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The current collector, one of the main components in the manufacture of composite electrodes, is mainly used to enhance the mechanical stability and improve the performance and cycle performance of the electrodes. During the electrochemical reaction, the lithium diffusion can induce compressive stress and affect the mechanical performance, lifespan, and performance of batteries. Therefore, this study analyzed the influence of copper foil on the mechanical response and degradation performance of electrodes. In addition, a mathematical model was developed to analyze the effect of copper foil on the stress–strain behavior of the electrodes. The results indicated that the stress and modulus of the graphite electrodes have a non-linear increase with the lithiation process. Based on those findings, utilizing a thinner and more compliant current collector could effectively mitigate the in-plane strain and the stress within electrodes. Thus, developing a thinner and softer copper foil could simultaneously enhance the mechanical properties and specific density of composite electrodes for the next-generation LiBs. [ABSTRACT FROM AUTHOR]

Electrochemical Double Layer Capacitors (EDLCs) with ionic liquid electrolytes outperform conventional ones using aqueous and organic electrolytes in energy density and safety. However, understanding the electrochemical behaviors of ionic liquid electrolytes under compressive/tensile strain is essential for the design of flexible EDLCs as well as normal EDLCs, which are subject to external forces during assembly. Despite many experimental studies, the compression/stretching effects on the performance of ionic liquid EDLCs remain inconclusive and controversial. In addition, there is hardly any evidence of prior theoretical work done in this area, which makes the literature on this topic scarce. Herein, for the first time, we developed an atomistic model to study the processes underlying the electrochemical behaviors of ionic liquids in an EDLC under strain. Constant potential non-equilibrium molecular dynamics simulations are conducted for EMIM BF4 placed between two graphene walls as electrodes. Compared to zero strain, low compression of the EDLC resulted in compromised performance as the electrode charge density dropped by 29%, and the performance reduction deteriorated significantly with a further increase in compression. In contrast, stretching is found to enhance the performance by increasing the charge storage in the electrodes by 7%. The performance changes with compression and stretching are due to changes in the double-layer structure. In addition, an increase in the value of the applied potential during the application of strain leads to capacity retention with compression revealed by the newly performed simulations. [ABSTRACT FROM AUTHOR]

The shortage of natural resources due to the progression of the human population and environmental pollution has become crucial concern topics to resolve. One of the best ways to resolve this is to develop renewable energy-based storage systems. Supercapacitors are emerging as promising storage systems via providing rapid charging/discharging and high power delivery, but there is a need to explore low-cost, environment-friendly, non-toxic, abundant, and biodegradable electrode materials for supercapacitors. In this regard, biopolymers are observed to be popular for storage applications as they are of high porosity, cost-effective, easily available, low-weight, and environment friendly and have biodegradability properties. The biopolymer-based electrode has a desirable morphology and high surface area and exhibits admirable electrochemical properties. The focus of this report is to highlight (i) the inclusive details of supercapacitors and their types along with strategies to improve their electrochemical performance, (ii) biopolymers and their types used for supercapacitor applications, (iii) various synthesis routes that could be adopted for designing electrode materials based on biopolymers for supercapacitors, and (iv) challenges and future scope of biopolymers as the electrode material in supercapacitor applications. The detailed study here in this report is found to be a topic of interest for the scientific community to fabricate and prepare low-cost, eco-friendly, high electrochemical performance exhibiting electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Ambulatory electrocardiogram (ECG) testing plays a crucial role in the early detection, diagnosis, treatment evaluation, and prevention of cardiovascular diseases. Clear ECG signals are essential for the subsequent analysis of these conditions. However, ECG signals obtained during exercise are susceptible to various noise interferences, including electrode motion artifact, baseline wander, and muscle artifact. These interferences can blur the characteristic ECG waveforms, potentially leading to misjudgment by physicians. To suppress noise in ECG signals more effectively, this paper proposes a novel deep learning-based noise reduction method. This method enhances the diffusion model network by introducing conditional noise, designing a multi-kernel convolutional transformer network structure based on noise prediction, and integrating the diffusion model inverse process to achieve noise reduction. Experiments were conducted on the QT database and MIT-BIH Noise Stress Test Database and compared with the algorithms in other papers to verify the effectiveness of the present method. The results indicate that the proposed method achieves optimal noise reduction performance across both statistical and distance-based evaluation metrics as well as waveform visualization, surpassing eight other state-of-the-art methods. The network proposed in this paper demonstrates stable performance in addressing electrode motion artifact, baseline wander, muscle artifact, and the mixed complex noise of these three types, and it is anticipated to be applied in future noise reduction analysis of clinical dynamic ECG signals. [ABSTRACT FROM AUTHOR]

Ammonium (NH4+) ion aqueous supercapacitors have gained significant attention due to their notable cost-effectiveness, safety profile, and environmental benefits. Despite this, the optimization of the capacitive performance of electrode materials for NH4+ ion storage remains inadequate. To tackle these challenges, we present a composite electrode depend upon molybdenum disulfide (MoS2) and indium tin oxide nanowires (MoS2@ITO NWs) as the primary host for (NH4+) ions. Additionally, we introduce a straightforward radio frequency nitrogen (N) plasma technique to incorporate nitrogen doping into the MoS2 film, thereby enhancing its performance. The introduction of N plasma doping into two-dimensional MoS2 results in an expansion of the interlayer distance and an improvement in electronic conductivity. This, in turn, facilitates the facile and highly reversible insertion and extraction of NH4+ ions during cycling. Consequently, the N plasma doping significantly enhances the device areal capacitance of MoS2@ITO NWs, increasing it from 78.6 to 161.8 mF cm−2 at 1 mA cm−2, with an exceptional capacity retention (>89.2% after 10 000 cycles) and superior rate capability up to 10 mA cm−2. The integration N of atoms within the straightforward hierarchical core–shell design strategy exhibits promising prospects for bolstering the performance of metal sulfide electrodes and other high-capacity electrode materials aimed at energy storage applications. [ABSTRACT FROM AUTHOR]

This work describes a low-cost wet chemical synthesis technique to produce TiN–ZnS nanocomposites suitable for high energy density supercapacitors. Ti, Zn, N, and S elements in the synthesized materials were verified using comprehensive morphological, structural, and surface chemical investigations. Due to improved electric conductivity and electroactivity, this TiN–ZnS nanocomposite electrode exhibited excellent capacitance and charge transport kinetics, outperforming individual TiN and ZnS electrodes in electrochemical performance. The TiN–ZnS || MnO2 electrode configuration in an asymmetric supercapacitor system exhibited a high energy density of 74.13 Wh kg−1 and an exceptional power density of 7648 W kg−1 at a current density of 9 A g−1. The TiN–ZnS electrode also showed a remarkable retention rate of 96.8% even after 10 000 cycles. This work highlights the potential of the TiN–ZnS composite as a high-performance electrode for supercapacitors. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDH) can be transformed from alkaline supercapacitor material into metal-cation storage cathode working in neutral electrolytes through electrochemical activation. However, the rate performance for storing large cations is restricted by the small interlayer distance of LDH. Herein, the interlayer distance of NiCo-LDH is expanded by replacing the interlayer nitrate ions with 1,4-benzenedicarboxylic anions (BDC), leading to the enhanced rate performance for storing large cations (Na+, Mg2+, and Zn2+), whereas almost the unchanged one for storing small-radius Li+ ions. The improved rate performance of the BDC-pillared LDH (LDH-BDC) stems from the reduced charge-transfer and Warburg resistances during charge/discharge due to the increased interlayer distance, as revealed by in situ electrochemical impedance spectra. The asymmetric zinc-ion supercapacitor assembled with LDH-BDC and activated carbon presents high energy density and cycling stability. This study demonstrates an effective strategy to improve the large cation storage performance of LDH electrodes by increasing the interlayer distance. [ABSTRACT FROM AUTHOR]

Developing advanced electrode materials for supercapacitors (SCs) has received incredible attention. The suitable electrode for high capacitance and energy density are significant challenges for SCs. This work reports an efficient hydrothermal synthesis of MoS2 nanosheets on carbon cloth (MoS2@CC). The large surface area of the binder-free MoS2@CC electrode provides rich active sites and an improved electrolyte ion diffusion rate. The MoS2@CC electrode exhibits good electrochemical performance by delivering a high specific capacitance of 947 F g−1 at the current density of 1.0 A g−1 and retains an excellent capacitance of 96.5% over 10 000 cycles. The high performance of the MoS2@CC electrode can be clarified through density functional theory (DFT) calculations. The DFT outcomes reveal that the electrode possesses favorable Li-ion intercalation and adsorption properties. The calculated adsorption energy of −0.352 eV at the hollow site shows the high stability of the system. The low energy barrier of path 1 (0.83 eV) easily facilitates Li-ions in the electrode material, which is beneficial for its fast electrochemical performance. The obtained results of the MoS2@CC electrode present improved pseudocapacitive performance, showing a significant possibility for high-performance SCs' application. [ABSTRACT FROM AUTHOR]

Organic electrochemical transistors (OECTs) hold great potential in various applications, including biosensing and neural network computation. Traditional "all-in-one" OECT device architecture faces the problems of unclear amplification mechanisms and complex side reactions, to name a few. The reaction cell OECT (RC-OECT) device architecture, proposed by Ting et al. [Adv. Funct. Mater. 31(19), 2010868 (2021)], effectively resolves these problems. Furthermore, in many applications of OECTs, such as high throughput (bio)sensing, an OECT device array instead of a single OECT is needed. Therefore, the size (area) of the OECT device, which represents the amount of occupied chip real estate and the integration of the device, matters. In this paper, we developed a hydrogen peroxide sensor based on the RC-OECT. We utilized an RC cathode modified by the poly(3,4-ethylenedioxythiophene) polystyrene sulfonate film and a Ag/AgCl OECT gate electrode for facilitating device integration, varied RC anode area, and achieved optimization of at least one of the two parameters, sensitivity and lower limit of detection (LLoD), in conjunction with the level of integration of the device. Multiple quantitative sensitivity metrics have been adopted in this work. We also evaluated the correlation between RC anode area and LLoD. In addition, a mechanistic analysis of the RC-OECT device structure, in terms of faradic and non-faradaic currents, was carried out to illustrate the interplay between sensing performance and the electrode area of the reaction cell. This mechanistic analysis provides insights for miniaturizing OECT devices with the RC-OECT architecture. [ABSTRACT FROM AUTHOR]

Efforts to improve energy storage depend greatly on the development of efficient electrode materials. Recently, strain has been employed as an alternate approach to improve ion mobility. While lattice strain has been well-researched in catalytic applications, its effects on electrochemical energy storage are largely limited to computational studies due to complexities associated with strain control in nanomaterials as well as loss of strain due to the phase change of the active material during charging–discharging. In this work, we overcome these challenges and investigate the effects of strain on supercapacitor performance in Li-ion-based energy devices. We synthesize epitaxial Fe3O4@MnFe2O4 (core@shell) nanoparticles with varying shell thickness to control the lattice strain. A narrow voltage window for electrochemical testing is used to limit the storage mechanism to lithiation–delithiation, preventing a phase change and maintaining structural strain. Cyclic voltammetry reveals a pseudocapacitive behavior and similar levels of surface charge storage in both strained- and unstrained-MnFe2O4 samples; however, diffusive charge storage in the strained sample is twice as high as the unstrained sample. The strained-MnFe2O4 electrode exceeds the performance of the unstrained-MnFe2O4 electrode in energy density by ∼33%, power density by ∼28%, and specific capacitance by ∼48%. Density functional theory shows lower formation energies for Li-intercalation and lower activation barrier for Li-diffusion in strained-MnFe2O4, corresponding to a threefold increase in the diffusion coefficient. The enhanced Li-ion diffusion rate in the strained-electrodes is further confirmed using the galvanostatic intermittent titration technique. This work provides a starting point to using strain engineering as a novel approach for designing high performance energy storage devices. [ABSTRACT FROM AUTHOR]

The widespread use of lithium–sulfur (Li–S) batteries is hindered by slow cathode kinetics, the shuttle effect, and dendrite growth on the anode. We show that these challenges can be overcome by replacing a linear ether (i.e., 1,2-dimethoxyethane) in commonly used electrolytes with a macrocyclic amine, 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane (TMTAC). Theoretical studies and experimental data indicate that the cavity of TMTAC matches a Li ion to form a robust solvation structure. Such a solvation structure not only leads to 3D deposition of Li2S on the cathode, which is responsible to the reduced overpotentials of Li2S nucleation and decomposition, but also suppresses Li dendrite growth on the anode. Moreover, the shuttle effect of polysulfides is effectively suppressed as the quantity of free TMTAC in the TMTAC-based electrolyte is substantially reduced. As a result, coin-type cells prepared with TMTAC-based electrolytes exhibit outstanding performance metrics for all key device parameters. Furthermore, pouch-type cells can be prepared with high sulfur loadings (e.g., 3.43 mg cm−2) and a low electrolyte to sulfur ratio (e.g., 6.16 μl mg−1) while maintaining a high areal specific capacity (3.38 mA h cm−2). This work demonstrates that the effective solvation of critical ions in energy storage devices is paramount to achieving peak performance. [ABSTRACT FROM AUTHOR]

Lithium batteries are promising techniques for renewable energy storage attributing to their excellent cycle performance, relatively low cost, and guaranteed safety performance. The performance of the LiFePO4 (LFP) battery directly determines the stability and safety of energy storage power station operation, and the properties of the internal electrode materials are the core and key to determine the quality of the battery. In this work, two kinds of commercial LFP batteries were studied by analyzing the electrical properties and material properties of the electrodes. After performing the rate and cycle performance tests of the battery cell, differential scanning calorimetry, scanning electron microscope, x-ray diffraction, and inductively coupled plasma were used to explore the performance of electrode materials to establish the correlation between the battery performance and the electrochemical reaction law of the internal materials and further to judge the influence of the key material properties on the battery performance. This work opens up an avenue for technical supervision of energy storage power stations. [ABSTRACT FROM AUTHOR]

This paper is focused on electrode design for piezoelectric tuning fork resonators. The relationship between the performance and electrode pattern of aluminum nitride piezoelectric tuning fork resonators vibrating in the in-plane flexural mode is investigated based on a set of resonators with different electrode lengths, widths, and ratios. Experimental and simulation results show that the electrode design impacts greatly the multimode effect induced from torsional modes but has little influence on other loss mechanisms. Optimizing the electrode design suppresses the torsional mode successfully, thereby increasing Rp/Rs by more than 80% and achieving a quality factor (Q) of 7753, an effective electromechanical coupling coefficient (kteff2) of 0.066%, and an impedance at series resonant frequency (Rm) of 23.6 kΩ. The proposed approach shows great potential for high-performance piezoelectric resonators, which are likely to be fundamental building blocks for sensors with high sensitivity and low noise and power consumption. HIGHLIGHTS: • A new strategy is explored for suppressing the multimode effect by tuning the electrode pattern of piezoelectric tuning fork resonators. • Comprehensive resonator performance improvement is achieved by effective multimode suppression. • Crucial parameters are improved simultaneously with Q = 7753, kteff2 = 0.066%, Rm = 23.6 kΩ, and an 86% higher Rp/Rs. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated the supercapacitor performance of pristine and composites of spinel NiCo2O4 with a multi-walled carbon nanotube (MWCNT) assembled in a two-electrode cell configuration. Spinel NiCo2O4 and NiCo2O4@MWCNT composites were synthesized via a facile hydrothermal method. The supercapacitive performance of as-synthesized NiCo2O4 and NiCo2O4@MWCNT fabricated on Ni-foam was studied in a 0.5M K2SO4 electrolyte using electrochemical measurement techniques. The symmetric cell configuration of NiCo2O4@MWCNT delivers high specific capacitance (374 F/g at 2 A/g) with high energy density and power density (95 Wh/kg and 3 964 W/kg, respectively) compared to that of pristine NiCo2O4 electrodes (137 F/g at 0.6 A/g). Furthermore, the energy storage performance of the asymmetric cells of NiCo2O4//MWCNT and NiCo2O4@MWCNT//MWCNT was studied to enhance cycling stability (retention of 74.85% over 3000 cycles). We have also theoretically studied the supercapacitance performance of pristine NiCo2O4 and NiCo2O4@SWCNT hybrid structures through its structural and electronic properties using density functional theory predictions. The higher specific capacitance of the NiCo2O4@SWCNT hybrid system with high power density and energy density is supported by the enhanced density of states near the Fermi level and increased quantum capacitance of the hybrid structure. We have theoretically computed the diffusion energy barrier of K+ ions of the K2SO4 electrolyte in the NiCo2O4 layer and compared it with the diffusion barrier for Na+ ions. The lesser diffusion energy barrier for K+ ions in the NiCo2O4 layer contributes toward higher energy storage capacity. Thus, owing to superior electrochemical performance of NiCo2O4 composites with MWCNTs, it can serve as a high-performance electrode material for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Metal electrode materials play a crucial role in determining the performance of microscale perovskite-based devices. However, it is a great challenge to in situ investigate the influence of different metal electrode materials on the performance of the same piece of a microscale perovskite due to the strong bonding between the perovskite and the electrode. To this end, a strategy to fabricate soft-sandwiched perovskite junctions by employing a liquid metal as top electrode was put forward. By taking full use of the adhesion of the top liquid metal electrode, the bottom electrode can be freely replaced by different metal materials without mechanical damage and chemical contamination. It is demonstrated that the shape of the instantaneous photocurrent upon light illumination and the rectification behavior of perovskite junctions can be controlled by the electrode materials and the light intensity. The shape of instantaneous photocurrent is mainly controlled by the light intensity rather than electrode materials. In contrast, the rectification ratio is mainly determined by the electrode materials instead of the light intensity. The underlying mechanism for these observations is elucidated based on the energy-level alignment in the junctions. The detachable soft junctions are expected to be widely applied to study the influence of external electrodes on the carrier transport of various microscale/nanoscale objects. [ABSTRACT FROM AUTHOR]

Lithium ion battery is a complex system, and any change in device parameters may significantly affect the overall performance. The prediction of battery behavior based on theoretical simulation is of great significance. In this work, the battery performance with LiNi1/3Co1/3Mn1/3O2 electrodes of different active material loading amounts was theoretically investigated, such as battery rate performance, capacity decay rate, energy and power density, SOC (State of Charge) change, temperature response, and heat source distribution. A 1D electrochemical–3D thermal coupling model was established, and the accuracy and predictability of the model were verified by experiments. An in-depth analysis of batteries under different discharge rates and batteries with different electrode loading amounts is carried out. The results show that the rate performance and capacity change with different electrode loading amounts, which is attributed to the variation in lithium ion diffusion. At the same time, the change in load affects the growth of lithium dendrites and the distribution of SOC, resulting in the thermal runaway of the battery and shortening the battery life. [ABSTRACT FROM AUTHOR]

The size of silicon (Si) particles and used binder directly affects the flow uniformity of the slurry, the mechanical properties, and the electrochemical performance of the electrode. In this study, we tried to clarify the adaptation law of Guar gum (GG) and sodium alginate (SA) with 200 nm-Si and 1 μm-Si from the above-mentioned aspects. The rheological properties of the slurry showed that the slurry with GG due to the gelatinization had a poorer dispersion than that with SA. The tests of zeta potentials, thermogravimetric analysis, peeling-off, and nano-indentation profiles explained the performance differences of the electrodes from the mechanical properties. Because of more hydrogen bond sites, the discharge specific capacity of the nm-Si/GG electrode (1116.05 mA h g−1) was higher than the nm-Si/SA electrode (657.74 mA h g−1) after 70 cycles. On the contrary, the μm-Si/SA electrode owing to a rigid skeleton in the SA molecule exhibited a discharge specific capacity of 1681.47 mA h g−1 after 50 cycles, while the μm-Si/GG electrode was 486.58 mA h g−1. In addition, the results inspire more reasonable optimization of the Si-based electrode design. [ABSTRACT FROM AUTHOR]

Traditional binders and conductive agents are important electrode additives that contribute to the mechanical integrity and conductivity of sodium ion batteries (SIBs), but they affect the energy density of the batteries. In this study, Ti3C2Tx MXene was used as a conductive binder for a Ge anode owing to its high conductivity and clay-like property, which not only combined the functionality of the binders and additives but also provided additional sodium ion storage capacity. Ultra-long lifetime (high-capacity retention of 88% after 20 000 cycles) and enhanced rate performance (124.5 at 1500 mA g−1) were observed for the as-designed Ge-Ti3C2Tx anode. The Ge-Ti3C2Tx anode exhibited a specific capacity of 125.7 mA h g−1 at a current density of 100 mA g−1 after 100 cycles even at −20 °C. This Ti3C2Tx MXene conductive binder may enhance the electrode performance of the SIBs and other energy storage devices. [ABSTRACT FROM AUTHOR]

In the elucidation of brain functions, neuroscience has garnered attention in the realization of brain-machine interfaces, deep brain stimulation, and artificial intelligence. Optogenetics is a biological technique used to control neural activities via optical stimulation. It is one of the most effective approaches used to investigate brain functions. This study proposed to employ the transparent recording electrode to enhance the performance of neural probes for optogenetics. Compared with conventional metal recording electrodes, the proposed transparent recording electrodes have the potential to obtain higher signal-to-noise ratios when placed over optical stimulation points. To develop transparent recording electrodes, we used ZnO-based materials with good biocompatibility and transparency for utilization as biomedical electrodes. Considering saline as one of the main components of living organisms, we investigated the fundamental electrochemical characteristics of ZnO-based electrodes in saline through electrochemical impedance spectroscopy and cyclic voltammetry. The results showed that nondoped ZnO and Al-doped ZnO, deposited by radio frequency magnetron sputtering, exhibited a broad potential window. An electrical double layer was found to strongly act on the interface between the electrodes and solution rather than a redox reaction. In addition, this study reports the effects of crystallization and dopant on the electrochemical characteristics of the ZnO-based electrodes. The transparent ZnO-based electrode developed herein is a promising candidate to enhance the performance of neural probes for optogenetics and can be effectively applied in biological devices. [ABSTRACT FROM AUTHOR]

This Letter investigates the effect of non-inert electrode thickness on the performance of complementary resistive switching (CRS). Five devices with different Ta electrode thicknesses (0, 2, 5, 10, and 20-nm) are fabricated. For devices with 2, 5, and 10-nm electrode thicknesses, CRS behavior can be obtained through an evolution process, while devices with 0 and 20-nm Ta electrode thicknesses always maintain stable bipolar resistive switching behavior. By analyzing the evolution process and current conduction mechanisms, the influence of non-inert electrode thickness on the performance of CRS is studied, and different oxidation degrees of a non-inert electrode are used to explain the different resistive switching performance in these devices. Aside from that, the model is verified by applying an asymmetric voltage sweeping method. This paper further clarifies the physical mechanism of CRS behavior in non-inert electrode resistive random access memory and provides a way to optimize the performance of CRS behavior. [ABSTRACT FROM AUTHOR]

The microstructural stability of composite electrodes during electrochemical cycling is critically important as it dictates the performance of Li-ion batteries. The issue becomes even more important for the high capacity alloying anode such as silicon that typically exhibits dramatic lithiation–delithiation-induced volume changes. The solid electrolyte interphase (SEI) layer formed on the active electrode surface has a profound effect on the overall microstructural stability of composite electrodes. An ideal SEI layer allows Li+ ions in and out of the electrode, but is an insulator to electrons, preventing the electrolyte from being further reduced. However, the SEI layers formed during initial lithiation may experience changes or degradation with subsequent cycling, adversely affecting the electrode performance. A combination of hyperpolarized 129Xe and 7Li nuclear magnetic resonance spectroscopies was applied to probe the microstructures of nanocomposite silicon electrodes at various stages of the lithiation–delithiation cycle. The results obtained from this study shed light on the degradation mechanism of nanocomposite Si electrodes upon electrochemical cycling and should prove useful in the effort to design more robust electrodes in the future. [ABSTRACT FROM AUTHOR]

We clarify the hysteretic behavior observed in lithiated silicon electrodes through the development and implementation of a model that describes the main features of the observed voltage hysteresis. Specifically, slow-scan voltammetry at 0.01 mV/s is used to study hysteresis in lithiated silicon thin-film electrodes. At higher scan rates, the curves U(x), where U is voltage and x is state of charge, depend on the scan rate, but no difference is seen in the curves when scanning at slow enough rates. For example, no difference is seen at 0.01 mV/s or at 0.005 mV/s, even though the same hysteretic behavior is observed for both scan rates, i.e., the lithiation curve differs significantly from the delithiation curve. The rate of 0.005 mV/s is the slowest that could be measured with state-of-the-art equipment. However, when a lithiating scan at 0.01 mV/s is suddenly set to open circuit conditions, the voltage slowly decays upwards, whereas the voltage decays downwards when delithiation is interrupted. From this, it is inferred that the rate invariance seen at 0.005 and 0.01 mV/s would have to break down at some lower scan rate, if it could be measured. A semiempirical model is used to describe many aspects of this behavior based on the assumption of a region of rate invariance, which breaks down at higher scan rates due to transport and kinetic losses, but which also breaks down at slower scan rates due to transients that are observable but remain unexplained. [ABSTRACT FROM AUTHOR]

Conducting polymers are widely used as electrode coatings in electrophysiology to lower impedance and achieve higher quality recordings and more efficient stimulation. Their availability as dispersions that can be processed directly from solution makes them particularly attractive for applications, where low cost and compatibility with mechanically flexible substrates are important. In this work, we demonstrate that poly(3,4-ethylenedioxythiophene)-based conducting polymer films can be made adhesive to skin and polyimide by adding acrylic ester copolymer microparticles to the solution. The resultant films remained highly conducting despite incorporating at most 2.5% conducting polymer. We show that adhesive cutaneous electrodes fabricated using these coatings show comparable performance to commercial electrodes in forearm electromyography. [ABSTRACT FROM AUTHOR]

Boron-based materials have various attractive properties and gained increased attention in recent years as promising materials for energy storage applications. Despite vast literature on structural and mechanical properties of transition metal diborides, hafnium diboride (HfB2) in particular, research that addresses the use of HfB2 as an electrode for supercapacitor devices is lacking. Herein, we report both the synthesis and characterization of HfB2 and its electrochemical performance as the electrode for all-in-one symmetric and asymmetric supercapacitor devices. HfB2 powders were synthesized by mechanical activation assisted carbothermal reduction of hafnium oxide and boron oxide precursors. To improve the electrochemical energy storage performance of the electrodes, point defects (either Hf or B vacancies/interstitials) were formed in HfB2 through annealing at different temperatures (1450 and 1650 °C) under a flowing Ar atmosphere. The origin of point defects and their localization on the surface in HfB2 were identified using electron paramagnetic resonance (EPR) spectroscopy and discussed both from chemical and materials point-of-view. The defective HfB2 electrode exhibited higher performance than that of the non-defective one with specific energy and power densities of 0.144 W h kg−1 and 33.3 W kg−1; specific charge–discharge capacities of 0.32 and 0.31 mA h g−1; and 115.5%, 106.2%, and 84.1% retention of the initial capacitances, respectively. The relation between the defect content and the improved supercapacitor performances was explained by employing several structural (x-ray diffractometer and x-ray fluorescence), electronic (EPR), and electrochemical (potentiostatic electrochemical impedance spectroscopy, cyclic voltammetry, galvanostatic cycling with potential limitation) characterization tools. [ABSTRACT FROM AUTHOR]

We investigate the effects of recessed source/drain (S/D) electrodes on the device performance of microwave-induced metal-oxide thin-film transistors (oxide-TFTs) by analyzing their contact resistances. High-performance top-gate-bottom-contact oxide-TFTs consisting of sol–gel-based high-k zirconium dioxide dielectric (ZrO2) and indium-gallium-zinc oxide (IGZO) semiconducting films were developed by employing microwave annealing. Vibration energy induced microwave annealing even at a low temperature (∼120 °C) with a short process time (10 min), which is sufficient to form dense metal–oxygen bonding while suppressing oxygen vacancies as defect states, resulted in high-quality sol–gel-based amorphous ZrO2 and IGZO films. The low-voltage operating oxide-TFTs with recessed S/D electrodes exhibited higher field-effect mobility (∼7.0 cm2 V−1 s−1) than those with elevated S/D electrodes (∼0.15 cm2 V−1 s−1). This result is attributed to the conformable deposition of the channel layer on the planar surface of S/D electrodes, leading to the improved interfacial characteristics. Relatively low effective contact resistance (∼79.7 Ω cm), which was extrapolated from a plot of the width-normalized resistance as a function of the channel length using a transmission line method, in oxide-TFTs with recessed S/D electrodes, is compared to that (∼1480.6 Ω cm) of elevated S/D electrodes. This was in good agreement with the Ohmic contact behavior contact where the low charge injection barrier improved charge transport. [ABSTRACT FROM AUTHOR]

In this paper, we have simulated the structure of n-type MoS2/silicon heterojunction solar cell and studied its function under different conditions. The optimization of parameters of the cell's layer has been carried out by using AFORS-HET software. In the present study, MoS2 has been considered as 3-D in nature instead of the reported 2-D nature. In order to ensure the formation of Schottky junction, electric contact has been made along the c-axis to collect the minority charge carriers. After optimizing the various parameters of n-type single layer MoS2, power efficiency of 12.44% has been achieved at the room temperature, which has further decreased to 9.042% as the layer number has increased up to 40. Furthermore, after optimizing the parameters of silicon wafer maximum efficiency of 16.4% has been achieved. Temperature dependence of the cell performance has also been studied and the maximum efficiency has been achieved at 300 K. In the present study, we have demonstrated that n-type ultrathin layer of MoS2 can be used as an excellent transparent conducting electrode. [ABSTRACT FROM AUTHOR]

The paucity of research on hydrogen evolution reaction (HER) under neutral conditions, which is a more sustainable way to produce H2 compared to acidic and alkaline HER, encourages the development of efficient catalytic materials and devices and deeper investigation of the mechanisms behind neutral HER. We present an electrode concept for facilitating HER under neutral conditions. The concept entails the use of annealing-reshaped silver (Ag) nanoparticle array on monolayer epitaxial graphene (MEG) on 4H-SiC. Measurements of HER performance show more positive onset potential of the cathodic HER for Ag-decorated MEG compared to that for pristine MEG, indicating improved water dissociation at Ag/MEG electrodes. Complementary morphological characterization, absorption measurements, and Raman mapping analysis enable us to ascribe the enhanced catalytic performance of electrodes decorated with 2 nm thick annealed Ag on the synergetic effect originating from simultaneous water reduction on circular Ag nanoparticles of 31 nm in diameter and on compressively strained Ag-free graphene regions. The overall results pave the way toward development of stable van der Waals heterostructure electrodes with a tunable metal–carbon interaction for fast HER under neutral conditions. [ABSTRACT FROM AUTHOR]

A new type of Ag/AgCl electrode as a marine electric field sensor is prepared using electrospray. The surface of the electrode is porous, and the particle size of AgCl is small and uniform with an average particle size of 1.43 µm, which accelerated the speed of the oxidation–reduction reactions. Therefore, the electrode with large specific surface area has high stability and low noise. The impedance, sensitivity, self-noise, and stability of the electrode are measured to study the electrochemical performance of the electrode. The impedance of the electrode is 7.9 Ω, and the electrode shows resistance characteristics, meaning that the electrode can well receive the weak ocean electric field signals with low signal distortion. The sensitivity experiment result shows that the electrode can well restore the sinusoidal electric field signal of 1 Hz (10 mV). The voltage drift is less than 5 µV/100 h, the self-potential is between −51 and 56 µV, and the self-noise of the electrode is 2.48 nV @ 1 Hz. The AgCl layer on the surface of the electrode is porous and thick, and the particle size of AgCl is small and uniform. This makes the electrode have excellent electrochemical performance. All the experimental results show that the electrode has ultra-low noise and excellent response to low frequency weak electric field signals. The electrode is of great significance to the exploitation of marine resources as the marine electric field sensor. [ABSTRACT FROM AUTHOR]

Supercapacitors are an important energy storage technology that combine the high energy density of batteries with the high power density of capacitors. Freestanding Mn2O3 electrodes fabricated via electrospinning and calcination have the potential to provide high power and energy densities with low fabrication costs. In this work, a theoretical model is produced to describe the effects of the electrospun structure on electrode performance. The model uses theoretical predictions of capacitive and faradaic energy storage, based on system parameters measured from real electrodes to produce a realistic model that can be used for engineering design and optimization of the electrodes. Porosity-controlled discharge time and extremely stable energy densities are predicted by the model. Results are compared to discharge curves of a real electrode to examine model fidelity. [ABSTRACT FROM AUTHOR]