Conductive Network Research Articles

Thermal conductivity enhancement of epoxy by a 3D Si3N4 crystal rod/grain skeleton fabricating from photovoltaic silicon waste

Silicon nitride (Si3N4) is one of the preferred fillers for the preparation of high thermal conductivity polymer composites because of its intrinsic high thermal conductivity and good electrical insulation. To maximize the thermal conductivity enhancement effect of the fillers in the composites, it is necessary to pre-construct a three-dimensional (3D) thermally conductive filler network. Herein, surfactant foaming was applied to pre-construct a 3D Si-containing framework from photovoltaic silicon waste (PSW), which was subsequently transformed into a porous skeleton consisting of Si3N4 rods and grains by in-situ nitridation reaction sintering. And finally, thermal conductive Si3N4/epoxy (EP) composites were fabricated after infiltrating EP into the network skeleton. When the filler content of Si3N4 was 41.00 vol%, the obtained Si3N4/EP composite showed the highest thermal conductivity of 2.99 W·m-1·K-1, which was 13.95 times higher than that of pure EP. Tests on running CPU and heating table showed that the Si3N4/EP substrate had excellent heat dissipation performance compared to the pure EP substrate. The 3D continuous network formed by "bridging" between two different morphologies of Si3N4 microcrystals contributed to providing effective multi-directional heat transfer paths and thereby improving the thermal conductivity of the composites. Overall, the low cost of raw silicon source originating from industrial waste as well as the simple and practical construction of heat-conducting filler network demonstrate the promising application of the Si3N4/EP composites fabricated in our work.

In-plane electrical conductivity of PEDOT:PSS/Halloysite composite thin films

PEDOT:PSS has found numerous applications in the field of advanced materials, especially in the development of organic electronics. Embedding nanoparticles into the polymer matrix has emerged as an effective strategy to modify the properties of PEDOT:PSS and develop advanced functional composites. Over the past decade, Halloysite nanotubes (HNT) have garnered significant interest and utility as nanofillers and/or templates due to their unique physical-chemical properties, small size, relatively low cost, and large availability. Interestingly, pairing PEDOT:PSS with non-conductive HNT has been demonstrated to enhance the charge transport properties of the composite film. Our discoveries show how the HNT can act as scaffolding for PEDOT:PSS by improving the local ordering of PEDOT chains and enabling the formation of conductive pathways. Consequently, the mechanism responsible for the observed changes in conductivity and the correlation between PEDOT:PSS and insulating nanofillers (HNT) could be different to that previously proposed. Hence, in this work it was observed that PEDOT:PSS/HNT composite films exhibited a non-linear conductivity dependence as a function of the HNT loading. From thermogravimetric analysis, infrared and UV-Vis-NIR spectroscopies, as well as impedance spectroscopy, a more complex interaction between the polymer chains and the nanotubes is revealed. Our study includes the modification of the interaction between the PEDOT chains and the nanofillers by using the secondary doping effect and functionalization of the nanotubes, which confirms our findings. These results represent a significant progress toward a deeper understanding of the emergence of a conductive polymer network on the nanofiller surface, leading to improvements in the electrical conductivity in the composite material.

Enhanced sensitivity and broadband response in porous triple periodic minimal surface piezoresistive sensors for telemedicine applications

Wearable pressure sensors with outstanding performance have garnered significant attention in fields such as telemedicine. However, the development of sensors that achieve both adjustable high sensitivity and a wide response range remains a formidable challenge. To address these issues, we propose the development of a flexible piezoresistive sensor featuring simultaneous macro- and microstructures. This is achieved by constructing a complex macro-topological skeleton using Fused Deposition Molding (FDM) technology and integrating supercritical carbon dioxide (ScCO2) foaming technology for microscopic pore creation. The unique conductive network structure, coupled with the Triple Periodic Minimal Surface (TPMS) metamaterial framework and microscopic pore architecture, endows the piezoresistive sensors with exceptional sensing performance, including high sensitivity (12.13 MPa−1), a broad response range (exceeding 30 MPa), and long-term fatigue resistance (over 26,000 s cycles). In addition, the sensors are shielded from electromagnetic interference, with a maximum EMI shielding effectiveness of 53.2 dB for the TMFM with a thickness of 2.3 mm. The effects of varying porosities and foaming pressures on sensitivity were analyzed using finite element simulations. Owing to these remarkable features, multiple foot movement recognition was successfully demonstrated with volunteer participants by assembling sensing unit array modules. Based on this, an intelligent fall warning recognition system is developed using machine learning. This system accurately distinguishes four types of activity behaviors—standing, walking, spraining foot, and falling—with accuracy rates of 98.9 %, 97.1 %, 98.9 %, and 95.1 %, respectively. The system automatically generates an alarm pattern for detected fall behaviors. These findings suggest that the combination of TPMS skeleton and micropores structure offers a promising strategy for developing sensors with adjustable sensitivity and wide detection range for wearable devices. This technology holds significant potential for applications in telemedicine assistance, particularly for the elderly and other vulnerable populations.

Solvent-free Acrylate/BCB drop-on-demand (DOD) inkjet dielectric ink for 3D printing

Currently, drop-on-demand (DOD) inkjet-printed dielectric inks used to produce next-generation high-frequency electronic devices fail to meet the requirements of circuit board substrates in terms of thermal, mechanical, and dielectric properties. To address this gap, we synthesized a low-viscosity acrylate monomer featuring an intrinsically low dielectric structure (hexafluorobisphenol A) and multiple cross-linking sites, and a benzocyclobutene monomer with low curing shrinkage and excellent thermomechanical properties. By mixing these monomers with other reactive diluents and verifying them through theoretical calculations and printing, we have developed a range of dielectric inks suitable for inkjet 3D printing. To enhance the overall performance of the cured inks, a sequential UV/thermal curing strategy was employed to form interpenetrating networks (IPNs). The optimal ink formulations met the requirements of circuit board substrates, demonstrating excellent heat resistance (Td5% = 334 °C, Tg = 181 °C), mechanical properties (tensile strength = 85 MPa, elongation at break = 13.5 %), and dielectric properties (Dk = 2.526 and Df = 0.113 at 15 GHz). These formulations meet the performance requirements for circuit board substrates and lead the industry in mechanical and dielectric properties. Furthermore, the feasibility of inkjet printing heterogeneous integrated electronic devices was verified, showing excellent print resolution and continuity of the conductive network. This work provides new insights into the future development of dielectric materials for inkjet 3D printing.

Microwave absorption properties of one-step formed CNTs/Fe3O4-carbonyl iron superflexible buckypaper by directional pressure filtration

In order to realize the integration of structure and function of microwave-absorbing materials, carbon nanotubes/magnetic nanoparticle buckypaper (CNT/MNP BP) self-supporting, ultra-flexible, ultra-thin and ultra-light composites were prepared by composing CNTs with MNPs through directional pressure filtration technology. The BP composite, with a bulk density of 0.62 g/cm3 and a thickness of 0.21 mm, can be uninterruptedly tightly wound around a 4 mm diameter glass rod many times without structural damage. The microwave-absorbing properties and magnetic properties of the CNT/MNP composites with different compositions and contents were systematically analyzed. The CNT-Fe3O4 Buckypaper with 33.3 wt% Fe3O4 content (CF33.3 %) has the best electromagnetic wave absorption capability, with a minimum reflection loss value of −52.01 dB and an effective absorption bandwidth of 4.08 GHz. The VSM test shows that the saturation magnetization strength of CF33.3 % is 38.4 emu/g. The excellent electromagnetic wave absorption performance is attributed to the polarization and conduction losses of CNTs, natural resonance, exchange resonance and eddy current losses of MNPs, and multiple scattering and reflection within the porous network structure of the composites. The CNTs and MNPs has good dispersion in the buckypaper, where CNTs construct a superflexible skeleton besides an excellent conductive network. The self-supporting superflexible CNT/MNP BP composites have a good application prospect in the field of wearable electronic devices in the future.

Centrifugation-modulated uniform antibacterial paper with well-interconnected hierarchical pores for flexible high-sensitivity humidity monitoring

Humidity-sensitive electrode architecture with high uniformity and enriched open pores is essential and crucial to the high-performance humidity monitoring. However, challenges remain pertaining to manufacturing consistency, remarkable water trapping and superior electrical conductivity. Herein, we demonstrated a facile and controllable centrifugal casting strategy for consistently constructing flexible antibacterial graphene oxide (GO)-silver nanowire (AgNW) humidity sensor, with ample well-interconnected hierarchical pores built by uniformly-distributed AgNWs and orientated GO nanosheets. The unique architectural features facilitated highly efficient transport and high-level trapping of water molecules, and meanwhile guaranteed continuous conductive network for accelerating electrochemical reactions of water molecules trapped inside the device, thereby boasting impressive humidity-sensing capability with a wide sensing range (7.6–95.6 % relative humidity (RH)), a low detection limit (3.8 % RH), good long-time stability (more than 100 days), exceptional folding durability (up to 1000 times), superior selectivity and sensitive monitoring in actual scenes. This work opens a promising route for architecting advanced humidity sensor with prominent monitoring ability toward future uses.

A flexible proximity-pressure–temperature tri-mode robotic sensor with stimulus discriminability, high sensitivity and wide perception range

Along with the explosive utilization of intelligent and bionic robotics, the rise of somatosensory system with excellent flexibility and multiple biological sensing characteristic emerges as a substantial crux of this domain. Herein, we propose a flexible high-performance multi-mode sensor for real-time proximity–pressure–temperature perception based on a monolithic sensing unit with fingerprint-like hierarchical architecture. The monolithic sensing unit, primarily constituted by a double-permeable ionic liquids/Multi-walled nanotubes conductive network, demonstrates dual-functionality in detecting pressure and temperature. Making use of the further synergy of rational topographical architecture engineering and feasible decoupling algorithm construction, extraordinary progress in sensing performances for both pressure and temperature are attained with negligible mutual interferences. Additionally, the sensor is capable of switching to touchless mode to detect objects at distance up to 200 mm, validating its remarkable proximity sensing ability. The multifunctional nature of sensor is further substantiated through its integration with a robotic hand, highlighting its practical applicability in advanced robotic systems.

High-efficient synthesis of straw-derived carbon quantum dots for facilitating methanogenic performance in high-load co-digestion of food waste and excess sludge

Anaerobic digestion (AD), as a crucial technology for organic waste resource recovery, faces the challenge of low efficiency in converting high-load organic substance into biogas. In this study, high-load AD system with food waste and excess sludge as co-substrates was constructed. The effect and mechanism of carbon quantum dots (CQD) derived from straw in promoting the performance of AD systems have been studied. The oxidation pretreatment of straw with H2O2 and acetic acid increased the yield of hydrothermal synthesis CQD to approximately 40%. The effect of different CQD on CH4 yield performance was further explored. The cumulative CH4 yield performance of the fermenter was improved after adding CQD. The CQD synthesized from pretreated straw and the nitrogen-doped CQD synthesized using Chlorella as the nitrogen source showed competitive promotion performance, increasing cumulative CH4 yield by 17.71% and 8.87%, respectively. These CQD can effectively accelerate the degradation of dissolved organic matter and thus improve the CH4 yield performance, with the most significant effect of CQD synthesized from pretreated straw. Electrochemical analysis and the correlation analysis between microorganisms and performance parameters showed that these CQD established an electron conductive network to enhance the electron transfer of the system. This well conductive conditions enriched hydrogenotrophic methanogenic (Methanosarcina), electroactive bacteria (Clostridium_sensu_stricto_1), and hydrolytic-acidifying bacteria (norank_f__Bacteroidetes_vadinHA17). This study significantly enhanced the yield of straw-derived CQD through green methods, and deeply revealed the potential promoting mechanisms of biomass-derived CQD by investigating the correlation between system performance and microorganisms in high-load AD systems

In-situ construction of high-performance artificial solid electrolyte interface layer on anode surfaces for anode-free lithium metal batteries

The electrochemical performance of lithium metal batteries (LMBs) was hampered by the uncontrolled growth of lithium (Li) dendrites. To address this issue, the extensive application of artificial solid electrolyte interphase (SEI) coatings on anode surfaces emerged as an effective solution. Electrospinning, as an innovative technique for fabricating artificial SEI layers on the surface of copper (Cu) foil, effectively mitigated Li volume strain during cycling. In this study, an electrospun organic–inorganic composite nanofiber membrane was in-situ fabricated on Cu foil, serving as an artificial SEI layer (CuWs) for anode-free LMBs (AF-LMBs) to enhance battery performance. Lithiophilic polyvinylpyrrolidone was used as the polymer matrix, and Cu nitrate served as the inorganic functional particles capable of in-situ redox reactions. The CuWs with their three-dimensional (3D) network structure accommodated electrode volume changes and suppressed Li dendrite growth during Li deposition and stripping. Additionally, CuWs facilitated the in-situ generation of Li nitrate (LiNO3), which helped stabilize SEI layer and enhance Li utilization. The release sites of LiNO3 on the nanofibers enabled the in-situ reduction of metallic Cu, providing nucleation sites for Li deposition and forming the 3D ion–electron hybrid conductive networks. This CuWs layer reduced interfacial resistance and nucleation barriers, promoting uniform Li+ distribution on the anode surface. Li-Cu cells incorporating CuWs exhibited remarkable cycling stability, enduring over 460 cycles at 1.0 mA cm−2 and 1.0 mAh cm−2 with an average Coulombic efficiency of over 98.6 %. In Li-poor cells, the LFP|PE|CuWs achieved stable cycling for more than 30 cycles at 1.0 C, with a capacity retention rate of 92.0 %. These findings demonstrated that the CuWs membrane significantly enhanced the electrochemical performance of Li-poor cells and provided a novel artificial SEI protective strategy for advanced AF-LMBs with high energy density.

Rice husk-based activated carbon/carbon nanotubes composites for synergistically enhancing the performance of lead-carbon batteries

Lead-carbon batteries (LCBs), an advanced form of lead-acid battery (LAB) technology, incorporate super-capacitive carbon materials into the negative electrode. Rice husk-based activated carbon (RHAC) is a promising additive for LCBs due to its favorable properties. However, RHAC's amorphous structure impedes electronic conduction, and its zigzag microporous channels hinder ion transport, leading to degraded high-rate performance. This study addresses these issues by growing carbon nanotubes (CNTs) in situ on RHAC through a one-step heat treatment, resulting in carbon nanotubes-loaded RHAC (CNTs/RHAC), and the electronic conductivity and ionic conductivity are simultaneously enhanced. When CNTs constitute 30 wt.% of CNTs/RHAC, the negative electrode achieves a cycle life of 4721 cycles at a 2C rate under 50% state of charge, which is 10.04 times that of the blank anode. The enhanced performance is attributed to the synergistic effects of CNTs and RHAC, where CNTs form long-range conductive networks among the negative electrode active material (NAM) and facilitate the diffusion and electro-deposition of Pb2+, while the high specific surface area (SSA) and hierarchical porous structure of RHAC enhance its capacitive function, leading to a stable lead-carbon composite structure.

Enhanced EMI Shielding Efficiency of Graphene Nanoplatelets and Glass Sphere Composite‐Loaded Ultralight Weight Flexible Polyurethane Foam

ABSTRACTGraphene nanoplatelets and glass sphere (GNP@GS) composite is prepared using a simple mixing process and is loaded in flexible polyurethane foam to produce ultralight weight, high‐performance, electromagnetic interference (EMI) shielding material. The presence of a glass sphere enhances the mobility of graphene nanoplatelets in a polymer matrix forming a continuous conductive network thereby achieving better electrical conductivity and enhanced EMI shielding efficiency. The electrical conductivity of the synthesized GNP@GS/PU foam composites was achieved between 5.69 × 10−8 and 13.25 × 10−4 S/cm at varying filler loading. The maximum shielding effectiveness (i.e., −24.43 dB) was found at 12 wt% GNP@GS‐loaded samples. The shielding results show that the composites have the potential to be employed as ultralight weight, flexible EM shielding materials. These materials are essential in many applications because they are good shield materials that prevent electronic equipment from electromagnetic‐interference, better heat dissipation from the device, and also flexible to support fall protection.

Exploring the thermal and optical characteristics of Ti3C2 MXene for enhanced photothermal conversion

Ti3C2 MXene, a member of the two-dimensional (2D) transition metal carbides family, has garnered significant attention for its exceptional photothermal properties. To understand the mechanistic underpinnings of this feature, we conducted a comprehensive first-principles density functional theory analysis. This study was aimed at investigating the electronic band structure and vibrational characteristics of Ti3C2 MXene to unravel its microscopic process of photothermal conversion. After obtaining its optical and thermal properties, the process by which the material moves from light absorption to heat release is elucidated. The presence of localized surface plasmon resonance (LSPR) effects in Ti3C2 is proved by Finite-difference time-domain (FDTD) simulations. The synergy between the high thermal conductivity network in the Ti layers and the LSPR phenomenon is believed to be responsible for the superior photothermal conversion capabilities. This investigation enhances the understanding of the intrinsic properties of Ti3C2 MXene, confirming its status as an ultrahigh photothermal conversion material.

In situ anchoring of FeNi nanoparticles into three-dimensional nitrogen-doped carbon framework as a self-supporting electrode for high-performance lithium storage

Constructing free-standing electrodes with superior lithium storage capacity and good mechanical performance are fascinating for next-generation lithium-ion batteries (LIBs). Nevertheless, their practical application is hindered by complicated synthesis procedures and high cost. Herein, a highly stable, self-supporting and flexible electrode material for LIBs was constructed by encapsulating spherical FeNi nanoparticles into one-dimensional N-doped carbon fiber film (FeNi/N- CFM) using the electrospinning technique and subsequent heat treatment. The FeNi/N-CFM can be directly used as anode materials for LIBs without conductive additive, current collector and binder. The synergistic effect of uniformly dispersed small FeNi nanoparticles and three-dimensional (3D) conductive network constructed by CF framework effectively improves the utilization rate of active materials, enhances the transport of both electrons and lithium ions, facilitates the electrolyte penetration, and promotes the lithium-ion storage kinetics and stability, thus leading to a greatly enhanced electrochemical performance. Benefiting from the unique architectural feature and flexibility, the FeNi/N-CFM composites employed as binder-free electrodes for LIBs exhibit good lithium storage performance (an initial discharge capacity of 1031.5 mA h g−1 and a reversible capacity of 481.3 mA h g−1 at 100 mA g−1 after 100 cycles), rate capacity (305.1 mA h g−1 at 1000 mA g−1) and outstanding reversibility (coulombic efficiency of around 100 % after 100 cycles). Furthermore, this work also provides a facile and effective pathway to design and fabricate free-standing electrodes.

Fabrication, evaluation, and mechanism of TPU nanocomposites containing MWCNTs–Fe2O3 hybrid conductive nanofillers for selective VOC sensing applications

AbstractVolatile organic compounds (VOCs) are highly harmful substances that can bring serious harm to the environment and human health. In this work, thermoplastic polyurethane (TPU) conductive nanocomposite sensors for selective gas sensing of VOCs were designed and fabricated using electrospun TPU fibers as templates and MWCNTs–Fe2O3 as conductive hybrid nanofillers through a homogeneous liquid impregnation method. The microstructure of TPU matrix fibers and the TPU nanocomposites, and their gas‐sensitive response performance to various VOCs, were investigated. The formation of MWCNTs–Fe2O3 nanofillers was confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, and Raman analysis. Field emission scanning electron microscope showed that MWCNTs–Fe2O3 nanofillers were uniformly coated on the surface of TPU, forming effective and complete conductive networks. The average volume resistivity of TPU nanocomposites (containing 4.76 wt% MWCNTs–Fe2O3) was reduced from 1.5 × 1012 Ω·mm in pure TPU matrix fiber to 2.93 × 105 Ω·mm. Gas‐sensitive performance tests with 500 ppm of ether, ammonia, formaldehyde, ethanol, xylene, toluene, benzene vapor, and acetone showed that the response value of TPU/MWCNTs–Fe2O3 nanocomposites to ether was 85.7%, and the resistance ratio of desorption to the initial one was 1.01, which was almost a complete recovery. In addition, the gas response values of TPU nanoconductive composites under different humidity environments show better stability.Highlights Novel TPU composites contain MWCNTs–Fe2O3 conductive nanofillers were proposed. Synthesized TPU nanocomposite fibers by electrospinning and liquid dip methods. TPU nanocomposite sensors combine fast response, selectivity, and repeatability. TPU nanocomposites exhibited high gas‐sensitive response selectivity to ether.

Constructing LiF‐Enriched Solid Electrolyte Interface on Graphene Arrays with Abundant Edges on Microscale Si‐C Anodes Toward High‐Energy Lithium‐Ion Batteries

AbstractSilicon (Si) anodes offer excellent lithium storage capacity for lithium‐ion batteries but face practical limitations due to significant volume expansion and low intrinsic electrical conductivity. These issues lead to side reactions that consume the electrolyte and impede ion‐electron transport, resulting in low areal loading (<2 mg cm⁻²) and restricted energy density. To address this, a scalable method is developed using spray drying of commercial graphite flakes (s‐Gr) and nanosilicon particles (n‐Si), followed by chemical vapor deposition to create microscale Si/C anodes (s‐Gr/n‐Si/VGs). Thin vertical graphene nanosheets (VGs) are grown on the surfaces and within the internal pores, forming a robust, micron‐sized Si/C spherical composite material. The VGs construct the conductive network, allowing the electrodes to operate at high areal loadings without pulverization and promoting LiF‐enriched solid electrolyte interphase for improved cycling stability. The s‐Gr/n‐Si/VGs maintain a capacity of 641.9 mAh g⁻¹ after 1000 cycles at 11.0 mg cm⁻², retaining 95.9% capacity. In pouch cells with NCM811 cathodes, the 5.0 Ah‐level cells achieved 80.0% capacity retention after 510 cycles at 1.0 C. This research provides a feasible pathway for manufacturing high‐performance, low‐cost, and scalable Si/C anodes suitable for high‐energy‐density lithium‐ion batteries.

Ti3C2Tx/Ni0.2Mn0.4Zn0.4Fe2O4 ferrite nanocomposites: Dual-loss mechanism with engineered composition for microwave absorption

Ni0.2Mn0.4Zn0.4Fe2O4 (NMZF) nanoparticles were anchored on the surface of MXene(Ti3C2Tx) to form Ti3C2Tx/NMZF nanocomposites for optimization of microwave absorption performance. The Ti3C2Tx/NMZF nanocomposites were synthesized by using a four-step strategy, including sonication, stirring, hydrothermal reduction and vacuum drying. More than 40 percent of the NMZF nanoparticles in this nanocomposite were assembled to form a conductive network. Meanwhile, the multilayer MXene acted as a framework to host the NMZF nanoparticles, providing dipolar polarization, interfacial polarization and eddy current loss. Benefiting from the structure design of MXene, combined with magnetic materials and optimized impedance matching, the Ti3C2Tx/NMZF exhibited a minimum reflection loss (RLmin) of −57.39 dB, with a thickness of 2.97 mm and an effective absorption bandwidth (EAB) of 3.2 GHz. Therefore, such a facile method could be used to construct nanocomposites with microwave absorption performance (-57.39 dB, 3.2 GHz), so as to address microwave pollution issues.

Construction of 3D modified hexagonal boron nitride thermal conductivity network by ice template method and research of high heat‐conducting coefficient of epoxy resin matrix composite material

Construction of <scp>3D</scp> modified <scp>hexagonal boron nitride</scp> thermal conductivity network by ice template method and research of high heat‐conducting coefficient of epoxy resin matrix composite material

Engineering the conductive network of missing-linker metal-organic framework for improved performance in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) face critical challenges such as interfacial side reactions, corrosion, and passivation of the zinc anode. In this work, we introduce a novel zinc anode featuring a 3D ordered macroporous (3DOM) architecture based on a missing-linker ZIF-8 framework (Zn@Fc-ZIF-8). This innovative design achieves remarkable stability, maintaining performance for over 4000 h at a current density of 0.25 mA cm−2 in a symmetric cell-over 30 times longer than a bare Zn anode. Additionally, by integrating carbon nanotubes (CNTs) within the 3DOM Fc-ZIF-8 skeleton to create a highly conductive network (3DOM Fc-ZIF-8/CNTs), we extend the anode's lifetime to 1500 h at a high current density of 5 mA cm−2. The strategic regulation of the ZIF-8 structure using ferrocene formic acid (Fc) and the incorporation of CNTs result in a full cell with the bi-functional Zn@Fc-ZIF-8/CNTs anode, achieving a high specific capacity of 380.5 mAh g−1 and a coulombic efficiency (CE) of 99.8 %. These findings underscore the significant potential of MOF-based anodes in addressing dendrite formation and advancing the practical application of ZIBs.

Nanosizing strategy to fabricate uniformly dispersed NiO/Ni/lignin porous carbon composites for high lithium storage

Nickel oxide is considered a promising anode material for lithium-ion batteries. Nevertheless, its performance is hindered by significant volume expansion and low electrical conductivity, particularly at larger particle sizes, which lead to a notable decrease in lithium storage capacity and rate performance. To address these challenges, we introduce a nanocomposite strategy to synthesise nickel oxide and lignin-derived porous carbon composites (LPC/Ni/NiO). Through in situ polymerization, lignin macromolecules form a uniform 3D network with nickel carbonate, which, during the subsequent carbonisation process, results in the formation of nickel oxide within a conductive carbon network. This approach reduces the nickel oxide to nanosize and enhances the composite's electrical conductivity, effectively integrating the buffering framework of porous carbon with the high storage capacity of nickel oxide. As a result, the LPC/Ni/NiO composite exhibited significantly improved lithium storage capacity. Notably, when employed as an anode material in lithium-ion half-cells, the optimized composite maintained an excellent specific capacity of 1065 mAh/g after 100 cycles at a current density of 0.2 A/g. It also shown exceptional rate performance, delivering a specific discharge capacity of 505 mAh/g at a current density of 2 A/g, with stable cycling performance. The electrochemical reaction process was further validated using in ex-situ EIS. This study offers valuable insights into scalable synthesis methods for oxide nanocomposites, highlighting their potential as promising anode materials for lithium-ion batteries.

Micro-Channel Cooling of Hot Spots Through Non-Uniform Aspect Ratio Designs

Abstract Electronic devices experience spatial variation in power dissipation, which results in high-temperature hot spots. These locations require aggressive thermal management, which can be complex and costly. Simple solutions such as single-phase micro-channels can provide adequate heat transfer, but they are not designed to control heat transfer locally. However, micro-channels can be tailored to control local flow rates and heat transfer, potentially mitigating hot spot temperatures. Using a conductive and convective resistance network for a micro-channel, an analytical model is generated for heat transfer within an individual passage. For a given channel width, this model relates the channel depth to its resistance through a power law. Over a wide range of heat fluxes, the optimal design balances local temperatures to within 3 K. The analytical model is validated using computational simulations of the optimized heat sink. For a randomly-generated, non-uniform power distribution, device temperatures are balanced with a sample standard deviation below 2.5%, which is significantly better than a baseline design. When heat spreading is incorporated, the temperature increase is smaller but remains uniform, indicating that the hot spots can be mitigated.