An Amino Acid-Enabled Separator for Effective Stabilization of Li Anodes.

Fundamentally suppressing Li dendrite growth is known to be critical for realizing the potential high energy density for Li-metal batteries (LMBs). Inspired by the ionic transport function of proteins, we previously discovered that utilizing natural proteins was able to stabilize the Li anode but have not demonstrated how a specific amino acid of the protein enabled the function. In this study, we decorate the separator with Leucine (Leu) amino acid assisted by poly(acrylic acid) (PAA) for effectively stabilizing the Li-metal anode, so as to dramatically improve the cycling performance of LMBs. The decorated separator improves electrolyte wettability and effectively suppresses Li dendrite growth. As a result, the amino acid-enabled separator prolongs the cycle life of the symmetrical Li|Li cells, exhibits higher Coulombic efficiency in the Li|Cu cells, and improves the cycling performance in LMBs with the LiFePO4 cathode. This work is an initial study on applying a specific amino acid of proteins to enhance the performance of batteries, providing a new strategy on guiding Li+ deposition, and laying an important foundation for functional separator design of high-energy-density batteries.

A novel structural design of cellulose-based conductive composite fibers for wearable e-textiles.

Cellulose-based conductive composite fibers hold great promise in smart wearable applications, given cellulose's desirable properties for textiles. Blending conductive fillers with cellulose is the most common means of fiber production. Incorporating a high content of conductive fillers is demanded to achieve desirable conductivity. However, a high filler load deteriorates the processability and mechanical properties of the fibers. Here, developing wet-spun cellulose-based fibers with a unique side-by-side (SBS) structure via sustainable processing is reported. Sustainable sources (cotton linter and post-consumer cotton waste) and a biocompatible intrinsically conductive polymer (i.e., polyaniline, PANI) were engineered into fibers containing two co-continuous phases arranged side-by-side. One phase was neat cellulose serving as the substrate and providing good mechanical properties; another phase was a PANI-rich cellulose blend (50 wt%) affording electrical conductivity. Additionally, an eco-friendly LiOH/urea solvent system was adopted for the fiber spinning process. With the proper control of processing parameters, the SBS fibers demonstrated high conductivity and improved mechanical properties compared to single-phase cellulose and PANI blended fibers. The SBS fibers demonstrated great potential for wearable e-textile applications.

A Bioinspired Coating for Stabilizing Li Metal Batteries.

With plenty of charges and rich functional groups, bovine serum albumin (BSA) protein provides effective transport for multiple metallic ions inside blood vessels. Inspired by the unique ionic transport function, we develop a BSA protein coating to stabilize Li anode, regulate Li+ transport, and resolve the Li dendrite growth for Li metal batteries (LMBs). The experimental and simulation studies demonstrate that the coating has strong interactions with Li metal, increases the wetting with electrolyte, reduces the electrolyte/Li side reactions, and significantly suppresses the Li dendrite formation. As a result, the BSA coating exhibits excellent stability in the electrolyte and improves the performance of Li|Cu and Li|Li cells as well as the LiFePO4|Li batteries. This work reveals that LMBs can benefit from the biological function of BSA, i.e., special transport capability of metallic ions, and lays an important foundation in design of protein-based materials for effectively enhancing the electrochemical performance of energy storage systems.

MOF-Enabled Ion-Regulating Gel Electrolyte for Long-Cycling Lithium Metal Batteries Under High Voltage.

High-voltage lithium metal batteries (LMBs) are a promising high-energy-density energy storage system. However, their practical implementations are impeded by short lifespan due to uncontrolled lithium dendrite growth, narrow electrochemical stability window, and safety concerns of liquid electrolytes. Here, a porous composite aerogel is reported as the gel electrolyte (GE) matrix, made of metal-organic framework (MOF)@bacterial cellulose (BC), to enable long-life LMBs under high voltage. The effectiveness of suppressing dendrite growth is achieved by regulating ion deposition and facilitating ion conduction. Specifically, two hierarchical mesoporous Zr-based MOFs with different organic linkers, that is, UiO-66 and NH2 -UiO-66, are embedded into BC aerogel skeletons. The results indicate that NH2 -UiO-66 with anionphilic linkers is more effective in increasing the Li+ transference number; the intermolecular interactions between BC and NH2 -UiO-66 markedly increase the electrochemical stability. The resulting GE shows high ionic conductivity (≈1 mS cm-1 ), high Li+ transference number (0.82), wide electrochemical stability window (4.9 V), and excellent thermal stability. Incorporating this GE in a symmetrical Li cell successfully prolongs the cycle life to 1200 h. Paired with the Ni-rich LiNiCoAlO2 (Ni: Co: Al = 8.15:1.5:0.35, NCA) cathode, the NH2 -UiO-66@BC GE significantly improves the capacity, rate performance, and cycle stability, manifesting its feasibility to operate under high voltage.

Highland barley Monascus purpureus Went extract ameliorates high-fat, high-fructose, high-cholesterol diet induced nonalcoholic fatty liver disease by regulating lipid metabolism in golden hamsters.

ETHNOPHARMACOLOGICAL RELEVANCE: Hepatocyte lipid accumulation is the main feature in the early stage of nonalcoholic fatty liver disease (NAFLD). Highland barley Monascus purpureus Went (HBMPW), a fermentation product of Hordeum vulgare Linn. var. nudum Hook. f. has traditionally been used as fermented foods in Tibet with the effect of reducing blood lipid in folk medicine. AIM OF THE STUDY: This study investigated the protective effects and molecular mechanism of highland barley Monascus purpureus Went extract (HBMPWE) on NAFLD in syrian golden hamster fed with high-fat, high-fructose, high-cholesterol diet (HFFCD). MATERIALS AND METHODS: HFFCD-induced NAFLD golden hamster model was established and treated with HBMPWE. Liver index, biochemical index, and hematoxylin and eosin (HE) staining were observed. Liver metabolomics and western blot analysis were employed. RESULTS: Our study found that HBMPWE ameliorated HFFCD induced dyslipidemia, weight gain and elevated the liver index. In addition, HBMPWE treatment significantly attenuated lipid accumulation in the liver and modulated lipid metabolism (sphingolipid, glycerophospholipid). Our data demonstrated that HBMPWE not only regulated the expression of proteins related to fatty acid synthesis and decomposition (SREBP-1/ACC/FAS/AceS1, PPARα/ACSL/CPT1/ACOX1), but also regulated the expression of proteins related to cholesterol synthesis and clearance (HMGCR, LDLR, CYP7A1). CONCLUSIONS: HBMPWE improved NAFLD through multiple pathways and multiple targets in body metabolism and could be used as a functional food to treat NAFLD and other lipid metabolic disorders.

Decoupled Ion Transport in Protein-Based Solid Electrolyte through Ab Initio Calculations and Experiments.

Decoupling the ion motion and segmental relaxation is significant for developing advanced solid polymer electrolytes with high ionic conductivity and high mechanical properties. Our previous work proposed a decoupled ion transport in a novel protein-based solid electrolyte. Herein, we investigate the detailed ion interaction/transport mechanisms through first-principles density functional theory (DFT) calculations in a vacuum space. Specifically, we study the important roles of charged amino acids from proteins. Our results show that the charged amino acids (i.e., Arg and Lys) can strongly lock anions (ClO4-). When locked at a proper position (determined from the molecular structure of amino acids), the anions can provide additional hopping sites and facilitate Li+ transport. The findings are supported from our experiments of two protein solid electrolytes, in which the soy protein (with plenty of charged amino acids) electrolyte shows much higher ionic conductivity and lower activation energy in comparison to the zein (lack of charged amino acids) electrolyte.

Building bimodal structures by a wettability difference-driven strategy for high-performance protein air-filters.

Building bimodal structures for air-filters is promising to reduce the airflow resistance without sacrificing the filtration efficiency. To do so, multi-jet electrospinning is among the most broadly used methods, yet the interplay between single fibers in electrospinning, which is significant to their morphologies, is overlooked. In this study, we report a wettability difference-driven strategy to fabricate a bimodal protein fabric with superior filtration performance. We surprisingly find that only by co-spinning of two proteins, zein and gelatin, with different wettability between them, a drastic change of fiber diameters is spontaneously achieved. The generated protein-blend fabric possesses bimodally distributed diameters of 270 nm for gelatin fibers and of 1.12 µm for zein fibers; both pure protein fabrics via single-jet electrospinning have diameters unimodally distributed in the range of 500-700 nm. The bimodal protein-blend fabric delivers exceptional removal efficiencies of 99.67% for PM2.5 and 98.80% for PM0.3, yielding an ultra-low airflow resistance of 38 Pa. The PM2.5 removal efficiency retains to be 96.04% after filtering 1000 L polluted air, indicating a good long-term performance. This study brings about a new insight into fabrication of bimodal structures using multi-jet electrospinning method and promotes the development of natural products for broad applications.

In-Situ Synthesis of N, O, P-Doped Hierarchical Porous Carbon from Poly-bis(phenoxy)phosphazene for Polysulfide-Trapping Interlayer in Lithium-Sulfur Batteries.

The shuttling of polysulfides is the most detrimental contribution to degrading the capacity and cycle stability of lithium-sulfur (Li-S) batteries. Adding a carbon interlayer to prevent the polysulfides from migrating is feasible, and a rational design of the structures and surface properties of the carbon layer is essential to increasing its effectiveness. Herein, we report a hierarchical porous carbon (HPC) created by carbonization of bis(phenoxy)phosphazene and in-situ doping of triple heteroatoms into the carbon lattice to fabricate an effective polysulfide-trapping interlayer. The generated carbon integrates the advantages of a hierarchical porous structure, a high specific area and rich dopants (N, O and P), to yield chemisorption and physical confinement for polysulfides and fast ion-transport synergistically. The HPC interlayer significantly improves the electrochemical performance of Li-S batteries, including an exceptional discharge capacity of 1509 mA h/g at 0.06 C and a high capacity retention of 83.7 % after 250 cycles at 0.3 C. This work thus proposes a facile in-situ synthesis of heteroatom-doped carbon with rational porous structures for suppressing the shuttle effect.

A Protein-Based Janus Separator for Trapping Polysulfides and Regulating Ion Transport in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are a promising candidate for the next-generation energy storage system, yet their commercialization is primarily hindered by polysulfide shuttling and uncontrollable Li dendrite growth. Here, a protein-based Janus separator was designed and fabricated for suppressing both the shuttle effect and dendrite growth, while facilitating the Li+ transport. The Li metal-protecting layer was a protein/MoS2 nanofabric with high ionic conductivity and good Li+ affinity, thus capable of homogenizing the Li+ flux and facilitating the Li+ transport. The polysulfide-trapping layer was a conductive protein nanofabric enabling strong chemical/electrostatic interactions with polysulfides. Combination of the two layers was achieved by an integrated electrospinning method, yielding a robust and integral Janus separator. As a result, a long-lived symmetric Li|Li cell (>700 h) with stable cycling performance was demonstrated. More significantly, the resulting Li-S battery delivered greatly improved electrochemical performance, including excellent rate capacity and remarkable cycle stability (with a low decay rate of 0.063 % per cycle at 0.5 A g-1 over 500 cycles). This study demonstrates the effectiveness of the Janus separator configurations for simultaneously addressing the shuttle effect and dendrite growth issues of Li-S batteries and broadens the applications of electrospinning in electrochemistry community.

Tug-of-War-Inspired Bio-Based Air Filters with Advanced Filtration Performance.

Integrating nanostructured active materials, antimicrobial components, and rational porous structures is one of the promising approaches for simultaneously boosting removal efficiency, antimicrobial capacity, mechanical property, hydrophobic performance, and air permeability of air filters. However, realizing these performances of an air filter still remains a big challenge. Herein, a multifunctional air filter zNFs-Ag@PT, which is composed of a unique substrate prepared from Ag nanoparticles (AgNPs)-paper towel (PT) microfibers and an upper layer formed from aligned zein nanofibers (zNFs) inspired by a "tug-of-war" repulsion force, is reported. The Ag@PT substrate is fabricated via in situ reduction; and zNFs are prepared by electrospinning a well-prepared zein Pickering emulsion onto a specially designed collector. The innovative collector is a partially conductive design composed of an insulative middle section and two conductive ends. It is demonstrated that the introduction of AgNPs not only endows the zNFs-Ag@PT filter with an effective antimicrobial activity but also provides the substrate with an anisotropic electric field to achieve stretched and aligned zein fibers forming thinner nanofibers than that without AgNPs. As a result, the filtration performances of a zNFs-Ag@PT filter are enhanced. This study initiates an effective way to fabricate bio-based multifunctional air filters with antimicrobial and filtration performances via combining nano- and biotechnology.

A Bimodal Protein Fabric Enabled via In Situ Diffusion for High-Performance Air Filtration.

Design and fabrication of bimodal structures are essential for successful development of advanced air filters with ultralow airflow resistance. To realize this goal, simplified processing procedures are necessary for meeting the practical needs. Here, a bimodal protein fabric with high-performance air filtration, and effectively lowered airflow resistance is reported. The various functional groups of proteins provide versatile interactions with pollutants. By utilizing a novel and cost-effective "cross-axial" configuration with an optimized condition (75° of contacting angle between solution nozzle and cospinning solvent nozzle), the diffusion in Taylor cone is in situ controlled, which results in the successful production of bimodal protein fabric. The bimodal protein fabric (16.7 g/m2 areal density) is demonstrated to show excellent filtration performance for removing particulate matter (PM) pollutants and only causes 17.1 Pa air pressure drop. The study of multilayered protein fabric air filters shows a further improvement in filtration performance of removing 97% of PM0.3 and 99% of PM2.5 with a low airflow resistance (34.9 Pa). More importantly, the four-layered bimodal protein fabric shows an exceptional long-term performance and maintains a high removal efficiency in the humid environment. This study presents an effective and viable strategy for fabricating bimodal fibrous materials for advanced air filtration.

A wet-processed, binder-free sulfur cathode integrated with a dual-functional separator for flexible Li-S batteries.

Developing flexible, robust and lightweight sulfur cathodes by rationally designing their structures and configurations through a viable and scalable strategy is a critical enabler for fulfilling flexible lithium-sulfur (Li-S) batteries. However, besides the requirements for cathode flexibility, intrinsic limitations from the shuttling of lithium polysulfides and the growth of Li dendrites have restricted the widespread implementations of Li-S batteries. Here, we report a wet-processed strategy by dissolving and recrystallizing S in a suitable solvent to fabricate a flexible, binder-free S cathode. Integrating the resulting S cathode with a dual-functional separator has demonstrated to be able to suppress both the shuttle effect and growth of dendritic Li. The wet-processed strategy not only enables the fabrication of flexible and binder-free S-nanomat cathodes, but also facilitates the deposition of the cathodes on the separators. Meanwhile, a dual-functional separator is fabricated by vapor-phase polymerization of polypyrrole (PPy) coating on both surfaces of the commercial separator, which leads to the reduction of the shuttle effect and the suppression of the growth of dendritic Li simultaneously. As a result, by integrating the S-nanomat and the dual-functional separator, the cathode exhibits exceptional mechanical properties and electrochemical performance. Li-S pouch cells are further demonstrated to show stable cycling performance in the bending state, indicating the feasibility of the integrated S cathode for flexible Li-S batteries.

Superresilient Hard Carbon Nanofabrics for Sodium-Ion Batteries.

Developing supermechanically resilient hard carbon materials that can quickly accommodate sodium ions is highly demanded in fabricating durable anodes for wearable sodium-ion batteries. Here, an interconnected spiral nanofibrous hard carbon fabric with both remarkable resiliency (e.g., recovery rate as high as 1200 mm s-1 ) and high Young's modulus is reported. The hard carbon nanofabrics are prepared by spinning and then carbonizing the reaction product of polyacrylonitrile and polar molecules (melamine). The resulting unique hard carbon possesses a highly disordered carbonaceous structure with enlarged interlayer spacing contributed from the strong electrostatic repulsion of dense pyrrolic nitrogen atoms. Its excellent resiliency remains after intercalation/deintercalation of sodium ions. The outstanding sodium-storage performance of the derived anode includes excellent gravimetric capacity, high-power capability, and long-term cyclic stability. More significantly, with a high loading mass, the hard carbon anode displays a high-power capacity (1.05 mAh cm-2 at 2 A g-1 ) and excellent cyclic stability. This study provides a unique strategy for the design and fabrication of new hard carbon materials for advanced wearable energy storage systems.

A Super-breathable "Woven-like" Protein Nanofabric.

Nanofabrics made from abundant natural protein that possesses enormous amounts of functional groups may have important applications such as air filtration. However, protein nanofabrics with randomly distributed nanofibers have very low mechanical properties and high airflow resistance, both of which seriously reduce the breathability. Here, a super-breathable zein (corn protein) fabric having a unique "woven-like" nanofibrous structure (w-PNF) via the accumulation effect between the charged nanofibers and the collector during electrospinning is reported. The resulting w-PNF exhibits remarkable tensile strength and modulus, which are 3 and 9 times, respectively, higher than the random protein nanofibrous materials. The filtration tests indicate that w-PNF presents super-breathable performance, including ultralow airflow resistance (1/12 of that of the nonwoven nanofabric) and high filtration efficiency for capturing PM2.5. As compared with the reported nanofabrics, w-PNF maintains the same airflow resistance at up to 4 times higher airflow rate. In addition, w-PNF presents visible-light transparency (80%) and high resolution even in microareas. This work provides a significant strategy for designing and fabricating nanofabrics for boosting the development of biological nanomaterials.

An Ultra-microporous Carbon Material Boosting Integrated Capacitance for Cellulose-Based Supercapacitors.

A breakthrough in advancing power density and stability of carbon-based supercapacitors is trapped by inefficient pore structures of electrode materials. Herein, an ultra-microporous carbon with ultrahigh integrated capacitance fabricated via one-step carbonization/activation of dense bacterial cellulose (BC) precursor followed by nitrogen/sulfur dual doping is reported. The microporous carbon possesses highly concentrated micropores (~ 2 nm) and a considerable amount of sub-micropores (< 1 nm). The unique porous structure provides high specific surface area (1554 m2 g-1) and packing density (1.18 g cm-3). The synergistic effects from the particular porous structure and optimal doping effectively enhance ion storage and ion/electron transport. As a result, the remarkable specific capacitances, including ultrahigh gravimetric and volumetric capacitances (430 F g-1 and 507 F cm-3 at 0.5 A g-1), and excellent cycling and rate stability even at a high current density of 10 A g-1 (327 F g-1 and 385 F cm-3) are realized. Via compositing the porous carbon and BC skeleton, a robust all-solid-state cellulose-based supercapacitor presents super high areal energy density (~ 0.77 mWh cm-2), volumetric energy density (~ 17.8 W L-1), and excellent cyclic stability.

Shi-Style Cervical Mobilizations Versus Massage for Cervical Vertigo: A Multicenter, Randomized, Controlled Clinical Trial.

Objectives: Large sample and high-quality evidence to evaluate the preliminary safety of the mobilizations and massage for cervical vertigo are not yet available. Thus, the present study aimed to investigate the comparative effectiveness and preliminary safety of Shi-style cervical mobilizations (SCM) compared with traditional massage (TM) in cervical vertigo patients. Design: A prospective, multicenter, open-label, randomized, controlled clinical trial with a 1:1 allocation ratio. Settings: Five academic medical centers. Subjects: A total of 360 adult patients with a diagnosis of cervical vertigo. Interventions: The patients were randomly allocated to either an SCM (n = 180) or TM (n = 180) group. The patients were treated during six sessions over 2 weeks. The primary outcome was the Dizziness Handicap Inventory (DHI) total scale score, and secondary outcomes included the DHI subscales, Chinese version of the Short-Form 36 Health Survey (CSF-36), and adverse events (AEs). Outcomes were assessed in the short term at 2 weeks, 1 month, and 3 months, and in the intermediate term at 6 months after randomization. Results: Significant changes were observed from the baseline in the DHI total scale and subscales at 2 weeks and 1, 3, and 6 months in both groups (all p < 0.05). However, the differences between the two groups were not significant (all p > 0.05). Furthermore, we noted significant changes from the baseline in SF-36 scores at 2 weeks in both groups (all p < 0.05), whereas CSF-36 scores were not significantly higher in the SCM group (all p > 0.05) compared with the TM group. No serious AEs were reported in either of the two groups. Conclusions: No differences in outcomes were detected between the SCM and TM groups in terms of treatment of cervicogenic dizziness. Efficacy trials are required to determine whether the improvement observed for each treatment was causally related to the interventions.

A Janus nanofiber-based separator for trapping polysulfides and facilitating ion-transport in lithium-sulfur batteries.

Endowing separators with the polysulfide-blocking function is urgently needed for high-performance lithium-sulfur (Li-S) batteries. Thus far, most of the reported research has focused on modifying conventional polyolefin separators but with poor thermal stability and low ionic conductivity. To address these issues, herein we report a Janus separator based on a thermally stable polymeric nanofabric designed with abilities to trap polysulfides and facilitate the transport of Li+ simultaneously. This Janus separator possesses a configuration of a carbon nanofiber (CNF) layer toward the sulfur cathode and the polyimide (PI) nanofabric toward the Li metal anode. It is demonstrated that the conductive CNF layer can effectively anchor and convert the polysulfides; meanwhile, the excellent wettability with liquid electrolytes and the highly porous structure of the PI nanofiber layer significantly promote the Li+-transport. In addition, the Janus separator presents notable advantages in thermal dimensional stability benefiting from the PI nanofabric. As a result, the Li-S battery armed with the Janus separator shows a high initial capacity (1393 mA h g-1 at 0.1 A g-1), stable cycling performance (822 mA h g-1 at 1 A g-1) and high coulombic efficiency of 99.6%.

Hierarchically Structured All-biomass Air Filters with High Filtration Efficiency and Low Air Pressure Drop Based on Pickering Emulsion.

Although a high-efficiency air filter can be achieved from electrospun nanofabrics, it has been challenging to reduce the pressure drop, increase the filtration capacity, and improve the production rate of the electrospinning process. Here, we report a hierarchically structured all-biomass air filter with high filtration efficiency and low air pressure drop based on applying Pickering emulsions to generate protein-functionalized nanostructures. Specifically, the air filter consists of cellulose nanofibers (CNF)/zein nanoparticles as active fillers prepared from Pickering emulsions and porous structures of microfibers as the frame from wood pulp (WP). The zein-protein-coated nanoparticles, CNF/zein, contribute in multiple ways to improve removal efficiency of the filters. First, the exposed functional groups of zein-protein help to trap air pollutants including toxic gaseous molecules via interaction mechanisms. Second, the nanoparticles with a high surface area promote the capture capability for small particulate pollutants. Meanwhile, the long-micron WP fibers forming a frame with large pores significantly reduce the pressure drop. Via adjusting the component ratios of in the Pickering emulsion, we report an optimized air filter with the high efficiency for capturing both types of pollutants: particulate matter (PM) and chemical gasses such as HCHO and CO, and the extremely low normalized pressure drop, that is, approximately 1/170 of the zein-based nano air filter by electrospinning. This study initiates a cost-effective strategy for forming a hierarchical nano- and microstructure, enabling high efficiency of capturing particulate pollutants of a wide size range and more species. More significantly, this is the first study in which Pickering emulsion is applied as a critical approach with integration of bio- and nano-technology to make high-performance, green air filters.

In Situ Armoring: A Robust, High-Wettability, and Fire-Resistant Hybrid Separator for Advanced and Safe Batteries.

Development of nonflammable separators with excellent properties is in urgent need by next-generation advanced and safe energy storage devices. However, it has been extremely challenging to simultaneously achieve fire resistance, high mechanical strength, good thermomechanical stability, and low ion-transport resistance for polymeric separators. Herein, to address all these needs, we report an in situ formed silica@silica-imbedded polyimide (in situ SiO2@(PI/SiO2)) nanofabric as a new high-performance inorganic-organic hybrid separator. Different from conventional ceramics-modified separators, this in situ SiO2@(PI/SiO2) hybrid separator is realized for the first time via an inverse in situ hydrolysis process. Benefiting from the in situ formed silica nanoshell, the in situ SiO2@(PI/SiO2) hybrid separator shows the highest tensile strength of 42 MPa among all reported nanofiber-based separators, excellent wettability to the electrolyte, good thermomechanical stability at 300 °C, and fire resistance. The LiFePO4 half-cell assembled with this hybrid separator showed a high capacity of 139 mAh·g-1@5C, which is much higher than that of the battery with the pristine PI separator (126.2 mAh·g-1@5C) and Celgard-2400 separator (95.1 mAh·g-1@5C). More importantly, the battery showed excellent cycling stability with no capacity decay over 100 cycles at the high temperature of 120 °C. This study provides a novel method for the fabrication of high-performance and nonflammable polymeric-inorganic hybrid battery separators.

Strategies for Building Robust Traffic Networks in Advanced Energy Storage Devices: A Focus on Composite Electrodes.

The charge transport system in an energy storage device (ESD) fundamentally controls the electrochemical performance and device safety. As the skeleton of the charge transport system, the "traffic" networks connecting the active materials are primary structural factors controlling the transport of ions/electrons. However, with the development of ESDs, it becomes very critical but challenging to build traffic networks with rational structures and mechanical robustness, which can support high energy density, fast charging and discharging capability, cycle stability, safety, and even device flexibility. This is especially true for ESDs with high-capacity active materials (e.g., sulfur and silicon), which show notable volume change during cycling. Therefore, there is an urgent need for cost-effective strategies to realize robust transport networks, and an in-depth understanding of the roles of their structures and properties in device performance. To address this urgent need, the primary strategies reported recently are summarized here into three categories according to their controllability over ion-transport networks, electron-transport networks, or both of them. More specifically, the significant studies on active materials, binders, electrode designs based on various templates, pore additives, etc., are introduced accordingly. Finally, significant challenges and opportunities for building robust charge transport system in next-generation energy storage devices are discussed.