Capacitance Of Electrode Research Articles

A comparative study on the structural, chemical, morphological and electrochemical properties of α-MnO2, β-MnO2 and δ-MnO2 as cathode materials in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are considered to be highly promising electrochemical energy storage device due to their affordability, inherent safety, large zinc resources, and optimal specific capacity. Among various cathode materials, manganese dioxide (MnO2) stands out for its high voltage, environmental benignity, and theoretical specific capacity. This study systematically investigates the phase formation and structural parameters of α-MnO2, β-MnO2, and δ-MnO2 synthesized via hydrothermal method, employing Rietveld refinement. FTIR and Raman spectroscopy confirms Mn-O and O-H bond formation. BET analysis reveals surface areas, and pore size distribution is calculated with BJH method. High-resolution XPS spectra exhibit a spin energy split of ~ 11.9 eV for Mn 2p confirming the presence of MnO2. Electrochemical studies shows an initial discharge capacities of 230.5, 188.74 and 263.30 mAh g− 1 at 0.1 A g− 1 for α-MnO2, β-MnO2 and δ-MnO2. The EIS spectra revealed the capacitive behaviour and electrode reaction kinetics where a RcT value of 484.14, 327.6, 162.5 Ω for α-MnO2, β-MnO2 and δ-MnO2. These study give insights into relation of various properties of MnO2 with electrochemical performance and its viability in grid storage applications.Graphical

A New Self-Made 16-Channel Capacitive Electrocardiography System: An Investigation and Validation for Non-Contact Electrodes

Generally, the electrocardiography (ECG) system plays an important role in preventing and diagnosing heart diseases. To further improve the amenity and convenience of using an ECG system, we built a customized capacitive electrocardiography (cECG) system with one wet electrode, sixteen non-contact electrodes, two ADS1299 chips, and one STM32F303-based microcontroller unit (MCU). This new cECG system could acquire, save, and display the ECG data in real time. The bias feedback as a critical technique was routed to the left hand with the wet Ag/AgCl electrode, which could greatly suppress the power line noise. After all artifacts were removed, the ECG signals could be discerned clearly. We demonstrated that the ECG signals acquired with the capacitive electrodes were similar to those with the wet electrode. Thus, we successfully provide a new configuration for cECG monitoring at home or in a clinical setting.

In Situ Characterization of Competitive (De)Lithiation in Silicon/Graphite Composite Electrodes via Electrode Curvature Measurement

AbstractIn silicon/graphite (Si/Gr) composite electrodes for lithium‐ion batteries, which have recently garnered significant attention, the competitive (de)lithiation between Si and Gr is recognized as crucial for understanding the internal electrochemical processes. In this work, an in‐situ method to characterize this competitive behavior is proposed, utilizing a self‐developed electrode curvature measurement system. After validating the parallel electrode configuration and the model battery, curvature measurements are simultaneously conducted on the parallel Si and Gr cantilevered electrodes throughout electrochemical cycling. Subsequently, by calibrating the correlation between capacity and curvature of the Gr electrode, the capacity evolution of Si and Gr within the Si/Gr electrode is determined, shedding light on the underlying competitive (de)lithiation behavior. During lithiation, the process transitions from “Si‐dominant” to “Gr‐dominant” and eventually reaching a “synchronous” stage. For delithiation, it moves from “Gr‐dominant” to “Si‐dominant”. The method proposed in this work, based on the measurement of macroscopic electrode deformation, offers a novel perspective for characterizing competitive (de)lithiation in electrodes with multiphase active materials.

Effects of structural design, interface optimization, and processing on the performance of lithium battery anode silicon nanomaterials

With an emphasis on the advancements in anode material research, this article offers a comprehensive summary of the major technologies used in lithium-ion batteries, a common type of electrochemical energy storage device. Because silicon has both benefits, such as low cost and high theoretical specific capacity, and significant drawbacks, including electrode pulverization and capacity loss due to volume expansion, it is the main focus of this study. This article goes into great detail on the use of silicon material nanosizing to enhance silicon anode performance, discussing how reducing particle size can mitigate the negative effects of volume changes during cycling. However, the section on compositing and structural design processes lacks sufficient depth, which limits the understanding of how these processes can further improve anode stability and efficiency. Furthermore, the article does not comprehensively cover the diverse methods utilized to enhance silicon anode performance, such as the incorporation of conductive additives or protective coatings. The challenges associated with the practical applications of silicon nanoparticles, such as scalability and cost-effectiveness, are examined in detail; nevertheless, the prospects for further research and technological advancements in these areas are not sufficiently addressed. This paper calls for more in-depth studies and innovations in compositing techniques, structural optimization, and practical solutions to realize the full potential of silicon anodes for advanced energy storage.

Passivated Zn Powders as Metal Anode

AbstractImpacted by heavy corrosion and poor connections, zinc (Zn) powders have rarely been considered as the raw materials of Zn‐ion aqueous batteries (ZABs). Nonetheless, the ease of controlling loadings of Zn powders entitles ZABs to better capacity match between negative and positive electrodes. Here, a simple and rapid chemical solution passivation method is reported, which leads to a thin, dense, and conformal passivation layer on Zn powder surface. The passivation layer suppresses parasitic reactions of Zn powder anode, mitigates corrosions, and extends the calendar life. Mixing with well‐dispersed carbon nanotubes, the passivated Zn powder anode is able to cycle 100 h under 3 mA cm−2 and 3 mAh cm−2 at depth of discharge of 41.3%. Besides, the anode with negative/positive electrode capacity ratio of 5.95 improves the energy density of the Zn powder||MnO2 full cell to 70 Wh Kg−1. Such a simple “one‐step” passivation method is believed to be a “drop‐in” technique applied in the scalable manufacture of ZABs.

Improved capacitance of NiO and nanoporous silicon electrodes for micro-supercapacitor application

We investigated the NiO/PS/Si and the NiO/Si electrodes to highlight the effect of the PS porous silicon on the enhancement of the electrode performance. We elaborated the PS with the stain etching method, whereas the NiO nickel oxide was synthesized using sol–gel and deposited through the spin coating technique. We showed that PS porous silicon significantly increased the active surface area and improved the electrical and electrochemical properties. Thus, we obtained promising results for NiO/PS/Si. The effective series resistance and interfacial resistances were reduced from 1.8 Ω cm2 and 42 Ω cm2 to 0.05 Ω cm2 and 0.29 Ω cm2 from NiO/Si to NiO/PS/Si, respectively. The capacitance increased from 12.34 µF cm−2 for NiO/Si to 9.64 mF cm−2 for NiO/PS/Si. We found similar capacity values from the CV cyclic voltammetry curves and IS impedance spectroscopy Nyquist plots. We obtained equivalent effective series resistance values from the charge–discharge and Nyquist plots, confirming our results. The NiO/PS/Si electrode showed good stability with only a 3% loss for 5000 galvanostatic cycles. The energy efficiency is estimated from the charge–discharge curves to be 91%.

W/WO3/TiO2 Multilayer Film with Elevated Electrochromic and Capacitive Properties.

Electrochromic capacitors, which are capable of altering their appearances in line with their charged states, are drawing substantial attention from both academia and industry. Tungsten oxide is usually used as an electrochromic layer material for electrochromic devices, or as an active material for high-performance capacitor electrodes. Despite this, acceptable visual aesthetics in electrochromic capacitors have almost never been achieved using tungsten oxide, because, in its pure form, this compound only displays a onefold color modulation from transparent to blue. Herein, we have designed W/WO3/TiO2 multilayer films by a magnetron sputtering device. The impact of TiO2 layer on the optical and electrochemical properties was investigated. The results show that the optimum thickness of the TiO2 layer is 10 nm. The as-prepared film displays a high coloration efficiency (CE) of 74.2 cm2 C-1, a high areal capacitance of 32.0 mF/cm2, an excellent rate performance (with the areal capacitance still retaining 87% of the maximum capacitance at a current density of 1 mA/cm2), and a high cycle life (with a capacity retention of 91% after 1000 cycles).

Mesoporous gold decorated MXene (Ti3C2Tx) flexible composite films for photo-enhanced solid-state micro-supercapacitors

Unique mesoporous Au NPs improved the capacitance, electrical conductivity, cycling stability and photocurrent response of MXene-based film electrodes.

A lithiophilic interphase enabled by thiophenol additive for stable lithium metal anode

Lithium metal is regarded as a highly promising anode material owing to its ultrahigh theoretical capacity and low electrode potential. Unfortunately, significant concerns including poor Coulombic efficiency (CE) and uncontrolled Li dendritic growth severely hinder its development. Constructing a stable solid electrolyte interphase (SEI) on the electrode surface has been considered a practical and effective approach to settle the previous issues. In this study, 4-(trifluoromethyl)thiophenol (TFTP), an organic thiophenol, is introduced as an electrolyte additive to generate a lithiophilic organosulfur interphase with lithiophilic S sites through in situ reaction, guiding uniform Li nucleation and Li plating. Additionally, the generation of LiF/Li3N-rich layer during the cycling further facilitates homogeneous Li deposition. Therefore, the reliable SEI results in a uniform Li morphology and rapid kinetic of Li deposition. Benefiting from the TFTP electrolyte, the Li–Li symmetric cell exhibits a long-lasting lifespan of 1200 hours, and the full cell coupling with sulfur cathode shows a remarkable discharge capacity of 733.6 mAh g−1 after 200 cycles.

Polythiophene side chain chemistry and its impact on advanced composite anodes for lithium-ion batteries.

In the development of high-performance lithium-ion batteries (LIBs), the design of polymer binders, particularly through manipulation of side-chain chemistry, plays a pivotal role in optimizing electrode stability, ion transport, and adaptability to the volume changes during cycling. In particular, poly[3-(potassium-4-butanoate)thiophene-2,5-diyl] (P3KBT) increases magnetite and silicon capacity and cycling stability. This work explores the impact of polythiophene alkyl sidechain length on anode characteristics, aiming to enhance performance in LIBs. P3KBT and its alkyl chain alternatives, poly[3-(potassium-5-pentanoate)thiophene-2,5-diyl] (P3KPT) and poly[3-(potassium-6-hexanoate)thiophene-2,5-diyl] (P3KHT) were systematically investigated over 300 charge-discharge cycles. The experiments were designed to assess how varying side-chain length affects the stability, ion transport, and capacity retention of the electrodes. The results revealed that P3KHT, with its longer alkyl chain, exhibited superior capacity retention and reduced charge-transfer resistance after 300 cycles compared to its shorter chain analogs. The findings demonstrate that tailored side chains can improve ion transport, structural integrity, and capacity retention, addressing critical challenges in LIBs such as capacity fade and electrode degradation. This research contributes to the development of next-generation LIBs with enhanced performance and reliability.

"Bridge" interface design modulates high-performance cellulose-based integrated flexible supercapacitors.

Flexible supercapacitors offer significant potential for powering next-generation flexible electronics. However, the mechanical and electrochemical stability of flexible supercapacitors under different flexibility conditions is limited by the weak bonding between neighboring layers, posing a major obstacle to their practical application. In this paper, natural coniferous pulp cellulose was successfully modified with ethylenediamine and NiSe2/Cell-NH2/MoS2 cellulose flexible electrodes (NCMF) were fabricated by phase transfer and hydrothermal methods. The amino-modified cellulose (Cell-NH2) acts as a "bridge" between NiSe2 and MoS2, significantly enhancing the interfacial bonding strength of the flexible electrode. The integrated flexible electrode exhibited a high area capacitance (2475 mF/cm2), strong tensile strength (10.3 MPa), and excellent cycling stability (92.1 % capacitance retention after 2500 cycles). The sandwich-structured monolithic supercapacitor achieved both a high electrode capacitance (56.78 F/cm2) and a high energy density (1971.53 μWh/cm2), while maintaining long cycling life (72.73 % capacitance retention after 2000 cycles) and large deformation capability. This makes it suitable for stable power supplies in electronic products and opens new possibilities for the flexible wearable industry. This technology enables stable power supplies for electronic products and paves the way for advancements in the flexible wearable industry.

Molecular mobility of thin films of poly(bisphenol-A carbonate) capped and with one free surface: from bulk-like samples down to the adsorbed layer.

The molecular mobility of thin films of poly(bisphenol A carbonate) (PBAC) was systematically investigated using broadband dielectric spectroscopy, employing two distinct electrode configurations. First, films were prepared in a capped geometry between aluminum electrodes employing a crossed electrode capacitor (CEC) configuration, down to film thicknesses of 40 nm. The Vogel temperature, derived from the temperature dependence of relaxation rates of the α-relaxation, increases with decreasing film thickness characterized by an onset thickness. The onset thickness depends on the annealing conditions, with less intense annealing yielding a lower onset thickness. Additionally, a broadening of the β-relaxation peak was observed with decreasing thickness, attributed to the interaction of phenyl groups with thermally evaporated aluminum, resulting in a shift of certain relaxation modes to higher temperatures relative to the bulk material. A novel phenomenon, termed the slow Arrhenius process (SAP), was also identified in proximity to the α-relaxation temperature. For films with thicknesses below 40 nm, nanostructured electrodes (NSE) were utilized, incorporating nanostructured silica spacers to establish a free surface with air. This free surface causes an enhancement in the molecular mobility for the 40 nm sample, preserving the β-relaxation as a distinct peak. The α-relaxation was detectable in the dielectric loss down to 18 nm, shifting to higher temperatures as film thickness is decreased. Notably, the onset thickness for the increase in Vogel temperature was lower in the NSE configuration compared to the CEC setup, attributed to the presence of the polymer-air interface.

Enhanced Clean Energy Generation through Capacitive Electrode Utilization in Reverse Electrodialysis

Abstract In this study, we explore the potential of a novel energy generation method, Capacitive Reverse Electrodialysis (CRED), which combines seawater and river water to produce electricity. CRED integrates a membrane stack, similar to Reverse Electrodialysis (RED), with capacitive electrodes. The salinity gradient between the two water sources generates a potential difference across ion-selective membranes, enabling sustainable energy production. Unlike traditional RED systems that rely on redox reactions, CRED utilizes capacitive electrodes, preventing saturation and enhancing system longevity by periodically switching the water flows and reversing the direction of the electric current. The larger membrane stack in CRED allows for greater charge accumulation than previous capacitive mixing methods, leading to higher voltage and more efficient energy capture. As a result, CRED achieves a power density approximately ten times higher than previous capacitive power extraction trials, reaching performance levels comparable to or exceeding those of conventional RED systems with redox-based electrodes. Overall, CRED demonstrates a promising alternative to traditional energy generation methods, offering a stable, secure, environmentally friendly, and high-performance solution for harnessing energy from the mixing of saltwater and freshwater.

Pyrolysis char from waste tyres its characteristics, upgrading and application

The pyrolysis of waste tyres can recycle energy and produce reusable products (oil, char and gas). Although there are many reviews in the literature in regard to the pyrolysis characteristics of waste tyres, but this paper critically looked as pyrolysis char as one of the useful product. Its physical characteristics include pore diameter, pore volume, specific surface area, and composition. The common detection techniques of the physical characteristics include elemental analysis, proximate analysis, SEM, EDS, TGA, XRF, BET, and Raman spectroscopy. The chemical characteristics of tyre char mainly include calorific value, the surface functional groups (i.e phenols, alcohols, carboxylic acid and C-O/C-O-C chemical structures) which can be determined by FT-IR, XRD. The higher sulfur retention on the surface of tyre char is obtained at low temperature compared with that obtained at high temperature. Tyre char could also be directly used as a catalyst material to decrease the operational cost, and improve the quality of pyrolysis oil and gas. The modified tyre char with high specific surface area and lower ash content could be used as an activated carbon adsorbent material, catalyst and catalyst support, capacitor electrode to create higher commercial value, as an adsorbent, in batteries and so on. It is suggested that the recycling applications of tyre char should be developed, which can create a high level of potential economic prospects for the waste tyre pyrolysis industry.

All‐Solid‐State Batteries with Extremely Low N/P Ratio Operating at Low Stack Pressure

AbstractAll‐solid‐state batteries (ASSBs) are emerging as promising candidates for next‐generation energy storage systems. However, their practical implementation faces significant challenges, particularly their requirement for an impractically high stack pressure. This issue is especially critical in high‐energy density systems with limited negative‐to‐positive electrode capacity ratios (N/P ratios), where uneven lithium (Li) stripping induces the formation of interfacial voids. This study addresses these challenges by introducing an anode with a novel structural design that operates effectively under practically viable conditions while significantly reducing the N/P ratio to less than one. The approach entails the integration of a lithiophilic magnesium (Mg) film beneath a thin layer of the silicon‐graphite (SiGr) active materials. This structure facilitates the deposition of excess Li beneath the SiGr layer during overcharging, which enables stable cycling even at room temperature and at a low stack pressure of 3 MPa. By mitigating the poor contact that is characteristic of ASSBs with a low stack pressure, and simultaneously increasing the energy density by lowering the N/P ratio, the design significantly advances the key electrochemical properties of ASSBs.

Irrigation System-Inspired Open-/Closed-Pore Hybrid Porous Silicon-Carbon Materials for Lithium-Ion Battery Anodes.

Porous silicon-carbon (Si-C) nanocomposites exhibit high specific capacity and low electrode strain, positioning them as promising next-generation anode materials for lithium-ion batteries (LIBs). However, nanoscale Si's poor dispersibility and severe interfacial side reactions historically hamper battery performance. Inspired by irrigation systems, this study employs a charge-driven Si dispersion and stepwise assembly strategy to fabricate an open-/closed-pore hybrid porous Si-C composite. Polydimethyl diallyl ammonium chloride (PDDA) is used to functionalize Si nanoparticles, inducing strong electrostatic repulsion for uniform dispersion. Subsequently, the PDDA functional layer on Si nanoparticle surfaces facilitates the stepwise self-assembly of acetic acid and chitosan, resulting in Si nanoparticles encapsulated within closed pores during carbonization. Simultaneously, the PDDA functional layers transform into a graphene coating on the Si nanoparticles. Conversely, regions of homogeneous acetic acid/chitosan, distant from the PDDA-functionalized Si nanoparticles, form an open-pore structure. The dual shielding effect of closed carbon pores and the graphene coating effectively isolates Si from the electrolyte, preventing interfacial side reactions. Open carbon pores enhance electrolyte-active material contact, reducing Li+ transport distances. The resulting composite material (PDDA@Si/C) demonstrated excellent cycling stability and superior rate performance as a LIB anode.

Lithium Storage Mechanisms and Electrochemical Behavior of a Molybdenum Disulfide Nanoparticle Anode

This study investigates the electrochemical behavior of molybdenum disulfide (MoS2) as an anode in Li‐ion batteries, focusing on the extra capacity phenomenon. Employing advanced characterization methods such as in situ and ex situ X‐ray diffraction, Raman spectroscopy, X‐ray photoelectron spectroscopy, and transmission electron microscopy, the research unravels the complex structural and chemical evolution of MoS2 throughout its cycling. A key discovery is the identification of a unique Li intercalation mechanism in MoS2, leading to the formation of reversible LixMoS2 phases that contribute to the extra capacity of the MoS2 electrode. Density function theory calculations suggest the potential for overlithiation in MoS2, predicting Li5MoS2 as the most energetically favorable phase within the lithiation–delithiation process. Additionally, the formation of a Li‐rich phase on the surface of Li4MoS2 is considered energetically advantageous. After the first discharge, the battery system engages in two main reactions. One involves operation as a Li‐sulfur battery within the carbonate electrolyte, and the other is the reversible intercalation and deintercalation of Li in LixMoS2. The latter reaction contributes to the extra capacity of the battery. The incorporation of reduced graphene oxide as a conductive additive in MoS2 electrodes notably improves their rate capability and cycling stability.

Paper-Based Capacitive Solid-State Reference Electrode with Carbon Nanotubes and Adsorbed Heavy-Metal Ions

We herein fabricated a capacitive solid-state reference electrode by loading a paper strip with carbon nanotubes (CNTs) to increase double-layer capacitance and adsorbing heavy-metal ions thereon to charge the electrical double layer and minimize the effects of other ions on the interfacial potential difference. CNTs were loaded by immersing the paper strip into a CNT solution followed by drying. By repeating these steps up to 20 times and adsorbing Cu2+, we stabilized the electrode potential and minimized the influence of other ions and electroactive compounds. The potential of the best-performing CNT electrode in the presence of different electrolytes and electroactive compounds ranged from 243 to 249 mV, exhibiting a variation of ≤6 mV over 60 min, whereas gold, carbon paste, and copper electrodes exhibited potential variations of tens of mV or larger. The influence of pH was negligible, although that of buffer components was not negligible in some cases. The CNT reference electrode was tested by potentiometric ion sensing and cyclic voltammetry and shown to be a viable alternative to a macroscopic Ag/AgCl electrode.

Carbon Dot Regulating NiSe/MnO2 Heterostructures for High-Performance Supercapacitors.

Structural regulation is an effective strategy for enhancing an electrode's energy storage performance. Herein, lignin-derived carbon dots (LCDs) are explored for the structural tailoring of NiSe/MnO2 to improve the electrochemical performance in supercapacitors. After the dendritic NiSe microcrystals are synthesized via a microwave method, NF/NiSe/MnO2-LCDs are prepared by another microwave process to form a composite mixture of LCDs, MnO2, and NF/NiSe. At 1 A g-1, NF/NiSe/MnO2-LCDs possess a specific capacitance of 2268 F g-1 and superb lifespans (84.43%, 3000 cycles) for their enhanced ion transport and rapid electron transfer. In addition, the NF/NiSe/MnO2-LCDs//AC ASC showed an energy density of 51.62 Wh kg-1 at 800 W kg-1 and extraordinary endurance with 88.46% retention (7000 loops). The NF/NiSe/MnO2-LCDs offer ideas to improve the capacity retention and storage capacity of electrodes for supercapacitors.

Boosting nickel nanoferrite’s specific capacitance with Azadirachta Indica for advanced supercapacitors

Nickel Ferrite (NiFe2O4) a valuable transition metal oxide possessing a spinel structure, it is extensively utilized in industry due to its compelling properties. In this present study the sol–gel auto-combustion synthesis method was employed using nitrates and citric acid in conjunction with double distilled water (DDW) and Azadirachta Indica extract. The X-ray diffraction (XRD) analysis revealed the formation of a cubic spinel phase with high crystallinity. Crystallite size of prepared Nickel Ferrite in double distilled water and Azadirachta Indica by Scherrer’s equation and Williamson-Hall plot (W-H) are 28.09 nm and 33.01 nm as well as 16.23 nm and 16.55 nm, with microstrains of 0.32739 % and 0.339 × 10−3 % respectively. The notable reduction in the crystallite size is observed when employing Azadirachta Indica compared to the double distilled water-based synthesis. The X-ray density of the synthesized sample in double distilled water and Azadirachta Indica are obtained as 3.935 (g cm−3) and 5.427 (g cm−3). Transmission electron microscopy (TEM) of Azadirachta Indica-based nanostructured Nickel Ferrite material exhibited a particle size of 17.06 nm. The study encompassed the calculation of various parameters such as hopping lengths, polaron radius, specific surface area, packing fraction, and dislocation density. Magnetic parameters are comprehensively examined using a vibrating sample magnetometer (VSM), revealing a Bohr magneton is 3.278. The shifting of coercivity curve observed towards right due to exchange bias effect and the unidirectional anisotropy for diamagnetic Azadirachta Indica based Nickel ferrite. Optical properties are investigated through UV–VIS and Fourier-transform infrared (FTIR) spectroscopy, resulting in a band gap energy of 1.75 eV and a porosity is 11.16 %. Electrochemical evaluation of Nickel Ferrite electrodes is conducted over a potential range from 0.0 to 1 V. The specific capacitance of Nickel Ferrite electrodes synthesized with double distilled water and Azadirachta Indica are determined as 511.9 F/g and 695 F/g respectively, at a scan rate of 50 mV/s, as evaluated through cyclic voltammetry (CV) measurements in Ag/AgCl (0.1 M NaOH as electrolyte). The specific capacitance of Nickel Ferrite, produced with double distilled water and Azadirachta Indica extract, is 686 F/g and 817.398 F/g respectively, as determined by Galvanostatic charge–discharge (GCD) measurements. The study conclusively demonstrated significantly improvement in the electrochemical performance of Nickel Ferrite, synthesized with Azadirachta Indica extract for supercapacitor application. Based on GCD and CV, the specific capacitance has been boosted significantly with Azadirachta Indica extract for supercapacitor application.