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Enabling reliable operation of energy storage devices over a wide temperature range without safety failures is an urgent prerequisite for extending their applications. Conventional liquid electrolytes in energy storage devices fail to reach this goal due to their limitations in freezing/boiling temperatures and flammability (for organic electrolytes). Here, we demonstrate a new class of aqueous eutectic electrolyte (AEE) based on a colligative property of lithium bis(trifluoromethane sulfonyl)imide (LiTFSI)-water binary mixture. The AEE (5.2 m LiTFSI in water) maximizes effect of freezing-point depression (below −40°C) and shows good electrochemical stability with electrode materials. We identify that a key-underlying mechanism of AEE is coordination of water molecules with Li+ and TFSI-. To explore potential use of AEE, we choose lithium-ion hybrid supercapacitors (HSC) as a model system. The AEE enables the HSC to provide exceptional high-rate cell performance over broad temperature ranges (−40°C ~ 100°C) without incurring fire or explosion.

The upcoming ubiquitous electronics era, which will find widespread popularity of flexible/wearable electronics, self-powered devices, and the Internet of Things (IoT), stimulates us to develop a new concept of advanced power sources beyond currently available battery technologies. Among several approaches to reach this goal, printed power sources with various form factors and flexibility have recently garnered considerable attention as a promising system. The form factor-free, printed power sources, driven by their design diversity, shape/performance compatibility with electronics, and scalable/low-cost processability, enable monolithic/seamless integration with complex/unconventional-shaped electronic devices, in comparison to conventional rigid/bulky counterparts. Here, we review the current status and challenges of the form factor-free, printed power sources, with a focus on their materials development. Various printing techniques and their process parameters exploited for the printed power sources are briefly described. Subsequently, ink materials and chemistry of major cell components are discussed. Based on the understanding of the printing techniques and materials, applications of the printed power sources are overviewed to highlight their exceptional shape aesthetics and electrochemical characteristics in the integrated electronics. Finally, we propose development directions and outlook of the form factor-free, printed power sources as a device-customized energy storage system, along with prospects of their future applications.

Summary The forthcoming smart and ubiquitous electronics era presents significant interest in wireless interconnectivity and shape aesthetics. To fulfill this demand, a new class of advanced power sources with various form factors that are different from existing commercial ones is needed. Printed power sources have recently garnered substantial attention because of their design diversity, shape and performance compatibility with electronics, and scalable and low-cost processability. They are fabricated directly on complex-structured objects via application-customized printing techniques, enabling monolithic integration and electrochemical coupling with target devices. In this Perspective, we describe the current status and challenges of printed power sources, focusing on their role as built-in power sources. Various printing techniques and ink materials and chemistry of electrodes and electrolytes are discussed as key enabling factors. Noteworthy progress in printed built-in power sources is reviewed to highlight their design diversity and electrochemical superiority. Finally, development direction and outlook of printed built-in power sources are discussed in conjunction with their application fields.

The battery separator is an essential component of batteries that strongly affects their performance. The control of their properties being particularly important for obtaining lithium-ion batteries with high cycling performance. Separators are placed between both electrodes, should show high ionic conductivity, excellent mechanical and thermal stability and can be divided into six main types: microporous membranes, nonwoven membranes, electrospun membranes, membranes with external surface modification, composite membranes and polymer blends. Considering the relevance of battery separators in the performance of lithium-ion batteries, this work provides the recent advances and an analysis of the main properties of the different types of separators. Despite the large efforts on this area, it is still necessary to improve their characteristics based on new materials developments for this battery component. This paper also summarizes the recent advances in different solid electrolytes based on polymer and ceramic materials for a transition from conventional batteries to solid state batteries, that will allow the next generation of high-performance, safer and sustainable batteries. Finally, the main research and development directions and future trends in the area of separator membranes for lithium-ion batteries are presented.

Wireless communication through linkage with a smartphone and other portable devices in the sensor area are essential for increasing the efficiency of utilization by storing sensing-value data. Thus, the demand for wireless technology is increasing due to the advantages it provides for the various applications that use these data. However, there is still considerable ambiguity concerning the low portability of such technology due to the increased volume with component integration, the high consumption of power, and the necessity of having a separate battery. Herein, we present solutions for these problems with demonstrations that involve 1) the miniaturization of the device by altering the structure of the built-in battery, 2) the use of a pressure-activated switch for the low-power driving technology, and 3) the implementation of a wireless communication platform by integrating a Bluetooth module with the devices. In addition, we demonstrate a human-interactive display that enables users to instantly observe the changes in the brightness of the organic light-emitting diodes (OLED) as the pressure changes. We show that the system can display the measured, real-time pressure values on the screens of mobile devices, which represents a significant advancement in the fields of energy science and biomedical science.

Electroactive organic-based electrode materials have garnered considerable attention as an emerging candidate to replace inorganic counterparts because of their lightweight, mechanical flexibility, and molecular diversity. Yet, their low energy and power densities associated with poor electronic conductivity and limited ion accessibility often impose a critical impediment for practical applications. Herein, we report that all-fibrous heteromat framework comprising intermingled polyacrylonitrile nanofibers and carbon nanotubes offers three-dimensional bicontinuous electron/ion conductive pathways toward organic-based active materials. At the same time, the framework eliminates heavy metallic current collectors to allow the overall mechanical flexibility of the rechargeable system. Nickel 2,6-naphthalenedicarboxylate (NiNDC) is prepared as a model organic-based anode material for this electrode strategy. Driven by the structural uniqueness, the self-standing heteromat NiNDC anode ultimately affords facile redox kinetics and outstanding electrochemical performance, while surpassing the performance of conventional lithium-ion battery organic-based anodes.

With the ever-growing interests in ubiquitous smart electronics and the Internet of Things, the demand for high-energy-density power sources with aesthetic versatility has increased tremendously. High-energy-density Li-metal batteries have attracted considerable attention for fulfilling the high-energy-density requirement of smart electronics. To obtain form factor-free Li-metal batteries with both design diversity and electrochemical reliability, printed solid-state electrolytes are required as a key component because of their viability for the printing/solidification-based fabrication process and electrode-customized chemical/physical properties. This review present an overview of printed solid-state electrolytes for form factor-free Li-metal batteries with a focus on the materials chemistry and fabrication requirements. In addition, their structural/physical/electrochemical properties were discussed in terms of compatibility with Li-metal batteries.

All-solid-state lithium-ion batteries (ASLBs) are receiving considerable attention due to their safety superiority and high energy density (achieved by bipolar configuration). Inorganic solid electrolytes are explored as a key-enabling material of the ASLBs. However, their critical challenges, including grain boundary resistance, interfacial instability with electrode materials and complicated processability, remain yet unresolved. Here, we demonstrate a new class of gel electrolyte with reversible thixotropic transformation and abuse tolerance as an effective and scalable approach to address the aforementioned longstanding issues. The gel electrolyte consists of (fluoropolymer/cellulose derivative) matrix and liquid electrolyte. The reversible thixotropic transformation is realized via sol-gel transition based on Coulombic interaction of the polymer matrix with liquid electrolyte. This unusual rheological feature allows the gel electrolyte to be printed in various forms. In addition, the gel electrolyte shows low crystallinity, thus playing a viable role in delivering high ionic conductivity. Based on understanding of rheological/electrochemical characteristics of the gel electrolyte, we fabricate a form factor-free pouch-type cell assembled with the gel electrolyte using sequential screen-printing process. The resultant cell shows exceptional safety upon exposure to various harsh abuse conditions, along with decent electrochemical performance.

Pt shells were synthesized on Pd-based alloy-cores via the chemical reduction method. Pt shells containing 1, 2, or 3 layers were prepared by controlling the amounts of Pt precursor used during synthesis. The thicknesses of Pt shell layers were calculated using the difference in the particle size between core and core-shell nanocatalysts, as determined from Cs-corrected scanning transmission electron microscopy (Cs-STEM) data. The shape and elemental distribution in the core-shell structured nanoparticles were analyzed using line profiles and elemental mapping from Cs-STEM. High-resolution X-ray diffraction and X-ray photoelectron spectroscopy analyses suggested that the structural and electronic properties of core-shell nanocatalysts were dependent on the number of shell layers. The activity and durability of the core-shell nanocatalysts were analyzed by the electrochemical method. Accelerated durability tests (ADT) were conducted in the potential range of 0.6–1 V for 10000 cycles, and the mass and specific activities of ADT were shown to be stable for the carbon-supported core-shell nanocatalyst with two Pt shell layers (core@Pt[2](*)/C). In addition, excellent electrochemical performance was observed for the core@Pt[2]/C sample before and after the ADT compared to the commercial samples as well as other samples prepared in this study. Importantly, the optimized Pt usage demonstrated in this study would significantly contribute to the commercialization of proton exchange membrane fuel cells.

This study was conducted to report loss of reduction and complications after single-tunnel coracoclavicular (CC) ligament reconstruction with autogenous semitendinosus tendon graft for acute acromioclavicular (AC) joint dislocations.This retrospective study included patients with acute, unstable AC dislocations (surgery within 6 weeks after trauma). We excluded patients with chronic injury and distal clavicle fractures with CC ligaments disruption. We measured the CC distance on anteroposterior radiographs of both clavicles, preoperatively, immediately postoperatively, and at the final follow-up visit. We evaluated clinical outcomes using the American Shoulder and Elbow Surgeons Shoulder Assessment and the University of California, Los Angeles Shoulder Rating Scale scores and perioperative complications.There were 30 patients (27 men and 3 women) with mean age of 41 years (range, 19-70 years). The mean follow-up period was 31 months (range, 12-186 months). Mean CC distance was 15.5 ± 3.7 mm (84% ± 14% of the contralateral shoulder) preoperatively, 8.9 ± 2.6 mm (9% ± 40%) immediately postoperatively (P .001), and 10.6 ± 3.3 mm (24% ± 39%) at the final assessment (P .001), showing an increase of the CC distance during the follow-up. Loss of reduction (defined as25% increase of CC distance) developed in 14 patients (47%), and complications occurred in 6 patients (20%), including 3 distal clavicle fractures through the tunnel. Final clinical scores were significantly lower in patients with complications (27 vs. 33 of the University of California, Los Angeles assessment [P .001] and 81 vs. 95 of the American Shoulder and Elbow Surgeons Shoulder assessment [P .001]).In acute AC joint dislocation, single-tunnel CC ligament reconstruction using autogenous tendon graft resulted in loss of reduction rate of 47% and a complication rate of 20%. The development of complications adversely affected clinical outcomes.

Coupling thin Li metal anodes with high-capacity/high-voltage cathodes such as LiNi0.8Co0.1Mn0.1O2 (NCM811) is a promising way to significantly increase lithium battery energy density. Yet, the realization of high performance full cells remains a formidable challenge. Here, we demonstrate a new class of highly coordinated, nonflammable carbonate electrolytes based on lithium bis(fluorosulfonyl)imide (LiFSI) in propylene carbonate/fluoroethylene carbonate mixtures. Utilizing an optimal salt concentration (4 M LiFSI) of the electrolyte results in a unique coordination structure of Li+-FSI−-solvent clusters, which is critical for enabling the formation of stable interphases on both the thin Li metal anode and high-voltage NCM811 cathode. Under highly demanding cell configuration and operating conditions (Li metal anode = 35 μm, areal-capacity/charge-voltage of NCM811 cathode = 4.8 mAh cm−2/4.6 V, and anode excess capacity (relative to the cathode) = 0.83), the Li metal-based full cell provides exceptional electrochemical performance (energy densities = 681 Wh kgcell−1/1026 Wh Lcell−1) coupled with nonflammability.

Coupling solar cells with energy storage devices promises to overcome longstanding issues on intermittency and longevity of the individual systems. To enable practical/versatile applications of the coupled power sources, their operating voltages should be widened and customized to the specific purpose. Here, we demonstrate for the first time a new class of voltage-tunable, all-day portable power supplies based on the monolithic integration of interdigitated back contact-structured crystalline silicon photovoltaic (cSiPV) modules and printed bipolar all-solid-state lithium-ion batteries (bASSBs). The voltages of the cSiPV and bASSB are respectively varied and also matched to widen operating voltage window (2.7 − 13.5 V) of the cSiPV–bASSB. Moreover, the cSiPV–bASSB achieves high overall efficiency (10.2%) and stable photo-rechargeable cyclability, which far exceed those of previously reported PV–battery systems. The cSiPV–bASSB is seamlessly unitized with various electronic devices and exhibits sustainable long-time operation under variable weather conditions.

We report the enhanced electrochemical performance of high voltage LiNi0.5Mn1.5O4 cathode by small amount of aliovalent doping in Li-site (Li0.995V0.005Ni0.5Mn1.5O4) and polyimide-carbon (PI–C) coating as well. Such small amount of V-doping in Li-sites leads to the crystallization of ordered spinel. The performances of the cathodes are studied in half-cell assembly at elevated temperature conditions (50, 55 and 60 °C). Although, the notable improvement in elevated temperature conditions are noted for Li0.995V0.005Ni0.5Mn1.5O4 phase at 50 °C, but not sustained while increasing to 55 and 60 °C. Nevertheless, the combined advantages of mixed conducting (ionic and electronic) features of PI-C, an excellent performance are noted for the Li0.995V0.005Ni0.5Mn1.5O4 phase after introducing the PI-C layer, irrespective of the testing temperature. Cyclic voltammetry and impedance studies are also performed to corroborate the Li-ion kinetics.

ESSs (Energy storage systems) for large-scale grid systems and next generation secondary battery systems require an ideal device that satisfies diverse properties such as a high energy density, high power density, low cost, and safe and reliable performance. In this study, we present a CUCap (cyclic ultracapacitor), which is comprised of two reservoirs and one flat flow capacitor cell with a cyclic continuous flow mode and independently tunable power rating and energy capacity. CUCap provides fast-charging and high capacity technology with a simple and practical design for high density and large-scale energy storage systems. The best performance appeared in slurry ratio (electrode to electrolyte) 1 to 7 with the total reservoir volume of 150 mL and the flow rate 300 ml/min, resulting in volumetric energy density, specific capacitance, and discharge time of 7.7 Wh L −1 , 14.2 F ml −1 , 100 min, respectively. Moreover, the slurry electrode of the CUCap cell had a maximum current density around 260 mA cm −2 which could possibly result in a fast-charging CUCap system.

In the present work, we have accomplished morphology-controlled synthesis of ternary Pt–Pd–Cu alloy nanoparticles, particularly for efficient electrocatalytic oxygen reduction reactions. By controlling over the degree of galvanic displacement at room temperature, we selectively introduced porous and hollow architectures into Pt-decorated Pd–Cu alloy nanoparticles. Porous morphology was accompanied with partially facilitated Pt substitution reaction while hollow shape was exclusively achieved when the galvanic reaction was coupled with additional pre-treatment process which could eventually make the following displacement reaction more facile. Not only the both porous and hollow Pt@PdCu/C catalysts exhibited enhanced ORR performances compared to commercial Pt/C, but also they displayed outstanding durability. In addition, we investigated the alloying effects between Pt and Pd–Cu composite and the presumable influences of lattice strain through preliminary theoretical calculation to account for the enhanced ORR efficiency and durability of the present catalysts.

Polymer containing isatin was synthesized by super acid-catalyzed carbon–carbon coupling reaction. Propylsulfonic acid was grafted on isatin unit by substitution reaction with potassium salt of 3-bromo-1-propanesulfonic acid. The sulfonic acid composition was regulated at 25–80 mol % of propylsulfonic acid in order to achieve expected ion exchange capacity of maximum 2.0 meq/g. The copolymers were of high molecular weight (inherent viscosity, ηinh = 1.2 dL/g) to afford a tough membrane by solution casting. All these membranes were casted from dimethylsulfoxide (DMSO). The structural properties of the synthesized polymers were investigated by 1H NMR spectroscopy. The membranes were studied by ion exchange capacity (IEC), water uptake, dimensional stability and proton conductivity assessment by comparing with Nafion®. As increasing the IEC values, the small hydrophobic components induced high proton conductivities and proton diffusion coefficients. These kinds of membranes without ether linkages showed low water swelling as well.

Polyelectrolytes have garnered significant attention as a key electrochemically-active component in a diversity of energy-related industry fields. Among enormous efforts to develop advanced polyelectrolytes, blending of different polyelectrolyte mixtures is suggested as a facile and efficient way. However, unavoidable thermodynamic immiscibility between the blend components has often caused serious challenges in the versatile fabrication of polyelectrolyte blends with desirable membrane properties. Here, as an unprecedented mixing strategy to address this issue, we demonstrate a new class of dual electrospray (DES)-assisted forced polymer blending. As a model system to explore the feasibility of this blending approach, Nafion and multiblock sulfonated hydrocarbon copolymer (denoted as sBlock) comprising sulfonated hydrophilic poly(arylene thioether sulfone) blocks and hydrophobic poly(arylene ether sulfone) blocks are chosen. The processing uniqueness and simplicity of the DES blending technique enable the successful fabrication of Nafion/sBlock blends (referred to as N/B blends) that are difficult to achieve with conventional blending methods due to their large miscibility difference. More notably, during the DES blending, nonsolvent-induced nanophase morphology reconstruction occurs in the N/B Blend, eventually giving rise to some difference in proton conductivity between experimental values and theoretically predicted ones. We envision that the DES-assisted forced blending strategy holds a great deal of promise as a versatile and scalable manufacturing technology to breakthrough the deadlock of thermodynamically immiscible polymer blends and also can be easily applicable to a wide variety of polymer blend systems.

The synthesis of conjugated polyphenylenes containing tetraphenylethylene (PPTPE) moiety, their functionalization with sulfonic acid groups, and the measurement of apposite parameters for PEMs are described. The polymers were prepared by Ni-catalyzed carbon–carbon coupling reaction of dichlorotetraphenylethylene and 2,5-dichlorobenzophenone. These polymers have all carbon–carbon linkages without any ether linkage on polymer backbone, which were not attacked by nucleophiles (H2O, hydrogen peroxide, hydroxide anion and radical), and the twisted structure provided good solubility in aprotic polar solvent. The sulfonic acid groups were introduced by sulfonation reaction with concentrated sulfuric acid. All these membranes were prepared from dimethylacetamide (DMAc) polymer solution. The membranes were studied by ion exchange capacity (IEC), water uptake, proton conductivity, and single cell performance. The chemical degradation test of the prepared membrane was performed by Fenton reagent, and compared with normal sulfonated poly(ether sulfone)s & Nafion.

Understanding and control of interfacial phenomena between electrode material and liquid electrolytes are of major scientific importance for boosting development of high-performance lithium ion batteries with reliable electrochemical/safety attributes. Here, as an innovative surface engineering approach to address the interfacial issues, a new concept of mixed ion/electron-conductive soft nanomatter-based conformal surface modification of the cathode material is presented. The soft nanomatter is comprised of an electron conductive carbonaceous (C) substance embedded in an ion conductive polyimide (PI) nanothin compliant film. In addition to its structural uniqueness, the newly proposed surface modification benefits from a simple fabrication process. The PI/carbon soft nanomatter is directly synthesized on LiCoO 2 surface via one-pot thermal treatment of polyamic acid (=PI precursor) and sucrose (=carbon source) mixture, where the LiCoO 2 powders are chosen as a model system to explore the feasibility of this surface engineering strategy. The resulting PI/carbon coating layer facilitates electronic conduction and also suppresses unwanted side reactions arising from the cathode material-liquid electrolyte interface. These synergistic coating effects of the multifunctional PI/carbon soft nanomatter significantly improve high-voltage cell performance and also mitigate interfacial exothermic reaction between cathode material and liquid electrolyte.

Anion exchange membranes of poly(tetra phenyl ether sulfone) containing hexa-imidazolium hydroxides on the hydrophilic segment of a polymer unit were synthesized by sequential polycondensation, chloromethylation, substitution with 1-methylimidazolium and ion exchange. They showed elevated molecular weight, high solubility in polar aprotic solvents and strong chemical and thermal stabilities in comparison to alkyl quaternary ammonium-functionalized polymers. Different levels of substitution and ion exchange were tested; the resulting ionomer membranes showed high ion exchange capacities (IECs) of up to 2.41 mmol g− 1. The imidazolium-functionalized copolymer membranes showed lower water affinity and high durability in alkaline condition. They exhibited hydroxide conductivity above 10− 2 S cm− 1 at room temperature and good chemical stability for up to 7 days without significant losses of ion conductivity.

Sulfonated multiblock poly(arylene ether sulfone) copolymers (SMPESs) containing phenolphthalein anilide (PPA) as a cardo group were prepared from the precursors of hydrophilic and hydrophobic block oligomers. The hydrophobic oligomer was prepared by 4,4′-dihydroxydiphenylsulfone and 4,4′-dichlorodiphenylsulfone. On the other hand, hydrophilic oligomer prepared by disodium-3,3′-disulfonate-4,4′-dichlorodiphenylsulfone (SDCDPS) and PPA. Post-sulfonation process was applied to add sulfonic acid group on PPA unit of MPES copolymers by using concentrated sulfuric acid. Sulfonated multiblock copolymers (SMPESs) with hydrophilic units of 15, 20 and 25 mol% were successfully synthesized by varying the different mole ratios to control the degree of sulfonation. SMPESs were studied by FT-IR, 1H-NMR spectroscopy, and thermo gravimetric analysis (TGA). Sorption experiment resulted the water uptake of SMPESs that was 16%–62% at 80 °C. The resulted ion exchange capacities (IEC) were 1.14–1.78 (meq/g), and proton conductivities were 65–93 (mS/cm) evaluated as increasing IEC by altering the temperature and relative humidity (RH).

Herein, anomalous behavior of proton conductivity and dimensional stability of sulfonated poly(arylene ether sulfone) (SPAES) nanofiber nonwoven fabric/silicate composite membrane (denoted as ‘SN/S membrane’) featuring dual phase co-continuous morphology, which could be potentially applied to proton exchange membrane fuel cells (PEMFCs), is systematically investigated. The SN/S membrane is fabricated via in situ sol–gel synthesis of tetraethoxysilane (TEOS)/3-glycidyloxypropyltrimethoxysilane (GPTMS) mixture directly inside the electrospun SPAES nonwoven. In comparison to a typical SPAES (matrix)/silicate (domain) composite membrane, the SN/S membrane having structural uniqueness provides significant improvement in relative humidity (RH) variation-driven dimensional change, although its proton conductivity is decreased due to the presence of ionically inert continuous silicate phase. A noteworthy finding of this study is that the phase morphology of composite proton exchange membranes plays a crucial role in determining the membrane properties such as proton conductivity and dimensional stability.

As a facile and scalable approach to the surface modification of high-voltage cathode materials for lithium-ion batteries, direct UV-assisted conformal coating of poly(tris(2-(acryloyloxy)ethyl) phosphate) (PTAEP) gel polymer electrolyte on as-formed LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM) cathode is presented. The smooth and continuous PTAEP coating layer with nanometer-thickness (∼20 nm) is successfully introduced on the NCM surface without impairing electronic/ionic conduction pathways preformed in the NCM cathode. Owing to this structural uniqueness, the PTAEP-coated NCM cathode significantly improves the high-voltage (4.6 V) cycling performance and mitigates the exothermic reaction between the delithiated NCM and liquid electrolyte. This demonstrates that the conformal PTAEP nanocoating layer proposed herein, which is completely different from conventional inorganic material-based coating layers, acts as a new ion-conductive protective film that effectively suppresses unwanted interfacial side reactions between the high-voltage cathode materials and liquid electrolyte.

We have previously demonstrated polyimide (PI) gel polymer electrolyte (GPE)-based nanoencapsulation as a new surface modification strategy for high-voltage cathode materials. In this study, in an endeavor to attain a more comprehensive understanding of the PI GPE-based surface modification, effects of structural variation of PI encapsulating layers (specifically, focusing on PI coating thickness) on cell performance and thermal stability of high-voltage (4.4 V) LiCoO 2 are investigated. Herein, PI coating thickness is tuned between approximately 10 and 40 nm by varying polyamic acid (synthesized from pyromellitic dianhydride/oxydianiline) concentration of coating solutions. As PI coating thickness is increased, discharge C-rate capability of cells is deteriorated due to undesired rise of ionic and electronic resistance of thick PI coating layers. On the other hand, thick PI encapsulating layers are effective in mitigating interfacial exothermic reaction between delithiated LiCoO 2 and liquid electrolyte. Notably, among the various PI coating thicknesses, average thickness of 10 nm imparts well-balanced enhancement in cell performance and thermal stability. These results demonstrate that structural fine-tuning (particularly, coating thickness) of PI encapsulating layers, acting as ion-conductive protective conformal thin films, plays a significant role in optimizing their beneficial coating effects on high voltage LiCoO 2 .

Porous structure-tuned cellulose nanofiber paper separators (designated as S-CNP separators) are demonstrated as a promising alternative to commercial polyolefin separators for use in lithium-ion batteries. A new architectural strategy based on colloidal silica (SiO 2 ) nanoparticle-assisted structural control is presented to overcome the difficulty in forming controllable porous structure of pure cellulose nanofiber paper separators (designated as CNP separators) from densely-packed cellulose nanofibers (CNFs). The new S-CNP separators proposed herein incorporate SiO 2 nanoparticles as a CNF-disassembling agent (i.e., as non-conductive spacer particles). This structural uniqueness allows loose packing of CNFs, thereby facilitating the evolution of more porous structure. The unusual porous structure of S-CNP separators can be fine-tuned by varying SiO 2 contents in the CNF suspension. Notably, the S-CNP separator (fabricated with 5 wt.% SiO 2 content) exhibits the highest ionic conduction due to the well-balanced combination of nanoporous structure and separator thickness, thus contributing to excellent cell performance. This study underlines that the colloidal SiO 2 nanoparticle-directed structural tuning of CNPs offers a promising route for the fabrication of advanced paper separators with optimized attributes and functionality.

New ionic liquids based on siloxane diimidazolium iodides ( SiDII1 , SiDII2 , SiDII3) were synthesized and used as electrolytes in dye-sensitized solar cells. Modification with siloxane materials has been considered as the most effective method to improve the excellent optical transparency and thermal stability after a great many efforts. The synthesized siloxane diimidazolium iodides are viscous liquid with different color. These electrolytes have different chain length with siloxane moieties. Thermogravimetric analysis showed good thermal stability. Among the three SiDII based electrolytes, SiDII1 showed a maximum photo-conversion efficiency of 6.2%. In addition, the performance of the DSSCs showed relatively reasonable compared with other conventional liquid type electrolytes.

In the development of high-voltage lithium-ion batteries, unwanted interfacial side reactions between delithiated cathode materials and liquid electrolytes pose a formidable challenge that needs to be urgently resolved. In this study, as a simple and effective approach to improve cell performance and thermal stability of high-voltage cells, we demonstrate direct surface modification of a cathode by UV-cured nanothickness poly(ethylene glycol diacrylate) (PEGDA) gel polymer electrolyte (GPE). Herein, the UV-crosslinking of EGDA oligomers is conducted directly on as-formed cathode (LiCoO 2 (LCO) is chosen as a model system), instead of application to LCO powders. This unusual coating process allows the successful formation of the conformal PEGDA nanocoating layer on the LCO surface without disrupting the preformed physical architecture of the LCO cathode (specifically, electronic networks and porous structure to be filled with liquid electrolyte). Owing to the structural novelty, the PEGDA-coated LCO cathode improves the cycling performance of high-voltage (=4.4 V) cells and suppresses the exothermic reaction between the delithiated LCO and liquid electrolyte, as compared to the pristine LCO cathode. These results underline that the conformal PEDGDA nanocoating layer proposed herein acts as a new ion-conductive protection film that effectively mitigates the undesired interfacial side reactions.

We demonstrate a facile approach for the fabrication of new silica (SiO 2 ) nanoparticles/polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP)-coated polyethylene terephthalate (PET) nonwoven composite separators for use in lithium-ion batteries. By varying the SiO 2 /PVdF-HFP composition ratio, we can fine-tune the porous structure of the composite separators. At a low SiO 2 /PVdF-HFP ratio, a nonporous structure featuring the PVdF-HFP matrix and SiO 2 domains is obtained. By contrast, an unusual porous structure (i.e., highly-percolated interstitial voids formed between close-packed SiO 2 nanoparticles) is developed at a high SiO 2 /PVdF-HFP ratio, where PVdF-HFP serves as a binder to interconnect SiO 2 powders. This drastic change in the morphology of the composite separators is further confirmed by observing their air permeability and ionic conductivity. Meanwhile, a PET nonwoven is employed as a mechanical substrate to suppress thermal shrinkage of the composite separators. On the basis of morphological characterization, the effects of the composition ratio-dependent structural evolution of the composite separators on the electrochemical performance of cells are investigated. Notably, the composite separator fabricated from a composition ratio of SiO 2 /PVdF-HFP = 90/10 (wt%/wt%) provides superior cell performance owing to a well-tailored microporous structure, as compared to a commercialized polyethylene (PE) separator.

In this study, nanoarchitectured polyimide (PI) gel polymer electrolyte (GPE)-coated lithium cobalt oxide (LiCoO 2 ) cathode materials are fabricated and their application to high-voltage lithium-ion batteries is explored. Distinctive features of the PI coating layer are the highly-continuous surface coverage with nanometer thickness (∼5 nm) and also the facile ion transport via the nanoscale layer. Based on the physicochemical characterization of the PI coating layer, its influence on the cell performance and thermal stability of high-voltage charged LiCoO 2 is investigated as a function of charge cut-off voltage (herein, 4.4, 4.5, and 4.6 V). The anomalous nanoarchitectured PI coating layer, which behaves as an ion-conductive protection barrier to mitigate the undesired side reactions predominantly occurring onto the charged LiCoO 2 surface, plays a viable role in improving the cell performance and alleviating the interfacial exothermic reaction between the delithiated LiCoO 2 and liquid electrolyte. Notably, these advantageous effects of the PI-coated LiCoO 2 become more pronounced as the charge cut-off voltage is increased, where liquid electrolyte is highly vulnerable to electrochemical decomposition.

A facile approach to the fabrication of nanoporous structure-tuned nonwoven composite separators is demonstrated for application in high-safety/high-rate lithium-ion batteries. This strategy is based on the construction of silica (SiO2) colloidal particle-assisted nanoporous structure in a poly(ethylene terephthalate) (PET) nonwoven substrate. The nanoparticle arrangement arising from evaporation-induced self-assembly of SiO2 colloidal particles allows the evolution of the unusual nanoporous structure, i.e. well-connected interstitial voids formed between close-packed SiO2 particles adhered by styrene-butadiene rubber (SBR) binders. Meanwhile, the PET nonwoven serves as a mechanical support that contributes to suppressing thermal shrinkage of the nonwoven composite separator. The aforementioned structural novelty of the nonwoven composite separator plays a key role in providing the separator with advantageous characteristics (specifically, good electrolyte wettability, high ionic conductivity, and benign compatibility with electrodes), which leads to the better cell performance than a commercialized polyethylene (PE) separator.

Evaporation-induced, close-packed silica (SiO 2 ) nanoparticle-embedded polyethylene terephthalate (PET) nonwoven composite separator membranes (hereinafter, referred to as “NW-separators”) are fabricated for application in high-voltage/high-rate lithium-ion batteries. The heat-resistant PET nonwoven is employed as a physical support to suppress thermal shrinkage of the NW-separator. A distinctive characteristic of the NW-separator is the well-connected interstitial voids formed between compactly packed SiO 2 nanoparticles adhered by polyvinylidene fluoride–hexafluoropropylene (PVdF–HFP) binders. This allows for the evolution of highly percolated, electrolyte-philic microporous architecture in the NW-separator. In comparison to a commercialized polyethylene (PE) separator, the NW-separator featuring the aforementioned structural uniqueness exhibits substantial improvements in porosity, air permeability, and electrolyte wettability, which contribute to the facile ionic transport and retarded growth of cell impedance during cycling. As a result, superior cell performance is obtained in the NW-separator. Notably, this advantageous effect of the NW-separator on cell performance becomes more pronounced at challenging charge/discharge conditions of high voltages (herein, 4.4 V) and high current densities.

Sulfonated SBA-15 mesoporous silica (SM-SiO2)-incorporated sulfonated poly(phenylsulfone) (SPPSU) composite membranes are fabricated for potential application in low-humidity proton exchange membrane fuel cells (PEMFCs). The SM-SiO2 particles are synthesized using tetraethoxy silane (TEOS) as a mechanical framework precursor, Pluronic 123 triblock copolymer as a mesopore-forming template, and mercaptopropyl trimethoxysilane (MPTMS) as a sulfonation agent. A distinctive feature of the SM-SiO2 particles is the long-range ordered 1-D skeleton of hexagonally aligned mesoporous cylindrical channels bearing sulfonic acid groups. Based on a comprehensive characterization of the SM-SiO2 particles, the effect of SM-SiO2 (as a functional filler) addition on the proton conductivity of the SPPSU composite membrane is examined as a function of temperature and relative humidity. An intriguing finding is that the proton conductivity of the SPPSU composite membrane exhibits a strong dependence on the relative humidity of measurement conditions. This anomalous behavior is further discussed with an in-depth consideration of the characteristics and dispersion state of SM-SiO2 particles, which affect the tortuous path for proton movement, water uptake, and state of water. Notably, at low-humidity conditions, the SM-SiO2 particles in the SPPSU composite membrane serve as an effective water reservoir to tightly retain water molecules and also as a supplementary proton conductor, whereas they behave as a barrier to proton transport at fully hydrated conditions.

Metabolic syndrome consists of metabolic abnormality with central obesity, hypertriglyceridemia, insulin resistance and hypertension. Adipose tissue has been known as a primary site of insulin resistance and its adipocyte size may be correlated with the degree of insulin resistance. A designed angiopoietin-1, COMP-Angiopoietin-1 (COMP-Ang1), mitigated high-fat diet-induced insulin resistance in skeletal muscle. In this study, we examined effects of COMP-Ang1 on adipocyte droplet size, vascular endothelial cell density in adipose tissue and metabolic parameters in db/db mice by administering COMP-Ang1 or LacZ (as a control) adenovirus. Administration of COMP-Ang1 decreased fat droplet diameter in epididymal and abdominal visceral adipocyte and visceral fat content in db/db mice. The density of vascular endothelial cell in adipose tissue was increased in db/db mice after treatment with COMP-Ang1. Serum resistin and tumor necrosis factor-α level was lower after treatment with COMP-Ang1 in db/db mice. COMP-Ang1 caused a restoration of fasting glycemic control in db/db mice and decreased serum insulin level and insulin resistance measured by HOMA index. These findings indicate that COMP-Ang1 regulates adipocyte fat droplet diameter, vascular endothelial cell density and metabolic parameters in db/db mice.

In an effort to improve the dimensional change and proton conductivity of sulfonated poly(phenylsulfone) (SPPSU) membranes and facilitate their application to proton exchange membrane fuel cells (PEMFC), we develop a new composite membrane featured with a multilayer structure. The multilayer structure consists of a SPPSU-impregnated SiO2 ceramic layer and a SPPSU layer. In contrast to a bulk composite membrane containing randomly dispersed SiO2 nanoparticles, this unusual multilayer-structured composite membrane has an independent ceramic layer comprising close-packed SiO2 nanoparticles and polyetherimide (PEI) binders. On the basis of structural characterization of the composite membranes, the effects of the multilayer structure on the membrane properties are investigated. The introduction of the SiO2 ceramic layer is found to be effective in not only suppressing dimensional change but also enhancing proton conductivity of the multilayered composite membrane. Another intriguing finding is that the decrease of proton conductivity at a low humidity condition encountered in conventional water-swollen membranes is retarded in the multilayered composite membrane. These improvements in the proton conductivity of the multilayered composite membrane are discussed by considering the morphological uniqueness and the water retention capability of hygroscopic SiO2 nanoparticles.

Porous substrate-reinforced composite membranes have been extensively investigated due to their promising application to proton exchange membrane fuel cells (PEMFC). In this study, we develop a new ceramic-based reinforcing porous substrate, which consists of hygroscopic silica (SiO2) nanoparticles interconnected by 3-glycidoxypropyltrimethoxysilane (GPTMS)-based silicate binders and a poly(paraphenylene terephthalamide) (PPTA) nonwoven support. This unusual ceramic substrate is featured with the strong mechanical strength, well-developed nanoporous structure (i.e., nanosized interstitial voids formed between the close-packed SiO2 nanoparticles), high hydrophilicity, and more notably, good water retention capability. The nanostructured pores of the ceramic substrate are subsequently impregnated with sulfonated poly(arylene ether sulfone) (SPAES, degree of sulfonation = 49.3%). In comparison to a pristine SPAES membrane, the ceramic substrate-reinforced SPAES composite membrane offers the significantly improved dimensional change and also effectively mitigates the steep decline of proton conductivity at low humidity conditions, which is further discussed by considering the state of water in the reinforced composite membrane.

We demonstrate a facile approach to fabrication of a self-standing plastic crystal composite electrolyte for a lithium-ion battery, wherein UV (ultraviolet)-cured ethoxylated trimethylolpropane triacrylate (ETPTA) networks are incorporated into a plastic crystal electrolyte (PCE, 1 M lithium bis-trifluoromethanesulphonimide (LiTFSI) in succinonitrile (SN)). An ETPTA monomer having trifunctional groups is successfully crosslinked within a very short UV-exposure time of 20 s without using any solvent, leading to the formation of a self-standing, transparent, and non-sticky plastic crystal composite electrolyte (X-PCCE). Owing to the introduction of the UV-cured ETPTA networks, the X-PCCE is capable of providing unprecedentedly robust mechanical strength even at a high concentration of PCE (i.e., ETPTA/PCE = 15/85%, w/w), along with affording high ionic conductivity. In contrast, a conventional plastic crystal composite electrolyte (F-PCCE) comprising polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP) and PCE is difficult to be fabricated as a self-standing film and easily deformed by weak external stress. Notably, the X-PCCE shows significant improvement in electrochemical stability and interfacial resistance toward lithium metal electrodes. Ionic conductivities of the X-PCCE and the F-PCCE are examined as a function of temperature and discussed under consideration of the interaction between SN, LiTFSI, and polymers in the plastic crystal composite electrolytes.

In an effort to improve thermal shrinkage and electrochemical performance of a separator for a lithium-ion battery, we develop a new composite separator by introducing ceramic coating layers onto both sides of a polyethylene (PE) separator. The ceramic coating layers are comprised of SiO 2 nanoparticles and polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) binders. In comparison to the dense structure of conventional nanocomposite coating layers, the ceramic coating layers are featured with close-packed SiO 2 nanoparticles, which affords a well-developed porous structure, i.e. highly connected interstitial voids formed between the nanoparticles. On the basis of this structural understanding of the composite separators, the effects of ceramic coating layers on the separator properties are investigated as a function of SiO 2 powder size. Owing to the existence of the heat-resistant SiO 2 coating layers, the composite separators show significant reduction in thermal shrinkage than the pristine PE separator. More intriguingly, in comparison to the large-sized (=530 nm) SiO 2 , the small-sized (=40 nm) SiO 2 offers a large number of SiO 2 nanoparticles in the ceramic coating layers, high porosity contributing to facile ion transport, and small increase in the cell impedance, which consequently allows substantial improvements in cell performances as well as thermal shrinkage of the separator.

In an endeavor to improve the discharge C-rate performance of lithium-ion polymer batteries targeting high-power applications, we develop a novel gel polymer electrolyte-coated separator, which is based on introduction of close-packed poly(methyl methacrylate) (PMMA) nanoparticle arrays onto a polyethylene (PE) separator. In contrast to a conventional PMMA dense coating layer, a noticeable feature of the PMMA nanoparticle array coating layer is its highly ordered nanoporous structure, i.e. well-connected interstitial voids formed between the close-packed PMMA nanoparticles. This unique morphology allows for not only favorable liquid electrolyte wettability but also facile ionic conduction of the PMMA nanoparticle arrays-coated separator, both of which play crucial roles in improving the discharge C-rate performance of cells assembled with the separator.

Gel polymer electrolytes containing 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide and a small amount of additive (vinylene carbonate, fluoroethylene carbonate, and ethylene carbonate) are prepared, and their electrochemical properties are investigated. The cathodic limit of the gel polymer electrolytes can be extended to 0 V vs. Li by the formation of a protective solid electrolyte interphase on the electrode surface. Using these gel polymer electrolytes, lithium metal polymer cells composed of a lithium anode and a LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode are assembled, and their cycling performances are evaluated at room temperature. The cells show good cycling performance, comparable to that of a cell assembled with gel polymer electrolyte containing standard liquid electrolyte (1.0 M LiPF 6 in ethylene carbonate/diethylene carbonate). Flammability tests and differential scanning calorimetry studies show that the presence of the ionic liquid in the gel polymer electrolyte considerably improves the safety and thermal stability of the cells.

We demonstrate a new reinforcing porous substrate for a proton-conducting composite membrane targeting proton exchange membrane fuel cells (PEMFC) applications. This porous substrate is based on hygroscopic SiO 2 nanoparticles-coated poly(paraphenylene terephthalamide) (PPTA) nonwovens. The SiO 2 nanoparticles (530 nm), which are interconnected by tetraethoxy silane (TEOS)-based silicate binders, play a crucial role in improving mechanical properties, hydrophilicity, and water retention capability of the substrate. The PPTA nonwoven serves as a support layer offering flexibility and toughness to the substrate. The SiO 2 nanoparticles-coated PPTA nonwoven substrate is subsequently impregnated with sulfonated poly(arylene ether sulfone) (SPAES, degree of sulfonation = 49.3%) that acts as a proton-conducting electrolyte. In comparison to a pristine SPAES membrane, the porous substrate-reinforced SPAES composite membrane presents the substantially improved dimensional change, and more intriguingly, is effective in suppressing the steep decline of proton conductivity at a low humidity condition of 30 °C/50% RH.

We demonstrate potential application of a new composite non-woven separator, which is comprised of a phase inversion-controlled, microporous polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) gel polymer electrolyte and a polyethylene terephthalate (PET) non-woven support, to high-voltage and high-power lithium-ion batteries. In comparison to a commercialized polyethylene (PE) separator, the composite non-woven separator exhibits distinct improvements in microporous structure and liquid electrolyte wettability. Based on the understanding of the composite non-woven separator, cell performances of the separator at challenging charge/discharge conditions are investigated and discussed in terms of ion transport of the separator and AC impedance of the cell. The aforementioned advantageous features of the composite non-woven separator play a key role in providing facile ion transport and suppressing growth of cell impedance during cycling, which in turn contribute to superior cell performances at harsh charge/discharge conditions such as high voltages and high current densities.

This work focuses on the preparation of gold nanoparticles decorated with well-defined polystyrene (PS) for PS-based thin nanocomposite films. Reversible addition–fragmentation chain transfer (RAFT) polymerization of styrene using dibenzyltrithiocarbonate (DBTTC) as a chain transfer agent (CTA) followed by a hydrolysis reaction produced a thiol end-capped PS. The polymer was successfully used as polymeric surface modifier in a two-phase gold nanoparticle (Au-NP) synthesis process, generating Au-NPs having average diameters ranging from 3 to 5 nm. The Au-NPs were incorporated into PS thin films to fabricate organic memory devices, exhibiting switching behaviors.

In an endeavour to improve not only the thermal shrinkage but also the electrochemical performance of separators in lithium-ion batteries, a novel composite separator is developed, i.e., a close-packed SiO2/poly(methyl methacrylate) (PMMA) binary nanoparticles-coated polyethylene (PE) separator. The introduction of SiO2 nanoparticles to the coating layer effectively suppresses thermal shrinkage of the composite separator. In contrast to a SiO2/PMMA coating layer having a film-shaped PMMA binder, the SiO2/PMMA binary nanoparticle coating layer employs PMMA particles as a binder. As a consequence, a highly porous structure, i.e., well-connected interstitial voids, is formed between the binary SiO2 and PMMA nanoparticles. The unique porous morphology allows favourable liquid electrolyte wettability and facile ionic conduction, which play a crucial role in improving cell performance such as the discharge capacity and the C-rate capability of the composite separator.