Smart materials for safe lithium-ion batteries against thermal runaway

In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost efficiency,a quantity of research has been conducted on the commercial application of LIBs.However,it is difficult to achieve satisfying safety and cycling performance simultaneously.There may be thermal runaway(TR),external impact,overcharge and overdischarge in the process of battery abuse,which makes the safety problem of LIBs more prominent.In this review,we summarize recent progress in the smart safety materials design towards the goal of preventing TR of LIBs reversibly from different abuse conditions.Benefiting from smart responsive materials and novel structural design,the safety of LIBs can be improved a lot.We expect to provide a comprehensive reference for the development of smart and safe lithium-based battery materials.

Emerging Trends in Damage Tolerance Assessment:A Review of Smart Materials and Self-Repairable Structures

The discipline of damage tolerance assessment has experienced significant advancements due to the emergence of smart materials and self-repairable structures.This review offers a comprehensive look into both traditional and innovative methodologies employed in damage tolerance assessment.After a detailed exploration of damage tolerance concepts and their historical progression,the review juxtaposes the proven techniques of damage assessment with the cutting-edge innovations brought about by smart materials and self-repairable structures.The subsequent sections delve into the synergistic integration of smart materials with self-repairable structures,marking a pivotal stride in damage tolerance by establishing an autonomous system for immediate damage identification and self-repair.This holistic approach broadens the applicability of these technologies across diverse sectors yet brings forth unique challenges demanding further innovation and research.Additionally,the review examines future prospects that combine advanced manufacturing processes with data-centric methodologies,amplifying the capabilities of these‘intelligent’structures.The review culminates by highlighting the transformative potential of this union between smart materials and self-repairable structures,promoting a sustainable and efficient engineering paradigm.

4D printing: interdisciplinary integration of smart materials, structural design,and new functionality

Four-dimensional printing allows for the transformation capabilities of 3D-printed architectures over time,altering their shape,properties,or function when exposed to external stimuli.This interdisciplinary technology endows the 3D architectures with unique functionalities,which has generated excitement in diverse research fields,such as soft robotics,biomimetics,biomedical devices,and sensors.Understanding the selection of the material,architectural designs,and employed stimuli is crucial to unlocking the potential of smart customization with 4D printing.This review summarizes recent significant developments in 4D printing and establishes links between smart materials,3D printing techniques,programmable structures,diversiform stimulus,and new functionalities for multidisciplinary applications.We start by introducing the advanced features of 4D printing and the key technological roadmap for its implementation.We then place considerable emphasis on printable smart materials and structural designs,as well as general approaches to designing programmable structures.We also review stimulus designs in smart materials and their associated stimulus-responsive mechanisms.Finally,we discuss new functionalities of 4D printing for potential applications and further development directions.

A Review of Smart Materials for the Boost of Soft Actuators,Soft Sensors,and Robotics Applications

With the advance of smart material science,robotics is evolving from rigid robots to soft robots.Compared to rigid robots,soft robots can safely interact with the environment,easily navigate in unstructured fields,and be minimized to operate in narrow spaces,owning to the new actuation and sensing technologies developed by the smart materials.In the review,different actuation and sensing technologies based on different smart materials are analyzed and summarized.According to the driving or feedback signals,actuators are categorized into electrically responsive actuators,thermally responsive actuators,magnetically responsive actuators,and photoresponsive actuators;sensors are categorized into resistive sensors,capacitive sensors,magnetic sensors,and optical waveguide sensors.After introducing the principle and several robotic prototypes of some typical materials in each category of the actuators and sensors.The advantages and disadvantages of the actuators and sensors are compared based on the categories,and their potential applications in robotics are also presented.

Review of Cellulose Smart Material: Biomass Conversion Process and Progress on Cellulose-Based Electroactive Paper

Cellulose is a renewable biomass material and natural polymer which is abundantly available on Earth,and includes agricultural wastes,forestry residues,and woody materials.The excellent and smart characteristics of cellulose materials,such as lightweight,biocompatibility,biodegradability,high mechanical strength/stiffness and low thermal expansibility,have made cellulose a highpotential material for various industry applications.Cellulose has recently been discovered as a smart material in the electroactive polymers family which carries the name of cellulose-based electroactive paper(EAPap).The shear piezoelectricity in cellulose polymers is able to induce large displacement output,low actuation voltage,and low power consumption in the application of biomimetic sensors/actuators and electromechanical system.The present study provides an overview of biomass pretreatment from various lignocellulosic cellulose(LC)resources and nanocellulose production via TEMPO-mediated oxidation reaction,followed by the production of different types of EAPap versus its performance,and lastly the applications of EAPap in different areas and industries.Specifically,LC biomass consists mainly of cellulose having a small content of hemicelluloses and lignins which form a defensive inner structure against the degradation of plant cell wall.Thus,selective approaches are discussed to ensure proper extraction of cellulosic fibers from complex biomass for further minimization to nano-dimensions.In addition,a comprehensive review of the development of cellulose-based EAPap as well as fabrication,characterization,performance enhancement and applications of EAPap devices are discussed herein.

Smart Material Based Complex Mode Active Control of Flexible Manipulators with Kinematic Redundancy

An active control methodology is presented for suppressing the vibratoryresponse of flexible redundant manipulators with bonded piezoceramic actuators and strain gagesensors. Firstly, the dynamic equation of the manipulator is decoupled by means of the complex modetheory and the state-space expression of the controlled system is developed. Secondly, a continuouslinear quadratic regulator (LQR) state feedback controller is designed based on the minimumprinciple. Thirdly, a full-order Luenberger state observer featuring an assigned degree of stabilityis determined via the duality between control and estimation. Finally, a numerical simulation iscarried out on a planar 3R flexible redundant manipulator. The simulation results reveal that thedynamic performance of the system is improved rapidly and significantly.

Field Sensing Characteristic Research of Carbon Fiber Smart Material

In order to research the field sensing characteristic of the carbon fiber smart material, the Tikhonov regularization principle and the modified Newton-Raphson(MNR) algorithm were adopted to solve the inverse problem of the electrical resistance tomography(ERT). An ERT system of carbon fiber smart material was developed. Field sensing characteristic was researched with the experiment. The experimental results show that the specific resistance distribution of carbon fiber smart material is highly consistent with the distribution of structural strain. High resistance zone responds to high strain area, and the specific resistance distribution of carbon fiber smart material reflects the distribution of sample strain in covering area. Monitoring by carbon fiber smart material on complicated strain status in sample field domain is realized through theoretical and experimental study.

Discrete Methods Based on First Order Reversal Curves to Identify Preisach Model of Smart Materials

Preisach model is widely used in modeling of smart materials. Although first order reversal curves （FORCs） have often found applications in the fields of physics and geology, they are able to serve to identify Preisach model. In order to clarify the relationship between the Preisach model and the first order reversal curves, this paper is directed towards： （1） giving the reason a first order reversal curve is introduced; （2） presenting, for identifying Preisach model, two discrete methods, which are analytically based on first order reversal curves. Herein also is indicated the solution＇s uniqueness of these two identifying methods. At last, the validity of these two methods is verified by simulating a real smart actuator both methods have been applied to.

Robust distributed controller design of rotational single-link smart materials beam

A dynamic modelling and controller design were presented for a single-link smart materials beam, a flexible beam bonded with piezoelectric actuators and sensors for better control performance. Taking into account bounded disturbances, a robust distributed controller was constructed based on the system model, which was described by a set of partial differential equations (PDEs) and boundary conditions (BCs) . Subsequently, a finite dimensional controller was further developed, and it was proven that this controller can stabilize the finite dimensional model with arbitrary number of flexible modes. Keywords Dynamic modelling - Robust distributed controller - Flexible beam - Smart material

Smart epidermal electrophysiological electrodes:Materials,structures,and algorithms

Epidermal electrophysiological monitoring has garnered significant attention for its potential in medical diagnosis and healthcare,particularly in continuous signal recording.However,simultaneously satisfying skin compliance,mechanical properties,environmental adaptation,and biocompatibility to avoid signal attenuation and motion artifacts is challenging,and accurate physiological feature extraction necessitates effective signal-processing algorithms.This review presents the latest advancements in smart electrodes for epidermal electrophysiological monitoring,focusing on materials,structures,and algorithms.First,smart materials incorporating self-adhesion,self-healing,and self-sensing functions offer promising solutions for long-term monitoring.Second,smart meso-structures,together with micro/nanostructures endowed the electrodes with self-adaption and multifunctionality.Third,intelligent algorithms give smart electrodes a“soul,”facilitating faster and more-accurate identification of required information via automatic processing of collected electrical signals.Finally,the existing challenges and future opportunities for developing smart electrodes are discussed.Recognized as a crucial direction for next-generation epidermal electrodes,intelligence holds the potential for extensive,effective,and transformative applications in the future.

Construction of smart propellant with multi-morphologies

Smart materials,which exhibit shape memory behavior in response to external stimuli,have shown great potential for use in biomedical applications.In this study,an energetic composite was fabricated using a UV-assisted DIW 3D printing technique and a shape memory material(SMP)as the binder.This composite has the ability to reduce the impact of external factors and adjust gun propellant combustion behavior.The composition and 3D printing process were delineated,while the internal structure and shape memory performance of the composite material were studied.The energetic SMP composite exhibits an angle of reversal of 18 s at 70°,with a maximum elongation typically reaching up to 280% of the original length and a recovery length of approximately 105%during ten cycles.Additionally,thermal decomposition and combustion behavior were also demonstrated for the energetic SMP composite.

Developments in 4D-printing:a review on current smart materials,technologies,and applications

Recent advances in additive manufacturing(AM),commonly known as three-dimensional(3D)-printing,have allowed researchers to create complex shapes previously impossible using traditional fabrication methods.A research branch that originated from 3D-printing called four-dimensional(4D)-printing involves printing with smart materials that can respond to external stimuli.4Dprinting permits the creation of on-demand dynamically controllable shapes by integrating the dimension of time.Recent achievements in synthetic smart materials,novel printers,deformation mechanism,and mathematical modeling have greatly expanded the feasibility of 4D-printing.In this paper,progress in the 4Dprinting field is reviewed with a focus on its practical applications.We discuss smart materials developed using 4D-printing with explanations of their morphing mechanisms.Additionally,case studies are presented on self-constructing structures,medical devices,and soft robotics.We conclude with challenges and future opportunities in the field of 4D-printing.

Self-healing Polymeric Hydrogels:Toward Multifunctional Soft Smart Materials

The concept of self-healing that involves a built-in ability to heal in response to damage wherever and whenever it occurs in a material,analogous to the healing process in living organisms,has emerged a couple of decades ago.Driven primarily by the demands for life-like materials and soft smart materials,therefore,the development of self-healing polymeric hydrogels has continually attracted the attention of the scientific community.Here,this review is intended to give an in-depth overview of the state-of-the-art advances in the field of self-healing polymeric hydrogels.Specifically,recently emerging trends in self-healing polymeric hydrogels are summarized,and notably,recommendations to endow these hydrogels with fascinating multi-functionalities including luminescence,conductivity/magnetism and shape memory etc are presented.To close,the current challenges and future opportunities in this field are also discussed.

Photosensitive peptide hydrogels as smart materials for applications

Photosensitive peptide hydrogels(PPHs) which allow photo-modulation on the self-assembly of peptides were broadly developed over the recent decades. The real-time and spatial modulation of hydrogel properties upon non-contact light illumination, allow the PPHs serving as super "smart" soft materials.Herein, we briefly summarized the PPHs preparing from the integration of diverse photosensitive moieties with peptides through gelation abilities, "smart" manner and applications. Moreover, a novel type of PPHs based on intramolecular biorthogonal photo-click reaction developed by our group has been demonstrated with relative mechanism and applications.

Thermal smart materials with tunable thermal conductivity:Mechanisms, materials, and applications

The demand for active and effective management of heat transfer is increasing in various modern application scenarios. The thermal conductivity of materials plays a key role in thermal management systems, and reversibly tunable thermal properties are one of the fundamental needs for materials. Thermal smart materials, whose thermal properties can be tuned with an external trigger, have attracted the attention of researchers. In this paper, we provide a brief review of current research advances in thermal smart materials in recent years in terms of fundamental physical mechanisms, thermal switching ratios, and their application value. We focus on typical thermal smart materials such as nanoparticle suspensions, phase change materials, polymers, layered materials tuned by electrochemistry and other materials tuned by a specific external field. After surveying the fundamental mechanisms, we present applications of thermal smart components and devices in temperature control, thermal circuits, phonon computers, thermal metamaterials, and so on. Finally, we discuss the limitations and challenges of thermal smart materials, as well as our predictions for future development.

Smart heat isolator with hollow multishelled structures

Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the capacity to automatically regulate heat conduction rate. In detail, this reaction tank should endow an ability that resists the heat loss when the reaction temperature is lower than the target, while accelerating the heat dissipation when the system is overheated. In this case, this smart reactor can not only minimize energy consumption but also reduce safety risks.Hollow structures are known to reduce heat conductivity. Particularly, the hollow structure with multishells can provide more interfaces and thus further inhibit heat transmission, which would be more favorable for heat isolation. Step forward, by coupling HoMSs with temperature-sensitive polymer, a smart heat isolation material has been fabricated in this work. It performs as a good heat isolator at a relatively lower temperature. A heat insulation effect of 6.5℃ can be achieved for the TSPU/3S–TiO_(2)HoMSs with a thickness of 1 mm under the temperature field of 50℃.The thermal conductivity of composite material would be raised under overheating conditions. Furthermore, this composite displays an unusual two-stage phase transformation during heating. Benefiting from the unique multishelled structure, energy is found to be gradually guided into the hollow structure and stored inside. This localized heat accumulation enables the composite to be a potential coating material for intelligent thermal-regulator and site-defined micro-reactor.

Research Status and Development Direction of Smart Clothing Materials

With the continuous development of technology and society, smart devices have filled people’s lives and become an indispensable part of people’s lives. At the same time, smart clothing has also been greatly developed. This article introduces several smart clothing materials, analyzes the current research status of smart clothing materials, and further discusses the applications of smart clothing materials in military, medical, intelligent decoration, and sports and leisure fields. Then the problems of smart clothing in safety, environmental protection, and industrial technology are analyzed, and the corresponding solutions to these problems are proposed, so as to provide reference and guidance for the future development of smart clothing in China. And the research shows that smart clothing will develop in the direction of fashion and diversification, function and comfort, safety and environmental protection, convenience and low cost in the future.

Two-Way 4D Printing： A Review on the Reversibility of 3D-Printed Shape Memory Materials

The rapid development of additive manufacturing and advances in shape memory materials have fueled the progress of four-dimensional （4D） printing. With the right external stimulus, the need for human interaction, sensors, and batteries will be eliminated, and by using additive manufacturing, more complex devices and parts can be produced. With the current understanding of shape memory mechanisms and with improved design for additive manufacturing, reversibility in 4D printing has recently been proven to be feasible. Conventional one-way 4D printing requires human interaction in the programming （or shapesetting） phase, but reversible 4D printing, or two-way 4D printing, will fully eliminate the need for human interference, as the programming stage is replaced with another stimulus. This allows reversible 4D printed parts to be fully dependent on external stimuli; parts can also be potentially reused after every recovery, or even used in continuous cycles-an aspect that carries industrial appeal. This paper presents a review on the mechanisms of shape memory materials that have led to 4D printing, current findings regarding 4D printing in alloys and polymers, and their respective limitations. The reversibility of shape memory materials and their feasibility to be fabricated using three-dimensional （3D） printing are summarized and critically analyzed. For reversible 4D printing, the methods of 3D printing, mechanisms used for actuation, and strategies to achieve reversibility are also highlighted. Finally, prospective future research directions in reversible 4D printing are suggested.

Smart Behavior of Carbon Fiber Reinforced Cement-based Composite

The electrical characteristics of cement-based material can be remarkably improved by the addition of short carbon fibers. Carbon fiber reinforced cement composite (CFRC) is an intrinsically smart material that can sense not only the stress and strain, but also the temperature. In this paper, variations of electrical resistivity with external applied load, and relation of thermoelectric force and temperature were investigated. Test results indicated that the electrical signal is related to the increase in the material volume resistivity during crack generation or propagation and the decrease in the resistivity during crack closure. Moreover, it was found that the fiber addition increased the linearity and reversibility of the Seebeck effect in the cement-based materials. The change of electrical characteristics reflects large amount of information of inner damage and temperature differential of composite, which can be used for stress-strain or thermal self-monitoring by embedding it in the concrete structures.

Friction Behavior of Magnetorheological Fluids with Different Material Types and Magnetic Field Strength

Magnetorheological （MR） fluid is a type of a smart material that can control its mechanical properties under a magnetic field. Iron particles in MR fluid form chain structures in the direction of an applied magnetic field, which is known as MR effect, resulting in variation of stiffness, shear modulus, damping and tribological characteristics of MR fluid. As MR effect depends on the density of particles in the fluid or the strength of a magnetic field, the experiments are conducted to evaluate the friction property under reciprocating motion by changing the types of MR fluid and the strength of a magnetic field. The material of aluminum, brass, and steel are chosen for specimen as they are the most common material in mechanical applications. The surfaces of specimen are also observed by optical microscope before and after experiments to compare the surfaces with test conditions. The comparing results show that the friction coefficient increases as the strength of a magnetic field increases in regardless of types of MR fluid or the material. Also the density of particle in MR fluid affects the friction characteristic. The results from this research can be used to improve the performance of mechanical applications using MR fluid.