Explore the vast range of titles available.

Constructing powerful anode/cathode interphases by modulate ion solvation structure is the principle of electrolyte design. However, the methodological and theoretical design principles of electrolyte/solvation structure and their effect on electrochemical performance are still vague. Here, we propose a cationic weakly coordinating-intervention strategy for modulating the Na + solvation sheathes and constructing robust anode/cathode interphases in sodium-metal batteries. Unlike the local highly concentrated electrolytes, 1,2-difluorobenzene can weakly coordinate with Na + thus transforming the solvation structure into Na + -anion-incorporated structures and strengthening anode/cathode interphases formation by combining with salt decomposition. Furthermore, the correlations between the electrode interface properties and solvation structure are revealed, which can be tuned by the weakly coordination. Ultimately, the modulated electrolyte achieves 97.5% Coulombic efficiency for 600 cycles in Na‖Cu cells at 1 mA cm −2 and a beneficial lifetime (2500 h) in Na‖Na cells. Meanwhile, Na‖PB cells have achieved long-term operation at 4.8 V, along with operation at wide temperatures. Here, authors propose a weakly coordinating-intervention strategy to modulate the Na+ solvation sheath and construct a robust interphase in sodium-metal batteries. Correlation between electrode interface properties and solvation structure is also stated.

Rechargeable lithium batteries using 5 V positive electrode materials can deliver considerably higher energy density as compared to state-of-the-art lithium-ion batteries. However, their development remains plagued by the lack of electrolytes with concurrent anodic stability and Li metal compatibility. Here we report a new electrolyte based on dimethyl 2,5-dioxahexanedioate solvent for 5 V-class batteries. Benefiting from the particular chemical structure, weak interaction with lithium cation and resultant peculiar solvation structure, the resulting electrolyte not only enables stable, dendrite-free lithium plating-stripping, but also displays anodic stability up to 5.2 V (vs. Li/Li + ), in additive or co-solvent-free formulation, and at low salt concentration of 1 M. Consequently, the Li | |LiNi 0.5 Mn 1.5 O 4 cells using the 1 M LiPF 6 in 2,5-dioxahexanedioate based electrolyte retain >97% of the initial capacity after 250 cycles, outperforming the conventional carbonate-based electrolyte formulations, making this, and potentially other dicarbonate solvents promising for future Lithium-based battery practical explorations. Rechargeable lithium batteries featuring 5 V cathodes offer high energy density yet struggle with stability. Here, the authors formulate an electrolyte incorporating dimethyl 2,5-dioxahexanedioate solvent, which facilitates stable lithium plating and stripping while offering an extended cycle life.

Thick electrodes represent an effective approach for augmenting energy density of batteries. However, their increased thickness invariably leads to longer electron and ion transport distance, limiting the utilization of active material and hindering practical application. Herein, an electron‐conducting‐enhanced and ion‐conducting‐enhanced strategy is presented for fabricating ultrahigh loading electrodes via constructing an interlaced 3D network. Carbon nanotubes (CNTs) serve as extended electron pathways. Different from the polyvinylidene fluoride binder which needs to be dissolved into molecules for preparing electrode, polytetrafluoroethylene (PTFE), however, exists as a separate phase inside the electrode, thus can become the extended pathways for electrolyte elongating due to its strong affinity to organic electrolyte. Note that based on the synergistic effect between CNT and PTFE, the latter can exhibit a form of long‐distance extension fibers rather than agglomeration. Finally, a LiFePO4 electrode with a record‐high loading of 141 mg cm−2 is successfully prepared. This electrode exhibits outstanding area capacity (20.7 mAh cm−2 at 0.2 C) and cycling stability with impressive energy density of 224 Wh kg−1 and 517 Wh L−1 in a full cell (graphite anode). The findings present a novel strategy for achieving high energy density in lithium‐ion batteries using existing material systems. A novel strategy is presented for fabricating thick electrodes by constructing expanded ion/electron channels where the polytetrafluoroethylene and carbon nanotube act crucial roles. An ultrahigh loading electrode, with a loading of 141 mg cm−2, elevates the energy density of lithium iron phosphate batteries to an impressive level of 224 Wh kg−1 and 517 Wh L−1, respectively.

Thick electrodes represent an effective approach for augmenting energy density of batteries. However, their increased thickness invariably leads to longer electron and ion transport distance, limiting the utilization of active material and hindering practical application. Herein, an electron‐conducting‐enhanced and ion‐conducting‐enhanced strategy is presented for fabricating ultrahigh loading electrodes via constructing an interlaced 3D network. Carbon nanotubes (CNTs) serve as extended electron pathways. Different from the polyvinylidene fluoride binder which needs to be dissolved into molecules for preparing electrode, polytetrafluoroethylene (PTFE), however, exists as a separate phase inside the electrode, thus can become the extended pathways for electrolyte elongating due to its strong affinity to organic electrolyte. Note that based on the synergistic effect between CNT and PTFE, the latter can exhibit a form of long‐distance extension fibers rather than agglomeration. Finally, a LiFePO 4 electrode with a record‐high loading of 141 mg cm −2 is successfully prepared. This electrode exhibits outstanding area capacity (20.7 mAh cm −2 at 0.2 C) and cycling stability with impressive energy density of 224 Wh kg −1 and 517 Wh L −1 in a full cell (graphite anode). The findings present a novel strategy for achieving high energy density in lithium‐ion batteries using existing material systems.

Abstract Since the introduction of poly(ethylene oxide) (PEO)-based polymer electrolytes more than 50 years, few other real polymer electrolytes with commercial application have emerged. Due to the low ion conductivity at room temperature, the PEO-based electrolytes cannot meet the application requirements. Most of the polymer electrolytes reported in recent years are in fact colloidal/composite electrolytes with plasticizers and fillers, not genuine electrolytes. Herein, we designed and synthesized a cross-linked polymer with a three-dimensional (3D) mesh structure which can dissolve the Li bis(trifluoromethylsulfonyl)imide (LiTFSI) salt better than PEO due to its unique 3D structure and rich oxygen-containing chain segments, thus forming an intrinsic polymer electrolyte (IPE) with ionic conductivity of 0.49 mS cm−1 at room temperature. And it can hinder the migration of large anions (e.g. TFSI−) in the electrolyte and increase the energy barrier to their migration, achieving Li+ migration numbers (tLi+) of up to 0.85. At the same time, IPE has good compatibility with lithium metal cathode and LiFePO4 (LFP) cathode, with stable cycles of more than 2,000 and 700 h in Li//Li symmetric batteries at 0.2 and 0.5 mAh cm−2 current densities, respectively. In addition, the Li/IPE/LFP batteries show the capacity retention >90% after 300 cycles at 0.5 C current density. This polymer electrolyte will be a pragmatic way to achieve commercializing all-solid-state, lithium-based batteries.

Weak key analysis is a key issue in the design of chaotic ciphers.While most of the existing research focusing on the degradation of the chaotic sequences which causes weak keys,we point out that the parameters for which the chaotic sequences do not degrade are still possible to be weak keys.In this paper,we propose a new approach based on the rigorous statistical test to improve the weak key analysis.The weak keys of a specific chaotic cipher are investigated by using our method and a large number of new weak keys are detected.These results verify that our method is more effective.On the other hand,although statistical tests are now widely adopted to test the chaos-based bit sequences,there are few reports of analysis results on the weak keys or weak sequences of chaotic cipher.Thus our work may be helpful for current research on statistical tests of chaotic cipher.

As a high-performance lightweight structural material with superior strength, Ti55531 titanium alloy has been widely adopted in critical load-bearing components such as landing gears and airframe frames in the aerospace sector to achieve significant weight reduction. However, when the tensile strength of Ti55531 exceeds 1250 MPa, the fracture toughness typically falls below 50 MPa·m1/2. In this study, we addressed this challenge by precisely controlling the cooling rate during β annealing heat treatment. Through careful regulation of the cooling rate from the high-temperature β phase region to the aging temperature region, the Widmanstätten structure was successfully introduced into the Ti55531 titanium alloy. The experimental results demonstrate that this microstructure achieves a high tensile strength of 1252 MPa at a cooling rate of 2.5 °C/min, while simultaneously improving the elongation and fracture toughness to 9% and 84 MPa·m1/2, respectively. Microstructural analysis reveals that the basket-weave structure plays a crucial role in maintaining high strength. Meanwhile, the Widmanstätten structure effectively increases the energy required for crack extension by resisting crack propagation and altering the crack propagation path, thus significantly enhancing fracture toughness. These findings offer a promising pathway for overcoming the traditional trade-off between strength and toughness in high-performance titanium alloys.

Ultrahigh-strength steels with yield strengths exceeding 3 GPa and appreciable ductility represent a transformative frontier in materials science. Conventional strengthening approaches, such as cold-work hardening, however, inevitably trade strength for total elongation, and thus are unable to deliver ductile 3 GPa steel. Here, we present a hierarchical microstructural architecture strategy applied to a designed maraging steel (Fe-16Ni-7Mo-1.6Ti-15Co-0.1Al, wt.%) that synergizes tailored precipitations with high-temperature severe plastic deformation. The multi-misfit nano co-precipitates, a high but spatially uniform density of dislocations, and ultrafine equiaxed grains are orchestrated into a hierarchical microstructure that delocalizes stress concentrations that commonly embrittle ultrahigh-strength materials and converts brittle cleavage fracture to ductile dimpling. Remarkably, the steel demonstrates 3 GPa yield strength with 47.5% reduction in area, 7.0% tensile elongation, and fracture toughness ( K Ic ) of 26.0 ± 0.2 MPa·m 1/2 , which far surpasses existing 3 GPa steels. Moreover, as it exhibits an excellent fatigue strength of 1.24 GPa at ambient temperature and a yield strength of 2 GPa at 500 °C, which is achieved in industrially viable billets, this strategy unlocks scalable damage-tolerant components for extreme environments. Researchers develop a martensitic steel with a hierarchical architecture of precipitates, dislocations and grain boundaries, achieving 3 GPa yield strength with 7% elongation. The material is successfully fabricated as 30-mm-diameter bars, demonstrating ductility and scalability.

The evolution of microstructures and mechanical properties with tempering temperature of a novel 2.5 GPa grade ultra-high strength steel with synergistic precipitation strengthening was investigated. With increasing tempering temperature, the experimental steel initially progressed from ε-carbides to M3C and then to M2C, followed by further coarsening of the M2C carbides and β-NiAl. Concurrently, the martensite matrix gradually decomposed and austenitized. The ultimate tensile strength and yield strength initially increased and subsequently decreased with rising tempering temperature, reaching peak value at 460 and 470 °C, respectively. Conversely, the ductility and toughness initially decreased and then increased with rising tempering temperature, reaching a minimum at 440 °C. The increase in strength was attributed to the secondary hardening effects resulting from carbide evolution and the precipitation of β-NiAl. The subsequent decrease in strength was due to the recovery of martensite and coarsening of precipitates. The decrease in ductility and toughness was linked to the precipitation of M3C, while their subsequent increase was primarily attributed to the dissolution of M3C and an increase in the volume fraction of reverted austenite. The high dislocation density of martensite, the film of reverted austenite, nanoscale M2C carbides, and ultrafine β-NiAl obtained during tempering at 480 °C resulted in the optimal mechanical properties of the experimental steel. The strength contributions from M2C carbides and β-NiAl were 1081 and 597 MPa, respectively.

Synergistic strengthening of nano−scaled M2C and β−NiAl has become a new route to develop ultra−high secondary−hardening steel. At present, the effect of Co on the synergistic precipitation behavior of duplex phases of M2C and β−NiAl has been rarely reported. This paper revealed the effects of Co on the mechanical properties and duplex precipitates of M2C and β−NiAl in a novel 2.5 GPa ultra−high strength secondary−hardening steel. The tensile tests indicated that a 10% Co−alloy steel achieved a much stronger secondary−hardening effects compared to a Co−free steel during aging process, especially in the early−aging state. Needle−shaped M2C and spherical β−NiAl particles were observed in both Co−alloy and Co−free steels. However, the number density, and volume fraction of M2C were significantly enhanced in the 10% Co−alloy steel. The Mo contents in M2C carbide and α−Fe after aging treatment were both analyzed through experimental determination and thermodynamic calculation, and the results indicated that Co decreased the solubility of Mo in α−Fe, thus promoting the precipitation of Mo−rich carbides.