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As a promising high capacity electrode material for lithium-ion batteries, germanium anodes are still to date restricted by the large volume change (＞300%) during repeated cycling, which leads to a short cycle life and poor cycle stability in practical application. To overcome these challenges, herein a facile fabrication is reported to encapsulate GeOx nanoparticles into hollow carbon shells using co-axial electrospinning. This core–shell structure has shown remarkable improvements in alleviating the volume change of GeOx during cycling, minimizing the contact area between electrolyte and GeOx to form a stable solid electrolyte interface film, and providing enhanced electrical conductivity. In addition, Ge nanoparticles in the GeOx composite can promote the reversible capacity for the reversible utilization of Li2O. As a result, such a GeOx@C composite electrode exhibits excellent cycling ability with a reversible specific capacity of 875 mA h g−1 at 160 mA g−1 after 400 cycles, along with an improved rate capacity of 513 mA h g−1 at a high current density of 1600 mA g−1 upon 500 cycles. [ABSTRACT FROM AUTHOR]

Silicon is one of the most promising anode materials for lithium ion batteries due to its high-specific capacity. However, its poor cycling stability and rate capability limit its practical use. Herein, we report the scalable fabrication of a unique three-dimensional porous silicon/TiOx/carbon (Si/TiOx/C, 0 ＜ x ＜ 2) binder free composite electrode for lithium ion batteries. The TiOx/C frameworks were incorporated by a slurry coating method followed by heat treatment, resulting in a well-connected three dimensional framework structure consisting of Si nanoparticles conformably embedded in the conducting TiOx/C matrix. The porous TiOx/C conductive framework effectively alleviates the volume change of Si during cycling and substantially improves the structural stability of electrode materials. Moreover, the amorphous TiOx/C conductive matrix provides high electrical conductivity and facilitates the electrochemical reaction between Li and Si. As a consequence, the Si/TiOx/C electrode exhibits a stable reversible specific capacity of 1696 mA h g−1 at 0.1 A g−1 after 100 cycles with 87% capacity retention and superior rate capability (754 mA h g−1 at 15 A g−1). The exceptional performance of the Si/TiOx/C electrode combined with the facile synthesis technique makes it promising for high energy lithium ion batteries. [ABSTRACT FROM AUTHOR]

Origami structures with reconfigurable mechanical properties are increasingly in demand in engineering applications. The Square-Twist (S-T) origami, featured with excellent reconfigurability and torsional bistability, has a broad application prospect. However, there are relatively few reports on the abundant mechanical properties of S-T origami, especially for those uncommon configurations. In this paper, to analyze the kinematics and mechanics of the unfolding motion, an equivalent theoretical model of the S-T origami is established, which could effectively solve the challenging issues of facet bending, self-contact, and diverse loading directions. With systematic finite element analyses and experimental tests of the S-T origami structures, the effectiveness of the theoretical model along with the optimization-based numerical approach is verified. During the unfolding process, significant distinctions in the potential energy profile and the force–displacement relations among the four different configurations of the S-T origami structure are uncovered. The effects of the design geometry and the material property on the constitutive relations of the S-T origami structure are comprehensively elucidated. Finally, we demonstrate that through folding reconfiguration, an S-T origami structure could exhibit five types of force–displacement relation that are qualitatively different, including bi-stable and mono-stable profiles. [ABSTRACT FROM AUTHOR]

Owing to high‐efficiency and scalable advantages of electrolysis in molten salts, electrochemical conversion of carbonaceous resources into graphitic products is a sustainable route for achieving high value‐added carbon. To understand the complicated kinetics of converting amorphous carbon (e.g. carbonized lignin‐biochar) into highly graphitic carbon, herein this study reports the key processing parameters (addition of Ni, temperature and time) and multi‐scale approach of nickel‐boosted electrochemical graphitization‐catalysis processes in molten calcium chloride. Upon both experiments and modellings, multi‐scale analysis that ranges from nanoscale atomic reaction to macroscale cell reveal the multi‐field evolution in the electrolysis cell, mechanism of electrochemical reaction kinetics as well as pathway of nickel‐boosted graphitization and tubulization. The results of as‐achieved controllable processing regions and multi‐scale approaches provide a rational strategy of manipulating electrochemical graphitization processes and utilizing the converted biomass resources for high value‐added use. [ABSTRACT FROM AUTHOR]

Large-scale β-MnO2 nanorods were synthesized by the hydrothermal method. In X band, the microwave attenuation of the β-MnO2 nanorods is evidently enhanced with increasing temperature from 293 to 773 K. The enhanced temperature-response attenuation of β-MnO2 nanorods is mainly attributed to the decrease in the real permittivity and the increase in the imaginary permittivity at high temperature. The decrease in real permittivity would be mainly ascribed to the increase in the disorder degree of orientational alignment of the intrinsic polar moment in the β-MnO2 nanorods with temperature increasing. The increase in imaginary permittivity may result from the lower resistivity with rising temperature. [ABSTRACT FROM AUTHOR]

Titanium resources, with many outstanding properties, is abundant in the earth's crust, while large-scale application of titanium has been substantially restricted by two key challenges, i.e. high production cost and low utilization. Currently, metallurgists have paid great attention to develop a new extraction process for achieving the goal. However, the sustainable recycling of titanium currently receives far less attention. Here, we develop a molten salt electrolysis for the high-quality recycling of titanium scarps. TC4 (Ti6Al4V) scrap, as a representative titanium alloy, is selected to investigate the separation effect in the molten salt electrolysis. Remarkably, anodic dissolution of the vanadium element in the TC4 alloy could be inhibited by decreasing anodic current density. Therefore, high priced vanadium metal powder could be collected from the anodic mud. Aluminum element in the TC4 alloy anode can dissolve into electrolyte in the form of Al ions, and then remains in the electrolyte via optimizing the electrolyte contents and electrolysis parameters. Finally, high purity titanium could be collected from the cathode. Consequently, this work is significant for the titanium sustainable recirculation or even the entire titanium industry because the titanium scraps will be converted into the high-grade titanium metal and other high priced metals. • Anodic process of the TC4 alloy is investigated to realize the high quality sustainable recovering of titanium scraps. • The influence of the composition of the electrolyte on the selective electro-deposition of titanium is revealed. • Purity metallic titanium has been produced at the cathode through molten salt electrolysis from titanium scraps. • High priced vanadium metal in the TC4 alloy can be collected from the anode mud. [ABSTRACT FROM AUTHOR]

Aluminum–sulfur (Al−S) batteries of ultrahigh energy‐to‐price ratios are a promising energy storage technology, while they suffer from a large voltage gap and short lifespan. Herein, we propose an electrocatalyst‐boosting quasi‐solid‐state Al−S battery, which involves a sulfur‐anchored cobalt/nitrogen co‐doped graphene (S@CoNG) positive electrode and an ionic‐liquid‐impregnated metal–organic framework (IL@MOF) electrolyte. The Co−N4 sites in CoNG continuously catalyze the breaking of Al−Cl and S−S bonds and accelerate the sulfur conversion, endowing the Al−S battery with a shortened voltage gap of 0.43 V and a high discharge voltage plateau of 0.9 V. In the quasi‐solid‐state IL@MOF electrolytes, the shuttle effect of polysulfides has been inhibited, which stabilizes the reversible sulfur reaction, enabling the Al−S battery to deliver 820 mAh g−1 specific capacity and 78 % capacity retention after 300 cycles. This finding offers novel insights to design Al−S batteries for stable energy storage. [ABSTRACT FROM AUTHOR]

Promoting interfacial kinetics of high‐nickel LiNi0.8Mn0.1Co0.1O2 (NMC811) is a critical strategy for enhancing rate capability of lithium‐ion batteries (LIBs). At the solid‐liquid interface of positive electrode, charge transfer across the cathode‐electrolyte interphase (CEI) is responsible for the interfacial redox reaction, which is dominated by desolvation process of Li+ and NMC811 CEI evolution. Since these two processes are significantly impacted by the solvation effect of electrolytes, herein single‐particle Raman spectroscopy and single‐particle probes are established to quantitatively study the influences of solvation effect on CEI evolution and desolvation process of Li+, respectively. Owing to oxidation of the unstable free cyclic carbonate ester from dissociation of solvation structure, the CEI is found to grow thicker during discharge process. Due to the decreased concentration of cyclic carbonate in the solvation structure, the desolvation process of Li+ in the ethyl methyl carbonate‐ethylene carbonate electrolyte can be reduced by 11.8% compared to that in the dimethyl carbonate‐ethylene carbonate electrolyte. With the presence of ethyl methyl carbonate‐ethylene carbonate electrolyte, thinner CEI and easier desolvation process of Li+ can be simultaneously achieved on the NMC811 surface. Accordingly, its corresponding LIBs deliver the highest specific capacity ≈138.8 mAh g−1 at 5C among the LIBs with the other commonly used electrolytes. [ABSTRACT FROM AUTHOR]

Nonaqueous organic aluminum batteries are considered as promising high‐safety energy storage devices due to stable ionic liquid electrolytes and Al metals. However, the stability and capacity of organic positive electrodes are limited by their inherent high solubility and low active organic molecules. To address such issues, here porphyrin compounds with rigid molecular structures present stable and reversible capability in electrochemically storing AlCl2+. Comparison between the porphyrin molecules with electron‐donating groups (TPP‐EDG) and with electron‐withdrawing groups (TPP‐EWG) suggests that EDG is responsible for increasing both highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, resulting in decreased redox potentials. On the other hand, EWG is associated with decreasing both HOMO and LUMO energy levels, leading to promoted redox potentials. EDG and EWG play critical roles in regulating electron density of porphyrin π bond and electrochemical energy storage kinetics behavior. The competitive mechanism between electrochemical redox reaction and de/adsorption processes suggests that TPP‐OCH3 delivers the highest specific capacity ~171.8 mAh g−1, approaching a record in the organic Al batteries. [ABSTRACT FROM AUTHOR]

Smart structures with manipulatable properties are highly demanded in many fields. However, there is a critical challenge in the pursuit of transparent windows that allow optical waves (wavelength of µm–nm) for transmitting while blocking microwave (wavelength of cm) in terms of absorbing electromagnetic energy, specifically for meeting the frequency requirement for the 5th generation (5G) mobile networks. For fundamentally establishing novel manipulatable microwave absorbing structures, here, new polymeric aqueous gels as both optically transparent materials and microwave absorbing materials are demonstrated, in which polar networks play significant roles in attenuating electromagnetic energy. By manipulating the hydrogen bonding networks, the resulting optically transparent solid‐state gels are able to offer the capabilities for absorbing microwaves. Interestingly, such gels can be switched into an optically opaque state via converting the amorphous state into a polycrystal state when the temperature is decreased. Such ionic conductive gels can endow the assembled sandwich windows with effective microwave absorbing capability in the range of 15–40 GHz, covering a branch of 5G frequency bands. The results highlight a new strategy for using ionic conductive gels to design and fabricate manipulatable microwave stealth structures for various applications. [ABSTRACT FROM AUTHOR]

LiNi0.8Co0.1‐Mn0.1O2 (NMC811) is widely used in high energy density lithium‐ion batteries, while dynamic variation of liquid‐solid interface induced by oxygen release/evolution results in unexpected performance decay. Surface coating is an effective strategy in promoting the stability of NMC811 materials, and both coating composition and nanostructure arrangement would substantially impact the dynamic variation of liquid‐solid interfaces. To understand such dynamic variation, here evolution and stability of two selected NMC811 materials coated with oxides (the same oxide composition but different nanostructure arrangements) are compared, i.e., concentration uniform core‐shell NMC811 (CUCS811) and concentration gradient core‐shell NMC811 (CGCS811). The gas evolution from the home‐setup operando gas monitors (at 45 and 65 °C) implies that CUCS811 presents more operation and thermal stability because of less amount of CO2 and CH4 along with prolonged interval time in gas production. Composition variation of interfaces indicates that CUCS811 presents more stable interfacial evolution behaviors since more F‐ and P‐rich species for stabilizing the solid‐electrolyte interfaces are detected. The stability analysis suggests that uniform arrangement of Al2O3 and boride in the coating is prone to prevent the interface from degradation upon dynamic interface variation, which is useful in promoting the performance stability of NMC811 positive electrode materials. [ABSTRACT FROM AUTHOR]

Coloration materials and devices with broad manipulatable color spectra and precisely controllable capability are highly pursued in various applications, such as camouflage engineering, optical sensors, anticounterfeiting technology, real‐time monitoring, and so on. For achieving the goals, in the present work, a conceptually novel bioinspired coloration film is demonstrated using nanoscale amorphous silicon (a‐Si) layer deposited on a reflective metal substrate. With precisely manipulating the reversible lithiation/delithiation behaviors, such coloration films enable to present consecutively tunable chromogenic property in a broad visible band, since the simultaneous changes in both chemical components and film thickness upon electrochemical processes substantially vary the conditions of destructive interference. Accordingly, the corresponding model based on electro‐chemomechanical coupling effects confirms the coloration mechanism induced by thickness and intrinsic properties (refraction index and optical absorptivity). Additionally, such coloration films also suggest universal design ability, namely tailoring the coloration spectra via simply changing film thicknesses and metal substrates. Thus, the results promise a versatile strategy for fabricating advanced coloration materials and devices that are pursued in specular reflection, sensing, anticounterfeiting, labels, displaying, and sensors. Bioinspired controllable electro‐chemomechanical silicon coloration films are established for achieving consecutively tunable chromogenic property in a broad visible band. The reversible chromatic ability is linked with electro‐chemomechanical evolutions in variable lithiated silicon nanofilms. The multiple‐coloration films are highly designable by simply manipulating the thickness of the silicon nanofilm and the categories of the metal substrate. [ABSTRACT FROM AUTHOR]

Rechargeable aluminum‐ion batteries (AIBs) are regarded as promising candidates for post‐lithium energy storage systems (ESSs). For addressing the critical issues in the current liquid AIB systems, here a flexible solid‐state AIB is established using a gel‐polymer electrolyte for achieving robust electrode–electrolyte interfaces. Different from utilization of solid‐state systems for alleviating the safety issues and enhancing energy density in lithium‐ion batteries, employment of polymeric electrolytes mainly focuses on addressing the essential problems in the liquid AIBs, including unstable internal interfaces induced by mechanical deformation and production of gases as well as unfavorable separators. Particularly, such gel electrolyte enables the solid‐state AIBs to present an ultra‐fast charge capability within 10 s at current density of 600 mA g−1. Meanwhile, an impressive specific capacity ≈120 mA h g−1 is obtained at current density of 60 mA g−1, approaching the theoretical limit of graphite‐based AIBs. In addition to the well‐retained electrochemical performance below the ice point, the solid‐state AIBs also hold great stability and safety under various critical conditions. The results suggest that such new prototype of solid‐state AIBs with robust electrode–electrolyte interfaces promises a novel strategy for fabricating stable and safe flexible ESSs. Flexible stable solid‐state Al‐ion batteries are constructed using the gel‐polymer electrolyte, Al anode, and graphite cathode. The novel polymeric electrolyte substantially promotes the overall energy storage performance via addressing the unstable internal interfaces induced by mechanical deformation and production of gases as well as unfavorable separators in the liquid systems, suggesting new strategies for achieving advanced flexible energy storage devices. [ABSTRACT FROM AUTHOR]

High performance flexible batteries are essential ingredients for flexible devices. However, general isolated flexible batteries face critical challenges in developing multifunctional embodied energy systems, owing to the lack of integrative design. Herein, inspired by scales in creatures, overlapping flexible lithium‐ion batteries (FLIBs) consisting of energy storage scales and connections using LiNi0.5Co0.2Mn0.3O2 (NCM523) and graphite electrodes are presented. The scale‐dermis structure ensures a high energy density of 374.4 Wh L−1 as well as a high capacity retention of 93.2% after 200 charge/discharge cycles and 40 000 bending times. A variable stiffness property is revealed that can be controlled by battery configurations and deformation modes. Furthermore, the overlapping FLIBs can be housed directly into the architecture of several flexible devices, such as robots and grippers, allowing to create multifunctionalities that go far beyond energy storage and include load‐bearing and variable flexibility. This study broadens the versatility of FLIBs toward energy storage structure engineering of flexible devices. [ABSTRACT FROM AUTHOR]

The calendering process, which is a common compaction technique, serves as the final step in the manufacturing of lithium-ion battery electrodes. Calendering plays an irreplaceable role in enhancing the volumetric energy density and electrochemical performance due to the densification of pore structure. To investigate the densification of active particles, this study designs and develops a micro-CT loading device, which can capture the in-situ evolution during the electrode compression. By combining the in-situ CT with discrete element method (DEM) scheme, we analyze the internal load transfer paths, particle contacts, and pore structure evolution during the densification. The results indicate that the particle compaction process can be divided into two stages, exhibiting a state transition from a non-uniform compaction stage to a uniform compaction stage, and the large particles show a higher breakage risk after over-compaction. This study successfully in-situ tracks the densification during electrode compression and it would promote a deeper understanding of the evolution of electrode microstructure and particle fracture, and optimize the structures and performance of electrodes. In situ CT technology and DEM have been used to understand the calendering process of the cathode for Li-ion battery, which shows a transition from a non-uniform compaction stage to a uniform compaction stage. [Display omitted] • Developed an in-situ micro-mechanical stage to characterize the cathode calendering process using CT. • Using DEM based on X-ray tomography to analyze the mechanical transfer path of active particles during calendering. • Revealed the transition from non-uniform compression to uniform compression in electrode densification. • Analyzed the potential fragmentation of active particles caused by the over compaction. [ABSTRACT FROM AUTHOR]

The safety of lithium-ion batteries is an essential concern where instant and accurate temperature sensing is critical. It is generally desired to put sensors inside batteries for instant sensing. However, the transmission of internal measurement outside batteries without interfering their normal state is a non-trivial task due to the harsh electrochemical environment, the particular packaging structures and the intrinsic electromagnetic shielding problems of batteries. In this work, a novel in-situ temperature sensing framework is proposed by incorporating temperature sensors with a novel signal transmission solution. The signal transmission solution uses a self-designed integrated-circuit which modulates the internal measurements outside battery via its positive pole without package breaking. Extensive experimental results validate the noninterference properties of the proposed framework. Our proposed in-situ temperature measurement by the self-designed signal modulation solution has a promising potential for in-situ battery health monitoring and thus promoting the development of smart batteries. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: Graphitic materials with intercalated sites are considered as the mostly used positive electrode materials in nonaqueous Al batteries. Unlike the small‐size cations, the intercalation/de‐intercalation of large‐size anions into/out of graphite would induce large volume expansion and micro‐structure reconfiguration, leading to unexpected coulombic efficiency in the full cells (<95% within initial several cycles). For understanding the irreversible processes induced by anion intercalation/de‐intercalation (AlCl4–), here the kinetics of first two cycles for the Al‐graphite batteries have been systematically studied. To study kinetics behaviors at representative states, a combined method upon galvanostatic intermittent titration technique and electrochemical impedance spectroscopy has been carried out. The achieved diffusion coefficients of the positive electrodes assembled with different graphite sizes suggest that size effect also plays a critical role in determining the electrochemical kinetics in the mass transport in both electrolyte and graphitic layers as well as in interface reaction. The morphologies and micro‐structures of the post‐cycled graphite electrodes have been also experimentally studied, which also well supports the irreversible intercalation/de‐intercalation behaviors in graphite electrodes. The results offer a significant platform to well understand the essential factors in tailoring coulombic efficiency from a kinetic view, which would be helpful in promoting the graphite electrodes in Al batteries. [ABSTRACT FROM AUTHOR]

The effective properties of lithium-ion battery (LIB) cathode are determined by both the volume fractions of constituents and the morphological features of microstructure. However, it is difficult to establish an accurate quantitative relationship between the macroscopic effective properties and microstructural features. Deep learning techniques, due to their exceptional nonlinear fitting capabilities, have been widely applied in various complex fields. Our study presents a generation scheme of numerous three-dimensional (3D) digital microstructures of cathode, using a deep convolutional neural network (CNN)-based stochastic reconstruction algorithm combining with the scanning electron microscope (SEM) images. The reconstructed samples are substituted with the corresponding finite element (FE) models, and the effective mechanical and electrochemical properties are assessed through the FE-based homogenization theory. Finally, the generated cathode samples and their effective properties are used to train the 3D CNN for performance prediction. This study demonstrates that the deep learning approaches can accurately and rapidly reconstruct the microstructure of cathode and predict their effective properties. Furthermore, the established framework can be extended to other heterogeneous materials. • Cathode microstructure feature extraction based on transfer learning is proposed. • A CNN-based stochastic reconstruction method for microstructures is developed. • CNN and homogenization theory are used for properties prediction of microstructures. [ABSTRACT FROM AUTHOR]

Silicon film with pre-crack was used to study the coupling effect of stress and electrochemical field around the crack tip. The in-situ experiments were established to monitor the crack to realize the stress concentration around the crack and simultaneously prevent the crack initiation. The ex-situ Auger electron spectroscopy experiments shown the remarkably Li redistributed phenomenon around the crack tip. Furthermore, the fully coupled finite element method was used to reveal the fundamental mechanisms of the Li gathering effect and the stress relaxation phenomenon around the crack tip. Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract Microwave absorbers as an effective way to reduce microwave radiation in stealth technologies and electromagnetic compatibility have attracted great attentions recently. Herein, a novel multifunctional carbon fiber (CF)/glass fiber (GF) reinforced lossy lattice metastructure for broadband microwave absorption and effective load bearing is proposed for the first time based on the structural similarity of photonic crystal and lightweight mechanical lattice. The lossy lattice is fabricated with nano lossy composite composed of multiwall carbon nanotube (MWCNT) and spherical carbonyl iron (CI) particles to manipulate complex permittivity and complex permeability. Sub-wavelength effect and structural optimization are applied for the metastructure to extend −10 dB absorption bandwidth from 3.42 GHz to 19.73 GHz with thickness of 3.5 mm. With solid attachment of CF and GF, the metastructure achieves high average equivalent strength of 167.35 MPa and fracture strain of 5.45%. A long plastic stage of the metastructure is observed after GF fracture or GF delamination in three-point flexural test. The integrated design of microwave absorbing and mechanical properties make it promising for practical applications in mass production. Graphical abstract Dielectric-magnetic lossy lattice metastructure composed of carbonyl iron and multiwall carbon nanotube is fabricated with a four-step method. Broadband absorption from 3.42 GHz to 19.73 GHz with thickness of 3.5 mm and large tensile strength of 167.35 MPa with fracture strain of 5.45% are achieved. Integrated design shed light on practical applications and mass production in stealthy technologies and lightweight armor. Image 102 [ABSTRACT FROM AUTHOR]

The non-uniform growth of lithium dendrites is the main factor causing internal short-circuits and thermal runaway in lithium-ion batteries. Due to the internal environment of the battery being a complex multi-field coupling, the mechanisms of triggering lithium deposition are still unclear. Here, a cross-sectional in-situ optical microscope device was fabricated to observe lithium dendrite evolution. The amount of irreversible and reversible lithium was quantified by the image binarization method and titration gas chromatography, which is used to analyze the relationship between separator deformation, current density, and lithium deposition. The greater the separator deformation and current density, the more irreversible lithium increases. The pore defect mapping algorithm was developed to reconstruct a high-precision three-dimensional finite element model of the separator, which was used to quantify the relationship between displacement loading and the microstructure evolution. A three-dimensional lithium deposition model was established on the actual microstructural parameters of the separator, predicting the concentration and electrochemical field of lithium deposition processes. A phase diagram of lithium precipitated failure in lithium-ion batteries with mechano-electrochemical coupling was developed with silicon-graphite electrode. This work will provide a new direction for understanding the mechanism of lithium deposition and guidance for commercial battery design. • The lithium dendrites evolution was observed by in-situ microscope. • A 3D finite element model of the separator was developed to predict porosity. • A multi-field coupled phase diagram was established for lithium deposition failure. [ABSTRACT FROM AUTHOR]

Calendering is an essential step in the manufacturing process of lithium-ion batteries. However, the intrusion of active particles into metal foil can damage the current collector during calendering. Here, we investigate the changes in surface morphology and the tensile properties of current collector after calendering. The damage mechanisms of tensile strength reduction for current collector due to compressive pressure are revealed by combining the calendering tests, tensile experiments, and simulations. Specifically, the DEM-FEM scheme is proposed, which combines the discrete element method (DEM) with the finite element method (FEM) to characterize the mechanical behavior of current collectors after the intrusion of active particles. The results show that the current collectors become more brittle and vulnerable with the increase of compressive pressure. Finally, the failure phase diagrams are presented during the winding and electrochemical processes. This study can reveal the failure behavior of current collectors and guides the electrode manufacturing optimization. [Display omitted] • A computational framework is developed for active particles pressed into the foil. • The evolution of surface morphology and mechanical properties of the current collector is revealed during calendering. • The effect of calendering pressure on current collectors is introduced into the winding process to optimize manufacturing. [ABSTRACT FROM AUTHOR]

Since smart materials and structures that holds the capability of automatically conducting shape transformation or functional variation upon environmental condition changes are critical in developing advanced components for intelligent devices and apparatus, such as sensors, actuators, self-recovery and self-healing systems. Generally, either physical or chemical approach would be applied to meet the stimulus-response modes for realizing smart shape or functional changes. In the present contribution, novel mechano-hydro-dielectric coupled graphene oxide hybrid sponges are proposed to integrate the physical and chemical approach into a smart material. Based on investigation on the decoupled features from mechano-dielectric (physical approach) and hydro-dielectric (chemical approach) modes, the mechano-hydro-dielectric coupled features suggest that integration of physical and chemical approaches would substantially promote the change ratios of each single approach, which implies both hydro-enhanced mechano-dielectric and mechano-enhanced hydro-dielectric coupled stimulus-response modes. According to the mechanism discussion from effective medium theory, the results from indicate that such mechano-hydro-dielectric coupled hybrid sponges promise a great stage to establish multifunctional sensors (both mechanical and humidity sensors) based on various physical-chemical coupled modes. [ABSTRACT FROM AUTHOR]

Since smart materials and structures are highly pursued for their great advantages in self-adaptable, self-healing and self-recoverable capability upon environmental condition change, here we demonstrate hydro-sensitive smart sandwich structures with self-adaptable electromagnetic interference (EMI) shielding ability via constructing polymeric porous non-woven-based spacers into highly conductive pyrolytic graphite papers. The spacers play the critical role in tuning the electromagnetic response capability, leading to substantially varying the electromagnetic shielding performance of the sandwich structures upon various water loadings. With the presence of polar water molecules, the porous polymeric spacers were significantly changed via creating polar induced interfaces. According to the electromagnetic shielding performance at initial, wet and re-dried conditions, the results suggest two types of smart structures, namely EMI shielding function switchable and function enhanced EMI shielding structures, which promises a novel platform for designing hydro-stimulus smart materials and structures for electromagnetic response applications. [ABSTRACT FROM AUTHOR]

Since achievement in electromagnetic (EM) technology dramatically promotes the critical requirement in developing advanced EM response materials, which are required to hold various advantageous features in light weight, small thickness, strong reflection loss and broadband absorption, the most important requirements, i.e. strong reflection loss and broadband absorption, are still highly pursued because of the intrinsic shortage in conventional EM absorbers. For addressing such critical problems, a unique three-dimensional nitrogen doped carbon monolith was demonstrated to understand the effects of the nitrogen doping on the dielectric and microwave absorption performance. The chemical components of the nitrogen doped carbon monoliths have been quantitatively determined for fully understanding the effects of nanoscale structures on the macroscopic composites. A modified Cole-Cole plot is plotted for guiding the chemical doping and material process, aiming to realizing the best matching conditions. The results have promised a universal route for achieving advanced materials with strong and broadband EM absorption. [ABSTRACT FROM AUTHOR]

Internal short circuit in lithium-ion batteries is a crucial hazard threatening. It is accurately difficult to monitor the internal signals in time of the lithium-ion batteries during the process of internal short circuit. Herein, a novel method is developed to monitor multiple signal evolution behaviour using a sealed tank and sensors. The internal signals of LFP batteries and NMC batteries exhibit different evolution behaviours, especially in the response sequence of pressure and gas. Battery capacity has an impact on ISC signal response sequence and time for LFP batteries, showing identical sequence and shorter time with the increase of capacity. The voltage and temperature are considered as sensitive signals for both LFP and NMC811 batteries that sensitive signals are defined based on their response speed. This operando technique provides a suitable platform for understanding the side reaction mechanism during thermal runaway in commercial LIBs. • A novel in-situ method was developed for internal short circuit measurement. • ISC behaviour of LFP and NMC811 batteries was investigated. • Battery capacity has an impact on ISC evolution behaviour for LFP batteries. • Established sensitive signals for internal short circuit in LFP and NMC811 batteries. [ABSTRACT FROM AUTHOR]

Ion intercalation and deintercalation (IID) reactions in rechargeable metal-ion batteries are affected by the electrochemical double layer (EDL) at solid-liquid interfaces. Yet, EDL effects on the kinetics of IID reactions are less considered. Here, we develop a hybrid quantum-classical model for IID reactions at graphite-electrolyte interfaces that accounts for the coupling of ion and electron transfer processes, and the influence of the inhomogeneous local EDL environment. The model is employed to understand how the structural deformation of the graphite electrode, the electric potential, and the solvent dipole moment shape the kinetics of IID reactions. [Display omitted] • Hybrid quantum-classical model explains mechano-electrochemical coupling effects. • Electrochemical driving factors are derived from a modified EDL model. • Smaller dipole moment of electrolyte accelerates the reaction kinetics. • Structural changes and electronic interactions affect the reaction kinetics. [ABSTRACT FROM AUTHOR]

Reconfigurable network structure with tunable multiple deformation modes exhibits promising applications in functional electromagnetic devices, frequency-reconfigurable antennas, flexible electronic devices, and robots with multiple motion modes due to its capability to realize multiple working characteristics in one device or system. In most previous studies on reconfigurable network structures with large deformation, researchers focus on tuning the deformation and mechanical properties for a specific deformation mode of the network structure. Therefore, designs for reconfigurable network structures to achieve multiple deformation modes and large deformation still remain a challenge. The inverse design of the reconfigurable network structure with desired mechanical responses under some specific external actuations is difficult due to the lack of theoretical models to describe the finite deformation of network structures actuated by external fields. This paper introduces a mechanical design strategy for the reconfigurable network structure to achieve a large deformation (over 45%) and multiple mechanical responses under the electrothermal actuation, including the uniform or non-uniform shrinkage and expansion, shearing, and bending deformation modes. Theoretical models for this reconfigurable network structure are developed to predict these unique mechanical responses and inversely design the reconfigurable network structure for the desired deformation modes in a facilitating method. The accuracy of the designed reconfigurable network structure is validated by the corresponding finite element analyses (FEAs) and experiments qualitatively and quantitatively. In accordance with these theoretical models, the deformed configuration and analytic solutions for some critical mechanical quantities, such as the electrothermally actuated effective strain for shrinkage, expansion and shearing deformation modes, and the bending angle for bending deformation modes, are obtained. The electrothermally actuated deformation of network structures can be tuned by the value of the normalized geometrical parameter d/t 1 and the electrothermal actuation strategy. Furthermore, demonstrative experiments and FE simulations illustrate that multiple deformation modes can be achieved in the same network structure through the individual actuation strategy. This work provides guidelines from the aspects of theoretical predictions, FEAs, and experiments for future designs of the reconfigurable network structures to achieve desired mechanical responses. [ABSTRACT FROM AUTHOR]

Inhomogeneity can accelerate performance degradation and reduce the lifetime of large-format batteries and battery modules. It is necessary to in-situ monitor the internal heterogeneous information and investigate the mechanical inhomogeneity of the batteries and modules. In this study, an in-situ measurement platform based on the integrating sensors and optical methods is developed. The internal stress and strain evolutions at the module-level are characterized and related to the deformation evolution at the cell-level. Both levels are suffering the serious mechanical inhomogeneity, which is quantitatively analyzed by the in-situ experiments and corresponding simulations, significantly affecting the long-term cyclic performance and consistency of the module. A new concept of mechanical consistency is introduced to correlate the mechanical inhomogeneity with module aging. This study can provide a basis for analyzing the aging mechanism and optimizing the structure of battery modules. • An in-situ measurement platform is developed to monitor mechanical parameters. • Multiple structural levels are suffering the serious mechanical inhomogeneity. • Heterogeneous features are mainly derived from the structure of the module. • Module inconsistency correlates with mechanical inhomogeneity in the module. [ABSTRACT FROM AUTHOR]

The demand for lithium-ion batteries is ever increasing while its safety is arousing great public concerns. The feature of a defective cell that may evolve to catastrophic failure is difficult to characterize, given the observation of the cell's internal structure is hard to make. Herein, this paper proposes a new method using thermography to characterize the evolution process from internal short circuit to thermal runaway inside a lithium-ion cell. The spatial and temporal temperature variation around the initiation point of the internal short circuit as well as the voltage and surface temperature are recorded in high frequency. The internal short circuit is triggered by the magnet and wax. The results show that the aluminum-anode-type internal short circuit can lead to thermal runaway by a sequence of the hot spot, gas generation, and combustion. Inadequate internal short circuit heat generation contributes to a temporary hot spot that gradually cools down to ambient temperature. Thermal runaway tends to occur when the hot spot above 150 °C reaches the area of 50 mm2 and the majority of the exothermic side reaction heat in the hot spot area is released within ca. 2s. These results are expected to guide the design of safer lithium-ion batteries. • Internal short circuit evolution is revealed by in-situ internal infra-red imaging. • The time sequence of thermal runaway caused by internal short circuit is analyzed. • Internal short circuits with inadequate heat cool down with limited thermal hazards. • Hot spot areas and side reaction heat distinguish thermal runaway initiation or not. [ABSTRACT FROM AUTHOR]

Abstract: The hydrogen release properties of the graphene supported Pd (Pd-G) catalysts doped LiBH4 were systematically investigated. It was found that the onset hydrogen desorption temperature of the LiBH4 doped with 5wt.% Pd-G-60 (with 60wt.% Pd loading) catalyst was about 105°C lower than that of the pure LiBH4 milled under the same conditions, and the other main dehydrogenation peaks of the Pd-G-60 doped LiBH4 were shifted to 410 and 605°C with an increased total weight loss of 12.6wt.%. Moreover, the dehydrogenation enthalpy was reduced from 74kJmol−1 H2 for the pure LiBH4 to ca. 43kJmol−1 H2 for the 15wt.% Pd-G-60 doped LiBH4. Importantly, the reversible rehydrogenation process was achieved under 3MPa H2 at 400 oC for 10h, and a capacity of ca. 6.6wt.% was obtained in the 30th cycle, which should be attributed to the evenly dispersed Pd nanoparticles. Meanwhile, LiBH4 was reformed and one new product, B16H20, was detected after the rehydrogenation process. [Copyright &y& Elsevier]

The microstructure evolution of electrodes with a mini-cylindrical battery was studied by deep learning combined with a cross-section polisher and scanning electron microscope. [Display omitted] • The evolution of electrode microstructure at different states of charge is studied, considering the influence of the battery structure. • A larger representative region of the electrode is obtained by a combination of scanning electron microscopy (SEM) and a cross-section polisher (CP). • A modified U-Net neural network approach is proposed to improve the accuracy of segmentation. The evolution of the microstructure of a battery electrode is closely related to battery performance. Characterization and visualization of the evolution of the microstructure is essential for optimization of manufactured electrodes. The validity of the battery structure representation affects the accuracy of the extracted microstructure parameters. In this study, a mini-cylindrical battery is designed to allow microstructure parameters to be obtained at different states of charge, bearing in mind the influence of the real battery structure. An argon-ion cross-section polisher is used to obtain a large area of the electrode for observation. In addition, an image segmentation method based on a modified U-Net neural network is developed to enhance the quality of the extracted microstructure. The relationship between porosity and thickness at different states of electrode charge is presented through experiments and deep learning of images. This method provides new insight into the evolution of electrode microstructure and can potentially guide the manufacturing of lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Polymeric composites with thermally conductive hybrid fillers are significant in the electronics and thermal dissipation, where thermal transport along with multifunctionality is required to meet the application needs. Introduction of hybrid fillers would induce multiple interface scattering and rational design on the filler contact should be the critical criteria, while there is insufficient principle. To promote the thermal transport capability, in this paper, a contact probability model has been established to quantitatively analyze the thermal conductivity and contact probability in the silicone rubber composites with hybrid fillers (including various aluminium oxides and silicon carbide whisker). The results from experiment and simulation suggest that three critical parameters, i.e. volume fraction, filler shape and filler size, are the essential factors of hybrid fillers on impacting the thermal conductivity of composites. With understanding the contact types of hybrid filler, the optimized thermal conductivity has been obtained in the composites with aluminium oxides and silicon carbide whisker fillers. The model and analysis here have provided new contact mechanism for understanding the thermal transport in composites, which could be extended to rationally design and fabricate other types of polymeric composites with hybrid fillers. [ABSTRACT FROM AUTHOR]