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Compositing carbon‐based materials with different properties can significantly improve the energy density of lithium‐ion batteries for applications that require high power, such as electric vehicles, owing to their effective current distribution. Nevertheless, the chemical reaction is not uniform throughout the entire depth of conventionally blended electrodes. This study proposes a hybrid patterned bilayer anode that comprises a blended layer of spherical crystalline graphite (SCG) and soft carbon and a single layer of SCG alone, which maintains a stable ionic reaction at the electrode surface and improves ion transport. This bilayer anode has a smaller, more uniform solid electrolyte interphase layer that is more evenly distributed throughout the electrode compared with the blended electrode. The electrode pattern interfaces, which are optimized by controlling the pattern size, ensure excellent mechanical adhesion and low internal resistance. Consequently, the patterned bilayer half‐cell achieves a high‐capacity retention of 85.9% after 500 charge–discharge cycles at 1 C. The full cell also attains an energy density of 178.7 Wh kg−1 with fast discharging at 10 C, which is 2.3 times higher than that of the single‐layer SCG electrode. [ABSTRACT FROM AUTHOR]

Sodium (Na) organic batteries have attracted great attention because of high abundance of Na, low-production cost, and structure diversity of organic electrode materials. Despite the efforts on organic Na-ion batteries, organic electrodes are still vulnerable to conventional electrolytes, and have a low conductivity which leads to continuous capacity fading and low-rate capability, respectively. In this study, we aimed to reduce solubility in electrolyte and enhance electrical conductivity of organic electrode by anchoring 2,5- dihydroxyterephtalic acid (DHTPA) to carbon black via esterification. Then, the sodiated DHTPA/CB powder was evaluated for an anode in Na-ion battery. The covalent-bonded organic/carbon black electrode retained 90 % of the initial capacity even after 100 cycles, and also showed excellent rate capability up to 1500 mA/g. The result sheds light on the commercialization of organic-based Na-ion batteries, and their large-scale applications to electric vehicles (EVs) and energy storage systems (ESSs) markets. [ABSTRACT FROM AUTHOR]

Abstract: In response to the demand for flexible and sustainable energy storage devices that exhibit high electrochemical performance, a supercapacitor system is fabricated using mulberry tree‐derived paper as a substrate and Poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) and carbon black as the active material. The mulberry paper‐based supercapacitor system demonstrates high energy density of 29.8–39.8 Wh kg−1 and power density of 2.8–13.9 kW kg−1 with 90.7% retention of its initial capacity over 15 000 charge–discharge cycles. In addition, the mulberry tree fibers are known to have superior mechanical strength and toughness and the mulberry paper‐based supercapacitor; as a result, exhibit high mechanical and chemical toughness; 99% of its initial capacity is retained after 100 repeated applications of bending strains, and twisting. 94% capacity retention is observed even after exposure to HCl and H2SO4 acid solutions. The fabrication methodology of the mulberry‐based supercapacitor is highly scalable and could be stacked to increase the energy storage capacity, where operation of light‐emitting diode lights with a drive voltage of 12 V integrated in a wearable device is demonstrated. [ABSTRACT FROM AUTHOR]

Self-healing features that mimic the biological mechanisms for self-repair have recently been applied to high-capacity but extreme volume expansion electrode materials such as silicon anodes to overcome the short cycle-life caused by electrical contact loss and active material pulverization. In this study, we adopt a freestanding composite design for effective relaxation of lithiation induced stresses and enhancement of electrochemical reliability. Silicon microparticles are homogenously dispersed and embedded within a self-healing polymer matrix that enables free volume expansion and contraction during lithiation and delithiation. The freestanding electrode, which does not require a separate current collector, demonstrated 91.8% capacity retention after 100 cycles at C/10 rate with an average specific capacity and gravimetric capacity, including current collector mass, of ∼2100 mA h g−1 and ∼1050 mA h g−1 respectively, which is a significant improvement compared to the conventional design of simple self-healing polymer coatings on silicon particle embedded current collectors. The fabricated freestanding silicon microparticle and self-healing polymer composite electrode demonstrated stable electrochemical performance after being completely cut, reattached, and cycled and retained at most 95% of its initial capacity. Overall, the proposed freestanding silicon microparticle and self-healing polymer composite design demonstrated excellent gravimetric capacity, cycle life, and self-healing capability without employing expensive and complex nanostructures. [ABSTRACT FROM AUTHOR]

This paper introduces oxygen-deficient black TiO2 with hierarchically ordered porous structure fabricated by a simple hydrogen reduction as a carbon- and binder-free cathode, demonstrating superior energy density and stability. With the high electrical conductivity derived from oxygen vacancies or Ti3+ ions, this unique electrode features micrometer-sized voids with mesoporous walls for the effective accommodation of Li2O2 toroid and for the rapid transport of reaction molecules without the electrode being clogged. In the highly ordered architecture, toroidal Li2O2 particles are guided to form with a regular size and separation, which induces the most of Li2O2 external surface to be directly exposed to the electrolyte. Therefore, large Li2O2 toroids (≈300 nm) grown from solution can be effectively charged by incorporating a soluble catalyst, resulting in a very small polarization (≈0.37 V). Furthermore, disordered nanoshell in black TiO2 is suggested to protect the oxygen-deficient crystalline core, by which oxidation of Ti3+ is kinetically impeded during battery operation, leading to the enhanced electrode stability even in a highly oxidizing environment under high voltage (≈4 V). [ABSTRACT FROM AUTHOR]

Lithium-rich layered oxides show promise as high-energy harvesting materials due to their large capacities. However, questions remain regarding the large irreversible loss in capacities for the first charge–discharge cycle due to oxygen removal in lattices related to layered Li2MnO3. Herein we present detailed studies on Li-rich Mn-based layered oxides of 0.4Li2MnO3–0.6LiNi1/3Co1/3Mn1/3O2 (Li-rich NCM) electrochemically activated between 2.5 V and 4.3 or 4.7 V vs. Li+/Li. Electron energy loss spectroscopy (EELS) and X-ray absorption spectroscopy (XAS) revealed unusual manganese reduction after the first charge up to a high voltage of 4.7 V. Moreover, the electronic structure did not fully recover to the original pristine of Mn4+ state after discharge. Interestingly, these phenomena were not limited to a single particle, but were observed across the entire electrode. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images and electron dispersive spectra (EDS) also showed a dramatic decline in oxygen content with highly porous morphologies, associated with oxygen vacancy formation following oxidation of O2− ions to O2. Our analysis suggests that an unstable manganese valence state with severe defects due to oxygen vacancies may lead to large irreversible capacity loss during the first charge–discharge cycle of Li-rich layered oxides. [ABSTRACT FROM AUTHOR]

The results of employing (Ti, Fe)-alloyed Si thin-film anode for Li-ion batteries are reported. The material demonstrates an impressive cyclic stability with stable operation for more than 500 cycles at a capacity higher than 1400 mAh g−1. Materials characterization using scanning electron microscopy and transmission electron microscopy illuminates an intriguing materials process behind the performance: ripple-like pattern formation via electrochemically driven segregation of the inactive elements (Ti and Fe). The ripple structure plays a buffer role by suppressing loss of the active material upon further cycling, allowing the anode to gradually transform into an array of microbumps. The morphological evolution helps the anode endure long cycles (even up to 1000 cycles) without catastrophic failure as the bumps shrank slowly and steadily, consistent with the electrochemical data. [ABSTRACT FROM AUTHOR]

In ultraviolet (UV) nanoimprint lithography, the adhesion between the UV-curable resin and the stamp must be carefully controlled to avoid deformation and breakage of the imprinted patterns during the stamp separation process. In this work, UV-curable resins with different amounts of release agent were prepared, and the adhesion properties of the resins were characterized quantitatively using a four-point bending test. The interfacial fracture energy between the UV-curable resin with a release agent and a glass wafer was measured based on the concept of interfacial fracture mechanics. The results were used to investigate the effect of the release agent on the reduction of the interfacial adhesion. The interfacial fracture energy between the resin containing the release agent and the glass wafer decreased with increasing concentration of the release agent. After the test, the fractured surfaces were analyzed using scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy, and the effect of the release agent on the adhesion was examined. [ABSTRACT FROM AUTHOR]

High theoretical capacity and low-cost copper sulfide (CuxS)-based anodes have gained great attention for advanced sodium-ion batteries (SIBs). However, their practical application may be hindered due to their unstable cycling performance and problems with the dissolution of sodium sulfides (NaxS) into electrolyte. Here, we employed metal organic framework (MOF-199) as a sacrificial template to fabricate nanoporous CuxS with a large surface area embedded in the MOF-derived carbon network (CuxS-C) through a two-step process of sulfurization and carbonization via H2S gas-assisted plasma-enhanced chemical vapor deposition (PECVD) processing. Subsequently, we uniformly coated a nanocarbon layer on the Cu1.8S-C through hydrothermal and subsequent annealing processes. The physico-chemical properties of the nanocarbon layer were revealed by the analytical techniques of high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). We acquired a higher SIB performance (capacity retention (~93%) with a specific capacity of 372 mAh/g over 110 cycles) of the nanoporous Cu1.8S-C/C core/shell anode materials than that of pure Cu1.8S-C. This encouraging SIB performance is attributed to the key roles of a nanocarbon layer coated on the Cu1.8S-C to accommodate the volume variation of the Cu1.8S-C anode structure during cycling, enhance electrical conductivity and prevent the dissolution of NaxS into the electrolyte. With these physico-chemical and electrochemical properties, we ensure that the Cu1.8S-C/C structure will be a promising anode material for large-scale and advanced SIBs. [ABSTRACT FROM AUTHOR]

Increasing the surface area to improve chemical activity is an unending task from conventional catalysis to recently emerging electrochemical energy conversion and storage. Here, a simple, vacuum‐deposition‐based method to form nanoporous structures of metals is reported. By utilizing thermal evaporation at a high pressure, fractal‐like nanoporous structures of Sn with porosity exceeding 98% are synthesized. The obtained nanostructure consists of nanoparticle aggregates, and the morphology can be controlled by adjusting the working pressure. The formation of the nanoporous structure is explained by homogeneous nucleation and diffusion‐limited aggregation, where nanoparticles produced by the repeated collisions of evaporated atoms adhere to the substrate without diffusion, forming porous aggregates. Due to the easy oxidation of Sn, the constituent nanoparticles are covered with amorphous SnOx and crystalline SnO phases. When the nanoporous Sn/SnOx aggregates are applied to a lithium‐ion battery anode through direct deposition on a Cu foil current collector without binders or conducting additives, the nanoporous Sn/SnOx anode shows greatly enhanced cyclability and exceptional rate performance compared to those of a dense Sn thin film anode. The approach investigated in this work is expected to provide a new platform to other fields that require highly porous structures. Highly porous structure of black Sn with porosity exceeding 98% is formed by high‐pressure thermal evaporation with morphology control via the pressure adjustment. The nanoporous structure explained by homogeneous nucleation and diffusion‐limited aggregation consists of core/shell‐like nanoparticle aggregates of Sn/SnOx. Applied to lithium‐ion battery anodes, it shows greatly enhanced cyclability and rate performance compared to a dense Sn thin film. [ABSTRACT FROM AUTHOR]

LTO (Li4Ti5O12) has been highlighted as anode material for next-generation lithium ion secondary batteries due to advantages such as a high rate capability, excellent cyclic performance, and safety. However, the generation of gases from undesired reactions between the electrode surface and the electrolyte has restricted the application of LTO as a negative electrode in Li-ion batteries in electric vehicles (EVs) and energy storage systems (ESS). As the generation of gases from LTO tends to be accelerated at high temperatures (40–60 °C), the thermal stability of LTO should be maintained during battery discharge, especially in EVs. To overcome these technical limitations, a thin layer of Al2O3 (~2 nm thickness) was deposited on the LTO electrode surface by atomic layer deposition (ALD), and an electrochemical charge-discharge cycle test was performed at 60 °C. The capacity retention after 500 cycles clearly shows that Al2O3-coated LTO outperforms the uncoated one, with a discharge capacity retention of ~98%. TEM and XPS analyses indicate that the surface reactions of Al2O3-coated LTO are suppressed, while uncoated LTO undergoes the (111) to (222) phase transformation, as previously reported in the literature. [ABSTRACT FROM AUTHOR]

Here, we fabricate poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-co-HFP) by electrospinning for a gel polymer electrolyte (GPE) for use in flexible Li-ion batteries (LIBs). As a solvent, we use N-methyl-2-pyrrolidone (NMP), which helps produce the cross-linked morphology of PVDF-co-HFP separator, owing to its low volatility. The cross-linked PVDF-co-HFP separator shows an uptake rate higher than that of a commercialized polypropylene (PP) separator. Moreover, the PVDF-co-HFP separator shows an ionic conductivity of 2.3 × 10−3 S/cm at room temperature, comparable with previously reported values. An LIB full-cell assembled with the PVDF-co-HFP-based GPE shows capacities higher than its counterpart with the commercialized PP separator, confirming that the cross-linked PVDF-co-HFP separator provides highly efficient ionic conducting pathways. In addition, we integrate a flexible LIB cell using the PVDF-co-HFP GPE with a flexible organic light emitting diode (OLED), demonstrating a fully flexible unit of LIB and OLED. [ABSTRACT FROM AUTHOR]

It is confirmed that oxygen‐deficient black TiO2 can operate as a stable cathode for Li‐O2 batteries, where the morphology of black TiO2 was modified to be hierarchically porous. This innovative cathode renders the reaction molecules and air (O2) to permeate reversibly, analogous to the function of the human respiratory system, while generating electricity from the reactions of Li and oxygen. This is reported by Seunghoon Nam, Yongjoon Park, Byungwoo Park, and co‐workers in article number 1700814. [ABSTRACT FROM AUTHOR]

Abstract: It was studied that FePt–Ta thin films prepared on MgO (100) buffer-layer by DC/RF magnetron co-sputtering have shown better magnetic properties and micro structural improvement. The Ta-doped FePt–Ta films indicate somewhat differences in micro structural ordering and the aspect of grain growth after annealing. With respect to magnetic property, the sample having 30% increased coercivity was obtained after a heat treatment at 700°C. In particular the addition of Ta (5.5%) enhances the L10 ordering of FePt at relatively high temperature (above 500°C). [Copyright &y& Elsevier]

Abstract: The interfacial adhesion energy between the resist and the substrate is very important in nanoimprinting because of problems with the resist sticking or pulling off during separation of the mold from the substrate. Substrate surface treatments with a self-assembled monolayer or oxygen plasma provide good adhesion between a resist coating and a silica substrate. In this paper, we describe the adhesion properties of a resist and a glass wafer measured using the four-point bending test. The interfacial adhesion energy between the resist and the glass wafer was evaluated for various substrate surface treatments of adhesion promoters and anti-sticking layers. The interfacial fracture energy without treatment was 1.23J/m2, and was in the range 0.49–2.57J/m2 for the other treatments tested. The interfacial fracture surfaces were also investigated by field emission scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy to determine the fracture mode at the interfaces. [Copyright &y& Elsevier]

Abstract: This paper describes the design of a thermal inchworm device to realize precision in-package positioning. The inchworm actuation mechanism includes two metallic actuators facing each other and a workpiece between them. Electrothermal actuation is used to move the workpiece in the desired direction by inputting electric currents in a particular sequence. Nickel is chosen as the material of the actuators due to its desirable electrical, thermal and mechanical properties and availability in fabrication facilities. ANSYS theoretical modeling shows the proposed design can achieve high actuation resolution (0.1μm) with large driving force and will provide power-free latching as well. The transient analysis defines the current input sequence needed to move the workpiece. The design has been carried out for specific application to optical fiber alignment but has potential for a wide range of other applications. [Copyright &y& Elsevier]

Geometrically multifunctional structures inspired by nature can address the challenges in the development of soft robotics. A bioinspired structure based on origami and kirigami can significantly enhance the stretchability and reliability of soft robots. This study proposes a novel structure with individual, overlapping units, similar to snake scales that can be used to construct shape-morphing batteries for untethered soft robots. The structure is created by folding well-defined, two-dimensional patterns with cutouts. The folding lines mimic the hinge structure of snakeskin, enabling stable deformations without mechanical damage to rigid cells. The structure realizes multi-axial deformability and a zero Poisson's ratio without off-axis distortion to the loading axis. Moreover, to maximize areal density, the optimal cell shape is designed as a hexagon. The structure is applied to a stretchable Li-ion battery, constructed to form an arrangement of electrically interconnected, hexagonal pouch cells. In situ electrochemical characterization and numerical simulation confirm that the shape-morphing scale battery maintains its performance under dynamic deformation with a 90% stretching ratio and 10-mm-radius bending curve, guaranteeing a long-lasting charging/discharging cycle life during cyclic bending and stretching (exceeding 36,000 cycles). Finally, the shape-morphing energy storage device is applied to movable robots, mimicking crawling and slithering, to demonstrate excellent conformability and deformability.

Binderless, additiveless Si electrode design is developed where a nanoporous ZnO matrix is coated on a Si microparticle electrode to accommodate extreme Si volume expansion and facilitate stable electrochemical cycling. The conversion reaction of nanoporous ZnO forms an ionically and electrically conductive matrix of metallic Zn embedded in Li 2 O that surrounds the Si microparticles. Upon lithiation, the porous Li 2 O/Zn matrix expands with Si, preventing extensive pulverization, while Zn serves as active material to form Li x Zn to further enhance capacity. Electrodes with a Si mass loading of 1.5 mg/cm 2 were fabricated, and a high initial capacity of ∼3900 mAh/g was achieved with an excellent reversible capacity of ∼1500 mAh/g (areal capacity ∼1.7 mAh/cm 2 ) beyond 200 cycles. A high first-cycle Coulombic efficiency was obtained owing to the conversion reaction of nanoporous ZnO, which is a notable feature in comparison to conventional Si anodes. Ex situ analyses confirmed that the nanoporous ZnO coating maintained the coalescence of SiMPs throughout extended cycling. Therefore, the Li 2 O/Zn matrix derived from conversion-reacted nanoporous ZnO acted as an effective buffer to lithiation-induced stresses from volume expansion and served as a binder-like matrix that contributed to the overall electrode capacity and stability.

LTO (Li₄Ti₅O 12 ) has been highlighted as anode material for next-generation lithium ion secondary batteries due to advantages such as a high rate capability, excellent cyclic performance, and safety. However, the generation of gases from undesired reactions between the electrode surface and the electrolyte has restricted the application of LTO as a negative electrode in Li-ion batteries in electric vehicles (EVs) and energy storage systems (ESS). As the generation of gases from LTO tends to be accelerated at high temperatures (40⁻60 °C), the thermal stability of LTO should be maintained during battery discharge, especially in EVs. To overcome these technical limitations, a thin layer of Al₂O₃ (~2 nm thickness) was deposited on the LTO electrode surface by atomic layer deposition (ALD), and an electrochemical charge-discharge cycle test was performed at 60 °C. The capacity retention after 500 cycles clearly shows that Al₂O₃-coated LTO outperforms the uncoated one, with a discharge capacity retention of ~98%. TEM and XPS analyses indicate that the surface reactions of Al₂O₃-coated LTO are suppressed, while uncoated LTO undergoes the (111) to (222) phase transformation, as previously reported in the literature., Competing Interests: The authors declare no conflict of interest.