Capacitance Of Electrode Research Articles

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.

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.

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.

Conductive Modification of Activated Carbon Fiber Cloths via Electrophoretic Deposition for Cathode in Lithium‐Ion Capacitor

AbstractWith the growing demand for high performance energy storage devices, the advanced manufacturing technology of electrodes, which is a crucial component, has become increasingly essential in academic research and industrial applications. Activated carbon fiber cloth (ACFC) is a promising candidate for lithium‐ion capacitor (LIC) electrodes due to its abundant internal space and pores. However, the wider application of ACFC is restricted by its inferior conductivity. The conventional coating process is costly in terms of both materials and time and is only applicable to surface treatment with limitations in treating shaped substrate such as ACFCs. To overcome the applications obstacles of ACFC in batteries and capacitors, we propose a novel strategy for modification that utilizes electrophoretic deposition (EPD) to deposit Super P onto the surface, thus enhancing its conductivity. After being deposited for 10 min at 80 V, the modified ACFC exhibited higher conductivity. When matched with Si@C anode, the assembled LIC demonstrates excellent initial specific areal capacitance (710 mF cm−2) and cycling retention, with 76.92% remaining after 100 cycles at a current density of 7 mA cm−2. When matched with Si@C anode, the assembled LIC demonstrates excellent initial specific areal capacitance (26.91 F g−1) and cycling retention, with 85.21% remaining after 100 cycles at a current density of 0.2 A g−1. This work showcases the potential of EPD technology in the realm of electrode preparation and offers insights for electrode manufacture in other systems.

Synthesis of urchin-like MnCo2O4 nanospheres as electrode material for supercapacitors

The morphology of MnCo2O4 has a significant effect on the electrochemical performance. In this paper, urchin-like MnCo2O4 nanospheres was successfully fabricated by a simple hydrothermal process and post-annealing treatment. The effects of addition of surfactant (Hexadecy ltrimethyl ammonium bromide) on the crystal structure, surface morphology and electrochemical performance of MnCo2O4 have been investigated. The results show that all the synthesized manganese cobalt oxides are composed of cubic spinel MnCo2O4. The addition of surfactant leads to the change of the morphology of MnCo2O4 from nanoarray to urchin-like nanospheres and increases the specific surface area, which is beneficial to improve the electrochemical performance of the MnCo2O4 electrode. The electrochemical test reveals that the urchin-like MnCo2O4 nanospheres delivered a high specific capacity of 2019 F/g at a 1 A/g and 1144 F/g at 5 A/g, respectively. The specific capacity of MnCo2O4 electrode reaches 512 F/g at 10 A/g and retains 96 % of the initial capacity after 2000 cycles at 10 A/g, which maintains an extraordinary cycling performance. In addition, an asymmetric supercapacitor (MnCo2O4//AC) with urchin-like MnCo2O4 nanospheres as a cathode and activated carbon (AC) as an anode was also assembled. Impressively, the assembled MnCo2O4//AC asymmetric supercapacitor exhibits a high energy density of 69 Wh/kg at a power density of 793 W/kg. The above research shows that the urchin-like MnCo2O4 nanospheres synthesized by adding surfactants are expected to be excellent high-performance energy storage electrode materials, which provides a new strategy for the synthesis of high-capacity nanoelectrode materials.

ZnMnCoS/rGO nanocomposite for an effective bifunctional electrode for overall water splitting and supercapacitor applications

Abstract Future energy storage and energy conversion devices will benefit from the development of active electrode materials that serve as both an electrocatalysts and an energy storage device. Recently, mixed metal sulfides are cheaper and have improved electrical and electrochemical performance than their oxide/hydroxide similarly has garnered a lot of interest for use in energy storage and electro catalysis applications. In this, mixed metal sulfides, as zinc manganese cobalt sulfide (ZMCS) and reduced graphene oxide composite zinc manganese cobalt sulfide (rZMCS) were successfully synthesized via hydrothermal route for overall water splitting and supercapacitor. The prepared materials are characterized through x-ray diffraction, x-ray photoelectron spectroscopy, Field emission scanning electron microscope, transmission electron microscope with elemental mapping and Brunauer–Emmett–Teller analysis. The ZMCS and rZMCS electrodes exhibit an over-potential of 258 and 170 mV for HER and 302 and 230 mV for OER at a density of current is 10 mA cm2 in 3 M KOH. Overall water splitting is carried out for rZMCS electrodes and it shows the long-term stability of 15 hrs. The specific capacitances of ZMCS and rZMCS electrodes are 1065 F g1 and 1167 F g1 at 1 A g1. The obtained electrode could maintain 96 % and 98 % until 5000 cycles. Asymmetric supercapacitor device rZMCS//rGO delivers a total amount of energy and power is 47.6 Wh kg1 and 925 W kg1 with could maintain 86 % upto 10000 cycles. The outcomes draw attention to the produced electrode able to be practical as a multifunctional electrode for energy storage and conversion devices.

Charging Ahead: The Evolution and Reliability of Nickel‐Zinc Battery Solutions

ABSTRACTNickel‐Zinc (Ni‐Zn) batteries offer an interesting alternative for the expanding electrochemical energy storage industry due to their high‐power density, low cost, and environmental friendliness. However, significant reliability challenges such as capacity fading, self‐discharge, thermal instability, and electrode degradation detract from their competitiveness in the market, hindering their widespread adoption. This study thoroughly examines the degradation mechanisms and approaches to improve the reliability of Ni‐Zn batteries: Starting with their basic chemistry, operating principles, and degradation pathways, strategies for improvement are explored including material modification, electrolyte optimization, cell design approaches, and thermal management techniques. Advanced characterization methods for data collection and reliability assessment are discussed, including electrochemical, structural, spectroscopic, and in situ techniques which are noted for their ability to identify key areas of concern for this cell chemistry. We further consider emerging trends such as novel materials, hybridization with other energy technologies, and the challenges of large‐scale implementation, emphasizing the need for standardized reliability testing protocols. Opportunities for the integration of advanced sensing, such as fiber Bragg grating (FBG) sensors for real‐time monitoring and anomaly detection, along with machine learning (ML) and prognostics and health management of Ni‐Zn batteries are highlighted, as these open the door to future research directions. This comprehensive review should serve as a resource for researchers, engineers, and industry experts aiming to advance and commercialize dependable, high‐performing Ni‐Zn battery technology for a sustainable energy future. image

Efficiently Designed Three-Dimensional Architecture of CoMn2O4 Decorated V2CTx MXene for Asymmetric Supercapacitors.

The structure, morphology, stoichiometry, and chemical characterization of the V2CTx MXene, CoMn2O4, and V2C@CoMn2O4 nanocomposite, prepared by using a soft template method, have been studied. The electron microscopy studies reveal that the V2C@CoMn2O4 composite incorporates mesoporous spheres of CoMn2O4 within the 2D layered structure of MXene. The specific capacitance of the composite electrode is ∼570 F g-1 at 1 A g-1, which is significantly higher than that of the sum of the individual components. It also exhibits great rate capability and a Coulombic efficiency of ∼96.5% over 10000 cycles. An asymmetric supercapacitor prototype created with V2C@CoMn2O4//activated carbon outperformed other reported ASCs in terms of achieving a high energy density of 62 Wh kg-1 at a power density of 440 W kg-1. The improved response of V2C@CoMn2O4 and ASC is attributed to the enhanced active area available for charge transfer and the synergistic interaction between CoMn2O4 spherical particles and nanolayered MXene. Supporting density functional theory (DFT) calculations are performed to understand the impact of composite heterojunction formation on its detailed electronic structure. Our atomistic simulations reveal that by incorporating CoMn2O4 in V2C, the density of electronic states at the Fermi level increases, boosting the charge transfer characteristics. These modifications in turn enhance the charge storage capabilities of heterojunction. Finally, the merits of the V2C@CoMn2O4 composite electrode are discussed by comparing it with those of other existing high-performance MXene-based composite electrodes.

A high sensitivity, low cost and fully decoupled multi-axis capacitive tactile force sensor for robotic surgical systems.

This paper presents the design of a multi-axis capacitive tactile force sensor with a fully decoupled output response for input normal and shear forces. A patterned elastomer is used as a dielectric layer between capacitive electrodes of the sensor that allows to achieve relatively higher sensitivity. The sensor is fabricated utilizing a low-cost rapid prototyping technique and is characterized for normal and shear forces in the range of 0 ~ 10 N and 0 ~ 3.1 N respectively. The achieved force sensitivity for the normal axis is 2.03%/N and for shear axes is 1.67%/N. The difference between the estimated force from the sensor and actual force applied is negligible, which demonstrates the accuracy of the sensor. The reliability of the sensor is analysed by performing hysteresis and repeatability tests. The hysteresis error is found to be 4.94% and 4.69% for normal and shear forces respectively. The repeatability error of the sensor is less than 5%, which shows the stability of the sensor. The high sensitivity, linear output response, high force measurement range, reliability and low cost make the proposed tactile sensor suitable for the force feedback in the robotic surgical systems.

Optimizing Reversible Phase‐Transformation of FeS2 Anode via Atomic‐Interface Engineering Toward Fast‐Charging Sodium Storage: Theoretical Predication and Experimental Validation

AbstractSodium‐storage performance of pyrite FeS2 is greatly improved by constructing various FeS2‐based nanostructures to optimize its ion‐transport kinetics and structural stability. However, less attention has been paid to rapid capacity degradation and electrode failure caused by the irreversible phase‐transition of intermediate NaxFeS2 to FeS2 and polysulfides dissolution upon cycling. Under the guidance of theoretical calculations, coupling FeS2 nanoparticles with honeycomb‐like nitrogen‐doped carbon (NC) nanosheet supported single‐atom manganese (SAs Mn) catalyst (FeS2/SAs Mn@NC) via atomic‐interface engineering is proposed to address above challenge. Systematic electrochemical analyses and theoretical results unveil that the functional integration of such two type components can significantly enhance ionic conductivity, accelerate charge transfer efficiency, and improve Na+‐adsorption capability. Particularly, SAs Mn@NC with Mn‐Nx coordination center can reduce the decomposition barrier of Na2S and NaxFeS2 to further accelerate reversible phase transformation of Fe/Na2S→NaFeS2→FeS2 and polysulfides decomposition. As predicted, such FeS2/SAs Mn@NC showcases outstanding rate capability and fascinating cyclic durability. A sequence of kinetic studies and ex situ characterizations provide the comprehensive understanding for ion‐transport kinetics and phase‐transformation process. Its practical use is further demonstrated in sodium‐ion full cell and capacitor with impressive electrochemical capability and excellent energy‐density output.

Selective ammonia recovery from wastewater by SDS-AC based microfiltration membrane flow electrode capacitor deionization

Flow Electrode Capacitance Deionization (FCDI) has been frequently used for NH4+ recovery from wastewater as a low-energy, high-efficiency electrochemical technique. However, issues such as high cost (mainly due to the use of ion-exchange membranes) and weak selectivity have limited the expansion of their applications. In this study, SDS-AC was prepared and applied in microfiltration membrane FCDI (MFFCDI) to recover ammonia (NH4+). The material characterization results showed that the surfactant was stably loaded on the AC surface, and the adsorption capacity of modified AC for NH4+ was greatly enhanced. During the recovery process, NH4+ migrated to the electrode chamber and immobilized on the SDS-AC, while Na+ migrated to the electrode chamber and then released to the desalination chamber due to co-ion repulsion. Based on this principle, selective recovery of NH4+ was achieved (selectivity = 3.51). At the end of the recovery, more than 70 % of the NH4+ was immobilized on the SDS-AC and the NH4+ could be desorbed with NaOH. The results of the recycling experiments showed good stability of the SDS-AC-based MFFCDI system, and the recovery of food waste fermentation liquor demonstrated that the system could realize the selective recovery of NH4+ from complex feed water. In summary, the SDS-AC-based MFFCDI technology has great potential for the application of NH4+ recovery from wastewater. Although the scale of this study was limited to the laboratory stage, it still shows potential for application in engineering. In the future, larger scale applications in engineering will be carried out and the environmental and economic benefits of the technology will be assessed through a full life cycle analysis.

Interface engineering enabling thin lithium metal electrodes down to 0.78 μm for garnet-type solid-state batteries

Controllable engineering of thin lithium (Li) metal is essential for increasing the energy density of solid-state batteries and clarifying the interfacial evolution mechanisms of a lithium metal negative electrode. However, fabricating a thin lithium electrode faces significant challenges due to the fragility and high viscosity of Li metal. Herein, through facile treatment of Ta-doped Li7La3Zr2O12 (LLZTO) with trifluoromethanesulfonic acid, its surface Li2CO3 species is converted into a lithiophilic layer with LiCF3SO3 and LiF components. It enables the thickness control of Li metal negative electrodes, ranging from 0.78 μm to 30 μm. Quasi-solid-state lithium-metal battery with an optimized 7.54 μm-thick lithium metal negative electrode, a commercial LiNi0.83Co0.11Mn0.06O2 positive electrode, and a negative/positive electrode capacity ratio of 1.1 shows a 500 cycles lifespan with a final discharge specific capacity of 99 mAh g−1 at 2.35 mA cm−2 and 25 °C. Through multi-scale characterizations of the thin lithium negative electrode, we clarify the multi-dimensional compositional evolution and failure mechanisms of lithium-deficient and -rich regions (0.78 μm and 7.54 μm), on its surface, inside it, or at the Li/LLZTO interface.

On the Origin of Capacity Increase in Rechargeable Magnesium Batteries with Manganese Oxide Cathodes and Copper Metal Current Collectors.

Rechargeable magnesium batteries (RMBs), with Cu as positive electrode current collector (CC), typically display a gradual capacity increase with cycling. Whereas the origin of this was suggested in gradual active material electro-activation, the fact that this is prevalent in many positive electrode material systems remains unexplained. Herein, we elucidate the underlying mechanism through a series of multiscale joint operando X-ray characterizations, including operando synchrotron X-ray diffraction and imaging technology. We select a series of manganese oxides as benchmark positive electrodes and find that no magnesium ions are stored within the lattices of these materials, despite an apparent cell capacity increase with cycling. The origin of capacity increase is rooted in the gradual electrochemical corrosion of metallic Cu, release of Cu(I, II) species in electrolyte, and their subsequent redox activity, resulting in apparent electrode capacity gains. Furthermore, the shuttle and redox speciation of Cu ions trigger the irreversible depletion of both the Cu CC (or any other source) and the magnesium metal, ultimately leading to cell failure. Our work suggests the need to reconsider the appropriateness of using Cu as a positive electrode CC for RMBs.

On the Origin of Capacity Increase in Rechargeable Magnesium Batteries with Manganese Oxide Cathodes and Copper Metal Current Collectors

Rechargeable magnesium batteries (RMBs), with Cu as positive electrode current collector (CC), typically display a gradual capacity increase with cycling. Whereas the origin of this was suggested in gradual active material electro‐activation, the fact that this is prevalent in many positive electrode material systems remains unexplained. Herein, we elucidate the underlying mechanism through a series of multiscale joint operando X‐ray characterizations, including operando synchrotron X‐ray diffraction and imaging technology. We select a series of manganese oxides as benchmark positive electrodes and find that no magnesium ions are stored within the lattices of these materials, despite an apparent cell capacity increase with cycling. The origin of capacity increase is rooted in the gradual electrochemical corrosion of metallic Cu, release of Cu(I, II) species in electrolyte, and their subsequent redox activity, resulting in apparent electrode capacity gains. Furthermore, the shuttle and redox speciation of Cu ions trigger the irreversible depletion of both the Cu CC (or any other source) and the magnesium metal, ultimately leading to cell failure. Our work suggests the need to reconsider the appropriateness of using Cu as a positive electrode CC for RMBs.

Sodium and Potassium Storage Behaviour in AgNbO3 Perovskite

AbstractIn this work, we report on the investigation the perovskite‐type AgNbO3 as a model negative electrode for sodium and potassium systems. We demonstrated that during the initial discharge, regardless of the inserted cation, the material undergoes an activation mechanism that induces a crystalline‐to‐amorphous transition. This transition, in turn, leads to an enhancement of the electrode capacity. At 5 A g−1 sodium‐ion AgNbO3 and Potassium‐ion AgNbO3 display capacities of 81 mAh g−1 and 60 mAh g−1, respectively. Furthermore, both electrodes display good cycling stability and efficiency over 350 cycles at 1 A g−1.

Electrochemical activation of MnS as an efficient conversion-type Cu2+ storage electrode

Electrochemical activation can turn inactive materials into active materials in situ for energy storage facilely, controllably and efficiently, which makes metal sulfides feasible for Cu2+ storage based on electrochemical activated into CuS. Among common heavy metal sulfides, MnS has the highest solubility product and high Cu2+ adsorption and exchange rate in the copper removal by vulcanization in nickel electrolytic anodic solution. Here, MnS is electrochemical activated in situ in aqueous Cu-ion battery, and the effects of crystal structure and particle size on the electrochemical activation of MnS were revealed. The results show that both α, γ-MnS can be electrochemical activated, and activation cycling number is related to the particle size of MnS. When the MnS particle size is ball-milled small enough (1–2 μm), MnS will be completely transformed into CuS during the first discharge process, and then CuS↔Cu2S will participate in the reversible conversion reaction for copper storage. When the MnS particle size is larger (> 10 μm), the α-MnS electrode capacity gradually increases and becomes stable after 30 cycles, and the capacity remains at 458.6 mAh g–1 after 300 cycles.

Recent Advances in High-Performance Carbon-Based Electrodes for Zinc-Ion Hybrid Capacitors

Aqueous zinc-ion hybrid capacitors (ZIHCs) have emerged as a promising technology, showing superior energy and power densities, as well as enhanced safety, inexpensive and eco-friendly features. Although ZIHCs possess the advantages of both batteries and supercapacitors, their energy density is still unsatisfactory. Therefore, it is extremely crucial to develop reasonably matched electrode materials. Based on this challenge, a surge of studies has been conducted on the modification of carbon-based electrode materials. Herein, we first summarize the progress of the related research and elucidate the energy storage mechanism associated with carbon-based electrodes for ZIHCs. Then, we investigate the influence of the synthesis routes and modification strategies of the electrode materials on electrochemical stability. Finally, we summarize the current research challenges facing ZIHCs and predict potential future research pathways. In addition, we suggest key scientific questions to focus on and potential directions for further exploration.

Design of Silicon-Based Anode Materials for High Energy Density Li-Ion Batteries

Compared to other types of batteries, lithium batteries have an extremely high energy density, which means they can store more energy while maintaining a smaller size and weight. The ideal electrode material must have a high lithium ion capacity to store many lithium ions. In addition, the electrode material must have good electronic conductivity to promote lithium ions' rapid entry and exit. However, traditional carbon materials have limited theoretical specific capacity, and the transmission of lithium-ion batteries in traditional materials is limited, resulting in a significant decrease in capacity. Silicon has a theoretical capacity of up to 4200mAh/g, more than ten times the capacity of commercial graphite negative electrodes. In addition, silicon and lithium can undergo alloying reactions to form Li Si alloys, which helps improve the material's specific capacity. This article first summarizes the advantages of electric vehicles and lithium-ion batteries. Then, the benefits and challenges of using silicon-based materials as negative electrodes for lithium-ion batteries were elaborated in detail, and finally, the prospects of silicon-based materials in lithium-ion battery applications were summarized. This article has reference significance in improving the energy density of lithium-ion batteries.

Zinc Ion Hybrid Capacitors: Four Essential Parameters Determining Device Energy Density.

Zinc ion hybrid capacitors (ZIHCs) with Zn metal faradic and carbon capacitive electrodes have potential applications in grid-scale energy storage systems and wearable devices. However, the high specific energy density reported in many recent studies is based on the mass of active carbon materials alone, with deficient device energy density. This perspective article discusses how four crucial parameters influence the device energy density of ZIHCs, including areal mass loading (mc) and specific capacity (Qg,c) of active carbon materials in cathodes, negative-to-positive electrode capacity ratio (N/P), and electrolyte-to-active carbon materials mass ratio (E/C). Using a representative device model, how the device energy density varies when these four parameters change is shown. Detailed analysis indicates that specific parameter windows with the four parameters within narrow ranges (e.g., mc = 10-20mg cm-2, Qg,c > 100 mAh g-1, N/P < 20, and E/C < 5) need to be achieved simultaneously to deliver application-relevant energy density (e.g., >30 Wh kg-1) in ZIHCs. It is hoped that these findings assist in objectively evaluating reported performance data and identifying essential issues for future research development to realize practical applications.