Manipulating a quantum state via electrostatic gating has been of great importance for many model systems in nanoelectronics. Until now, however, controlling the electron spins or, more specifically, ...the magnetism of a system by electric-field tuning has proven challenging
. Recently, atomically thin magnetic semiconductors have attracted significant attention due to their emerging new physical phenomena
. However, many issues are yet to be resolved to convincingly demonstrate gate-controllable magnetism in these two-dimensional materials. Here, we show that, via electrostatic gating, a strong field effect can be observed in devices based on few-layered ferromagnetic semiconducting Cr
Ge
Te
. At different gate doping, micro-area Kerr measurements in the studied devices demonstrate bipolar tunable magnetization loops below the Curie temperature, which is tentatively attributed to the moment rebalance in the spin-polarized band structure. Our findings of electric-field-controlled magnetism in van der Waals magnets show possibilities for potential applications in new-generation magnetic memory storage, sensors and spintronics.
With the explosive growth of intelligent devices, low-cost multifunctional materials will be in great demand in the near future. Preparation of flexible polymer composites from waste plastics can not ...only reduce the production cost but also alleviate the environmental concern. Herein, the thermoplastic polymers from waste cross-linked polyethylene (CLPE) cables were efficiently recycled by partially breaking the cross-linking points in the solid state and, thus, fully utilized in the low-cost, high-strength, and all-weather electromagnetic interference (EMI) shielding materials. Briefly, with the assistance of the homemade solid-state shear milling (S3M) reactor, the waste CLPE cables were converted into fine micropowders at a large scale. The obtained decross-linked CLPE powders were coated with carbon nanotubes (CNTs), and then the coated complex particles were compacted together during the microwave sintering process. In this way, the segregated structure with CNTs selectively enriched at the interfaces of the CLPE phases was successfully constructed by taking full advantage of the selective heating mode of the microwave and the remaining cross-linked structure in CLPE. The sintered CLPE/CNTs containing 7.0 wt % CNTs exhibit an electrical conductivity of 22.6 S/m and an EMI shielding effectiveness (EMI SE) of 35.0 dB, respectively. More importantly, the resulting composite shows superior stability in electrical and EMI shielding properties even under extreme conditions, such as acid/alkali solution soaking and repeated bending deformation. The segregated CLPE/CNT composite also shows excellent mechanical properties with tensile strength above 20 MPa and elongation at a break of 280%. This interfacial engineering strategy offers an effective method to convert the unrecyclable waste plastic into value-added materials, showing great significance in resource recycling utilization.
Electrochemical Li-alloying reactions with Li-rich alloy phases render a much higher theoretical capacity that is critical for high-energy batteries, and the accompanying phase transition determines ...the alloying/dealloying reversibility and cycling stability. However, the influence of phase-transition characteristics upon the thermodynamic properties and diffusion kinetic mechanisms among the two categories of alloys, solid-solutions and intermetallic compounds, remains incomplete. Here we investigated three representative Li-alloys: Li–Ag alloy of extended solid-solution regions; Li–Zn alloy of an intermetallic compound with a solid-solution phase of a very narrow window in Li atom concentration; and Li–Al alloy of an intermetallic compound. Solid-solution phases undertake a much lower phase-transition energy barrier than the intermetallic compounds, leading to a considerably higher Li-alloying/dealloying reversibility and cycling stability, which is due to the subtle structural change and chemical potential gradient built up inside of the solid-solution phases. These two effects enable the Li atoms to enter the bulk of the Li-Ag alloy to form a homogeneous alloy phase. The pouch cell of the Li-rich Li20Ag alloy pairs with a LiNi0.8Co0.1Mn0.1O2 cathode under an areal capacity of 3.5 mAh cm–2 can retain 87% of its initial capacity after 250 cycles with an enhanced Coulombic efficiency of 99.8 ± 0.1%. While Li-alloying reactions and the alloy phase transitions have always been tightly linked in past studies, our findings provide important guidelines for the intelligent design of components for secondary metal batteries.
The most successful lithium‐ion batteries (LIBs) based on ethylene carbonate electrolytes and graphite anodes still suffer from severe energy and power loss at temperatures below −20 °C, which is ...because of high viscosity or even solidification of electrolytes, sluggish de‐solvation of Li+ at the electrode surface, and slow Li+ transportation in solid electrolyte interphase (SEI). Here, a coherent lithium phosphide (Li3P) coating firmly bonding to the graphite surface to effectively address these challenges is engineered. The dense, continuous, and robust Li3P interphase with high ionic conductivity enhances Li+ transportation across the SEI. Plus, it promotes Li+ de‐solvation through an electron transfer mechanism, which simultaneously accelerates the charge transport kinetics and stands against the co‐intercalation of low‐melting‐point solvent molecules, such as propylene carbonate (PC), 1,3‐dioxolane, and 1,2‐dimethoxyethane. Consequently, an unprecedented combination of high‐capacity retention and fast‐charging ability for LIBs at low temperatures is achieved. In full‐cells encompassing the Li3P‐coated graphite anode and PC electrolytes, an impressive 70% of their room‐temperature capacity is attained at −20 °C with a 4 C charging rate and a 65% capacity retention is achieved at −40 °C with a 0.05 C charging rate. This research pioneers a transformative trajectory in fortifying LIB performance in cryogenic environments.
A coherent Li3P coating on the graphite surface enhances Li+ transport across the solid electrolyte interphase and promotes Li+ de‐solvation. This accelerates charge transport kinetics and against propylene carbonate solvent co‐intercalation. Full‐cells with Li3P‐coated graphite anode and PC‐based electrolytes exhibit 70% capacity retention at −20 °C (4 C charging rate) and 65% at −40 °C (0.05 C charging rate).
In view of their high lithium storage capability, phosphorus‐based anodes are promising for lithium‐ion batteries. However, the low reduction potential (0.74 V versus Li+/Li) of the commonly used ...ethylene carbonate‐based electrolyte does not allow the early formation of a solid electrolyte interphase (SEI) prior to the initial phosphorus alloying reaction (1.5 V versus Li+/Li). In the absence of a protective SEI, the phosphorus anode develops cracks, creating additional P/electrolyte interfaces. This results in the loss of P and the formation of a discontinuous SEI, all of which greatly reduce the electrochemical performance of the anode. Here, the effect of solvent reduction potential on the structure of the SEI is investigated. It is found that solvents with a high reduction potential, such as fluoroethylene carbonate, decompose to form an SEI concomitantly with the P alloying reaction. This results in a continuous, mechanically robust, and Li3PO4‐rich SEI with improved Li‐ion conductivity. These attributes significantly improve the cyclic stability and rate performance of the phosphorus‐based anode.
Electrolyte with a high reduction potential decomposes to form solid electrolyte interph SEI concomitantly with the alloying reaction of phosphorus‐based anode, which results in a continuous, mechanically robust, and Li3PO4‐rich SEI, and inhibits the oxidation of phosphorus inside the electrode.
Skin tissue regeneration and repair is a complex process involving multiple cell types, and current therapies are limited to promoting skin wound healing. Mesenchymal stromal cells (MSCs) have been ...proven to enhance skin tissue repair through their multidifferentiation and paracrine effects. However, there are still difficulties, such as the limited proliferative potential and the biological processes that need to be strengthened for MSCs in wound healing. Recently, three-dimensional (3D) bioprinting has been applied as a promising technology for tissue regeneration. 3D-bioprinted MSCs could maintain a better cell ability for proliferation and expression of biological factors to promote skin wound healing. It has been reported that 3D-bioprinted MSCs could enhance skin tissue repair through anti-inflammatory, cell proliferation and migration, angiogenesis, and extracellular matrix remodeling. In this review, we will discuss the progress on the effect of MSCs and 3D bioprinting on the treatment of skin tissue regeneration, as well as the perspective and limitations of current research.
This work investigates the safety improvement and failure mechanism of a a 56.5 Ah high-energy–density Li-ion cell with solid electrolyte via external short circuit, high-precision penetration, and ...accelerating rate calorimetry tests.
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•Safety and failure of a 56.5 Ah Li-ion cell with solid electrolyte is unravelled.•Detailed failure behaviors of cell components and signal variations are correlated.•A sequence matrix summarizing the key events during cell thermal runaway is proposed.
Safety issues of high-energy–density (HED) Li-ion cells have raised wide concerns and are impeding their application in electric vehicles (EVs). Developing the so-called quasi-solid or semi-solid Li-ion cells with solid-state electrolytes (SSEs) is a promising strategy but generally compromises the cell’s electric performance. Moreover, the safety improving and failure mechanisms remain not fully understood. This study demonstrates a large-format (56.5 Ah) HED (260 Wh kg−1) Li-ion cell with significantly improved safety and good electric performances, which is realized by partial substitution of the liquid electrolyte with lithium aluminium titanium phosphate (LATP) SSE and rational cell material matching. The cell can pass various penetration tests with minimal temperature rises (≤20 °C), showing extraordinarily high tolerances for mechanical abuses, and exhibited a retarded thermal runaway (TR) evolution process during the accelerating rate calorimetry (ARC) test, providing valuable time for deploying predicting, alarming, and preventing tactics for the battery management systems (BMSs). X-ray computed tomography and a large depth-of-field digital microscope were used to uncover the detailed failure behaviors of cell materials, which were correlated to the variation of detectable external cell signals (impedance, voltage, and temperature) that could serve as the basis for upgrading the BMS. We expect that the insights achieved could guide the rational design and management of safe HED Li-ion cells.
In response to the unique topographical challenges posed by mountainous environments, this paper investigates a probabilistic model of electric vehicle charging load, taking into account the unique ...traffic behavior and regional characteristics of mountainous cities. Regarding the traffic behavior, first, a traffic road network model for mountainous cities is proposed. Next, the travel chain theory is combined with the road chain to consider the functional partition of the city, which can better describe the travel patterns and charging behavior of users. Based on the analysis of traffic behavior, by exploring the influences of ambient temperature, road grade, and the undulating nature of mountainous roads, an improved Floyd shortest path algorithm is used for path decision-making, leading to the development of an EV power consumption model specifically tailored for mountainous cities. Based on this model, the prediction of EV load in mountainous cities is subsequently conducted. Overall, this study proposes a more realistic EV load prediction model by integrating traffic behavior, regional characteristics and user travel patterns, and the simulation results demonstrate the adaptability as well as the effectiveness of the method for application in mountainous cities.
Adversarial misuse, particularly through `jailbreaking' that circumvents a model's safety and ethical protocols, poses a significant challenge for Large Language Models (LLMs). This paper delves into ...the mechanisms behind such successful attacks, introducing a hypothesis for the safety mechanism of aligned LLMs: intent security recognition followed by response generation. Grounded in this hypothesis, we propose CodeChameleon, a novel jailbreak framework based on personalized encryption tactics. To elude the intent security recognition phase, we reformulate tasks into a code completion format, enabling users to encrypt queries using personalized encryption functions. To guarantee response generation functionality, we embed a decryption function within the instructions, which allows the LLM to decrypt and execute the encrypted queries successfully. We conduct extensive experiments on 7 LLMs, achieving state-of-the-art average Attack Success Rate (ASR). Remarkably, our method achieves an 86.6\% ASR on GPT-4-1106.
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