With the rapid expansion of electric vehicles, ensuring the safety of high-energy-density lithium-ion batteries has become increasingly critical. Ternary cathodes such as LiNi x Co y Al 1-x-y O 2 (NCA) are widely adopted due to their high energy density; however, their thermal and electrochemical stability deteriorate significantly under overcharge and elevated-temperature conditions. Although previous studies have investigated battery degradation using electrochemical diagnostic techniques, most have focused on isolated stressors or low-rate, constant-temperature conditions, providing limited insight into degradation mechanisms under realistic, coupled abuse scenarios. In this study, we systematically investigate the degradation behavior of 18650-type NCA lithium-ion cells subjected to 3C overcharge at elevated temperatures ranging from 30 to 50 °C. Incremental capacity analysis (ICA) and electrochemical impedance spectroscopy (EIS) reveal distinct temperature-dependent degradation pathways: at 30 °C, gradual attenuation of the Ni 4+ /Ni 3+ reduction peak near 4.1 V indicates progressive loss of electrochemical reversibility, whereas at 50 °C a new reduction feature around 3.1 V emerges, suggesting delayed lithium-ion transport and abrupt interfacial deterioration. These electrochemical signatures correlate with increased interfacial resistance and are further supported by material analysis, confirming lattice collapse, carbon structure collapse, and heterogeneous growth of the cathode–electrolyte interphase (CEI). Notably, elevated temperatures induce the formation of a thicker yet structurally discontinuous CEI, while lower temperatures result in thinner but more gradually degraded interphases. Gas evolution measurements further reveal contrasting behaviors, with sharp CO 2 release at 30 °C beyond a critical degradation point and suppressed gas evolution at 50 °C, likely due to the thickened CEI. These results highlight the synergistic nature of degradation under concurrent overcharge and thermal stress, offering new insights into degradation mechanisms of ternary cathode lithium-ion batteries under realistic abuse conditions.

This study demonstrates an absorption-dominated, high-efficiency electromagnetic interference (EMI) shielding architecture that synergistically integrates a ferroelectric layer with a dual-conductivity gradient configuration. A hierarchical multilayer architecture was successfully fabricated via a sequential hot-pressing process, achieving a total thickness of 2.2 mm. Optimal shielding performance was achieved by controlling the thickness and electrical conductivity of each constituent layer, including a porous PVDF layer for impedance matching, a Vanadium (V)-doped ZnO/PVDF ferroelectric layer, and a conductivity gradient PVDF/MXene assembly. The superior EMI shielding performance is attributed to a multi-stage attenuation mechanism operating across the hierarchical layers. The outermost porous surface layer provides effective impedance matching at the air-material interface, minimizing initial surface reflection, while promoting internal multiple reflections and scattering. Subsequently, the embedded ferroelectric layer efficiently dissipates the incident EM energy into thermal energy through enhanced dipole polarization and dielectric loss. Furthermore, the interfacial polarization induced by the dual-conductivity gradient structure significantly amplifies the overall absorption mechanism. Experimental results demonstrate an outstanding EMI shielding efficiency (SE) of 63 dB and a high absorption coefficient of 0.80 at X-band frequencies. This study presents a rational design strategy for low-reflection, absorption-dominant EMI shielding materials.

Quantitatively determining a material's tendency to gain or lose electrons is crucial for triboelectric devices but remains challenging. Here, we introduce a dual-reference triboelectric sensor integrated with deep learning to rapidly estimate surface potential. An unknown material is contacted with two reference surfaces of opposite triboelectric polarity, producing paired electrical signals that act as internal calibration. A deep neural network maps these dual signals to the material's effective surface potential, capturing interaction patterns that conventional analytical models cannot resolve. The system reliably quantifies surface-potential differences across diverse materials, achieving prediction errors below 8% and clearly distinguishing materials across the triboelectric series. The dual-reference design enhances robustness by compensating for environmental and measurement variations, yielding similar to 85% improved accuracy over single-reference methods. Overall, our results show that combining nanogenerator-based sensing with data-driven analysis enables accurate, quantitative interpretation of triboelectric responses and significantly broadens the functional capabilities of triboelectric sensors.

This study investigates the degradation behavior of 18650 lithium-ion cells employing NCA-based cathodes under high-rate (3C) overcharge conditions at practical operating temperatures (30-50 degrees C). Using incremental capacity analysis (ICA), we observed temperature-dependent electrochemical changes: at 30 degrees C, the Ni4+ reduction peak near 4.1 V progressively faded with cycling, indicating gradual structural degradation; at 50 degrees C, a distinct new reduction feature emerged at similar to 3.1 V, associated with delayed lithium-ion transport and abrupt interfacial instability. These contrasting signatures suggest fundamentally different degradation pathways. Analyses using EIS, Raman spectroscopy, and EDS revealed that elevated temperatures accelerate CEI growth while inducing pronounced lattice distortion and surface carbon collapse. In contrast, lower temperatures yielded thinner but gradually developing interfacial layers. Gas evolution profiles further supported this divergence, with limited CO2 evolution at 50 degrees C-attributed to CEI-bound immobilization-despite more severe structural damage. The results demonstrate that cathode and interfacial degradation are shaped by the combined effects of thermal and electrochemical stress. This work provides useful guidance for diagnostics and underlines the importance of managing concurrent stressors in the design of safe, high-energy batteries.

Electromagnetic interference (EMI) shielding materials with high efficiency and absorption-dominated performance are crucial for addressing the challenges posed by electromagnetic wave pollution in modern electronics. In this work, we developed a high-performance EMI shielding material by integrating functionalized CNTs (f-CNTs) into a dual gradient conductivity-porosity structure. The multilayer structure was fabricated using a facile hot-pressing method, enabling the combination of films with varying porosity and conductivity. This approach facilitates the scalable production of large-area shielding materials and allows for the customization of EMI shielding properties by adjusting the layer characteristics. The resulting composite exhibited outstanding EMI shielding effectiveness (SE) of up to 60.5 dB across the X-band frequency range, with an absorptivity of approximately 0.77. The porosity gradient effectively minimized impedance mismatch, enhancing absorption and internal scattering, while the conductivity gradient promoted the dissipation of residual EM waves through Ohmic loss and interfacial polarization. These synergistic effects contributed to the absorption-dominant shielding mechanism. This study introduces a design and fabrication strategy for high-performance EMI shielding materials, combining gradient porosity and conductivity to achieve superior absorption and shielding efficiency. The proposed method offers a scalable and versatile approach for tailoring electromagnetic shielding materials.

Lithium metal is regarded as a promising next-generation battery material due to its high theoretical energy capacity (3860mAh/g). Additionally, it has low redox potential of -3.04V relative to the standard hydrogen electrode. Despite these advantages, lithium metal suffers from critical safety concerns. Non-uniform deposition of lithium leads to dendrite formation, which can penetrate the battery separator, causing internal short circuits and potentially triggering fire. To address this challenge, conventional polyolefin-based separators have been widely used; however, their insufficient thermal and mechanical stability are still limited. Polyvinylidene fluoride (PVDF)-based separators have emerged as alternatives due to their better chemical stability and wettability. However, they still exhibit low ionic conductivity and mechanical strength. Notably, low ionic conductivity creates large ion concentration gradients, which further exacerbate non-uniform lithium deposition and pose significant safety risks. In this work, we introduce the fabrication of PVDF-HFP (polyvinylidene fluoride-co-hexafluoropropylene) nanofiber separators by incorporating lithium-doped ZnO (Li-doped ZnO) nanoparticles (NPs) as a filler and propose a method to enhance its ionic conductivity. ZnO is well known for its ability to improve electrolyte wettability and mechanical strength. In particular, wettability is expected to be enhanced by strengthening the dipole effect of ZnO, as the dipole moment creates localized electric field, facilitating lithium-ion transport. However, ZnO, while being a piezoelectric material, is not inherently ferroelectric. To apply the dipole effect more effectively, a phase transformation into a ferroelectric material is required, which can be achieved through lithium doping. To achieve this, ZnO was doped with lithium to induce ferroelectric properties, enabling the formation of a permanent dipole. This Li-doped ZnO was then integrated as a filler material into the PVDF-HFP nanofiber matrix. Through polarization process, permanent dipoles are induced in the Li-doped ZnO, which establishes a polarization field. This polarization field facilitates lithium-ion transport through the separator, effectively minimizing the ion concentration gradient on the anode surface. As a result, the ionic conductivity of the PVDF-HFP separator incorporating 5wt% Li-doped ZnO NPs was improved to 4.33mS/cm, compared to 2.17mS/cm for the pristine PVDF-HFP separator. This improvement directly promotes more uniform lithium-ion transport, thereby suppressing dendrite growth. By ensuring even ion distribution, the separator reduces localized current densities, which significantly enhances long-term cycling stability and mitigates capacity fading during repeated charge-discharge cycles. Figure 1

The application of 3D printing for the development of electromagnetic interference (EMI) shielding materials is currently constrained by a limited range of material options and design schemes. In this work, we developed conductivity-modulated polylactic acid (PLA)-MXene composite filaments for fused deposition modeling (FDM) 3D printing, demonstrating excellent printability and durability. Utilizing these filaments, we propose a design scheme focused on absorption-dominant EMI shielding materials. Our design features non-conductive PLA with larger pores at the incident surface, transitioning to layers with increasing conductivity and decreasing pore sizes. This gradient structure minimizes reflection by providing impedance matching and enhances absorption by extending the propagation path of EM waves through multiple reflections and scattering within the pores. Additionally, interfacial polarization effects between air, PLA, and MXene nanoflakes strengthen the absorption mechanisms. Both simulation and experimental results confirm that the combined gradient conductivity and pore size structures significantly improve EMI shielding effectiveness (EMI SE) and absorptivity, achieving an EMI SE of 65 dB and an absorptivity of 0.76 in the X-band. Our findings underscore its potential to create adaptable, high-performance EMI shields suitable for complex geometries and reducing secondary interference.

Electromagnetic interference (EMI) shielding materials are essential for reducing unwanted electromagnetic radiation and ensuring the reliable operation of electronic devices. Among various EMI shielding strategies, absorption-dominated materials have gained significant attention due to their ability to reduce secondary reflection while maintaining high shielding effectiveness. This work provides a comprehensive overview of absorption-based EMI shielding materials, focusing on MXene- and carbon-based nanomaterials. The integration of these conductive nanomaterials into polymer matrix composites enables the development of lightweight, flexible, and easy-to-fabricate shielding materials. Furthermore, structural modifications such as foam architectures, gradient structures, and 3D-printed designs have been explored to enhance EM wave absorption while minimizing reflection. Additionally, novel strategies, including molecular-level surface functionalization, electrical polarization, and triboelectric surface charging effects, along with their synergistic interactions, have been explored to further suppress reflectivity and optimize absorption mechanisms. The practical applications of these materials span multi-band frequency EMI shielding, including 5G telecommunications, IoT devices, and automotive radar systems. Looking ahead, the integration of artificial intelligence (AI) and machine learning (ML) for materials design and optimization is expected to accelerate the discovery of next-generation high-performance, absorption-dominant EMI shielding materials. By leveraging data-driven approaches, researchers can predict shielding effectiveness, optimize material properties, and reduce experimental costs, leading to more efficient and scalable material development. This review highlights the current advancements, challenges, and future opportunities in absorption-dominant EMI shielding materials, providing an overview of highly efficient, lowreflectivity EMI shielding solutions.

Tactile perception, a vital sensory function, enables humans to interact directly with their environment, responding to various stimuli such as pressure, temperature, and texture. Recent advancements in functional materials and micro-nano fabrication have led to the development of highly flexible tactile sensors with excellent spatial resolution and sensitivity. However, replicating the complexity of human tactile perception remains challenging, necessitating innovative sensor designs that can mimic human touch. This study presents a multifunctional tactile sensor with multimodal capabilities, capable of simultaneously detecting pressure, temperature, and surface properties by integrating distinct sensing mechanisms. The sensor utilizes PVDF/Ti3C2 and PVDF-TrFE/Ti3C2 composites for static and dynamic pressure sensing, respectively, and PEDOT: PSS/Ti3C2 for temperature measurement. Additionally, a triboelectric layer with patterned PDMS enables effective surface differentiation. Each sensing layer was integrated using a hot rolling press technique, with Ti3C2 enhancing the sensor's conductivity, piezoelectric performance, and thermal sensitivity. The multimodal sensor demonstrates simultaneous detection of static and dynamic stimuli, temperature variations, and surface material properties, making it suitable for advanced applications in robotics and healthcare where complex tactile feedback is essential.

Fine inhalable particulate matter (PM2.5) is a harmful airborne pollutant, with serious repercussions to public health worldwide. To prevent the influx of PM2.5 into the indoor living and working space, we conceived the design of a "filtration window" that exhibits efficient PM2.5 filtration capabilities while having sufficient transparency and physical durability. In this work, we demonstrate the successful fabrication of a transparent (similar to 80%) PM2.5 filter based on nanofibrous poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE), which captures PM2.5 by electrostatic mechanisms originating from the ferroelectric property of the copolymer. The embedded PVDF-TrFE-based nanofibrous filter exhibits a notable PM2.5 removal efficiency of 93%, which is on par with those of medical-grade face masks. Simultaneously, owing to its dense packing, the PVDF-TrFE nanofibrous filter is highly durable, allowing it to be cleaned with water for reuse, and withstands its structural integrity even under a wind flow of 15 m/s, altogether making it practically viable as a functional window unit.

High output performance of degradable triboelectric nanogenerators (TENGs) is achieved by synergistically combining nanofibrous structures, chemical surface modification, and composite formation using ferroelectric fillers.

Achieving high-performance electromagnetic interference (EMI) shielding materials with ultra-low reflectivity, minimal volume, and light weight is challenging. This study addresses this by introducing a nanofiber (NF)-based structure composed of MXene nanoflakes and ferroelectric barium titanate oxide (BTO) nanoparticles embedded within polyurethane (PU) fibers, and surface-bound branched polyethyleneimine (PEI(b)) on the NFs. This design enhances the flexibility and lightness of the EMI shielding materials while effectively minimizing reflectivity. A key approach in this study is the functionalization of the NFs with branched polyethyleneimine (PEI(b)), which reduces reflectivity and enhances EMI shielding effectiveness (SE). The surface-bound molecules increase the effective surface area, improving the absorption efficiency of incident electromagnetic waves without adding weight or volume. Additionally, the surface-bound PEI(b) molecules synergistically enhance the polarization of the embedded BTO nanoparticles and amplify the triboelectric charging effect, crucial for achieving ultra-low reflectivity and high EMI SE. Combining the optimized composite NF design with these enhancement methods, this study achieves significant advancements in EMI SE, reaching an EMI SE of 72 dB, an absolute EMI SE (SSEt) of 28,460 dB & sdot;cm2g- 1, and a reflectivity of 0.09, all without increasing weight or volume. This approach exemplifies how the strategic application of surface-bound molecules can enhance EMI shielding effectiveness and achieve ultra-low reflectivity through the effective expansion of the absorption surface and synergistic enhancement of piezoelectric and triboelectric effects.

Creating a high-frequency electron system demands a high saturation velocity (υsat). Herein, we report the high-field transport properties of multilayer van der Waals (vdW) indium selenide (InSe). The InSe is on a hexagonal boron nitride substrate and encapsulated by a thin, noncontinuous In layer, resulting in an impressive electron mobility reaching 2600 cm2/(V s) at room temperature. The high-mobility InSe achieves υsat exceeding 2 × 107 cm/s, which is superior to those of other gapped vdW semiconductors, and exhibits a 50-60% improvement in υsat when cooled to 80 K. The temperature dependence of υsat suggests an optical phonon energy (ℏωop) for InSe in the range of 23-27 meV, previously reported values for InSe. It is also notable that the measured υsat values exceed what is expected according to the optical phonon emission model due to weak electron-phonon scattering. The superior υsat of our InSe, despite its relatively small ℏωop, reveals its potential for high-frequency electronics, including applications to control cryogenic quantum computers in close proximity.

Spin transport in heterojunctions between magnetic insulators and heavy metals has garnered significant attention due to its potential in spintronics applications. In this study, we employed the metal-organic decomposition (MOD) method to fabricate high-quality yttrium iron garnet (Y3Fe5O12-YIG) films on (111)-oriented gadolinium gallium iron garnet (Gd3Ga5O12-GGG) substrate. We conducted a thorough characterization of the crystallinity, surface morphology, and magnetic properties of the YIG films at various thicknesses. The obtained samples exhibited smooth surfaces with roughness mean-square (RMS) below 0.6 nm. Epitaxial growth was maintained for films up to 116 nm in thickness but deteriorated beyond that. The magnetic anisotropy demonstrated an easy axis in the in-plane direction, accompanied by a low coercivity of 4.8 +/- 0.4 Oe. The spin Seebeck effect voltage measurement shows the highest signal for 366 nm thick film and is reduced if the thickness increases. Furthermore, we investigated spin transport across the YIG/Pt interface using spin Hall magnetoresistance. The average spin-mixing conductance (Gr) was determined to be 5.79 +/- 0.54 x 1014 Omega- 1m- 2, a value comparable to those reported in previous studies.

MXene (Ti3C2Tx), known for its exceptional electrical conductivity, unique two-dimensional structure, extensive surface functionality, and hydrophilicity, has emerged as a leading candidate for electromagnetic interference (EMI) shielding applications. Despite these excellent characteristics, EMI shielding materials based on MXene mostly utilize the reflection mechanism, which may cause secondary interferences. This study introduces an approach to utilize MXene as absorption-dominant EMI shielding materials. By engineering a porous layer of polyvinylidene fluoride (PVDF) atop MXene nanoflakes, we achieved a synergistic enhancement in EMI shielding effectiveness (SE) and absorptivity. The PVDF foam serves as an effective impedance matching layer, substantially enhancing the absorption of electromagnetic waves into the shielding material. Incorporating electrically conductive MXene nanoflakes to form a thin film creates a robust conductive network, fully leveraging its inherent performance. This network efficiently dissipates EM waves, thereby significantly enhancing the EMI SE. The shielding performance of this composite was thoroughly evaluated across both the X-band (8.2 GHz-12.4 GHz) and the Ka-band (26.5 GHz-40 GHz) frequencies. It demonstrated high EMI SE, attributed to mechanisms predominantly based on absorption. Specifically, it achieved an EMI SE of approximately 63.3 dB with high absorptivity (0.74) in the X-band and approximately 73.3 dB with high absorptivity (0.85) in the Ka-band. These findings underscore its potential as a route to develop absorption-dominant EMI shielding materials.

A new actuation technique is introduced for overcoming the complexity and radiation performance degradation issues of actuators-based reconfigurable antennas. We employ shape memory alloy (SMAlloy) spring actuators to control the positioning of the fluidic channels, in contrast to the manual filling/loading and evacuating/offloading of dielectric fluids employed in conventional fluidically reconfigurable antennas. To demonstrate this new actuation method, a simple low-cost frequency reconfigurable microstrip patch antenna is fabricated, and two SMAlloy spring actuators are incorporated along the microfluidic channels in the axes of the radiating slots. Electrical control of the pitch of the two SMAlloy springs enables mechanical movement/transformation of the microfluidic channels in two directions along the axes of the radiating slots to attain the required frequency-switching characteristics of the antenna. It should be noted that in contrast to the traditional switching techniques where switches are positioned over the radiating aperture, the proposed method does not deteriorate the performance of the antenna because SMAlloy springs are underneath the radiating patch.

The application of 3D printing for the development of electromagnetic interference (EMI) shielding materials is currently constrained by a limited range of material options and design schemes. In this work, we developed conductivity-modulated PLA-MXene composite filaments for fused deposition modeling (FDM) 3D printing, demonstrating excellent printability and durability. Utilizing these filaments, we propose a design scheme focused on absorption-dominant EMI shielding materials. Our design features non-conductive PLA with larger pores at the incident surface, transitioning to layers with increasing conductivity and decreasing pore sizes. This gradient structure minimizes reflection by providing impedance matching and enhances absorption by extending the propagation path of EM waves through multiple reflections and scattering within the pores. Additionally, interfacial polarization effects between air, PLA, and MXene nanoflakes strengthen the absorption mechanisms. Both simulation and experimental results confirm that the combined gradient conductivity and pore size structures significantly improve EMI shielding effectiveness (EMI SE) and absorptivity, achieving an EMI SE of 65 dB and an absorptivity of 0.76 in the X-band. Our findings underscore its potential to create adaptable, high-performance EMI shields suitable for complex geometries and reducing secondary interference.