High‑Entropy Electrode Materials:Synthesis,Properties and Outlook

High-entropy materials represent a new category of high-performance materials,first proposed in 2004 and extensively investigated by researchers over the past two decades.The definition of high-entropy materials has continuously evolved.In the last ten years,the discovery of an increasing number of high-entropy materials has led to significant advancements in their utilization in energy storage,electrocatalysis,and related domains,accompanied by a rise in techniques for fabricating high-entropy electrode materials.Recently,the research emphasis has shifted from solely improving the performance of high-entropy materials toward exploring their reaction mechanisms and adopting cleaner preparation approaches.However,the current definition of high-entropy materials remains relatively vague,and the preparation method of high-entropy materials is based on the preparation method of single metal/low-or medium-entropy materials.It should be noted that not all methods applicable to single metal/low-or medium-entropy materials can be directly applied to high-entropy materials.In this review,the definition and development of high-entropy materials are briefly reviewed.Subsequently,the classification of high-entropy electrode materials is presented,followed by a discussion of their applications in energy storage and catalysis from the perspective of synthesis methods.Finally,an evaluation of the advantages and disadvantages of various synthesis methods in the production process of different high-entropy materials is provided,along with a proposal for potential future development directions for high-entropy materials.

Advances in Graphene‑Based Electrode for Triboelectric Nanogenerator

With the continuous development of wearable electronics,wireless sensor networks and other micro-electronic devices,there is an increasingly urgent need for miniature,flexible and efficient nanopower generation technology.Triboelectric nanogenerator(TENG)technology can convert small mechanical energy into electricity,which is expected to address this problem.As the core component of TENG,the choice of electrode materials significantly affects its performance.Traditional metal electrode materials often suffer from problems such as durability,which limits the further application of TENG.Graphene,as a novel electrode material,shows excellent prospects for application in TENG owing to its unique structure and excellent electrical properties.This review systematically summarizes the recent research progress and application prospects of TENGs based on graphene electrodes.Various precision processing methods of graphene electrodes are introduced,and the applications of graphene electrode-based TENGs in various scenarios as well as the enhancement of graphene electrodes for TENG performance are discussed.In addition,the future development of graphene electrode-based TENGs is also prospectively discussed,aiming to promote the continuous advancement of graphene electrode-based TENGs.

Microstructure and thermal properties of dissimilar M300–CuCr1Zr alloys by multi-material laser-based powder bed fusion

Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel.Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone.Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150%compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.

Implantable probe with integrated reference electrode for in situ neural signal and calcium ion monitoring

Monitoring the electrophysiology activity of neurons and blood calcium signals can enable a better understanding of disease-related neural system circuits.However,currently,in situ calcium ion monitoring tools are scarce and exhibit low integration and limited sensitivity.In this letter,we propose an implantable probe with an integrated in situ Ag/AgCl reference electrode(ISA/ARE)that can monitor action potential(AP)and Ca^(2+) concentrations.

A drug-loaded flexible substrate improves the performance of conformal cortical electrodes

Cortical electrodes are a powerful tool for the stimulation and/or recording of electrical activity in the nervous system.However,the inevitable wound caused by surgical implantation of electrodes presents bacterial infection and inflammatory reaction risks associated with foreign body exposure.Moreover,inflammation of the wound area can dramatically worsen in response to bacterial infection.These consequences can not only lead to the failure of cortical electrode implantation but also threaten the lives of patients.Herein,we prepared a hydrogel made of bacterial cellulose(BC),a flexible substrate for cortical electrodes,and further loaded antibiotic tetracycline(TC)and the anti-inflammatory drug dexamethasone(DEX)onto it.The encapsulated drugs can be released from the BC hydrogel and effectively inhibit the growth of Gram-negative and Gram-positive bacteria.Next,therapeutic cortical electrodes were developed by integrating the drug-loaded BC hydrogel and nine-channel serpentine arrays;these were used to record electrocorticography(ECoG)signals in a rat model.Due to the controlled release of TC and DEX from the BC hydrogel substrate,therapeutic cortical electrodes can alleviate or prevent symptoms associated with the bacterial infection and inflammation of brain tissue.This approach facilitates the development of drug delivery electrodes for resolving complications caused by implantable electrodes.

Ionic Liquid-Enhanced Assembly of Nanomaterials for Highly Stable Flexible Transparent Electrodes

The controlled assembly of nanomaterials has demon-strated significant potential in advancing technological devices.However,achieving highly efficient and low-loss assembly technique for nanomate-rials,enabling the creation of hierarchical structures with distinctive func-tionalities,remains a formidable challenge.Here,we present a method for nanomaterial assembly enhanced by ionic liquids,which enables the fabrication of highly stable,flexible,and transparent electrodes featuring an organized layered structure.The utilization of hydrophobic and non-volatile ionic liquids facilitates the production of stable interfaces with water,effectively preventing the sedimentation of 1D/2D nanomaterials assembled at the interface.Furthermore,the interfacially assembled nanomaterial monolayer exhibits an alternate self-climbing behavior,enabling layer-by-layer transfer and the formation of a well-ordered MXene-wrapped silver nanowire network film.The resulting composite film not only demonstrates exceptional photoelectric performance with a sheet resistance of 9.4Ωsq^(-1) and 93%transmittance,but also showcases remarkable environmental stability and mechanical flexibility.Particularly noteworthy is its application in transparent electromagnetic interference shielding materials and triboelectric nanogenerator devices.This research introduces an innovative approach to manufacture and tailor functional devices based on ordered nanomaterials.

Flexible,high-density,laminated ECoG electrode array for high spatiotemporal resolution foci diagnostic localization of refractory epilepsy

High spatiotemporal resolution brain electrical signals are critical for basic neuroscience research and high-precision focus diagnostic localization,as the spatial scale of some pathologic signals is at the submillimeter or micrometer level.This entails connecting hundreds or thousands of electrode wires on a limited surface.This study reported a class of flexible,ultrathin,highdensity electrocorticogram(ECoG)electrode arrays.The challenge of a large number of wiring arrangements was overcome by a laminated structure design and processing technology improvement.The flexible,ultrathin,high-density ECoG electrode array was conformably attached to the cortex for reliable,high spatial resolution electrophysiologic recordings.The minimum spacing between electrodes was 15μm,comparable to the diameter of a single neuron.Eight hundred electrodes were prepared with an electrode density of 4444 mm^(-2).In focal epilepsy surgery,the flexible,high-density,laminated ECoG electrode array with 36 electrodes was applied to collect epileptic spike waves inrabbits,improving the positioning accuracy of epilepsy lesions from the centimeter to the submillimeter level.The flexible,high-density,laminated ECoG electrode array has potential clinical applications in intractable epilepsy and other neurologic diseases requiring high-precision electroencephalogram acquisition.

Rational Design of Ruddlesden-Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells

Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting activity.However,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting durability.This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen transport.The D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling durability.This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.

Unveiling Organic Electrode Materials in Aqueous Zinc-Ion Batteries:From Structural Design to Electrochemical Performance

Aqueous zinc-ion batteries(AZIBs)are one of the most compelling alternatives of lithium-ion batteries due to their inherent safety and economics viability.In response to the growing demand for green and sustainable energy storage solutions,organic electrodes with the scalability from inexpensive starting materials and potential for biodegradation after use have become a prominent choice for AZIBs.Despite gratifying progresses of organic molecules with electrochemical performance in AZIBs,the research is still in infancy and hampered by certain issues due to the underlying complex electrochemistry.Strategies for designing organic electrode materials for AZIBs with high specific capacity and long cycling life are discussed in detail in this review.Specifically,we put emphasis on the unique electrochemistry of different redox-active structures to provide in-depth understanding of their working mechanisms.In addition,we highlight the importance of molecular size/dimension regarding their profound impact on electrochemical performances.Finally,challenges and perspectives are discussed from the developing point of view for future AZIBs.We hope to provide a valuable evaluation on organic electrode materials for AZIBs in our context and give inspiration for the rational design of high-performance AZIBs.

Recent progress of self-supported air electrodes for flexible Zn-air batteries

Smart wearable devices are regarded to be the next prevailing technology product after smartphones and smart homes,and thus there has recently been rapid development in flexible electronic energy storage devices.Among them,flexible solid-state zinc-air batteries have received widespread attention because of their high energy density,good safety,and stability.Efficient bifunctional oxygen electrocatalysts are the primary consideration in the development of flexible solid-state zinc-air batteries,and self-supported air cathodes are strong candidates because of their advantages including simplified fabrication process,reduced interfacial resistance,accelerated electron transfer,and good flexibility.This review outlines the research progress in the design and construction of nanoarray bifunctional oxygen electrocatalysts.Starting from the configuration and basic principles of zinc-air batteries and the strategies for the design of bifunctional oxygen electrocatalysts,a detailed discussion of self-supported air cathodes on carbon and metal substrates and their uses in flexible zinc-air batteries will follow.Finally,the challenges and opportunities in the development of flexible zinc-air batteries will be discussed.

A high Li-ion diffusion kinetics in multidimensional and compact-structured electrodes via vacuum filtration casting

Manufacturing process,diffusion co-efficient and areal capacity are the three main criteria for regulating thick electrodes for lithium-ion batteries(LIBs).However,simultaneously regulating these criteria for LIBs is desirable but remains a significant challenge.In this work,niobium pentoxide(Nb_(2)O_(5))anode and lithium iron phosphate(LiFePO_(4))cathode materials were chosen as the model materials and demonstrate that these three parameters can be simultaneously modulated by incorporation of micro-carbon fibers(MCF)and carbon nanotubes(CNT)with both Nb_(2)O_(5) and LFP via vacuum filtration approach.Both as-prepared MNC-20 anode and MLC-20 cathode achieves high reversible areal capacity of≈5.4 m A h cm^(-2)@0.1 C and outstanding Li-ion diffusion coefficients of≈10~(-8)cm~2 s~(-1)in the half-cell configuration.The assembled MNC-20‖MLC-20 full cell LIB delivers maximum energy and power densities of244.04 W h kg^(-1)and 108.86 W kg^(-1),respectively.The excellent electrochemical properties of the asprepared thick electrodes can be attributed to the highly conductive,mechanical compactness and multidimensional mutual effects of the MCF,CNT and active materials that facilitates rapid Li-ion diffusion kinetics.Furthermore,electrochemical impedance spectroscopy(EIS),symmetric cells analysis,and insitu Raman techniques clearly validates the enhanced Li-ion diffusion kinetics in the present architecture.

The use of carbon-based particle electrodes in three-dimensional electrode reactors for wastewater treatment

The use of three-dimensional(3D)electrodes in water treatment is competitive because of their high catalytic efficiency,low energy consumption and promising development.The use of particle electrodes is a key research focus in this technology.They are usually in the form of particles that fill the space between the cathode and anode,and the selection of materials used is important.Carbon-based materials are widely used because of their large specific surface area,good adsorption performance,high chemical stability and low cost.The principles of 3D electrode technology are introduced and recent research on its use for degrading organic pollutants using carbon-based particle electrodes is summarized.The classification of particle electrodes is introduced and the challenges for the future development of carbon-based particle electrodes in wastewater treatment are discussed.

Probabilistic-Ellipsoid Hybrid Reliability Multi-Material Topology Optimization Method Based on Stress Constraint

This paper proposes a multi-material topology optimization method based on the hybrid reliability of the probability-ellipsoid model with stress constraint for the stochastic uncertainty and epistemic uncertainty of mechanical loads in optimization design.The probabilistic model is combined with the ellipsoidal model to describe the uncertainty of mechanical loads.The topology optimization formula is combined with the ordered solid isotropic material with penalization(ordered-SIMP)multi-material interpolation model.The stresses of all elements are integrated into a global stress measurement that approximates the maximum stress using the normalized p-norm function.Furthermore,the sequential optimization and reliability assessment(SORA)is applied to transform the original uncertainty optimization problem into an equivalent deterministic topology optimization(DTO)problem.Stochastic response surface and sparse grid technique are combined with SORA to get accurate information on the most probable failure point(MPP).In each cycle,the equivalent topology optimization formula is updated according to the MPP information obtained in the previous cycle.The adjoint variable method is used for deriving the sensitivity of the stress constraint and the moving asymptote method(MMA)is used to update design variables.Finally,the validity and feasibility of the method are verified by the numerical example of L-shape beam design,T-shape structure design,steering knuckle,and 3D T-shaped beam.

Correction: Surface Patterning of Metal ZincElectrode with an In-Region Zincophilic Interfacefor High-Rate and Long-Cycle-Life Zinc MetalAnode

Correction to:Nano-Micro Letters(2024)16:112 https://doi.org/10.1007/s40820-024-01327-2 In the supplementary information the following corrections have been carried out:1.Institute of Energy and Climate Research,Materials Synthesis and Processing,Forschungszentrum Jülich GmbH,52425 Jülich,Germany.Corrected:Institute of Energy and Climate Research:Materials Synthesis and Processing(IEK-1),Forschungszentrum Jülich GmbH,52425 Jülich,Germany.

Spinal intradural electrodes: opportunities, challenges and translation to the clinic

Damage to the spinal cord disrupts the electrically active nerve cells which normally transmit afferent and efferent signals,resulting in loss of motor,sensory,and autonomic functions.Potential treatments for spinal cord injury utilizing implanted spinal electrodes can be broadly classified into three different categories.The first of these approaches is“spinal stimulation”where electrodes,usually positioned above the level of injury,provide electrical stimulation to target and disrupt pain signals before they reach the brain.The second approach uses“activity-dependent neuro-technologies”,in which electrodes positioned below the level of injury initiate a complex spatiotemporal pattern of stimulation at the lumbar spinal cord to generate a walking gait in the limbs(Minev et al.,2015;Wagner et al.,2018).

The effects of inner electrode shape on the performance of dielectric barrier discharge reactor for oxidative removal of NO and SO_(2)

Seagoing vessels are responsible for more than 90%of global freight traffic,but meanwhile,emission pollutants(NO_(x)and SO_(x))of seagoing vessels also cause serious air pollution.Nonthermal plasma(NTP)combined with wet scrubbing technology is considered to be a promising technology.In order to improve the oxidation efficiency and energy efficiency of the NTP reactor,the screw and rod inner electrodes of dielectric barrier discharge(DBD)reactor were investigated.To analyze the mechanism,the optical emission spectra(OES)of NTP were measured and numerical calculation was applied.The experiment results show that the NO oxidation removal efficiency of screw electrode is lower than that of rod electrode.However,the SO_(2)removal efficiency of screw electrode is higher.According to the OES experiment and numerical calculation,the electric field intensity of the screw electrode surface is much higher than that of the rod electrode surface,and it is easier to generate N radicals to form NO.For the same energy density condition,the OH radical generation efficiency of the screw electrode reactor is similar to that of the rod electrode,but the gas temperature in the discharge gap is higher.Therefore,the SO2 oxidation efficiency of the thread electrode is higher.This study provides guidance for the optimization of oxidation efficiency and energy consumption of DBD reactor.

Multi-Material Topology Optimization of 2D Structures Using Convolutional Neural Networks

In recent years,there has been significant research on the application of deep learning(DL)in topology optimization(TO)to accelerate structural design.However,these methods have primarily focused on solving binary TO problems,and effective solutions for multi-material topology optimization(MMTO)which requires a lot of computing resources are still lacking.Therefore,this paper proposes the framework of multiphase topology optimization using deep learning to accelerate MMTO design.The framework employs convolutional neural network(CNN)to construct a surrogate model for solving MMTO,and the obtained surrogate model can rapidly generate multi-material structure topologies in negligible time without any iterations.The performance evaluation results show that the proposed method not only outputs multi-material topologies with clear material boundary but also reduces the calculation cost with high prediction accuracy.Additionally,in order to find a more reasonable modeling method for MMTO,this paper studies the characteristics of surrogate modeling as regression task and classification task.Through the training of 297 models,our findings show that the regression task yields slightly better results than the classification task in most cases.Furthermore,The results indicate that the prediction accuracy is primarily influenced by factors such as the TO problem,material category,and data scale.Conversely,factors such as the domain size and the material property have minimal impact on the accuracy.

Recent Advances in Nanoengineering of Electrode-Electrolyte Interfaces to Realize High-Performance Li-Ion Batteries

A suitable interface between the electrode and electrolyte is crucial in achieving highly stable electrochemical performance for Li-ion batteries,as facile ionic transport is required.Intriguing research and development have recently been conducted to form a stable interface between the electrode and electrolyte.Therefore,it is essential to investigate emerging knowledge and contextualize it.The nanoengineering of the electrode-electrolyte interface has been actively researched at the electrode/electrolyte and interphase levels.This review presents and summarizes some recent advances aimed at nanoengineering approaches to build a more stable electrode-electrolyte interface and assess the impact of each approach adopted.Furthermore,future perspectives on the feasibility and practicality of each approach will also be reviewed in detail.Finally,this review aids in projecting a more sustainable research pathway for a nanoengineered interphase design between electrode and electrolyte,which is pivotal for high-performance,thermally stable Li-ion batteries.

An in-situ self-etching enabled high-power electrode for aqueous zinc-ion batteries

Sluggish storage kinetics is considered as the main bottleneck of cathode materials for fast-charging aqueous zinc-ion batteries(AZIBs).In this report,we propose a novel in-situ self-etching strategy to unlock the Palm tree-like vanadium oxide/carbon nanofiber membrane(P-VO/C)as a robust freestanding electrode.Comprehensive investigations including the finite element simulation,in-situ X-ray diffraction,and in-situ electrochemical impedance spectroscopy disclosed it an electrochemically induced phase transformation mechanism from VO to layered Zn_(x)V_(2)O_5·nH_(2)O,as well as superior storage kinetics with ultrahigh pseudocapacitive contribution.As demonstrated,such electrode can remain a specific capacity of 285 mA h g^(-1)after 100 cycles at 1 A g^(-1),144.4 mA h g^(-1)after 1500 cycles at 30 A g^(-1),and even 97 mA h g^(-1)after 3000 cycles at 60 A g^(-1),respectively.Unexpectedly,an impressive power density of 78.9 kW kg^(-1)at the super-high current density of 100 A g^(-1)also can be achieved.Such design concept of in-situ self-etching free-standing electrode can provide a brand-new insight into extending the pseudocapacitive storage limit,so as to promote the development of high-power energy storage devices including but not limited to AZIBs.

Textured Asymmetric Membrane Electrode Assemblies of Piezoelectric Phosphorene and Ti_(3)C_(2)T_(x)MXene Heterostructures for Enhanced Electrochemical Stability and Kinetics in LIBs

Black phosphorus with a superior theoretical capacity(2596 mAh g^(-1))and high conductivity is regarded as one of the powerful candidates for lithium-ion battery(LIB)anode materials,whereas the severe volume expansion and sluggish kinetics still impede its applications in LIBs.By contrast,the exfoliated two-dimensional phosphorene owns negligible volume variation,and its intrinsic piezoelectricity is considered to be beneficial to the Li-ion transfer kinetics,while its positive influence has not been discussed yet.Herein,a phosphorene/MXene heterostructure-textured nanopiezocomposite is proposed with even phosphorene distribution and enhanced piezo-electrochemical coupling as an applicable free-standing asymmetric membrane electrode beyond the skin effect for enhanced Li-ion storage.The experimental and simulation analysis reveals that the embedded phosphorene nanosheets not only provide abundant active sites for Li-ions,but also endow the nanocomposite with favorable piezoelectricity,thus promoting the Li-ion transfer kinetics by generating the piezoelectric field serving as an extra accelerator.By waltzing with the MXene framework,the optimized electrode exhibits enhanced kinetics and stability,achieving stable cycling performances for 1,000 cycles at 2 A g^(-1),and delivering a high reversible capacity of 524 m Ah g^(-1)at-20℃,indicating the positive influence of the structural merits of self-assembled nanopiezocomposites on promoting stability and kinetics.