Graphene and graphene oxide (GO), as wonder materials, have penetrated nearly every field of research. One of their most attractive features is the functionality and assembly of graphene or GO, in ...which they can be considered to be chemically functionalized building blocks for creating unconventional porous graphene materials (PGMs) that not only combine the merits of both porous materials and graphene, but also have major advantages over other porous carbons for specific applications. The chemistry and approaches for functionalizing graphene and GO are first introduced, and typical procedures for pore creation (e.g., in‐plane pores, 2D laminar pores, and 3D interconnected pore assemblies), self‐assembly, and tailoring mechanisms for PGMs to highlight the significance of precise control over the pore morphology and pore size are summarized. Because of their unique pore structures, with different morphologies and intriguing properties, PGMs serve as key components in a variety of applications such as energy storage, electrocatalysis, and molecular separation. Finally, the challenges relating to PGMs from the understanding of chemical self‐assembly to specific applications are discussed, and promising solutions on how to tackle them are presented. This provides an insightful outlook for the future development of the chemistry and applications of PGMs.
Recent advances in the chemistry of graphene and porous graphene materials, including surface chemistry, interface chemistry, assembly chemistry, and functionalization chemistry, and their potential applications are reviewed. Additionally, their porous structure‐performance relationships for energy storage and conversion, electrocatalysis, and molecular separation are summarized.
Accurately placing very small amounts of electrolyte on tiny micro-supercapacitors (MSCs) arrays in close proximity is a major challenge. This difficulty hinders the development of densely-compact ...monolithically integrated MSCs (MIMSCs). To overcome this grand challenge, we demonstrate a controllable electrolyte directed assembly strategy for precise isolation of densely-packed MSCs at micron scale, achieving scalable production of MIMSCs with ultrahigh areal number density and output voltage. We fabricate a patterned adhesive surface across MIMSCs, that induce electrolyte directed assembly on 10,000 highly adhesive MSC regions, achieving a 100 µm-scale spatial separation between each electrolyte droplet within seconds. The resultant MIMSCs achieve an areal number density of 210 cells cm
and a high areal voltage of 555 V cm
. Further, cycling the MIMSCs at 190 V over 9000 times manifests no performance degradation. A seamlessly integrated system of ultracompact wirelessly-chargeable MIMSCs is also demonstrated to show its practicality and versatile applicability.
The urgent need of modern society for portable energy‐consuming devices has boosted the development of high‐power supercapacitors and high‐energy batteries. Major prerequisites for augmenting wider ...practical applications are advanced electrode materials and deeper insights into the underlying electrochemical processes. Owing to their unique physicochemical properties, 2D materials, such as graphene, transition metal carbides, nitrides, and dichalcogenides, hold special promise. Characterizing their behavior under real operating conditions (operando) or at the site of operation (in situ) without disassembling the device helps uncover essential kinetic information, which may, otherwise, be lost. By identifying both harmful and beneficial mechanisms, these in situ and operando characterization techniques allow researchers to alleviate critical issues in existing materials and develop new materials with enhanced properties. Herein, a brief introduction including the preparation and the electrochemical energy storage application of 2D materials is first presented. The main concern, thereby, is the influence of preparation methods on the resulting electrode structure and electrochemical performance. Then, the electrochemical mechanisms underlying the operation of supercapacitors and lithium batteries are discussed in detail. Finally, the perspective and future direction of applying the in situ and operando techniques to model 2D materials in revealing some important processes are highlighted.
In‐depth understanding of electrochemical processes with the assistance of in situ and operando characterization is key for electrochemical energy storage. The latest advances of the most promising 2D materials applied in energy storage are reviewed, and the current understanding about their charge storage and degradation mechanisms inferred from relevant in situ and operando techniques is illustrated.
Highlights
The first assembled flexible phase change nonwoven is reported by wet-spinning.
The unprecedented thermal properties of such flexible phase change nonwoven are achieved.
Such phase change ...nonwoven is highly applicable for mask and cloth intelligent temperature control.
Phase change materials have a key role for wearable thermal management, but suffer from poor water vapor permeability, low enthalpy value and weak shape stability caused by liquid phase leakage and intrinsic rigidity of solid–liquid phase change materials. Herein, we report for the first time a versatile strategy for designed assembly of high-enthalpy flexible phase change nonwovens (GB-PCN) by wet-spinning hybrid graphene-boron nitride (GB) fiber and subsequent impregnating paraffins (e.g., eicosane, octadecane). As a result, our GB-PCN exhibited an unprecedented enthalpy value of 206.0 J g
−1
, excellent thermal reliability and anti-leakage capacity, superb thermal cycling ability of 97.6% after 1000 cycles, and ultrahigh water vapor permeability (close to the cotton), outperforming the reported PCM films and fibers to date. Notably, the wearable thermal management systems based on GB-PCN for both clothing and face mask were demonstrated, which can maintain the human body at a comfortable temperature range for a significantly long time. Therefore, our results demonstrate huge potential of GB-PCN for human-wearable passive thermal management in real scenarios.
The unprecedented development of flexible, wearable, and miniaturized electronics has envisaged a glorious future for mankind. However, at the same time, it has escalated the demand for microscale ...electrochemical energy storage devices (MEESDs). With abundant resources, low cost and properties similar to lithium, sodium ion MEESDs (NIMEESDs), e.g., sodium ion microcapacitors (NIMCs) and microbatteries (NIMBs), have emerged as high‐performance and competitive candidates for effectively powering microelectronics. Herein, the state‐of‐the‐art advances and recent developments in designing high‐performance NIMEESDs are reviewed. The study begins by introducing NIMEESDs, focusing on distinct device configurations, including stacked, interdigital, fiber‐shaped, and 3D geometries. Subsequently, the recent achievements of various well‐designed microelectrodes in Na ion storage covering intercalation, conversion, and alloying‐type reaction mechanisms are systematically discussed. Based on the device architecture, the status of high‐power and high‐energy NIMCs and NIMBs is presented. More attention is paid to the exceptional flexibility, aesthetic versatility, shape diversity, and tailored integration of NIMEESDs. Finally, future challenges associated with NIMEESDs and corresponding prospects are discussed from the viewpoint of electrochemical active materials, electrode structure, microfabrication process, and self‐powered integrated microsystems.
Recent advances and present status of sodium ion microelectrochemical energy storage devices with different reaction mechanisms and device architectures are summarized. Furthermore, the future perspectives are highlighted from active materials and device configurations to microfabrication methods and integrated microsystems.
Two-dimensional MXenes are key high-capacitance electrode materials for micro-supercapacitors (MSCs) catering to integrated microsystems. However, the narrow electrochemical voltage windows of ...conventional aqueous electrolytes (≤ 1.23 V) and symmetric MXene MSCs (typically ≤ 0.6 V) substantially limit their output voltage and energy density. Highly concentrated aqueous electrolytes exhibit lower water molecule activity, which inhibits water splitting and consequently widens the operating voltage window. Herein, we report ultrahigh-voltage aqueous planar asymmetric MSCs (AMSCs) based on a highly concentrated LiCl-gel quasi-solid-state electrolyte with MXene (Ti3C2Tx) as the negative electrode and MnO2 nanosheets as the positive electrode (MXene//MnO2-AMSCs). The MXene//MnO2-AMSCs exhibit a high voltage of up to 2.4 V, attaining an ultrahigh volumetric energy density of 53 mWh cm−3. Furthermore, the in-plane geometry and the quasi-solid-state electrolyte enabled excellent mechanical flexibility and performance uniformity in the serially/parallel connected packs of our AMSCs. Notably, the MXene//MnO2-AMSC-based integrated microsystem, in conjunction with solar cells and consumer electronics, could efficiently realize simultaneous energy harvesting, storage, and conversion. The findings of this study provide insights for constructing high-voltage aqueous MXene-based AMSCs as safe and self-sufficient micropower sources in smart integrated microsystems.
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Resistive strain/pressure sensors have attracted intensive attention due to their irreplaceable role in the fields of motor behavior monitoring, human health diagnosis, and human machine interface. ...Notably, the material and structural design have significant impacts on the performance of resistive strain/pressure sensors. Biomass-derived carbons (BDCs) are considered as popular candidates for realizing the fabrication of resistive strain/pressure sensors because of their excellent properties such as abundant sources, diverse structures, and satisfactory electrical conductivity. This review presents the recent progress of BDCs in the field of resistive strain/pressure sensors and their key challenges. First, the classification methods, evaluation criteria and sensing mechanisms of previously reported resistive strain/pressure sensors are systematically outlined and discussed. Subsequently, the preparation of BDCs with different macrostructures, including one-dimensional (1D), 2D, and 3D structures, and their recent progress in the field of resistive strain/pressure sensors are summarized. Next, the respective advantages of BDCs with different macroscopic structures in the field of resistive strain/pressure sensors are carefully analyzed, and the relationship between different structures and the comprehensive sensing performances of devices is discussed. Finally, the future prospects and major challenges are proposed for BDC-based resistive strain/pressure sensors, and some key future research directions are given.
The increasing demand for portable, wearable, and miniaturized electronics has substantially promoted the immense development of planar microsupercapacitors (MSCs) built on a single substrate. ...Atomically thin two-dimensional (2D) nanosheets, by virtue of their intrinsically unique structure and fascinating electrochemical properties, provide a new material platform for the creation of high performance planar MSCs in which the electrolyte ions can completely utilize flat architecture and ultrathin thickness of 2D nanosheets, parallel to the direction of ionic diffusion along the plane of 2D nanosheets. Herein, we present an overview and perspective on diverse 2D materials for planar MSCs. First, an introduction is presented to highlight the advances of MSCs, the uniqueness of 2D materials in the assembly of planar MSCs with three different configurations, i.e., stacked, interdigital, and 3D planar geometries, and the progress of microfabrication techniques for microelectrodes of MSCs. Second, the state-of-the-art 2D materials to manufacture planar MSCs, including graphene, transition metal oxides/hydroxides, transition metal dichalcogenides, metal carbides, metal nitrides, phosphorene, boron nitride, metal-organic frameworks, and covalent-organic frameworks, are systemically discussed in detail. Special emphasis is given to the multiple roles of 2D materials for functional components as active materials, current collectors, additives/binders, and separators for planar MSCs. Finally, the existing challenges and prospective solutions of 2D materials for planar MSCs with high performance and various innovative form factors are proposed.
This review offers the systematical summary and discussion of lithium cobalt oxide cathode with high-voltage and fast-charging capabilities from key fundamental challenges, latest advancement of key ...modification strategies to future perspectives, laying the foundations for advanced lithium cobalt oxide cathode design and facilitating the acceleration of research and development of constructing high energy density and high power density lithium-ion batteries.
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Lithium-ion batteries (LIBs) with the “double-high” characteristics of high energy density and high power density are in urgent demand for facilitating the development of advanced portable electronics. However, the lithium ion (Li+)-storage performance of the most commercialized lithium cobalt oxide (LiCoO2, LCO) cathodes is still far from satisfactory in terms of high-voltage and fast-charging capabilities for reaching the double-high target. Herein, we systematically summarize and discuss high-voltage and fast-charging LCO cathodes, covering in depth the key fundamental challenges, latest advancements in modification strategies, and future perspectives in this field. Comprehensive and elaborated discussions are first presented on key fundamental challenges related to structural degradation, interfacial instability, the inhomogeneity reactions, and sluggish interfacial kinetics. We provide an instructive summary of deep insights into promising modification strategies and underlying mechanisms, categorized into element doping (Li-site, cobalt-/oxygen-site, and multi-site doping) for improved Li+ diffusivity and bulk-structure stability; surface coating (dielectrics, ionic/electronic conductors, and their combination) for surface stability and conductivity; nanosizing; combinations of these strategies; and other strategies (i.e., optimization of the electrolyte, binder, tortuosity of electrodes, charging protocols, and pre-lithiation methods). Finally, forward-looking perspectives and promising directions are sketched out and insightfully elucidated, providing constructive suggestions and instructions for designing and realizing high-voltage and fast-charging LCO cathodes for next-generation double-high LIBs.
The escalating demand for micro/nano-sized devices, such as micro/nano-robots, intelligent portable/wearable microsystems, and implantable medical microdevices, necessitates the expeditious ...development of integrated microsystems incorporating energy conversion, storage, and consumption. Critical bottlenecks in microscale energy storage/sensors and their integrated systems are being addressed by exploring new technologies and new materials, e.g., MXene, holding great potential for developing lightweight and deformable integrated microdevices. This review summarizes the latest progress and milestones in the realization of MXene-based micro-supercapacitors (MSCs) and sensor arrays, and thus discusses the design fundamentals and key advancements of MXene-based energy conversion-storage-consumption integrated microsystems. Finally, we outline the key challenges in fabricating MXene-based MSCs/sensors and their self-powered integrated microsystems, which is crucial for their practical applications. Particularly, we illuminate viable solutions to such unsolved issues and highlight the exciting opportunities.
This review emphasizes the importance of integrated microsystems that incorporate MXene-based energy conversion, storage, and consumption for meeting the escalating demand for micro/nano-sized devices. The latest advancements in MXene-based micro-supercapacitors (MSCs) and sensor arrays are summarized, along with key developments in fundamental design. Critical bottlenecks in MXene-based MSCs/sensors and their integrated systems are being addressed through the exploration of new technologies and materials, as well as the development of lightweight and deformable integrated microdevices. The key challenges in fabricating MXene-based MSCs/sensors and their self-powered integrated microsystems are outlined, along with viable solutions and exciting opportunities. Display omitted
•The review provides comprehensive coverage of the latest developments in MXene-based integrated microsystems.•The review thoroughly discussed MXene-based integrated devices, including MSC arrays, sensors, and hybrids.•The review highlights the significant challenges and prospects of MXene-based integrated microsystems.
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