A Robust Mixed Phase Niobium Oxide Flexible Electrode for Fast Charging Li-Ion Batteries

Flexible and lightweight energy storage systems have received tremendous interest recently due to their potential applications in wearable electronics, roll-up displays, and other devices. To manufacture such systems, flexible electrodes with desired mechanical and electrochemical properties are critical. Herein we present a novel method to fabricate conductive, highly flexible, and robust film supercapacitor electrodes based on graphene/MnO(2)/CNTs nanocomposites. The synergistic effects from graphene, CNTs, and MnO(2) deliver outstanding mechanical properties (tensile strength of 48 MPa) and superior electrochemical activity that were not achieved by any of these components alone. These flexible electrodes allow highly active material loading (71 wt % MnO(2)), areal density (8.80 mg/cm(2)), and high specific capacitance (372 F/g) with excellent rate capability for supercapacitors without the need of current collectors and binders. The film can also be wound around 0.5 mm diameter rods for fabricating full cells with high performance, showing significant potential in flexible energy storage devices.

Against the backdrop of swiftly evolving flexible electronics and wearable device technologies, polymer electrolytes are increasingly recognized as pivotal materials for safe and high-performance solid-state battery systems. This review systematically summarizes the recent progress in solvent-free polymer electrolytes, gel polymer electrolytes, and composite polymer electrolytes, focusing on their ion conduction mechanisms, performance optimization strategies, and applications in flexible energy storage systems. The unique advantages of polymer electrolytes, such as high safety, flexibility, and processability, are highlighted, along with critical challenges in ionic conductivity, mechanical strength, and interface compatibility. Emerging applications in supercapacitors, wearable electronics, and medical devices are discussed, emphasizing the importance of multi-scale structural design and interdisciplinary innovation. Future perspectives include the integration of dynamic bionic design, in situ characterization, 3D printing, and artificial intelligence-driven material screening to address current bottlenecks, paving the way for next-generation flexible energy storage technologies.

Hybridization design of materials and devices for flexible electrochemical energy storage

The rapid development of wearable electronics requires developing flexible and efficient energy storage systems. To this end, novel flexible fiber and fabric batteries attract increasing attention due to their combined superiorities in flexibility, weavability, and miniaturization compared with conventional bulky structures. Herein, the recent progress in the electrode fabrication, structure design, and battery performance of fiber and fabric batteries is summarized, and the possibility of battery textiles, challenges, and future directions to satisfy the requirement of the next‐generation flexible energy storage systems is also highlighted.

Robust Free-standing Electrodes for Flexible Lithium-ion Batteries Prepared by a Conventional Electrode Fabrication Process

Self-assembled three-dimensional Ti3C2Tx nanosheets network on carbon cloth as flexible electrode for supercapacitors

To meet the rapid development of flexible, portable, and wearable electronic devices, extensive efforts have been devoted to develop matchable energy storage and conversion systems as power sources, such as flexible lithium-ion batteries (LIBs), supercapacitors (SCs), solar cells, fuel cells, etc. Particularly, during recent years, exciting works have been done to explore more suitable and effective electrode/electrolyte materials as well as more preferable cell configuration and structural designs to develop flexible power sources with better electrochemical performance for integration into flexible electronics. An overview is given for these remarkable contributions made by the leading scientists in this important and promising research area. Some perspectives for the future and impacts of flexible energy storage and conversion systems are also proposed.

The proportion of renewable power generation in the world has been increasing in recent years. However, the fluctuations and uncertainties of renewable power generation bring a considerable challenge to future unit scheduling. Therefore, the generation flexibility in power systems becomes more critical as a large amount of renewable generation is integrated into power systems. The use of flexible generators with energy storage systems is one of the most efficient methods of improving power system flexibility. The primary purpose of this study is to explore the effect of generation flexibility on the cost of unit scheduling. A flexibility index is used to evaluate the generation flexibility in the Taiwan power system, and a multi-scenario analysis for renewable power integration is considered. This study also considers various system constraints, such as the unit commitment of actual hydro and thermal units, the scheduling of flexible internal combustion engines (ICEs) and energy storage systems, and possible curtailments of renewable power generation. According to the seasonable characteristics of renewable power generation, this study provides a suitable capacity for flexible ICE units and energy storage systems. Furthermore, this study demonstrates that the cost of unit scheduling is effectively reduced by increasing flexible ICE units and energy storage systems. The results of this study can be used as a reference for power systems in preparing flexible generating units and energy storage systems under the integration of a large amount of renewable power generation in the future.

Low-cost flexible electromagnetic interference (EMI) shielding materials are attracting considerable attention because of the rapid development of wearable smart electronics, such as wearable health monitoring systems, and flexible energy storage and harvesting systems. In the present study, we developed ultrathin, flexible, and high-performance EMI shielding materials using Ag nanocrystals (NCs) through low-cost, room-temperature wet chemical processes conducted at atmospheric pressure. Sequential ligand-exchange and reduction processes not only substantially reduced the distance between the Ag NCs but also induced intensive metallic fusion of the Ag NCs, resulting in large-scale three-dimensional interconnected conductive pathways. The fused Ag NC thin films exhibited high electrical conductivity (∼24,000 S/cm for a film ∼800 nm thick) and outstanding mechanical stability, offering stable EMI shielding performance over 1000 cycles of various mechanical deformations, including twisting, crumpling, and folding. In addition, compared with most previously reported solution-based materials, our Ag NC thin films demonstrated an excellent EMI shielding effectiveness value of ∼60 dB in the X-band range 8.2–12.2 GHz at much thinner thickness (∼1.3 μm). With the advantages of easy processing, good mechanical flexibility, and high-performance EMI shielding, the fused NC thin films developed in the present work represent innovative potential EMI shielding materials for next-generation wearable smart electronics.

Flexible batteries have garnered a great deal of attention as a promising power source for versatile-shaped electronic devices including bendable smart phones, roll-up displays and wearable electronics, which play crucial roles in facilitating the advent of wearable electronics era. One formidable challenge for development of the flexible batteries arises from difficulties in securing solid-state electrolytes with reliable electrochemical/mechanical properties. Currently available liquid electrolytes show good electrochemical performance suitable for practical applications, however, they often suffer from safety failures due to unwanted leakage problems and flammable characteristics. Moreover, liquid electrolytes limit choices in cell design due to their fluidic attributes, which essentially require the use of separator membranes and packaging canisters with fixed dimension in cell assembly. These shortcomings of liquid electrolytes motivate us to develop advanced solid-state electrolytes that can easily conform to complex-structured substrates such as three-dimensional (3D) electrodes and also ensure sufficient mechanical deformability for reliable use.Herein, as electrolyte breakthrough to advance flexible batteries, a new class of bendable, shape-conformable and thermally-stable composite polymer electrolyte is demonstrated and also its potential application to flexible batteries featuring shape diversity is explored. More notably, the composite polymer electrolyte can be directly writable and printable onto complicated/contoured electrodes, without the aid of processing solvents. The unique structural/compositional designs and well-tuned rheological properties, in collaboration with direct UV-assisted nanoimprint lithography, allow for successful fabrication of solid-state composite polymer electrolytes in geometries that lie far beyond those accessible with conventional electrolytes. As an alternative electrolyte to exceed conventional carbonate-based liquid electrolytes, plastic crystal electrolytes (PCEs) have been investigated. The PCEs, which are composed of lithium salts and plastic crystals bearing good solvation capability, are characterized with unusual thermal stability and ionic transport behaviors. Among various plastic crystal candidates, succinonitrile (SN) is known to show excellence in thermal stability and ionic transport due to high boiling point and structural defects (i.e., trans-gauche isomerism) of plastic crystal phase. Despite of these advantageous characteristics, application of the PCEs to flexible batteries is staggered due to their poor mechanical properties. Most of PCEs are excessively plastic and even more show liquid-like behavior at room temperature. In this talk, we present a wide variety of material strategies to improve the physicochemical properties (in particular, focusing on mechanical flexibility) of SN-based PCEs, which are mainly devoted to integrating with functional polymer matrix that serves as a mechanical framework. The structural design concept demonstrated herein for the synthesis of plastic crystal polymer electrolytes can be suggested as a versatile and scalable electrolyte platform to bring unprecedented opportunities in progress of next-generation flexible energy storage/conversion devices. References Keun-Ho Choi, Sung-Ju Cho, Se-Hee Kim, Yo Han Kwon, Je Young Kim, Sang-Young Lee, "Thin, deformable, and safety-reinforced plastic crystal polymer electrolytes for high-performance flexible lithium-ion batteries", Adv. Funct. Mater. online published.Sang-Young Lee, Keun-Ho Choi, Yo Han Kwon, Hye-Ran Jung, Heon-Cheol Shin, Je Young Kim, "Progress in flexible energy storage and conversion systems, with a focus on cable-type lithium ion battery", Energy Environ. Sci. 2013, 6, 2414. (featured as a back cover image).Eun-Hye Kil, Keun-Ho Choi, Hyo-Jeong Ha, Sheng Xu, John A. Rogers, Mi Ri Kim, Young-Gi Lee, Kwang-Man Kim, Kuk Young Cho, Sang-Young Lee, "Imprintable, bendable, and shape-conformable polymer electrolytes for versatile-shaped lithium-ion batteries", Adv. Mater. 2013, 25, 1395. (featured as a back cover image).

Fabrication of carbon cloth supported Ni@Fe double hydroxide based electrode for flexible supercapacitor applications

Flexible sodium-ion based energy storage devices: Recent progress and challenges

: The electrodes are the basis for building flexible lithium-ion batteries (FLIBs), and many attempts have been made to develop flexible electrodes with high efficiency in terms of electrical conductivity, chemical and mechanical properties. Most studies showed relatively satisfactory results when testing the electrochemical properties of laboratory-produced electrodes, but most of these electrodes could not meet the expected requirements of flexible electrodes in practical applications. Quantitative production faces many problems that must be overcome, such as the gradual decline in electrochemical performance, deformation of the electrode structure, high production costs, and difficulties in the production process itself. In this research, developments in the production of flexible electrodes, especially those that depend on carbon materials and metal nanoparticles, will be discussed and summarized in this research. The electrochemical performance and stability of the produced flexible electrodes will be compared. The factors contributing to the progress in the production of flexible lithium-ion batteries will also be discussed.

The unending demand for portable, flexible, and even wearable electronic devices that have an aesthetic appeal and unique functionality stimulates the development of advanced power sources that have excellent electrochemical performance and, more importantly, shape versatility. The challenges in the fabrication of next-generation flexible power sources mainly arise from their limited form factors, which prevent their facile integration into differently shaped electronic devices, and from the lack of reliable electrochemical materials that exhibit optimized attributes and suitable processability. This review describes the technological innovations and challenges associated with flexible energy storage and conversion systems such as lithium-ion batteries and supercapacitors, along with an overview of the progress in flexible proton exchange membrane fuel cells (PEMFCs) and solar cells. In particular, recently highlighted cable-type flexible batteries with extreme omni-directional flexibility are comprehensively discussed.

Review: 162 refs.