Volume Expansion Research Articles

Influence of further hydration on UHPC matrix properties

To investigate the evolution laws governing the macroscopic properties of ultra-high-performance concrete (UHPC) matrices under further hydration effect, a further hydration test was performed by varying the cement fineness and slag powder content. The influence mechanism of further hydration on strength was analyzed. The results revealed that the bound water content for further hydration and expansion strain for UHPC matrix with medium fineness cement achieved the minimum values, and the compressive strength reached the lowest value after 21 d of further hydration. Both the bound water content for further hydration and expansion strain showed a tendency to increase with increasing slag powder content, and the higher the slag powder content, the earlier was the peak strength achieved. The volume expansion of further hydration products caused the matrix to crack, and further hydration was manifested as damage effect, resulting in a decrease in strength.

Measuring exploration: evaluation of modelling to generate alternatives methods in capacity expansion models

Abstract As decarbonisation agendas mature, macro-energy systems modelling studies have increasingly focused on enhanced decision support methods that move beyond least-cost modelling to improve consideration of additional objectives and tradeoffs. One candidate is modelling to generate alternatives (MGA), which systematically explores new objectives without explicit stakeholder elicitation. This paper provides comparative testing of four existing MGA methodologies and proposes a new Combination vector selection approach. We examine each existing method’s runtime, parallelizability, new solution discovery efficiency, and spatial exploration in lower dimensional (N ⩽ 100) spaces, as well as spatial exploration for all methods in a three-zone, 8760 h capacity expansion model case. To measure convex hull volume expansion, this paper formalizes a computationally tractable high-dimensional volume estimation algorithm. We find random vector provides the broadest exploration of the near-optimal feasible region and variable Min/Max provides the most extreme results, while the two tie on computational speed. The new Combination method provides an advantageous mix of the two. Additional analysis is provided on MGA variable selection, in which we demonstrate MGA problems formulated over generation variables fail to retain cost-optimal dispatch and are thus not reflective of real operations of equivalent hypothetical capacity choices. As such, we recommend future studies utilize a parallelized combined vector approach over the set of capacity variables for best results in computational speed and spatial exploration while retaining optimal dispatch.

Dramatic Enhancement Enabled by Introducing TiN into Bread-like Porous Si-Carbon Anodes for High-Performance and Safe Lithium Storage.

Doping modifications and surface coatings are effective methods to slow volume dilatation and boost the conductivity in silicon (Si) anodes for lithium-ion batteries (LIBs). Herein, using low-cost ferrosilicon from industrial production as the energy storage material, a bread-like nitrogen-doped carbon shell-coated porous Si embedded with the titanium nitride (TiN) nanoparticle composite (PSi/TiN@NC) was synthesized by simple ball milling, etching, and self-assembly growth processes. Remarkably, the porous Si structure formed by etching the FeSi2 phase in ferrosilicon alloys can provide buffer space for significant volume expansion during lithiation. Highly conductive and stable TiN particles can act as stress absorption sites for Si and improve the electronic conductivity of the material. Furthermore, the nitrogen-doped porous carbon shell further helps to sustain the structural stability of the electrode material and boost the migration rate of Li-ions. Benefiting from its unique synergistic effect of components, the PSi/TiN@NC anode exhibits a reversible discharge capacity up to 1324.2 mAh g-1 with a capacity retention rate of 91.5% after 100 cycles at 0.5 A g-1 (vs fourth discharge). Simultaneously, the electrode also delivers good rate performance and a stable discharge capacity of 923.6 mAh g-1 over 300 cycles. This research can offer a potential economic strategy for the development of high-performance and inexpensive Si-based anodes for LIBs.

TEM-EELS analysis reveals the W-atom mediated radiation-induced amorphization in M23C6

To gain a mechanistic understanding of the phase stability of M23C6 upon irradiation, the bulk W-doped M23C6 (Cr-W-C system) in the range of 0–12 at.% W concentration was prepared and subjected to helium beam irradiation, following with a thorough electron energy loss spectroscopy (EELS) analysis. Radiation-induced amorphization (RIA) was observed only at the 4 W sample with a W concentration of ∼12 at.%. Analysis of the low-loss spectrum showed that the inelastic mean free path (λ) could be applied an effective indicator of the presence of an amorphous phase. The white line ratio of the carbon K-edge spectrum showed that the chemical bonding state in the crystalline state is mainly 2p3/2 bonding, and it changes to dominantly 2p1/2 bonding accompanying with the crystal-to-amorphous (c-a) transition. Discussion on the relationship between the change in λ (Δλ) and the lattice parameter (Δa) due to irradiation reveals that Δa is not dependent on Δλ, indicating that Δλ is mainly caused by the volume expansion due to the c-a transition. In addition, a crystalline state is remained even after a lattice parameter change of ∼1.5 % in 0 W and 1W-samples, whereas, a lattice expansion of ∼0.2 % would trigger the occurrence of crystal-to-amorphous transition in the 4W-sample. The detailed EELS analysis demonstrated that the constitutional W atoms play an important role in facilitating the occurrence of RIA in M23C6, that is, the phase instability accompanying the lattice expansion due to irradiation was emphasized by the addition of W in M23C6. The insights obtained here suggest that a higher W concentration in M23C6 is more susceptible to RIA, and therefore the resistance to amorphization is achievable by decreasing the W concentration in the steels.

Recent Advances in Cost‐Effective ZnO‐Based Electrode Material for Lithium‐Ion Batteries

AbstractFuel cell and lithium ion battery (LIB) technologies are increasingly recognized as cutting‐edge power sources that are gradually displacing various versions of older systems. High‐performance electrode materials must be developed for enhanced next‐generation LIBs. Because of their low cost, high theoretical specific capacity, and environmental friendliness, nanoparticles based on zinc oxide (ZnO) have been regarded as promising alternatives. However, significant problems including intrinsic poor conductivity and significant volume expansion have made ZnO‐based nanomaterials for less viable. In this review we discussed about the mechanism of lithium ion battery and how strategies to overcome intrinsic poor conductivity and significant volume expansion of ZnO‐based nanomaterials. Followed by the best methods for improving the lithium ion storage capacity of ZnO‐based materials as cathode and anode separately reviewed. And summarized the challenges and potential lines of inquiry for Zn‐based nanomaterials in the future.

Carbon matrix NiFeP/C nanoparticles anchored on Ti3C2Tx nanosheets as heterostructure high-performance anode for lithium-ion batteries

Engineered micro-nano heterogeneous architectures for transition metal phosphide (TMPs) anode materials in lithium-ion batteries (LIBs) provide multifunctional active components. These components synergistically interact to address pivotal challenges of pronounced volume expansion and sluggish reaction kinetics within the electrode. Consequently, this engineering design approach significantly enhances the overall battery performance. In this study, a self-assembled approach is employed to integrate hybridized NiFe-PBA nanocubes with two-dimensional (2D) monolayer MXene (Ti3C2Tx), producing a heterostructured NiFeP/C@Ti3C2Tx composite. In this meticulously engineered architecture, the interface between the outer MXene layer and NiFeP embedded within the carbon matrix exhibits several distinct superiorities, such as rapid interfacial ion migration, multidirectional migration pathways, and strong spatial adaptability. The resulting non-uniform phase structure effectively mitigates electrode expansion and enhances electronic conductivity. Consequently, the NiFeP/C@Ti3C2Tx-15 composite demonstrates distinct performance advantages over NiFeP/C without MXene. The composite achieves a specific capacity of 689.4 mAh g⁻¹ at 200 mA g⁻¹ over 300 cycles, double that of NiFeP/C. Furthermore, density functional theory (DFT) calculations validate the electronic conductivity facilitated by the heterointerface between MXene and NiFeP, substantiating the strategic significance of the heterostructure in advancing high-performance anode materials for lithium-ion batteries.

Effects of the extrusion process on the physical properties of micro pellets and the growth performance of juvenile Nile tilapia

The present study aimed to evaluate the effect of different extrusion processes on the physical properties of micro pellets and how the alterations affect the growth performance of juvenile Nile tilapia. Four experimental diets were produced with the same formulation, but with different extrusion processes: CE: cold extrusion (18 ºC); HE: hot extrusion (100 ºC); D1: double extrusion, first a hot extrusion (100 ºC) of all the ingredients followed by cold extrusion (18 ºC); D2: double extrusion, first a hot extrusion (100 ºC) of the plant-based ingredients followed by mixing with the animal-based ingredients and milling, then cold extrusion (18 ºC). Juvenile tilapia (0.83 ± 0.01 g; 3.68 ± 0.19 cm) were distributed in 20 experimental units (60 L; n=5; 20 fish per unit) in a completely randomized design for four weeks. The micro pellets of the experimental HE diet presented a positive expansion rate (2.86 ± 0.45 %) and a lower bulk density (465.9 ± 3.45 g/L). The D1 and D2 micro pellets presented higher bulk density (671.0 ± 2.98 and 612.8 ± 4.99 g/L, respectively). All the micro pellets showed high durability (>95 %). The D2 micro pellets showed low water resistance (24.4 ± 3.51 %), resulting in a high leaching rate of nutrients (>68 %). The HE and D1 micro pellets showed a higher absorption rate in water (3.65 ± 0.29 and 3.66 ± 0.21 g water/g, respectively). The water solubility index of the micro pellets was not influenced by the different extrusion processes (P > 0.05), nor were survival and feed consumption. The fish fed with the HE diet showed greater weight gain (3.84 ± 0.44 g), and the lowest weight gain was in the fish fed with the CE diet (3.05 ± 0.39 g) (P < 0.05). Feed conversion was lower in fish fed the HE (1.06) and D1 (1.11) diets (P < 0.05). Fish fed the HE diet had the highest values for relative growth rate (9.08 ± 0.62 %/d), protein retention (30.6 ± 2.61 %) and protein efficiency (2.26 ± 0.22 %) (P < 0.05). Fish fed the CE diet had the lowest values for relative growth rate (7.82 ± 0.51 %/d), protein retention (21.4 ± 2.72 %) and protein efficiency (1.55 ± 0.23 %) (P < 0.05), though the values are in line with those in the literature. In conclusion, hot extrusion resulted in micro pellets with better physical properties and fish with higher growth performance. Double extrusion, first a hot extrusion of the plant-based ingredients followed by mixing with the animal-based ingredients and milling, then cold extrusion is not recommended due to high levels of nutrient leaching. Cold extrusion and double extrusion, first a hot extrusion of all the ingredients followed by cold extrusion processing can be considered for producing micro diets for juvenile tilapia, especially when less investment in the extrusion process is desired.

High-capacity and long-life Fe2O3/MOFs composite anodes: Preparation, characterization, morphology regulation and electrochemical performance

Among the various transition metal oxides used in lithium-ion battery anodes, iron oxide (Fe2O3) has received extensive attention due to its low cost, good environmental compatibility and high theoretical capacity. However, the volume expansion and structural collapse during the charging-discharging cycling process significantly limited the practical application of Fe2O3. Herein, we demonstrate enhanced electrochemical properties and stability of Fe2O3 by anchoring it on metal-organic frameworks (MOFs). Through adjusting the MOF ligands and introducing humic acid (HA), we reached rational control of the morphology for the Fe2O3/MOF composites. The optimized sample, namely Fe2O3@HA-Fe-ATA, shows 3D cauliflower-like structure with abundant pores, which are beneficial to the active sites exposure, electrolyte penetration, as well as the tolerance toward volume expansion. Consequently, high reversible capacity of 1442.7 mAh g−1 (at 0.1 A g−1), excellent rate performance (<11 % capacity decrease when current density increases from 0.1 A g−1 to 1 A g−1), and satisfactory cycle stability (91 % capacity retention after 500 cycles at 1 A g−1) are obtained. This work demonstrates that the rational design of MOF by introduction of appropriate ligand is a very efficient approach to optimize the electrochemical properties of the resultant electrode material.

Reciprocal regulation between rural settlement expansion and human-elephant conflict in China's wild elephant range

Human-wildlife conflict (HWC) and its socioeconomic impacts are a pressing global issue. Accurately quantifying HWCs and their interaction with residential development is crucial for rural revitalization and biodiversity conservation efforts. This study investigates the interplay between rural residential expansion (RRE) with human-elephant conflict (HEC) in southern Yunnan Province using high-accuracy yearly land use/land cover data and Asian elephant accident data. A piecewise regression along with several metrics, including expansion intensity and rate of rural residential land, and residential density, were employed to analyze the spatial-temporal change characteristics of RRE. Then, a geographical detector and a bivariate spatial autocorrelation model were used to reveal the driving mechanisms of RRE, with particular emphasis on the spatial relations between RRE and HECs. The results indicate that HECs had a significant negative impact on RRE, exhibiting higher expansion intensity and rate of rural residential land in non-HEC areas than in HEC areas. High spatiotemporal consistency between accelerated RRE and intensified HECs occurred from 2010 onwards, which aligns with the year when the trend of settlement area expansion changed. RRE activities and ensuing land use conversions led to increased occurrences of HECs, which negatively affected the RRE. Compared to HECs, topography and locational factors exhibited a secondary effect on RRE activities. The findings underscore reciprocal feedback mechanisms between RRE and HECs and the elevated risk of adverse interactions between humans and elephants within the range of China's wild elephants, providing theoretical support for coordinating conservation initiatives for Asian elephants with rural revitalization in the border areas of Southwest China.

The impact of milling degree on physicochemical, nutritional, rheological, textural properties, and in vitro digestibility of rice: From brown rice to white rice

The objective of this study was to characterize the rice milling fractions acquired at each stage of a commercial milling system. This characterization included an analysis of color, ash content, dietary fiber, mineral composition, as well as antinutritional compounds like phytic acid, trypsin inhibitor activity, and saponin. Additionally, we investigated in vitro starch and in vitro protein digestibility, along with pasting, cooking, and textural properties.Our findings revealed that milling improved the visual appeal of rice (e.g., volume expansion, weight gain, whiteness) and notably enhanced its starch digestibility. However, milling reduced dietary fiber, mineral content, antinutrients, cooking time, and texture characteristics such as hardness, chewiness, gumminess, springiness, and cohesiveness to varying degrees. Certain parameters, such as dietary fiber, exhibited a gradual change with the duration of milling, while others, such as mineral content and texture, showed significant variation at the initial stage of milling, particularly at the first mill.

Iron-based bimetallic oxide carbon composites with superior lithium storage capabilities serve as anode in lithium-ion batteries

Transition metal oxides (TMOs) have emerged as highly promising electrode materials for lithium-ion batteries (LIBs) owing to their versatile valence states and distinctive morphological attributes. Bimetallic oxides, in particular, exhibit the ability to mitigate the volume expansion associated with lithium alloying and de-alloying processes. Despite these advantages, metal oxides often suffer from drawbacks such as poor conductivity, limited cycle stability, and a propensity for lithiation. Addressing the challenges of low electronic conductivity, significant volume expansion, and inadequate uniformity, we synthesized two bimetallic oxide-based carbon composites via a “one-pot” solvothermal approach: ZnFe2O4@C and MnFe2O4@C. These composites are enveloped in a carbon shell derived from anhydrous ethanol. Notably, the specific discharge capacities of ZnFe2O4@C and MnFe2O4@C surpass those of their respective single metal oxide counterparts. Following nearly 300 cycles of charge and discharge operations at a current density of 100 mA g−1, ZnFe2O4@C exhibited a specific discharge capacity of 1528 mAh g−1, while MnFe2O4@C demonstrated a capacity of 1283 mAh g−1. The synthesis method offers simplicity, high yield, and uniform morphology, making it a promising avenue for enhancing the performance of LIBs electrode materials.

In Situ-Constructed Multifunctional Composite Anode with Ultralong-Life Toward Advanced Lithium-Metal Batteries.

Metallic lithium is the most competitive anode material for next-generation high-energy batteries. Nevertheless, the extensive volume expansion and uncontrolled Li dendrite growth of lithium metal not only cause potential safety hazards but also lead to low Coulombic efficiency and inferior cycling lifespan for Li metal batteries. Herein, a multifunctional dendrite-free composite anode (Li/SnS2) is proposed through an in situ melt-infusion strategy. In this configuration, the 3D cross-linked porous Li2S/Li22Sn5 framework facilitates the rapid penetration of electrolytes and accommodates the volume expansion during the repeated Li-plating process. Meanwhile, the lithiophilic Li2S phases with a low Li+ transport barrier ensure preferential Li deposition, effectively avoiding uneven electron distribution. Moreover, the Li22Sn5 electron conductors with appropriate Li+ bonding ability guarantee rapid charge transport and mass transfer. Most importantly, the steady multifunctional skeleton with sufficient inner interfaces (Li2S/Li22Sn5) in the whole electrode, not only realizes the redistribution of the localized free electron, contributing to the decomposition of Li clusters, but also induces a planar deposition model, thus restraining the generation of Li dendrites. Consequently, an unprecedented cyclability of over 6500h under an ultrahigh areal capacity of 10mAhcm-2 and a current rate of 20mAcm-2 is achieved for the prepared Li2S/Li22Sn5 composite anode. Moreover, the assembled Li/SnS2||LiFePO4 (LFP) pouch full-cells also demonstrate remarkable rate capability and a convincing cycling lifespan of more than 2000 cycles at 2 C.

Structure-directing agent mediated synthesis of SnS2 coupled with UltrapheneTM as highly stable anode material for sodium-ion battery

Sodium-ion battery (SIB) with abundant resources has been intensively developed as the efficient energy storage device. Tin disulfide (SnS2) is one of the attractive anode materials due to its high capacity and two-dimensional structure. Nevertheless, volume expansion and low conductivity result in the poor rate performance and stability. In this study, three strategies are applied to design efficient SnS2-based anode materials for the SIB. Two precursor solvents of deionized water (DIW) and ethanol and one structure-directing agent of cetyltrimethylammonium bromide (CTAB) are incorporated to synthesize SnS2. The commercial UlrapheneTM is further mixed with SnS2 to design composites (U/s-SnS2) with different ratios. The optimal SnS2 and U/s-SnS2 anodes respectively show the specific capacities of 187.7 and 326.3 mAh/g at 1.6 A/g. After 100 cycles, the U/s-SnS2 anode still attains specific capacities of 308.7 and 438.9 mAh/g at 1.0 and 0.1 A/g corresponding to capacity retentions of 74.5 % and 80.1 %, respectively. The excellent rate performance and cycling stability of the U/s-SnS2 anode are attributed to the smaller charge-transfer resistance and the larger Na+ diffusion coefficient. This work successfully brings a blueprint for adopting several useful strategies to improve the electrochemical performance of SnS2. The effects for all parameters are also carefully explained.

The expansion of the GRB 221009A afterglow

We observed γ-ray burst (GRB) 221009A using very long baseline interferomety (VLBI) with the European VLBI Network (EVN) and the Very Long Baseline Array (VLBA), over a period spanning from 40 to 262 days after the initial GRB. The high angular resolution (mas) of our observations allowed us, for the second time ever, after GRB 030329, to measure the projected size, s, of the relativistic shock caused by the expansion of the GRB ejecta into the surrounding medium. Our observations support the expansion of the shock with a &gt; 4σ-equivalent significance, and confirm its relativistic nature by revealing an apparently superluminal expansion rate. Fitting a power law expansion model, s ∝ ta, to the observed size evolution, we find a slope a = 0.69−0.14+0.13. Fitting the data at each frequency separately, we find different expansion rates, pointing to a frequency-dependent behaviour. We show that the observed size evolution can be reconciled with a reverse shock plus forward shock, provided that the two shocks dominate the emission at different frequencies and, possibly, at different times.

Crops Feed Rain to Drylands in Northwest China

AbstractAs a key region supplementing China's limited croplands, Northwest China has undergone rapid cropland expansion over the past decades to satisfy rising food demand from population growth and socio‐economic development. Although cropland expansion may overconsume local water resources in general, in Northwest China, increased precipitation and enhanced glacier melt have increased the water available for croplands. Counterintuitively, the enhanced evapotranspiration (ET) resulting from this cropland expansion could benefit remote ecologically vulnerable natural vegetation through atmospheric moisture recycling. In this study, we used a moisture tracking model to quantify contributions of croplands and cropland expansion to local precipitation and the consequent precipitation supply to natural vegetation in Northwest China. We found that the croplands contributed 27.69 billion m3/year (2.13%) of regional total precipitation and supplied 17.30 billion m3/year (2.39%) of precipitation over natural vegetation, and the cropland expansion resulted in a net increase of 80.25 million m3/year (1.07% of the total increase) in regional precipitation and 36.23 million m3/year (4.56% of the total increase) in precipitation supply for natural vegetation. Among different types of natural vegetation, grasslands received the most precipitation supply due to its vast area, followed by forests and shrublands. The more arid regions experienced not only faster rates of cropland expansion but also obtained a greater increase in regional precipitation and precipitation supply to natural vegetation. Our study quantifies the ecological impacts of cropland expansion through moisture recycling in Northwest China. This shows the complexities of water competition between agricultural development and ecological conservation in drylands and elsewhere.

Experimental & numerical investigations of ultra-high-speed dynamics of optically induced droplet cavitation in soft materials

Perfluorocarbon (PFC) droplets represent a novel class of phase-shift contrast agent with a promise in applications in biomedical and bioengineering fields. PFC droplets undergo a fast liquid-gas transition upon exposure to acoustic or optical triggering, offering a potential adaptable and versatile tool as contrast agent in diagnostics imaging and localized drug delivery vehicles in therapeutics systems. In this paper, we utilize advanced imaging techniques to investigate ultra-high-speed inertial dynamics and rectified quasi-static (low-speed) diffusion evolution of optically induced PFC droplet vaporization within three different hydrogels, each of different concentrations, examining effects such as droplet size and PFC core on bubble dynamics and material viscoelastic properties. Gelatin hydrogels reveal concentration-dependent impacts on bubble expansion and material elasticity. Embedding PFC droplets in gelatin increases internal pressure, resulting in higher equilibrium radius and continuous bubble growth during quasi-static evolution. Similar trends are observed in fibrin and polyacrylamide matrices, with differences in bubble behavior attributed to matrix properties and droplet presence. Interestingly, droplet size exhibits minimal impact on bubble expansion during inertial dynamics but influences quasi-static evolution, with larger droplets leading to continuous growth beyond 60 seconds. Furthermore, the core composition of PFC droplets significantly affects bubble behavior, with higher boiling point droplets exhibiting higher maximum expansion and faster quasi-static dissolution rates. Overall, the study sheds light on the intricate interplay between droplet characteristics, matrix properties, and multi-timescale bubble dynamics, offering valuable insights into their behavior within biomimetic hydrogels.

Microstructure evolution and fracture characteristics of GH4079 superalloy during high-temperature tensile process

An investigation of the thermal deformation characteristics and fracture mechanisms of the GH4079 superalloy was conducted through a series of hot tensile experiments conducted across a range of strain rates (from 0.01 s−1 to 1 s−1) and temperatures (from 970 °C to 1160 °C). The impact of MC carbides on the thermal deformation characteristics and dynamic recrystallization (DRX) of GH4079 superalloys, which are known for their challenging deformability, was analyzed to provide insights into enhancing the thermal workability of these formidable superalloys. The results suggest that DRX consistently preferentially occurs near MC carbides. The MC carbide plays a nucleation role in the particle-induced dynamic recrystallization mechanism, as determined via EBSD analysis. In addition, the primary grain boundary is the preferred nucleation site for DRX initiation. The promotion of DRX within the GH4079 alloy is considerably facilitated by the increased stored energy and nucleation site density resulting from the larger and more numerous carbides present at the grain boundaries. Moreover, the presence of carbides leads to uncoordinated deformation of the alloy during tensile deformation, which is also the induction factor of alloy cracking. With increasing strain rates and temperatures, the window of control over the hot deformation structure of the alloy diminishes. During the high-temperature deformation process of the GH4079 alloy, it is necessary to control the temperature within the range of approximately 1120 °C–1140 °C and the strain rate within the range of 0.1 s−1 to 1 s−1 to obtain a fine and uniform grain structure, delay material failure, and thus enhance the thermal processing performance of the material.

A statistical approach towards determining the governing parameters in volume expansion behavior of polypropylene foams

This study delves into the complex relationship between molecular structures and properties within polypropylene (PP) foams, with a particular focus on how various material parameters influence foamability. Multiple linear regression was adopted to efficiently assess the impact of eleven material parameters on foam expansion behavior. A primary finding is the significant role of branching index (g'vis) in shaping the expansion profile (i.e., the foaming window, maximum expansion ratio (Φmax), and optimum foaming temperature (Toptimum)). Additionally, Z-average molecular weight (Mz) is identified as crucial factor influencing the foaming window. Furthermore, the Winter-Chambon parameter n, indicator of the relaxation behavior of a resin in the terminal zone, is distinguished as a key parameter in determining Φmax. The crystallization temperature (Tc) also plays a pivotal role, particularly in its relationship with Toptimum. The research further highlights the significance of long-chain branching (LCB) and suggests strategies for cost reduction by minimizing the degree of LCB without compromising foaming performance, achievable through the adjustment of Mz and n. This strategy was exemplified through the comparison of two LCB PP resins, PP-12 and PP-22, demonstrating the feasibility of achieving similar foamability with adjustments in material parameters. The findings offer a detailed assessment of these parameters' influence on foamability, presenting valuable guidelines for optimizing PP foam production and customizing material properties for targeted applications.

Porous silicon/carbon composites as anodes for high-performance lithium-ion batteries

Silicon anodes are promising for use in lithium-ion batteries. However, their practical application is severely limited by their large volume expansion leading to irreversible material fracture and electrical disconnects. This study proposes a new top-down strategy for preparing microsize porous silicon and introduces polyacrylonitrile (PAN) for a nitrogen-doped carbon coating, which is designed to maintain the internal pore volume and lower the expansion of the anode during lithiation and delithiation. We then explore the effect of temperature on the evolution of the structure of PAN and the electrochemical behavior of the composite electrode. After treatment at 400 -, the PAN coating retains a high nitrogen content of 11.35%, confirming the presence of C―N and C―O bonds that improve the ionic-electronic transport properties. This treatment not only results in a more intact carbon layer structure, but also introduces carbon defects, and produces a material that has remarkable stable cycling even at high rates. When cycled at 4 A g−1, the anode had a specific capacity of 857.6 mAh g−1 even after 200 cycles, demonstrating great potential for high-capacity energy storage applications.

Synergistic Structural Integrity and Remarkable Structural Stability of NC@Si Anodes for Lithium-ion Batteries

The silicon-based anode has attracted wide attention because of its high theoretical specific capacity, which is expected to greatly improve the batteries’ energy density. However, during the charge-discharge cycles, the great volume expansion of the anode active silicon seriously restricts its electrochemical stability. Herein, N-doping carbon-coated silicon microsphere was prepared for lithium-ion batteries. Benefit from the core-shell structure formed from silicon carbon, the volume change of silicon anode during the cycle is well coordinated. What's more, N-doping carbon reduces the reaction energy barrier between silicon and lithium and accelerates the electrochemical reaction, which improves the cycling performance of the battery. The specific capacity of the prepared button battery is as high as 2913.13 mAh g−1 at the current density of 0.21 mA g−1, and the average coulomb efficiency is higher than 99.84% during the cycling. And the capacity of NC@SiO2 anode gradually stabilizes after 500 cycles.