Search Results (14)

A novel process for the synthesis of binder-free, porous nickel/polythiophene-functionalized sulfur (Ni/S-PTh) composite cathodes for lithium–sulfur (Li–S) batteries is introduced in this paper. Initially, a polyvinyl butyl polymer scaffold is 3D printed, then coated with a graphite-based conducting layer, and, finally, it is pulse-plated for nickel deposition to produce a high-surface-area, mechanically stable current collector. S-PTh particles are afterwards co-deposited into the Ni matrix through composite electrodeposition. After the dissolution of the polymer template, the resulting self-standing electrodes still maintain porous structure with uniform sulfur distribution and a distinct transition between the dense Ni layer and the Ni/S-PTh composite layer. Electrochemical characterization of the Ni/S-PTh composite cathodes by galvanostatic cycling at C/10 rate results in an initial specific discharge capacity of ~1120 mAh·g⁻¹ and a specific capacity of ~910 mAh·g⁻¹ after 200 cycles, resulting in a high capacity retention of ~81 %. For our novel approach, no steps at high temperatures or toxic solvents are involved and the need for polymer binders and conductive additives is avoided. These results demonstrate the potential of composite electrodeposition in combination with 3D printing for producing sustainable, high-performance sulfur cathodes with tunable architecture. Full article

Copper foil has been widely adopted as the anode current collector in commercial lithium-ion batteries (LIBs) due to its exceptional electrical conductivity, mechanical flexibility, and low cost. However, the smooth surface of copper foil often leads to active material delamination during cycling, resulting in accelerated capacity degradation. To address this limitation, this study developed a novel composite current collector featuring a high specific surface area and rough porous architecture through a dip-coating method. The fabrication process employs copper mesh as a structural skeleton, integrated with carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) as functional fillers. Compared to conventional metallic copper foils, the composite current collector demonstrates superior interfacial wettability, enhanced adhesion strength, and reduced contact resistance. When paired with graphite as the active material, the graphite composite electrode exhibits outstanding cycling stability and rate capability. Specifically, the graphite composite electrode delivers a specific capacity of 297.9 mAh g⁻¹ with 94.3% capacity retention after 200 cycles at 0.5 C, significantly outperforming the graphite–copper foil counterpart (238.3 mAh g⁻¹, 81.2% retention). This work provides an innovative strategy for enhancing battery performance through the rational design of efficient and durable current collectors. Full article

With the increasing demand for Li resources worldwide, the easy recycling of Li-ion batteries materials becomes essential. We report a binder-free cathode consisting of carbon nanotubes (CNTs) and LiFePO₄ (LFP) nanoparticles embedded in a 3D Al network. The electrode stability depends on the CNT ratio, where 3% CNT-wrapping LFPs provide a stable structure free of detachment from Al foam, as observed on Al foil. The binder-free cathode sheet exhibited excellent performance for high-rate discharge and long-term cycle life. Materials on the cathode can be easily detached with ultrasonic treatment when immersed in organic solvent, which is advantageous for a green and high-efficiency strategy of recycling all valuable materials compared to the binder-used electrode. Full article

Using three-dimensional (3D) metal foams as current collectors is considered to be a promising approach to improve the areal specific capacity and meet the demand for increased energy density of lithium-ion batteries. Electrodes with an open-porous metal foam as current collector exhibit a 3D connected electronic network within the active mass, shortening the electron transport pathways and lowering the electrodes’ intrinsic electronic resistance. In this study, NMC622 cathodes using an aluminium foam as current collector with a measured areal capacity of up to 7.6 mAh cm⁻² were investigated. To this end, the infiltrated foams were densified to various thicknesses between 200 µm and 400 µm corresponding to an electrode porosity between 65% and 30%. The microstructural analysis reveals (i) the elimination of shrinking cavities and a decrease in the porosity of the infiltrated active mass, (ii) an improved contact of active mass to the current collector structure and (iii) a pronounced clogging of the surface pores. The electrochemical properties such as capacity and rate capability are correlated to the electrode’s microstructure, demonstrating that densification is necessary to improve active material utilization and volumetric capacity. However, strong densification impairs the rate capability caused by increased pore resistance and hindered electrolyte accessibility. Full article

Lithium (Li) metal is perceived as the “holy grail” of anodes for secondary batteries due to its innate merits. Regrettably, the commercial application of Li metal anodes (LMAs) has been hampered by problems derived from the uncontrollable growth of Li dendrites, which could result in formation of short-circuits, thereby leading to fatal safety accidents. Here, a three-dimensional lithiophilic gold (Au)-coated copper (Cu) pentagonal pyramid array (Au@CuPPA) is constructed on planar Cu foil via electrodeposition followed by a chemical reduction method. Owing to the features of the lithiophilic layer and 3D porous structure, the proposed Au@CuPPA can not only facilitate Li-ion migration and charge transfer, but also effectively diminish the nucleation overpotential. Consequently, an even and steady Li plating/stripping process for up to 460 h and with a charge capacity of 3 mAh cm⁻² is accomplished by using the Au@CuPPA current collector. The Li@Au@CuPPA|LiFePO₄ full cell achieves a high Coulombic efficiency (CE) of 99.4% for 150 cycles at 0.5 C with a capacity retention of 92.4%. Full article

Metal–organic frames (MOFs) have recently been used to support redox enzymes for highly sensitive and selective chemical sensors for small biomolecules such as oxygen (O₂), hydrogen peroxide (H₂O₂), etc. However, most MOFs are insulative and their three-dimensional (3D) porous structures hinder the electron transfer pathway between the current collector and the redox enzyme molecules. In order to facilitate electron transfer, here we adopt two-dimensional (2D) metal–organic layers (MOLs) to support the HRP molecules in the detection of H₂O₂. The correlation between the current response and the H₂O₂ concentration presents a linear range from 7.5 μM to 1500 μM with a detection limit of 0.87 μM (S/N = 3). The sensitivity, reproducibility, and stability of the enzyme sensor are promoted due to the facilitated electron transfer. Full article

In recent years, the development of lightweight electrode materials with excellent performance (energy density versus power density) has increased the number of uses for supercapacitors. Creating three-dimensional skeletal network structures with excellent specific capacitance and high energy density is still challenging. This study utilized a straightforward one-pot hydrothermal technique to construct a supercapacitor based on hydrogel 3D skeletal networks comprising rGO nanosheets with VS₂/WS₂ nanoparticles. The rGO appeared as flakes and layers, interconnected in nature, allowing for more ion transport pathways and a larger active surface area for EDLC performance. The heterostructured VS₂ and WS₂ nanoparticles were homogeneously anchored to the rGO layers and were porous in the hydrogel structure. The functioning rGO, rGO-VS₂, and rGO-VS₂-WS₂ composite hydrogel electrodes were created without a binder on the Ni foam current collector using a hydraulic press. The rGO-VS₂-WS₂ composite hydrogel electrode showed excellent supercapacitor performance of 220 F g⁻¹ at 1 A g⁻¹ in 3M KOH electrolyte, which was more than those of the GO (158 F g⁻¹) and rGO-VS₂ (199 F g⁻¹) hydrogels under similar conditions. Hydrogel electrodes made of rGO-VS₂-WS₂ had a power density of 355 Whkg⁻¹ and a high energy density of 30.55 Whkg⁻¹. It maintained a high energy density of up to 21.11 W/kg⁻¹, even at a high power density of 3454 W/kg⁻¹. Given the 3D shape and the excellent surface properties of rGO nanosheets with VS₂ and WS₂ nanoparticles as the hydrogel, this electrode has essential properties that make it a good choice for making high-performance capacitors. Full article

Rechargeable lithium-metal batteries (LMBs), which have high power and energy density, are very attractive to solve the intermittence problem of the energy supplied either by wind mills or solar plants or to power electric vehicles. However, two failure modes limit the commercial use of LMBs, i.e., dendrite growth at the surface of Li metal and side reactions with the electrolyte. Substantial research is being accomplished to mitigate these drawbacks. This article reviews the different strategies for fabricating safe LMBs, aiming to outperform lithium-ion batteries (LIBs). They include modification of the electrolyte (salt and solvents) to obtain a highly conductive solid–electrolyte interphase (SEI) layer, protection of the Li anode by in situ and ex situ coatings, use of three-dimensional porous skeletons, and anchoring Li on 3D current collectors. Full article

Conductive and flexible CuS films with unique hierarchical nanocrystalline branches directly grown on three-dimensional (3D) porous Cu foam were fabricated using an easy and facile solution processing method without a binder and conductive agent for the first time. The synthesis procedure is quick and does not require complex routes. The structure and morphology of the as-deposited CuS/Cu films were characterized by X-ray diffraction and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and transmission electron spectroscopy, respectively. Pure crystalline hexagonal structured CuS without impurities were obtained for the most saturated S solution. Electrochemical testing of CuS/Cu foam electrodes showed a reasonable capacity of 450 mAh·g⁻¹ at 0.1 C and excellent cyclability, which might be attributed to the unique 3D structure of the current collector and hierarchical nanocrystalline branches that provide fast diffusion and a large surface area. Full article

One of the most challenging targets in oxygen reduction reaction (ORR) electrocatalysts based on N-doped carbon materials is the control of the pore structure and obtaining nanostructured thin films that can easily be incorporated on the current collector. The carbonization of nitrogen-containing polymers and the heat treatment of a mixture of carbon materials and nitrogen precursor are the most common methods for obtaining N-doped carbon materials. However, in this synthetic protocols, the surface area and pore distribution are not controlled. This work enables the preparation of 2D-ordered N-doped carbon materials through the carbonization of 2D polyaniline. For that purpose, aniline has been electropolymerized within the porous structure of two different templates (ordered mesoporous Silica and ordered mesoporous Titania thin films). Thus, aniline has been impregnated into the porous structure and subsequently electropolymerized by means of chronoamperometry at constant potential. The resultant samples were heat-treated at 900 °C with the aim of obtaining 2D N-doped carbon materials within the template structures. Polyaniline and polyaniline-derived carbon materials have been analyzed via XPS and TEM and characterized by electrochemical measurements. It is worth noting that the obtained 2D-ordered mesoporous N-doped carbon materials have proved to be highly active electrocatalysts for the ORR because of the formation of quaternary nitrogen species during the heat treatment. Full article

Lithium–sulfur batteries (LSBs) are regarded as one of the most promising energy-recycling storage systems due to their high energy density (up to 2600 Wh kg⁻¹), high theoretical specific capacity (as much as 1672 mAh g⁻¹), environmental friendliness, and low cost. Originating from the complicated redox of lithium polysulfide intermediates, Li–S batteries suffer from several problems, restricting their application and commercialization. Such problems include the shuttle effect of polysulfides (Li₂S_x (2 < x ≤ 8)), low electronic conductivity of S/Li₂S/Li₂S₂, and large volumetric expansion of S upon lithiation. In this study, a lotus root-like nitrogen-doped carbon nanofiber (NCNF) structure, assembled with vanadium nitride (VN) catalysts, was fabricated as a 3D freestanding current collector for high performance LSBs. The lotus root-like NCNF structure, which had a multichannel porous nanostructure, was able to provide excellent (ionically/electronically) conductive networks, which promoted ion transport and physical confinement of lithium polysulfides. Further, the structure provided good electrolyte penetration, thereby enhancing the interface contact with active S. VN, with its narrow resolved band gap, showed high electrical conductivity, high catalytic effect and polar chemical adsorption of lithium polysulfides, which is ideal for accelerating the reversible redox kinetics of intermediate polysulfides to improve the utilization of S. Tests showed that the VN-decorated multichannel porous carbon nanofiber structure retained a high specific capacity of 1325 mAh g⁻¹ after 100 cycles at 0.1 C, with a low capacity decay of 0.05% per cycle, and demonstrated excellent rate capability. Full article

In this study, we present a three-dimensional (3-D), multi-scale, multi-physics lithium-ion battery (LIB) model wherein a microscale spherical particle model is applied to an electrode particle domain and a comprehensive 3-D continuum model is applied to a single cell domain consisting of current collectors, porous electrodes, and a separator. Particular emphasis is placed on capturing the phase transition process inside the lithium iron phosphate (LFP) particles that significantly influences the LIB charge and discharge behaviors. The model is first validated against the experimental data measured at various discharge rates. In general, the model predictions compare well with the experimental data and further highlight key electrochemical and transport phenomena occurring in LIBs. Besides elucidating the phase transition evolution inside LFP particles and location-specific heat generation mechanism, multi-dimensional contours of species concentration, temperature, and current density are analyzed under a 3-D cell configuration to provide valuable insight into the charge and discharge characteristics of LIBs. The present multi-scale LIB model can be applied to a realistic LIB geometry to search for the optimal design and operating conditions. Full article

New three-dimensional (3D) porous electrode concepts are required to overcome limitations in Li-ion batteries in terms of morphology (e.g., shapes, dimensions), mechanical stability (e.g., flexibility, high electroactive mass loadings), and electrochemical performance (e.g., low volumetric energy densities and rate capabilities). Here a new electrode concept is introduced based on the direct growth of vertically-aligned carbon nanotubes (VA-CNTs) on embroidered Cu current collectors. The direct growth of VA-CNTs was achieved by plasma-enhanced chemical vapor deposition (PECVD), and there was no application of any post-treatment or cleaning procedure. The electrochemical behavior of the as-grown VA-CNTs was analyzed by charge/discharge cycles at different specific currents and with electrochemical impedance spectroscopy (EIS) measurements. The results were compared with values found in the literature. The as-grown VA-CNTs exhibit higher specific capacities than graphite and pristine VA-CNTs found in the literature. This together with the possibilities that the Cu embroidered structures offer in terms of specific surface area, total surface area, and designs provide a breakthrough in new 3D electrode concepts. Full article

Well-ordered 3D mesoporous indium tin oxide (ITO) films obtained by a templated sol-gel route are discussed as conductive porous current collectors. This paper explores the use of such films modified by electrochemical deposition of zinc oxide (ZnO) on the pore walls to improve the electron transport in dye-sensitized solar cells (DSSCs). Mesoporous ITO film were dip-coated with pore sizes of 20–25 nm and 40–45 nm employing novel poly(isobutylene)-b-poly(ethylene oxide) block copolymers as structure-directors. After electrochemical deposition of ZnO and sensitization with the indoline dye D149 the films were tested as photoanodes in DSSCs. Short ZnO deposition times led to strong back reaction of photogenerated electrons from non-covered ITO to the electrolyte. ITO films with larger pores enabled longer ZnO deposition times before pore blocking occurred, resulting in higher efficiencies, which could be further increased by using thicker ITO films consisting of five layers, but were still lower compared to nanoporous ZnO films electrodeposited on flat ITO. The major factors that currently limit the application are the still low thickness of the mesoporous ITO films, too small pore sizes and non-ideal geometries that do not allow obtaining full coverage of the ITO surface with ZnO before pore blocking occurs. Full article