kinetics in both discharge and charge processes is urgently needed. Graphene‐, or graphene‐like carbon‐supported atomically dispersed metal catalysts (G‐ADMCs) have been demonstrated to show excellent activity in various electrocatalytic reactions, making them promising candidates. Different from G‐ADMCs for catalysis, which only require high activity in one direction, G‐ADMCs for rechargeable batteries should provide high activity in both discharging and charging. This review provides guidance for the design and fabrication of bifunctional G‐ADMCs for next‐generation rechargeable batteries based on conversion reactions. The key challenges that prevent their reversible conversion, the origin of the activity of bifunctional G‐ADMCs, and the current design principles of bifunctional G‐ADMCs for highly reversible conversion, have been analyzed and highlighted for each conversion‐type battery. Finally, a summary and outlook on the development of bifunctional G‐ADMC materials for next‐generation batteries with a high energy density and excellent energy efficiency are given.
This review analyzes the key factors that hinder the reversible conversion of conversion‐type materials, provides a fundamental understanding of graphene‐, or graphene‐like carbon‐supported atomically dispersed metal catalysts (G‐ADMCs), and provides guidance on the bifunctional G‐ADMCs to be used in high‐performance next‐generation batteries, including aqueous metal–air batteries, nonaqueous alkali metal‐O2 and ‐CO2 batteries, alkali metal‐chalcogen batteries, and alkali metal‐ion batteries.
Single‐atom metal catalysts (SACs) are used as sulfur cathode additives to promote battery performance, although the material selection and mechanism that govern the catalytic activity remain ...unclear. It is shown that d‐p orbital hybridization between the single‐atom metal and the sulfur species can be used as a descriptor for understanding the catalytic activity of SACs in Li–S batteries. Transition metals with a lower atomic number are found, like Ti, to have fewer filled anti‐bonding states, which effectively bind lithium polysulfides (LiPSs) and catalyze their electrochemical reaction. A series of single‐atom metal catalysts (Me = Mn, Cu, Cr, Ti) embedded in three‐dimensional (3D) electrodes are prepared by a controllable nitrogen coordination approach. Among them, the single‐atom Ti‐embedded electrode has the lowest electrochemical barrier to LiPSs reduction/Li2S oxidation and the highest catalytic activity, matching well with the theoretical calculations. By virtue of the highly active catalytic center of single‐atom Ti on the conductive transport network, high sulfur utilization is achieved with a low catalyst loading (1 wt.%) and a high area‐sulfur loading (8 mg cm−2). With good mechanical stability for bending, these 3D electrodes are suitable for fabricating bendable/foldable Li–S batteries for wearable electronics.
A descriptor, the d–p hybridization state between single‐atom metal catalysts (SACs) and sulfur species, is proposed to guide the design of SACs for Li–S batteries. The large‐sized and flexible 3D electrodes with optimized SACs achieve high specific energy with low catalyst loading and high sulfur loading. The good mechanical stability for bending also shows potential for fabricating bendable/foldable Li–S batteries.
Lithium metal batteries (LMBs) are considered promising candidates for next‐generation battery systems due to their high energy density. However, commercialized carbonate electrolytes cannot be used ...in LMBs due to their poor compatibility with lithium metal anodes. While increasing cut‐off voltage is an effective way to boost the energy density of LMBs, conventional ethylene carbonate‐based electrolytes undergo a number of side reactions at high voltages. It is therefore critical to upgrade conventional carbonate electrolytes, the performance of which is highly influenced by the solvation structure of lithium ions (Li+). This review provides a comprehensive overview of the strategies to regulate the solvation structure of Li+ in carbonate electrolytes for LMBs by better understanding the science behind the Li+ solvation structure and Li+ behavior. Different strategies are systematically compared to help select better electrolytes for specific applications. The remaining scientific and technical problems are pointed out, and directions for future research on carbonate electrolytes for LMBs are proposed.
The performance of carbonate electrolytes for lithium metal batteries (LMBs) is highly influenced by the solvation structure of Li+. A comprehensive overview of strategies is presented for regulating the solvation structure of Li+ in carbonate electrolytes to improve Li+ behavior and the performance of LMBs. The remaining questions and perspectives for advanced carbonate electrolytes for LMBs are also outlined.
Poly(ethylene oxide) (PEO)‐based electrolytes are promising for all‐solid‐state batteries but can only be used above room temperature due to the high‐degree crystallization of PEO and the intimate ...affinity between ethylene oxide (EO) chains and lithium ions. Here, a homogeneous‐inspired design of PEO‐based solid‐state electrolytes with fast ion conduction is proposed. The homogeneous PEO‐based solid‐state electrolyte with an adjusted succinonitrile (SN) and PEO molar ratio simultaneously suppresses the PEO crystallization and mitigates the affinity between EO and Li+. By adjusting the molar ratio of SN to PEO (SN:EO ≈ 1:4), channels providing fast Li+ transport are formed within the homogeneous solid‐state polymer electrolyte, which increases the ionic conductivity by 100 times and enables their application at a low temperature (0–25 °C), together with the uniform lithium deposition. This modified PEO‐based electrolyte also enables a LiFePO4 cathode to achieve a superior Coulombic efficiency (>99%) and have a long life (>750 cycles) at room temperature. Moreover, even at a low temperature of 0 °C, 82% of its room‐temperature capacity remains, demonstrating the great potential of this electrolyte for practical solid‐state lithium battery applications.
Homogeneous‐inspired design of solid‐state polymer electrolytes with fast ion conduction is proposed. By adjusting the molar ratio of succinonitrile to poly(ethylene oxide) (SN:EO≈1:4), channels providing fast Li+ transport are formed within the homogeneous solid‐state polymer electrolyte, which increases the ionic conductivity by 100 times and enables their application at a low temperature (0–25 °C).
Rocking‐chair based lithium‐ion batteries (LIBs) have extensively applied to consumer electronics and electric vehicles (EVs) for solving the present worldwide issues of fossil fuel exhaustion and ...environmental pollution. However, due to the growing unprecedented demand of LIBs for commercialization in EVs and grid‐scale energy storage stations, and a shortage of lithium and cobalt, the increasing cost gives impetus to exploit low‐cost rechargeable battery systems. Dual‐ion batteries (DIBs), in which both cations and anions are involved in the electrochemical redox reaction, are one of the most promising candidates to meet the low‐cost requirements of commercial applications, because of their high working voltage, excellent safety, and environmental friendliness compared to conventional rocking‐chair based LIBs. However, DIB technologies are only at the stage of fundamental research and considerable effort is required to improve the energy density and cycle life further. We review the development history and current situation, and discuss the reaction kinetics involved in DIBs, including various anionic intercalation mechanism of cathodes, and the reactions at the anodes including intercalation and alloying to explore promising strategies towards low‐cost DIBs with high performance.
Beyond conventional batteries: This Review presents the development history and state of the art of DIBs and presents the reaction kinetics and corresponding critical issues including the various anionic intercalation mechanisms of cathodes, and the reactions at the anodes, including intercalation and alloying, to explore promising strategies towards low‐cost DIBs with high performance.
Extensive research on two-dimensional (2D) materials has triggered the renaissance of an old topic, that is, the intercalation and exfoliation of layer materials. Such top-down exfoliation produced ...2D materials and their dispersions have several advantages including low cost, scalable production capability, solution processability, and versatile functionalities stemming from the large number of species of layer materials, and show promising potential in many applications. In recent years, many new methods have been developed for exfoliating layer materials to 2D materials for different application purposes. In this review the different exfoliation approaches are first systematically analyzed from the viewpoint of methodology, and the advantages and disadvantages of each method are compared. Second, the assembly of exfoliated 2D materials into macrostructures by solution-based techniques is summarized. Third, the state-of-the-art applications of 2D material dispersions and their assemblies in electronics and optoelectronics, electrocatalysis, energy storage,
etc.
, are discussed. Finally, insights and perspectives on current research challenges and future opportunities regarding the exfoliation and applications of 2D materials in dispersions are considered.
A comprehensive review on the exfoliation of layer materials into 2D materials, their assembly, and applications in electronics and energy.
Lithium–sulfur (Li–S) batteries are highly appealing for next‐generation electrochemical energy storage owing to their high theoretical energy density, environmental friendliness, and low cost. ...However, the insulating nature of sulfur and migration of dissolved polysulfide intermediates lead to low active material utilization and fast capacity decay, which pose a significant challenge to their practical applications. Here, this paper reports a multifunctional carbon hybrid with metal–organic frameworks (MOFs)‐derived nitrogen‐doped porous carbon anchored on graphene sheets (NPC/G) serving as a sulfur host. On the one hand, the high surface area and nitrogen‐doping of the carbon nanoparticles enable effective polysulfide immobilization through both physical confinement and chemical adsorption; on the other hand, the highly conductive graphene provides an interconnected conductive framework to facilitate fast electron transport, improving the sulfur utilization. As a result, the NPC/G‐based sulfur cathode exhibits a high specific capacity of 1372 mAh g−1 with good cycling stability over 300 cycles. This approach provides a promising approach for the design of MOFs‐derived carbon materials for high performance Li–S batteries.
A multifunctional carbon hybrid with metal–organic frameworks‐derived nitrogen‐doped porous carbon in situ formed on graphene sheets is prepared for sulfur accommodation. Benefiting from the high conductivity, abundant pore structure and nitrogen doping of the carbon hybrid, the as‐obtained sulfur electrode shows excellent electrochemical performance with a high specific capacity of 1372 mAh g−1 and good cycling stability over 300 cycles.
Graphene is a potential nanofiller that can dramatically improve the properties of polymer‐based composites at a very low loading. This article reviews the state‐of‐the‐art progress in the ...fabrication, properties, and uses of polymer composites with different kinds of graphene fillers. The results so far reported in the literature indicate that graphene/polymer composites are promising multifunctional materials with significantly improved tensile strength and elastic modulus, electrical and thermal conductivity, etc. Despite some challenges and the fact that carbon naotube/polymer composites are sometimes better in some particular performance, graphene/polymer composites may have wide potential applications due to their outstanding properties and the availability of graphene in a large quantity at low cost.
Review: The recent development in the fabrication, properties, applications and fundamental challenges of graphene/polymer composites is reviewed. Graphene/polymer composites are promising multifunctional materials with significantly improved mechanical, electrical, and thermal properties and may have wide potential applications.
