Excellent Electrochemical Performance Research Articles

Electrostatic Interactions Dominate the Surface Assembly of Silicon‐Based Nanospheres on Carbon Nanofibers for Flexible Lithium‐Ion Batteries

AbstractThe construction of flexible freestanding silicon‐based electrodes eliminates the addition of inactive materials, improving the overall energy density, and effectively avoiding the disadvantage of active materials being easily separated from the collector due to the volume effect. However, many reports of flexible freestanding electrodes lack long‐term cycling stability. Here, 3 different silicon‐based freestanding electrodes are designed and find that the freestanding electrode with surface assembly dominated by electrostatic interactions can significantly improve long‐term cycling stability. Owing to better mechanical properties, this surface‐assembled electrode demonstrates unique flexibility. The conductive framework and unique void structure not only reveal the excellent lithium‐ion diffusion capability and charge‐transfer kinetics but also provide ample space for the volume expansion of the silicon‐based material, which endows electrodes with excellent electrochemical performance. With 2 folds, the capacity remains at 471 mA h g−1 after 1000 cycles (0.5 A g−1). In addition, the as‐prepared flexible pouch cell maintains high capacity and cycling stability after folding, with an average capacity degradation of only 0.01% per cycle during 1000 cycles, highlighting its considerable potential in the development of flexible devices. Remarkably, such interfacial assembly on the fiber surface also enables the modulation of multilayer assembly.

One-step pulsed laser deposition of carbon/metal oxynitride composites for supercapacitor application

Abstract Advanced material composite of nanocarbons and metal-based materials provides a synergistic effect to obtain excellent electrochemical charge-storage performance and other properties. Herein, 3D porous carbon-metal oxynitride nanocomposites with tunable carbon/metal and oxygen/nitrogen ratio are synthesized uniquely by simultaneous ablation from two different targets by single-step pulsed laser deposition at room temperature. Co-ablation of titanium and vanadium nitride targets together with graphite allowed us to synthesize carbon-metal oxynitride porous nanocomposite and exploit them as a binder-free thin film supercapacitor electrode in
aqueous electrolyte. We show that the elemental composition ratio and hence the structural properties can be tuned by selecting target configuration and by manipulating the ablation position. We investigate how this tuning capability impacts their charge-storage performances. We anticipate the utilization of as-synthesized various composites in a single PLD production run as next-generation active materials for flexible energy storage and optoelectronic applications.

Anion Doping and Dual-Carbon Confinement Strategies to Synergistically Boost the Sodium Storage Performance of Cobalt-Based Sulfides.

Cobalt-based sulfides (CSs) are generally regarded as potentially valuable anode materials for sodium-ion batteries (SIBs) due to their excellent theoretical capacity and natural abundance. Nevertheless, their slow reaction kinetics and poor structural stability restrict the practical application of the materials. In this study, the dual-carbon-confined Se-CoS2@NC@C hollow nanocubes with anion doping are synthesized using ZIF-67 as the substrate by resorcin-formaldehyde (RF) encapsulation and subsequent carbonization and sulfurization/selenization. RF- and ZIF-67-derived dual-carbon skeleton hollow structures with a robust carbon skeleton and abundant internal space minimize cyclic stress, mitigate volume changes and maintain the structural integrity of the material. More importantly, Se doping increases the lattice spacing of CoS2, weakens the strength of Co-S bonds, and modulates the electronic structure around Co atoms, thereby optimizing the adsorption energy of the material. As a result, the hollow nanocubes of Se-CoS2@NC@C demonstrates excellent electrochemical performance as the anode for SIBs, delivering a high reversible capacity of 549.4 mAh g-1 at 0.5 A g-1 after 100 cycles and a superb rate performance (541.1 mAh g-1 at 0.2 A g-1, and 393.3 mAh g-1 at 5 A g-1). This study proposes a neoteric strategy for synthesizing advanced anodes for SIBs through the synergy of anion doping engineering and dual-carbon confinement strategy.

Hierarchical porous self-supporting graphite carbon electrodes based on the biomimetic structure for supercapacitors

Regulating pore structure, improving conductivity, and reducing the influence of binders are considered important ways to improve the performance of carbon-based electrode materials for supercapacitors. This study successfully prepares a highly graphitized hierarchical porous self-supporting carbon electrode without the need for binders, conductive agents, and current collectors using low-cost and abundant pine wood as the precursor and K2FeO4 as the activator and catalyst. The self-supporting electrode inherits the biological structure of biomass and forms a large number of micro mesopores through activation, showing an excellent 3D interconnected pore structure, and achieves a high degree of graphitization with the ID/IG ratio of being only 0.47. The self-supporting electrode facilitates the effective transport of electrolyte ions and electrons, demonstrating excellent electrochemical performance. It achieves an area specific capacitance of 3.64 F cm−2 under a current density of 5 mA cm−2. Two identical self-supporting electrodes are employed to construct a symmetric supercapacitor. The supercapacitor exhibits an energy density of 148.61 μWh cm−2 at a power density of 1 mW cm−2, with a capacity retention rate of 89.26 % after 10,000 charge-discharge cycles.

1D Textile Yarn Battery with MoS2@Si Anode and NCM Cathode

AbstractWearable electronics are surging for various applications ranging from critical functions like personal health monitoring to communication and entertainment. To power these electronic devices, advanced high‐performing textile‐based batteries are reckoned. In this work, a 1D textile yarn battery is designed using silicon (Si) nanoparticles wrapped in molybdenum disulfide (MoS2) as an anode and layered Ni‐rich material Li[Ni0.8Co0.1Mn0.1]O2 (NCM) as a cathode. The anode materials design is selected to ensure the use of Si due to its high specific capacity but suppressing its known issue of volume expansion by layered MoS2 nanosheets and, at the same time, MoS2 providing channels for lithium‐ion (Li‐ion) transport during electrochemical cycles. The NCM cathode, on the other hand, is adopted as it has higher energy density and improved cycle life. The full yarn battery (FYB) delivered an excellent electrochemical performance (areal capacity of 3.13 mAh cm−2, power density of 421 mW cm−3, and energy density of 78.9 mWh cm−3) with a capacity retention of 86% at 0.1 C and coulombic efficiency of 91.3%. This work pointed out a new way to design and fabricate textile‐based batteries with high‐performance materials using simple, cost‐effective, and scalable approaches targeting to be used as energy sources for future wearable electronics.

A Recyclable Polyimide Derived Hard Carbon as a High‐Performance Negative Electrode Material for Sodium‐Ion Batteries

AbstractHard carbon, characterized by high ion storage capacity, low operating voltage, and excellent cycling stability, is considered an ideal negative electrode material for sodium‐ion batteries. However, the high cost and low carbon yield of thermosetting precursors limit their practical application in SIBs, while low‐cost and high‐yield raw materials exhibit highly ordered carbon structures and narrow interlayer spacing under high‐temperature carbonization. Discarded polyimide materials are inexpensive, which offer a high carbon yield and possess good thermal stability and thermoplasticity, with functional groups of imide rings (−CO−N−CO−) on their main chains. This study recycled and converted polyimide materials into hard carbon materials from discarded engineering plastics, investigating the influence of carbonization temperature on the degree of graphitization, interlayer spacing, and pore structure of the materials to achieve high reversible sodium storage capacity. After carbonization at 1300 °C, the polyimide material exhibited 319 mAh g−1 reversible capacity and excellent electrochemical performance (with a capacity retention of 91.92 % after 100 cycles at a 0.5 C current rate) and rate performance (up to 242.5 mAh g−1 at 2 C). This study provided a simple, high‐yield, and effective method for the reuse of discarded organic polymers, promoting the sustainable utilization of resources.

Free‐Standing Si@C/CNFs Prepared by Simple Electrospinning as a Stable Anode for Lithium‐Ion Batteries

AbstractThe development of free‐standing and foldable electrodes with excellent electrochemical performance is paramount for flexible electronic devices. However, the silicon‐based free‐standing anodes lack a straightforward preparation process. Herein, we successfully designed a hierarchical Si@C/CNFs composite material by combining hydrothermal and electrospinning techniques, in which the carbon‐coated silicon (Si@C) is served as the primary nanostructure and carbon nanofibers (CNFs) from electrospinning are maintained as the network matrix, resulting in a free‐standing anode. Owing to the amorphous carbon coating on Si nanoparticles and the formation of a 3D network structure of CNFs, which tightly encases the primary Si@C nanostructure, the Si@C/CNFs electrode demonstrates exceptional conductivity and flexibility. This dual carbon‐layer structure further enhances kinetics and mitigates the volume expansion of Si nanoparticles. The Si@C/CNFs electrode exhibits a high specific capacity (1573 mAh g−1 at 0.1 A g−1), exceptional rate capability, and excellent cycling stability (78.5 % capacity retention after 100 cycles). Thus, Si@C/CNFs can be a promising material for the anode electrode in flexible lithium‐ion batteries.

Amino Group-Aided Efficient Regeneration Targeting Structural Defects and Inactive FePO4 Phase for Degraded LiFePO4 Cathodes.

It is urgent to develop efficient recycling methods for spent LiFePO4 cathodes to cope with the upcoming peak of power battery retirement. Compared with the traditional metallurgical recovery methods that lack satisfactory economic and environmental benefits, the direct regeneration seems to be a promising option at present. However, a simple direct lithium replenishment cannot effectively repair and regenerate the cathodes due to the serious structural damage of the spent LiFePO4. Herein, the spent LiFePO4 cathodes are directly regenerated by a thiourea-assisted solid-phase sintering process. The density functional theory calculation indicates that thiourea has a targeted repair effect on the antisite defects and inactive FePO4 phase in the spent cathode due to the associative priority of amino group (─NH2) in thiourea with Fe ions: Fe3+─N > Fe2+─N. Meanwhile, the pyrolysis products of thiourea can also create an optimal reducing atmosphere and inhibit the agglomeration of particles in the high temperature restoration process. The regenerated LiFePO4 exhibits an excellent electrochemical performance, which is comparable to that of commercial LiFePO4. This targeted restoration has improved the efficiency of direct regeneration, which is expected to achieve large-scale recycling of spent LiFePO4.

Corn Husk Derived Activated Carbon/Siloxene Composite Electrodes based Symmetric Supercapacitor with High Energy Density and Wide Temperature Tolerance

AbstractIn the present work, novel composite material comprising of corn husk derived activated carbon and siloxene nanosheets have been explored as new class of multicomponent electrode material for fabricating high energy density supercapacitors with wide temperature tolerance. The activated carbon obtained from corn husk (ACH–900) with high surface area and pore volume acts as an ideal framework for hosting siloxene nanosheets (S) that allows the overall siloxene–corn husk derived activated carbon (ACH–900/S) composite to deliver excellent electrochemical performance. The as‐prepared ACH–900/S composite electrode exhibited a high specific capacitance of 415 F g−1 at 0.25 A g−1 and retained 73.4 % of its initial capacitance even at a high current density of 30 A g−1 in 1 M Na2SO4 electrolyte. In addition, the symmetric supercapacitor assembled with “acetonitrile/water‐in‐salt (AWIS)” electrolyte exhibited an energy density of 57.2 W h kg−1 at 338 W kg−1 with a cyclic stability of 92.8 % after 10000 cycles at 5 A g−1 current density. Besides, the fabricated ACH–900/S supercapacitor can operate over wide temperature range from 0 to 100 °C. This work opens up new frontiers to develop low‐cost safe supercapacitors with wide temperature tolerance and excellent electrochemical performance.

High-quality femtosecond laser cutting of battery electrodes with enhanced electrochemical performance by regulating the taper angle: Promoting green manufacturing and chemistry

Laser cutting electrode technology is an environmentally friendly and sustainable manufacturing method that offers many benefits, such as low energy consumption and greenhouse gases, no waste production, no tool wear, flexible manipulation, and multi-scale processing. However, achieving high cutting quality with adjustable notch shape and controllable dimension precision is still a cutting-edge challenge. In addition, the influence of laser cutting on the microscopic structure and electrochemical performance of battery electrodes has not been fully illustrated. Here, the Li4Ti5O12 (LTO) electrode is cut using a femtosecond laser technology. The processing parameters are systematically optimized, and the influence of laser cutting taper structure on the structure and performance of LTO electrodes is comprehensively investigated. It is found that laser photoionization and the generated plasma could create oxygen vacancies and thus more Ti3+/Ti4+ defects in the LTO electrodes, resulting in increased electronic conductivity. Moreover, proper taper structure could help improve electrolyte infiltration as well as Li+ diffusion kinetics. As a result, the laser cutting LTO electrode with the optimized taper angle of T = 0.004 shows excellent electrochemical performance. The capacity retention is more than 99.2 % after 400 cycles at 1C, and the specific capacity reaches ∼60 mAh g−1 at a high rate of 60C, which is about 1.7 times higher than that of mechanically cutting LTO electrodes. The outstanding electrochemical performance is also demonstrated by LiFePO4||Li4Ti5O12 full cells. This work could pave the way for the development and application of laser technology in cutting battery electrodes.

Advanced MXene/Graphene Oxide/Lignosulfonate Inks for 3D Printing Thick Electrodes with Vertically Aligned Pores to Dually Boost Mass Loading and Areal Capacitance

AbstractDirect ink writing 3D printing, using ink extrusion, promises to transform conventional 2D thin electrodes into 3D thick architectures for high‐performance supercapacitors. However, formulating 3D printing inks and designing 3D architectures for electrodes remain challenges. In this work, a novel MXene/graphene oxide/lignosulfonate (MGL) ink with excellent rheological properties is developed for 3D printing MGL thick electrodes with vertically aligned architectures. The MGL ink exhibited excellent shear‐thinning properties for smooth 3D printing and shape retention after printing. The 3D‐printed MGL thick electrode, with a thickness of up to 4 mm, achieved a breakthrough mass loading of 72.1 mg cm−2, resulting in an extremely high areal capacitance of 8.6 F cm−2 that is 9.6 times greater than the value observed for the bulk MGL electrode (0.9 F cm−2). Additionally, supercapacitors using the 3D MGL electrode achieved an energy density of 505.3 µWh cm−2, significantly surpassing the value for bulk MGL electrode (52.8 µWh cm−2). This enhancement is attributed to the efficient design of the electrodes, where vertically aligned pores in the 3D MGL electrode enhanced ion transfer and reaction kinetics. This study demonstrates an innovative approach for formulating inks and provides guidance for designing 3D thick electrodes with rapid ion transport and excellent electrochemical performance.

Hierarchical Nanostructures of Iron Phthalocyanine Nanowires Coated on Nickel Foam as Catalysts for the Oxygen Evolution Reaction.

In this paper, iron phthalocyanine nanowires on a nickel foam (FePc@NF) composite catalyst were prepared by a facile solvothermal approach. The catalyst showed good electrochemical oxygen evolution performance. In 1.0 M KOH electrolyte, 289 mV low overpotential and 49.9 mV dec-1 Tafel slope were seen at a current density of 10 mA cm-2. The excellent electrochemical performance comes from the homogeneous dispersion of phthalocyanine nanostructures on the surface of the nickel foam, which avoids the common agglomeration problem of such catalysts and provides a large number of active sites for the OER reaction, thus improving the catalytic performance of the system.

Enhancing electrochemical energy storage in Zinc hybrid capacitors using 3D-printed GO/AC electrodes with Oxygen functional groups

Zinc-ion hybrid capacitors (ZIHCs), promising for energy storage, encounter challenges such as mismatched positive and negative electrode capacities. Addressing this, increasing the thickness of positive electrode proves effective. However, traditional thick electrodes show an extended ion diffusion paths, which slows reactions and decreasing charge-discharge efficiency. Innovations in electrode structures have been achieved through 3D printing technology with an "embedded" composite material of activated carbon and graphene oxide, creating grids with varying layers to explore the relationship between layer number and capacitor performance. Density Functional Theory (DFT) simulations confirm the crucial role of oxygen functional groups on graphene oxide in enhancing storage capacity, with these findings supported by excellent electrochemical performance in tests. Precise control of electrode structures through 3D printing optimizes ion transport pathways, achieving a high specific capacity of 0.92 mAh cm−2 at a current density of 10 mA cm−2, maintaining 86.4 % cycle stability after 8,000 cycles. These results underscore the potential of 3 D printing to advance electrode design and suggest new directions for research.

Synergistic design of processable Nb2O5-TiO2 bilayer nanoarchitectonics: enabling high coloration efficiency and superior stability in dual-band electrochromic energy storage

This paper introduces a proof of concept for a dual-band electrochromic (EC) device to modulate solar light transmission across visible and near-infrared regions selectively. EC materials based on ion insertion/extraction mechanisms also present the possibility for energy storage, widening its functionality to the supercapacitor platform. The bi-functional performance of dual-band radiation control and energy storage was achieved by exploiting two earth-abundant metal oxides that could absorb two different spectral regions when electrochemically charged. The bilayer structure was prepared using a one-step hydrothermal method, which produced Nb2O5-TiO2 bilayer on fluorine-doped tin oxide (FTO) conducting glass substrates. The nano-dimensions of the active materials endorse the development of high-transparency thin film under open circuit conditions. The variations in the TiO2 annealing temperature influence the crystallinity and surface morphology of the thin films, which influence the performance of dual-band EC energy storage. The well-optimized NT-500 sample facilitated exclusive electron-charge transport, producing excellent electrochemical performance in dual-band EC and energy storage. A large optical modulation of 80.4 % and 89.8 % at 600 nm and 800 nm (near-infrared) was achieved with an enhanced areal capacitance of 88.1 mF/cm2 and excellent cycling stability after continuous coloring/bleaching cycles for 18,000 s. This paper presents a prototype bi-functional device based on NT-500, which showed independent control and modulation of visible and near-infrared transmittance. Notably, the device retained excellent energy storage performance alongside its advanced optical functionalities. This bilayer nanostructure capitalizes on the inherent electrochemical properties of both materials and introduces novel features that can potentially revolutionize the platform of EC-energy storage.

Ether-Based Gel Polymer Electrolyte for High-Voltage Potassium Ion Batteries.

Low-concentration ether electrolytes cannot efficiently achieve oxidation resistance and excellent interface behavior, resulting in severe electrolyte decomposition at a high voltage and ineffective electrode-electrolyte interphase. Herein, we utilize sandwich structure-like gel polymer electrolyte (GPE) to enhance the high voltage stability of potassium-ion batteries (PIBs). The GPE contact layer facilitates stable electrode-electrolyte interphase formation, and the GPE transport layer maintains good ionic transport, which enabled GPE to exhibit a wide electrochemical window and excellent electrochemical performance. In addition, Al corrosion under a high voltage is suppressed through the restriction of solvent molecules. Consequently, when using the designed GPE (based on 1 m), the K||graphite cell exhibits excellent cycling stability of 450 cycles with a capacity retention of 91%, and the K||FeFe-Prussian blue cell (2-4.2 V) delivers a high average Coulombic efficiency of 99.9% over 2200 cycles at 100 mA g-1. This study provides a promising path in the application of ether-based electrolytes in high-voltage and long-lasting PIBs.

Integrated Structural Modulation Inducing Fast Charge Transfer in Aqueous Zinc-Ion Batteries.

Aqueous Zn-ion batteries (AZIBs) are promising energy-storage devices owing to their exceptional safety, long cycle life, simple production, and high storage capacity. Manganese oxides are considered potential cathode materials for AZIBs, primarily because of their safety, low cost, simple synthesis, and high storage capacity. However, MnO2-based cathodes tend to deteriorate structurally during long-term cycling, which reduces their reversible capacity. In this study, an advanced α-MnO2@SnO2 nanocomposite via facile hydrothermal synthesis is developed. The synergistic effects of lattice disorder and increased electron conductivity in the α-MnO2@SnO2 nanocomposite mitigate structural degradation and enhance the overall electrochemical performance. The nanocomposite exhibits a high reversible capacity of 347 mAh g-1 at a current density of 100mA g-1 after 50 cycles. Furthermore, it exhibits excellent rate performance and stable capacity even after 1000 cycles, maintaining a capacity of 78 mAh g-1 at a high current density of 5 A g-1. This excellent electrochemical performance is attributed to the reversible Zn intercalation in α-MnO2@SnO2 nanocomposites due to the increased structural stability and fast ion/electron exchange caused by the distortion of the tunnel structure, on the basis of various ex situ experiments, density functional theory calculations, and electrochemical characterizations.

VO2-C Cathode Material Prepared from Reduction of V2O5 by Citric Acid for Aqueous Zinc Ion Batteries

Designing and synthesizing cathode materials with high specific capacity and stability for aqueous zinc ion battery remains a significant challenge. In this study, citric acid was selected as the reducing agent for converting V2O5 to VO2 with a carbon matrix using the hydrothermal method. The introduction of citric acid not only created a distinct microstructure in V4+ materials but also provided carbon matrix, which resulted in a fast diffusion of zinc ion and a good conductivity. This carbon containing vanadium-oxide material exhibited excellent electrochemical performance as a cathode material for aqueous zinc ion batteries, showing a high specific capacity of 399.33 mAh g−1 at 1 A g−1, and a capacity retention rate up to 98.3% after cycling for 1000 cycles at a high current density of 5 A g−1.

Reviving Sodium Tunnel Oxide Cathodes Based on Structural Modulation and Sodium Compensation Strategy Toward Practical Sodium-Ion Cylindrical Battery.

As a typical tunnel oxide, Na0.44MnO2 features excellent electrochemical performance and outstanding structural stability, making it a promising cathode for sodium-ion batteries (SIBs). However, it suffers from undesirable challenges such as surface residual alkali, multiple voltage plateaus, and low initial charge specific capacity. Herein, an internal and external synergistic modulation strategy is adopted by replacing part of the Mn with Ti to optimize the bulk phase and construct a Ti-containing epitaxial stabilization layer, resulting in reduced surface residual alkali, excellent Na+ transport kinetics and improved water/air stability. Specifically, the Na0.44Mn0.85Ti0.15O2 using water-soluble carboxymethyl cellulose as a binder can realize a capacity retention rate of 94.30% after 1,000 cycles at 2C, and excellent stability is further verified in kilogram large-up applications. In addition, taking advantage of the rich Na content in Prussian blue analog (PBA), PBA-Na0.44Mn1-xTixO2 composites are designed to compensate for the insufficient Na in the tunnel oxide and are matched with hard carbon to achieve the preparation of coin full cell and 18650 cylindrical battery with satisfactory electrochemical performance. This work enables the application of tunnel oxides cathode for SIBs in 18650 cylindrical batteries for the first time and promotes the commercialization of SIBs.

Laser micro/nano structuring of three-dimensional porous gradient graphene: Advanced heater for antibacterial surfaces and ion-selective electrode for sweat sensing

The development of three-dimensional (3D) gradient porous graphene (GPG) patterns, leveraging the remarkable properties and unique structure of graphene, has garnered considerable attention owing to their excellent electrochemical and electrothermal performances. Among the numerous graphene synthesis methods, laser-induced graphene (LIG) stands out as an eco-friendly and practical approach for creating patterned graphene structures on commercial films, with synthetic details varying depending on the application. Unlike conventional LIG with uniform geometric characteristics, we developed an innovative approach for circular line-scribed ultraviolet (UV)-LIG patterning; these approaches utilize a high overlapping factor and low power to achieve uneven graphitization. A comprehensive analysis of the 3D GPG was conducted via specific surface area measurements, contact angle analyses, sheet resistance measurements, X-ray photoelectron spectroscopy, and Raman spectroscopy. These 3D GPG structures exhibit large surface areas, low sheet resistance, and superior ion transport, thus improving heater and ion-selective electrode (ISE) performances. The fabricated 3D GPG heaters were successfully applied to antibacterial surfaces, and the ISEs were applied in a sweat sensor was demonstrated owing to the remarkable combination of high surface area, low electrical resistance, and unique 3D porous structure.

Polyrrole-encapsulated TiSe2 with Excellent Electrochemical Performance for Potassium-Ion Storage

TiSe2 as a potential electrode for potassium-ion batteries, has garnered significant attention owing to its stable ion storage property. Nevertheless, the inadequate electronic conductivity of TiSe2 impedes its practical implementation. In this investigation, we adopt a polymerization method to fabricate TiSe2@PPy, which boasts enhanced conductivity and exceptional performance. Once coated with polypyrrole, the TiSe2@PPy composites demonstrate the optimum electrochemical performance, providing a charge capacity of 67.4 mAh g-1 at 1C with a capacity retention of 68.4% after 170 cycles. The PPy coating enhances the conductivity of TiSe2 and enables potassium-ion batteries to exhibit outstanding electrochemical performance. Ex-situ Raman and FTIR tests are utilized to comprehend the electrochemical reaction between K+ and the TiSe2@PPy electrode during cycling. Overall, this work introduces a PPy coating on TiSe2, which presents a novel concept for the development.