Flexible energy storage devices made from natural fiber braids have garnered significant attention due to their abundant availability， low cost， and mature and reliable structural design. However， these natural fiber materials typically suffer from low specific surface area and energy storage density. To address this issue， this study employs a multi-step treatment method， such as incorporating high-temperature carbonization， heterogeneous element doping， strong alkali etching， and MXene electrochemical active material coating，to treat commercial cotton fabrics. The effects of these multi-step treatments on the materials are explored through analyses of their chemical composition， microscopic morphology， microporous structure， and energy storage behavior. The results show that after multi-step treatment， the material maintains a good flexible characteristic， realizes the co-doping of N and S elements， and improves the microstructure of the carbon cloth material. Specifically， the average pore size on the surface of the carbon cloth decreases from 36.44 nm to 2.03 nm， while its specific surface area increased dramatically from 1.78 m²/g to 1043.37 m²/g， representing an increase of 58516%. Additionally， the total pore volume rises from 0.0162 mL/g to 0.53 mL/g. Following complex treatment， the carbon cloth achieves high specific capacitance of 530.83 F/g. However， the material still faces challenges regarding poor rate capability and unstable energy storage performance， which require further improvement in subsequent studies. This research outlines directions and provides technical and theoretical references for enhancing the energy storage performance of flexible carbon-based materials.

Flexible textile composite materials have received increasing attention in the application of variable configuration aircraft due to their flexibility， and foldable and unfoldable properties. However， there are still great uncertainties about their mechanical properties. Uniaxial tensile experiments with five off-axial angles were conducted to study the uniaxial tensile mechanical behaviors of a quartz fiber/silicone rubber flexible textile composite material. A hyperelastic constitutive model was established based on the characteristics of the brittleness of quartz fiber and the toughness of silicone rubber， and the strain energy density function was decoupled into the strain energy density functions from fiber elongations along the warp and weft yarns direction， and the strain energy density function coupling silicone rubber elongation and fiber shear. The model parameters were determined based on the uniaxial tensile test data. Comparison with the results of off-axis tensile test shows that the prediction error of the hyperelastic constitutive model for the in-plane tensile behavior is less than 3.88%. According to the flexible and deformable characteristics of the quartz fiber/silicone rubber flexible textile composite material， a circular membrane pneumatic loading test verification method is adopted， which can uniformly apply load to the membrane surface. The proposed hyperelastic constitutive model is realized by the user subroutine UANISOHYPER_INV of the finite element software Abaqus， and the error between simulation data and experimental data is less than 2.9%， indicating that the established hyperelastic constitutive model has good applicability for mechanical characterization of the quartz fiber/silicone rubber flexible textile composite material.

Flexible pressure and strain sensors have attracted increasing attention with the rapid development of medical and electronic interconnection.Ionic conductive hydrogels demonstrate more potential for flexible electronics sensors because of their excellent physicochemical properties such as biomimetic structures， suitable mechanical properties， and excellent biocompatibility. The classification， preparation methods， characteristics of ionic conductive hydrogels，and their applications in flexible pressure and strain sensors were reviewed. First， the sensing modes of ionic conductive hydrogels in pressure and strain sensors were introduced. Then， according to the different conductive principles， they were divided into three categories：metal ion hydrogels， ionic liquid hydrogels， and polyelectrolyte hydrogels. Their applications and research progress in pressure and strain sensors were systematically introduced from synthesis methods， performance characteristics，and improvement methods.Their potential application prospects and development trends were analyzed. The current challenges were summarized and prospects were made. It was believed that ionic conductive hydrogels still have great exploration space and application potential in intelligent flexible sensing.

Triboelectrification （TE） is a physical phenomenon that exists on the surface of almost all materials， and the TE of semiconductor materials is different from the electrification of dielectric materials.At the dynamic interface between one semiconductor and another semiconductor or a metal， mechanical friction causes the continuous breaking and rebuilding of chemical bonding between atoms at the interfaces， which could release a quantized energy that is the binding energy of two atoms （or called as bindington） to excite non-equilibrium electron-hole pairs.These electrons and holes can be separated by the built-in electric field formed at the p-n junctions （or Schottky junction， semiconductor heterojunction）， so as to output direct-current （DC） electricity in the external circuits. This phenomenon is defined as the tribovoltaic effect. It is similar to the photovoltaic effect， but the difference is the exciting energy sources. In the tribovoltaic effect， electron-hole pairs are excited by the energy released by the instantaneous transition of atoms at the interface or the energy released when new bonds are formed at the interface； while the photovoltaic effect is excited by photo energy.This article reviews the research progress of DC nanogenerators based on the tribovoltaic effect， including mechanism research， material and device design， surface modification enhancement strategies， etc. We also discuss the possible applications of tribovoltaic devices as flexible DC power sources for wearable electronics， with emphases on their device design， performance optimization，and potential application scenarios.

At present， most smart wearable devices are smart watches， wristbands， etc.， which have the problems of high rigidity， poor comfort and frequent charging， making it difficult to meet the requirements of ergonomics and clothing comfort. They cannot be worn for a long time to achieve all-weather monitoring. Textile triboelectric nanogenerator （T-TENG） can be integrated into shoes and clothing as flexible power sources and self-powered sensors， making it an ideal wearable device for active human health monitoring and enforcement. However， most of the reported T-TENG need to be packaged and then integrated into clothing before use， resulting in a reduced air permeability of clothing. In addition， most of the current studies are in the laboratory stage， and the properties of T-TENG such as durability， sensitivity and stability in actual use are not fully considered. In this paper， the basic working mode， material selection， manufacturing method， integrated footwear and clothing mode， and application scenarios of T-TENG were reviewed. The preparation methods of T-TENG for nanofiber membrane and textile composite materials， fiber/yarn-based T-TENG， and fabric-based T-TENG were mainly discussed. New strategies for the development and integration of comfortable T-TENG in the future were proposed， including the large-scale preparation of T-TENG， the integration of T-TENG and traditional clothing， the compatibility of T-TENG monitoring accuracy and comfort， and the durability and stability of T-TENG.

The applications of wearable sensors in sports， medicine， rehabilitation， and other fields， have greatly facilitated the capture and monitoring of human movement index signals effectively avoiding sports injuries， reducing the frequency of medical treatment， and even saving many lives. With the application and popularization of wearable sensors， suitable flexible energy supply systems are the key to its development. In recent years， researchers have studied and designed a variety of flexible energy supply systems based on different energy release methods， among which flexible Zn-ion batteries stand out due to their high energy density， high elastic modulus， high cycle stability， and high safety. We reviewed the research progress in flexible Zn-ion batteries for wearable sensors， mainly introducing and summarizing the batteries components （such as current collector， electrode （cathode and anode）， separator， electrolyte， and packaging） and the application of wearable sensors. Finally， the current problems and challenges of flexible Zn-ion batteries are discussed.

Wearable materials and devices are developing toward flexibility， lightness， imperceptibility， intelligence， and long-term wearability to meet the personalized needs such as physiological and psychological demands of human body. This trend brought innovation to the field of sports and health monitoring， receiving extensive attention from the academic and industrial communities. However， while meeting the individualized development needs of the human body， wearable flexible materials and devices also face challenges in terms of mechanical robustness， signal stability， soft-hard interface connection， and biocompatibility. Therefore， this review aims to discuss the materials， structures， and fabrication processes for constructing wearable flexible materials and devices from the perspective of practical sports and health monitoring needs，and proposes the major challenging factors and their solutions in terms of mechanical， electrical， and biological performance. Finally， this paper predicts the future development directions of wearable flexible electronic materials and devices， including fully flexible integration， enhanced mechanical robustness， high-precision signal decoupling and recognition， stability，and sensitivity of monitoring， rapid responsiveness， ultra-thin imperceptible design， multimodal signal processing， as well as intelligent adaptive feedback.

Electronic skin is a novel type of flexible and wearable sensor that mimics human skin perception， exhibiting characteristics such as lightweight， softness， and flexibility. It has the capability to convert external stimuli into diverse output signals， showing substantial potential in health monitoring and human-computer interaction. This article provides a comprehensive review from the perspective of intelligent materials for constructing electronic skin， focusing on commonly used substrates， conductive fillers， and their geometric structures. It discusses the requirements for biocompatibility， adhesion， self-healing， and self-powering performance of electronic skin based on the complex environmental conditions it faces in applications. It points out that in the research process， there are still issues such as poor comprehensive perception of human skin， complex and expensive fabrication processes， and delayed response to sensory signals. By optimizing materials and structures to enhance the basic performance of electronic skin， the development trend is to build outstanding performance， multifunctionality， and simultaneous detection of various external stimuli. Electronic skin shows great potential in medical diagnosis， soft robotics， smart prosthetics， and human-machine interaction.

Wearable devices have good portability and imperceptibility， realizing expected functions after being worn. Drug delivery refers to delivering drugs into the body with suitable carriers or techniques to generate therapeutic effects to improve the stability and bioavailability of drugs.The application of wearable devices in drug delivery can rationally release drugs when receiving disease signals or user orders and monitor in-vivo drug concentrations， reducing the dependency of doctors or hospitals， and achieving optimal disease treatment timing and outcomes. Wearable drug delivery systems can be worn directly on the body surface and are non-invasive and self-administered. Microneedle-skin patches， wound healing patches， and smart contact lenses are popular wearable devices explored in drug delivery. This review is a summary of the application of wearable devices in disease treatment， such as diabetes， wound healing， eye diseases， cancer， and other diseases， and drug delivery in recent five years， summarizing the challenges for the development of wearable drug delivery systems， and prospecting its development direction.

Chitosan hydrogel with excellent degradability and biocompatibility has become an important material for constructing flexible strain sensors. Flexible strain sensors based on chitosan conductive hydrogels have superb environmental adaptability and are widely used in biomedical fields such as health monitoring and implantable devices. The preparation method and conductive mechanism of chitosan-based conductive hydrogels were reviewed. The current status of chitosan-based conductive hydrogels in low temperature resistant， self-repairing， and self-adhesive functional flexible strain sensors was summarized. Finally， it is pointed out that the optimization of the preparation process， the application of new materials， and the use of artificial intelligence are the key research directions for the future of chitosan-based conductive hydrogels for flexible strain sensors， aiming to provide theoretical foundations and practical guidance for the further development of multifunctional applications of flexible strain sensors.

Flexible pressure sensors can be attached to the human skin to sense external pressure signals， and have the characteristics of wide sensing range， short response time， high sensitivity， and durability. Therefore， they are widely used in the fields of electronic skin and human-computer interaction. Flexible pressure sensors are usually composed of flexible substrates， active materials and conductive electrodes. Among them， one or more of the active materials form a sensing material by compounding with a flexible substrate， and its deformation under external excitation will cause changes in parameters such as resistance， thereby achieving sensing function.In addition， by introducing microstructure， the compressibility and sensitivity to small pressure of the sensing material can be increased， and its sensing performance can be improved. In this paper， the research progress in flexible pressure sensors doped with carbon-based， metal-based， and black phosphorus-based active materials on film and fabric substrates was reviewed. The preparation methods， electromechanical properties and application scenarios of different sensors were discussed， and the advantages and disadvantages of various sensors were summarized. On this basis， the research on how to achieve wide-range pressure detection， commercialization， non-toxicity of the production process and long-term biocompatibility experiments of smart wearable flexible pressure sensors in the future is prospected.

The carbon fiber triaxial woven fabric has good application prospects in the field of space deployment devices because of its advantages of stable structure， light density and quasi-isotropic. In order to study the deformation properties of carbon fiber triaxial woven fabric/thermoplastic polyurethanes （TPU） flexible composite， TPU and carbon fibertriaxial woven fabric were composited by hot pressing. The unit cell model of triaxial woven fabric was established by metallographic microscope and SEM.The moment of inertia of different sections was calculated by the model， the moment of inertia of the weft section is greater than that of the warp， and the triaxial woven fabric is more difficult to deform in the weft direction. Drape experiments were performed on carbon fiber plain fabric and triaxial woven fabric.The results show that the deformation ability of the triaxial woven fabric is stronger than plain fabric， and the warp direction deformation of triaxial woven fabric is greater than the weft when it is draped， which is consistent with the calculation result of the moment of inertia of the model section； triaxial woven fabric is subjected to tensile tests in the 0°，15°and 30°directions， the load curve changes and ultimate loads of the three angles are analyzed at different strain stages.

With the development of miniaturized wearable electronics，flexible energy storage devices with soft，flexible，small size，and high energy density have attracted widespread attention. Aramid nanofibers (ANF) were utilized as fiber reinforcement and pillared structure materials to prepare MXene/ANF flexible self-supporting electrode through vacuum filtration, which were subsequently assembled into all-solid-state symmetric supercapacitors.With the increase of ANF content to 15%，the mechanical properties of MXene/ANF self-supporting electrode increase to 151.5 MPa，while the conductivity decrease to 1371.1 S/cm. The MXene/ANF Self-supporting electrode shows a high specific capacitance of 432.7 F/g at the current density of 1 A/g. The assembled symmetric all-solid-state supercapacitors exhibit excellent mechanical flexibility and remarkable cycling stability,with an energy density of 25.7 Wh/kg at the power density of 523.1 W/kg and about 88.9% capacitance retention over 10000 cycles.

The wood was used as raw material to obtain the wood skeleton by matrix-removal. And the high-strength wood-based composite hydrogels with PVA/PAM double network structure were constructed by in-situ polymerization. The change rules of macro/micro functional morphological characteristics, mechanical properties, optical properties and chemical composition of the wood-based composite hydrogels were systematically investigated by adjusting the mass ratio of PVA and PAM in the hydrogel system. The results show that introducing a small amount of PVA into the PAM/wood skeleton composite hydrogels and constructing a double network structure can effectively enhanced the mechanical properties of the wood-based composite hydrogels. As a result, the wood-based composite hydrogels show tensile properties with a maximum tensile strength and fracture elongation of 16.47 MPa and 11.61%. Furthermore, the wood-based composite hydrogel is used as a flexible substrate with a conductivity of 1.8 S/m to assemble and build sensor components. The results indicate that the flexible sensor exhibits stable and repeatable relative current signal changes under a variety of deformations.

The foaming agent alkyl polyglucoside was added into graphene oxide dispersion to generate graphene oxide microbubble agglomerates, which were then combined with polyurethane sponge skeleton through impregnating, the as-obtained composite sponge was rapidly frozen in liquid nitrogen and reduced by hydrazine vapor to form the reduced graphene oxide/polyurethane composite sponge with special three-dimensional hierarchical porous structure as well as superhydrophobicity and flexible piezoresistive sensing performance. The results show that the reduced graphene oxide/polyurethane composite sponge-based flexible stress-strain sensor has a sensitivity of up to 3.8(gauge factor, GF), a response time as low as 45 ms. In addition, reduced graphene oxide/polyurethane composite sponge has good superhydrophobicity with water contact angle(WCA) up to 152.5°, which has potential application in the complex environment such as wet and underwater.

The carbon cloths made of carbon fiber as 3D integrated cathode for lithium-ion batterie were studied. The graphitization degree of three types of carbon cloths after heat treatment were qualitatively analyzed and quantitatively calculated. Using lithium metal as the counter electrode, the graphitized carbon cloth electrodes show first discharge specific capacities of 83.6, 94.5 mAh∙g^-1 and 115.2 mAh∙g^-1 under 0.1-0.5 V, respectively. After 50 cycles, the specific capacities of carbon cloth electrodes remain 55.0, 80.0 mAh∙g^-1 and 88.0 mAh∙g^-1.With LiFePO₄-loaded graphitized carbon cloths as cathodes, the initial discharge specific capacities of electrodes are 73.2, 109.5 mAh∙g^-1 and 130.2 mAh∙g^-1, respectively. The carbon cloth whose graphitization degree is 76.02% shows stable specific capacity of about 90.0 mAh∙g^-1 after 50 cycles, and shows better comprehensive performances. This carbon cloth is more suitable for the integrated flexible cathode of lithium-ion batteries. By establishing the mechanical model of the interaction between LiFePO₄ particles and carbon fiber, the relationship between mechanical, electrical and electrochemical properties of the integrated cathode were discussed.Using carbon cloth as an integrated cathode for lithium-ion batteries can simplify the conventional production process and innovate its production process.

Sweat contains many physiological information about the body, such as electrolytes, metabolites, hormones, temperature, etc. Sweat-based wearable sensors enable real-time, continuous, non-invasive monitoring of multimodal bio-metrics at the molecular level, and are widely studied for their significant potential in areas such as motion sensing, disease prevention, and health management. This paper described the five modules of substrate, sweat collection, sensing, power supply and decision making in the integrated structure of wearable sweat sensors, highlighted the excellent performance and applications of nanostructures (such as metal-based and carbon-based materials) in electrochemical sensing sensitive materials, and finally discussed the challenges of wearable sweat sensors in terms of trace sweat collection and variability of physicochemical variables in multi-parameter sensing, meanwhile, future directions of wearable sweat sensing are proposed for two key problems of sweat collection and real-time calibration, including bionic microfluidics and multi-parameter feedback regulation methods to achieve efficient collection and accurate detection of microscopic sweat, promote the application and development of real-time early warning of sweat sensing for chronic major diseases.

Polyester fabric/polyvinyl chloride (PET/PVC) flexible composites were widely used in outdoor products such as sports and leisure, advertising and printing due to its light weight, high strength and good processability. However, under extreme weather conditions such as high temperature and high humidity for a long time, it was very easy to decrease the mechanical properties due to water absorption. Therefore, PET fabric was modified by fluorine-containing block copolymer, and then the wicking resistant PET fabric reinforced PVC resin matrix flexible composites (F-PET/PVC) were obtained by roll coating, then, the mechanism of hygrothermal aging was further explored. The results show that the water contact angle of PET fabric increases from 0° to 114.5°, the wicking height of F-PET/PVC decreases by about 94.29%, and the peeling performance decreases by about 15.87%, when the concentration of anti-wicking agent reaches 20 g/L. In addition, the hygrothermal aging test shows that the hygrothermal aging resistance of F-PET/PVC is better than that of PET/PVC, and the interfacial peeling strength and tensile strength loss rate is decreased from 7.41% and 3.61% to 3.08% and 0.48%, respectively. It is expected to provide a reference for the durability design of environmental fabric-reinforced resin matrix composites.

With the development of the Internet of Things， the rapid development of miniaturized self-powered electronic products and further micro-modulation greatly stimulate the urgent demand for microscale electrochemical energy storage devices. In each electrochemical energy storage device， the supercapacitor based on the plane pattern shape is highly compatible with modern electronic products in terms of functional features such as miniaturization and integration. In this work， the flexible 3D interdigital electrode symmetric micro capacitor was prepared by the combination of semiconductor preparation technology and electrophoresis printing technology， and the 3D printing was carried out by using oxygen enriched activated carbon ink. The 3D interdigital symmetric electrode was prepared by adjusting and optimizing the electric field strength， line width， number of printing layers and other parameters. The energy dispersive spectrometer （EDS）， scanning electron microscopy（SEM），rheometer，electrochemical workstation and test system were used to characterize materials， pastes and microcapacitor devices， and to explore the influence of materials and pastes on the performance of 3D interdigital microcapacitor. The results that the 3D interdigital supercapacitor prepared by the combination of semiconductor and electrophoresis printing process has good performances， and its area capacitance can reach 22.3 mF·cm^-2. In addition， the device can achieve 96% capacity retention after 2000 cycles through packaging optimization. This simple and controllable 3D jet printing technology provides an effective way to prepare advanced miniaturized electrochemical energy storage devices.

Polymer ionic gel is a new type of gel system composed of ionic liquid (IL) and polymer matrix, which has excellent extensibility, high conductivity and good stability. It has broad application space in the field of flexible electronic products, and has attracted the attention of researchers at home and abroad. Based on the investigation of the research progress in related fields in recent years, the matrix classification of polymer ionic gel materials was summarized, the modification methods of conductive hydrogels were discussed, the application of ionic gel in related fields was expounded, and on this basis, the challenges faced by polymer ionic gel and its future development direction were summarized and prospected. It was pointed out that the development of ionic gel with excellent mechanical properties, high conductivity and degradability is the focus of future research. At the same time, improving the environmental stability of ionic gel and reducing the preparation cost of ionic gel are urgent problems to be solved in practical applications. The preparation and application of ionic gel will promote the rapid development of flexible electronic materials.

The development of energy storage devices that can withstand large and complex deformation is crucial for emerging wearable electronic devices. At present, hydrogels made of conductive polymers have achieved the fusion of high conductivity and versatility during processing. A simple two-step copolymerization method was used to successfully construct a hydrogel supercapacitor with a rich microporous structure: polyvinyl alcohol(PVA) and polyacrylamide(PAM) form a double cross-linked network hydrogel, which endows rigid polymer aniline with flexibility. In addition, polyacrylamide improves the mechanical strength of polyaniline-based hydrogels, making polyaniline-based(NPP)hydrogels have good mechanical and electrochemical properties, and the tensile strength and specific capacitance are 0.3 MPa and 269.12 F·g^-1 under 1 A·g^-1, respectively. The addition of polyaniline(PANI) reduces the internal resistance of polyvinyl alcohol and polyacrylamide double cross-linked network hydrogel(PP) electrode, and its modified resistance value is 39.184 Ω, which makes the NPP hydrogel realize higher electron transmission capacity. The flexible development and integration of such hydrogels provide an alternative strategy of energy systems for diverse applications such as supercapacitors.

With the development of high temperature fields, such as automotive, petroleum, nuclear power and aerospace, piezoelectric materials with wide temperature range, as the core component of nondestructive testing and sustainable self-powered equipment used in these extreme environments, have become the hotspot of research in recent years. However, even the piezoelectric materials with wide temperature range owning excellent piezoelectricity and high temperature stability, the devices made of them could not have both flexibility and high-temperature resistance due to the embrittlement and hardness, resulting in the limitation in the application of high temperature precision operation and wearable health testing. Therefore, the flexible design of piezoelectric materials with wide temperature range, which can realize the preparation of high-temperature resistant, soft piezoelectric device and ultimately broaden the high temperature potential of device, become an important development direction for piezoelectric field. The research progress of piezoelectric materials with wide temperature range was introduced first in this paper, which includes materials (PZT, BT, KNN) used in the environment below 300 ℃ and Ⅲ-N material used in 500-1000 ℃. Then the flexible design technology was collected based on these materials, including direct-growth, growth-transfer and nano-composite. In the meantime, the influence of types of substrates or composite matrix on the high-temperature stability of final device was also analyzed.

The flexible wearable pressure sensor has unique properties such as high comfort, strong braid ability and the ability to imitate human skin to sensitively perceive and respond to external stimuli. It can be used as the artificial electronic skin which will be widely applied in medical detections, disease diagnosis, human motion tracking and health monitoring, etc. In recent years, the design, construction, performance exploration and development of flexible wearable pressure sensors have attracted extensive attention from researchers. The nanofibrous membranes prepared by electrospinning have the advantages of high porosity, large specific surface area and easy to be functionalized, which make them have extensive applications in the field of flexible sensors. The research and progress of electrospun nanofibers in flexible wearable pressure sensors were reviewed in this paper. The major characteristics of the wearable pressure sensors were briefly introduced, and the advantages of electrospinning technology and electrospinning nanofibers in the preparation of flexible wearable pressure sensors were described. The types and applications of the flexible wearable pressure sensors based on electrospinning in different fields were emphatically discussed. Finally, the low-cost manufacture of flexible wearable pressure sensors with high resolution, high sensitivity and accurate response was briefly summarized and prospected.

Flexible energy storage devices are at the forefront of next-generation power supplies, one of the most important components of which is the gel electrolyte. The dual network gel electrolyte for PAM/P123 zinc ion batteries was prepared by free radical polymerization. It was found that the addition of a small amount of triblock copolymer P123 can macroscopically improve the tensile strength, toughness and compressive strength of the gel electrolyte. Microscopically, the gel skeleton forms 0.6 μm mesopores and increases the surface pore distribution density, thereby improving the wettability of the electrolyte. The PAM/P123 series electrolytes not only have a high average swelling rate, but also have a higher conductivity than pure PAM electrolyte in the range of -30℃ to 65℃. Among which, PAM/P123-2 is a series of electrolytes with the best performance, with an average swelling rate of 1920.79%, and the conductivity at 0℃ is 36.2 mS·cm^-1.The Zn/MnO₂ battery prepared by using PAM/P123-2 gel electrolyte is stable during cycling at 0℃, with the capacity retention rate reaching 82.39% after 1000 cycles.

With the rapid development of portable and wearable electronic devices, research on flexible energy storage devices has gradually shifted to the directions of miniaturization, softness and intelligence. At the same time, people have higher requirements for the energy density, power density and mechanical properties of the device. As the core part of flexible energy storage devices, electrode material is the key to determining device performance. With the development of flexible energy storage electronic devices, there is an urgent need for new battery technology and fast, low cost and precise control of their microstructure preparation methods. Therefore, the research and development of new energy storage devices such as flexible lithium/sodium-ion batteries, flexible lithium-sulfur batteries, and flexible zinc-air batteries have become the current research hotspots in academia. The current research status of flexible energy storage battery electrodes in recent years was discussed in this paper, the design of flexible electrode materials (independent flexible electrodes and flexible substrate electrodes), and the preparation process of flexible electrode materials of different dimensions (one-dimensional materials, two-dimensional materials and three-dimensional materials) and applications of flexible energy storage electrodes (flexible lithium/sodium ion batteries, flexible lithium-sulfur batteries, flexible zinc-air batteries) were compared and analyzed, and the structural characteristics and electrochemical properties of electrode materials were discussed. Finally, the current problems faced by flexible energy storage devices were pointed out, and the future focus of flexible energy storage devices was the research and development of new solid electrolytes, the rational design of device structures and the continuous optimization of packaging technology.

Human skin can sense the information from the environment and play a significant role in the contact with the outside world. Electronic skins, which mimic the characteristics of human skin and the ability to perceive the environment have a wide range of applications in the fields of medical monitoring, bionic prostheses and robotic tactile perception. Compared with traditional wearable sensors, electronic skin is lighter, more flexible, more malleable, and has the characteristics of wireless, transparent, and compatibility with human skin, therefore, has become one of the emerging research fields. The electronic skin can continuously sense large number of physical and biochemical parameters of the human body, human motion and gas to monitor human health, sports condition and surrounding gases in various environments in real-time. In this review, the state-of-the-art of the materials used to making electronic skins, including zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) micro/nano-materials, polymeric materials, hydrogel materials and their composites, were discussed, and the practical applications of the electronic skin constructed based on these core materials were concluded in terms of health monitoring, motion monitoring as well as gas monitoring. It was pointed out that there are still some remaining technical problems in the research process of electronic skin such as high cost and complex process.The development trend of electrode skin was towards multi-function and simultaneous detection of multiple external stimuli, and it had broad application prospects in the fields of medical equipment robbotics and future manufacturing.

With the development of electronic information technology and people's pursuit of convenient life, smart flexible wearable devices have attracted the attention of many scholars. In the development of smart wearable devices, flexible conductive materials play a vital role. As the most basic flexible conductive textile material, conductive yarn is widely used in smart wearable products. However, most traditional textile materials are insulating materials and cannot directly form conductive yarns and smart wearable products. The preparation methods and application research progress of metal-based conductive yarns, carbon-based conductive yarns, and conductive polymer-based conductive yarns, as well as the application research progress in wearable strain sensors, wearable supercapacitors, wearable electric heating devices and other aspects were introduced. The problems that need to be solved in the research of conductive yarns in recent years were analyzed, mainly including improving the conductivity, flexibility and environmental stability of conductive yarns. In addition, in view of the convenience, comfort, washing durability, and sensitivity required by smart wearable devices, it was proposed that the sensitivity, durability of flexible conductive yarn and the combination of textile materials and conductive materials have become the main development of wearable flexibles smart product.

Taking the preparation of electrode materials of supercapacitors, the study of properties and the performance of assembled asymmetric supercapacitors as the core contents, and improving the electrochemical performance of supercapacitors as the main purpose, the in-situ polymerization method was used to prepare carboxylated multi-walled carbon nanotubes (PI-MWCNTs) grafted polyimide solution, which is used as the precursor of nitrogen-doped carbon to realize the growth of composites on the surface of carbon cloth and as electrode material.Manganese dioxide-carbon cloth (MnO₂-CC) as the positive electrode, Polyimide-carbon cloth grafted with multi-walled carbon nanotubes as negative electrode (PI-MWCNTs-CC), build asymmetric supercapacitors. The structure and electrochemical properties of the electrode materials were characterized by scanning electron microscopy, raman spectroscopy, surface area and pore size testing, X line photoelectron spectroscopy, cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. According to the study, when the scan rate is 20 mV/s, asymmetric capacitor potential window can be increased to 1.3 V and its volume specific capacity is 1.80 F/cm³.When the power density is 14.08 mW/cm³, the energy density can reach up to 0.423 mWh/cm³.

Perovskite solar cells(PSCs) are paid much attention due to simple preparation and high photoelectric conversion efficiency. Carbon nanofiber films(CNFs) prepared by electrospinning have high specific surface area, electrical properties and chemical stability, but the application in PSCs is limited due to their brittleness. The flexible and conductive Ag/ZrO₂/C composite nanofiber films were prepared by electrospinning and hydrothermal method. After that, it was applied as the counter electrode of flexible PSCs and the effect of Ag nanoparticles with different concentrations on the performance of the composite nanofiber films and the PSCs were studied. The results show that when the concentration of precursor solution rises from 0 g/mL to 0.030 g/mL, the coating effect of Ag nanoparticles on the Ag/ZrO₂/C composite nanofiber improves obviously and all the composite nanofiber films display the excellent flexibility and modulus of elasticity (0.479 MPa), meanwhile, the conductivity of the films increases from 866 S/m to 4862 S/m, so as to enhance the hole-electron transport capacity of the films and the performance of flexible PSCs. When the solution concentration is 0.030 g/mL, the PSCs have best photoelectric conversion efficiency(PCE) of 6.05% and optimal current density (18.44 mA/cm²). It is of great significance to further improve the performance of flexible PSCs and the application of flexible carbon nanofiber films.

The basic structure, working principle, and the development process and research status of resistive random access memory (RRAM) were outlined. Material systems, including dielectric materials, electrode materials, and substrate materials, as well as broad trends and recent researches of flexible RRAM were summarized; the performance characteristics of flexible RRAM, including storage performance and mechanics performance, were analyzed. The significance and challenge of developing flexible RRAM were explicated. Problems existing in this area and possible approaches to the problems were also put forward. It was concluded that the highly conductive stretchable electrode and the steadily stored stretchable dielectric are primary direction in the future.

ANSYS finite element simulation software was used to simulate the heating process of silver coated yarns in fabric. The thermal filed distribution of heating fabric in different condition was analyzed by adjusting the distance between the silver coated yarns and output voltage. The heating fabric was prepared by the results of finite element simulation. The electrical heating property of heating fabric was researched and contrast with the results of finite element simulation. The result shows that, the equilibrium temperature of silver coated yarns rise with the increase of output voltage. The temperature is 109.7℃ by the output voltage is 7V. The distance of silver coated yarn in fabric is 3mm, which makes the surface temperature of heating uniform while the cost of silver coated yarns is lower. The equilibrium temperature and the heating speed rise with the increase of power density. The results of simulation are consistent with the actual results and the deviation is less than 4.5%. The results of finite element simulation can be important reference to guide the fabrication of heating fabric based on silver coated yarns.

Traditional electronic strain sensors based on metal and semiconductor materials have poor flexibility and wear-ability, which are not applicable for stretchable sensors. With the development of flexible electronic materials, wearable electronic devices show great market prospects. Flexible strain sensors have many unique advantages, such as good biocompatibility, wearable, stretchability and elasticity, which become a hotspot of research. The research progress is the preparation technology, performance and application of PDMS based piezoresistive and capacitive flexible strain sensors were summarized in this paper. Finally, challenges, important directions and perspectives related to PDMS flexible strain sensors were prospected.

In recent years, "green" cellulose nanopaper made of nanocellulose has been considered as an alternative substrate for flexible electronics due to its unsurpassed quintessential physical and chemical properties, for example, biodegradability, light mass, mechanical flexibility, transparency, thermal stability, and compatible with well-established roll-to-roll manufacturing techniques. Nanopaper substrates for flexible electronics have gradually been a hotspot of research in academic and industrial community due to the increasing environmental concerns on electronic waste. The latest progresses in nanopaper substrates for flexible electronics were reviewed. The preparation, properties, and device applications of nanopaper substrates were elucidated in details, with specific emphasis on the current application status of nanopaper substrates in organic thin-film transistors, solar cells, and organic light emitting diodes. Moreover, several personal insights on the existing challenges and future research direction of nanopaper substrates were considered based on current advances.

A novel method to fabricate flexible free-standing electrodes with textile structure for lithium-ion batteries was provided by applying extrusion-based three-dimensional (3D) printing technology. Meanwhile, highly concentrated poly(vinylidene fluoride) (PVDF) is used as viscosity modifier, carbon nanotube (CNT) as conducting additive, and lithium iron phosphate (LFP) or lithium titanium oxide (LTO) as cathode or anode active materials respectively to develop printable inks with obvious shear-thinning behavior, and with the apparent viscosity and storage modulus platform value of over 10⁵Pa·s, which is beneficial to the printability and enable complex 3D structures solidification. The electrochemical test shows that both printed electrodes have similar charge and discharge specific capacities under current density of 50mA·g^-1. To explore the feasibility of the printed electrodes, a pouch cell with as-printed LFP and LTO electrode as cathode and anode respectively is assembled. The pouch cell without deformation delivers discharge specific capacities of approximately 108mAh·g^-1, and there is a tiny increase in discharge specific capacities of around 111mAh·g^-1 for bended pouch cell.

Using CNFs as the substrate, CNFs/RGO_n films were prepared by layer-by-layer assembly method. Further, a new supercapacitor (S-RGP) was fabricated by these CPGP thin film electrodes which were got by in-situ polymerization of PANI on CNFs/GG films. The characteristics of CRGP film electrodes, such as absorbance, crystallization feature and configuration were analyzed by XRD, UV-visible spectrophotometry and SEM. The CV curve, GCD and EIS electrochemical characteristics of supercapacitors S-RGP were further tested. The results indicate that the surface of CRGP films was nonuniform, and some active substance kept in the gap between PANI and substrates paper leading to less internal resistance in S-RGP supercapacitor. Electrochemical characteristics measurement shows that the S-RGP supercapacitor has lower ESR, and its capacitance performance cannot be affected by bending because of relative flexibility. S-RGP supercapacitors have weak electrochromic properties, for the PANI film is thick and thus lower opaque by in-situ polymerization process of PANI on CNFs/RGO_n films.