Research

18 pages, 24917 KiB

Open AccessEditor’s ChoiceArticle

Using Hierarchically Structured, Nanoporous Particles as Building Blocks for NCM111 Cathodes

by Werner Bauer, Marcus Müller, Luca Schneider, Marcel Häringer, Nicole Bohn, Joachim R. Binder, Julian Klemens, Philip Scharfer, Wilhelm Schabel and Helmut Ehrenberg

Nanomaterials 2024, 14(2), 134; https://doi.org/10.3390/nano14020134 - 06 Jan 2024

Cited by 1 | Viewed by 920

Abstract

Nanoparticles have many advantages as active materials, such as a short diffusion length, low charge transfer resistance, or a reduced probability of cracking. However, their low packing density makes them unsuitable for commercial battery applications. Hierarchically structured microparticles are synthesized from nanoscale primary [...] Read more.

Nanoparticles have many advantages as active materials, such as a short diffusion length, low charge transfer resistance, or a reduced probability of cracking. However, their low packing density makes them unsuitable for commercial battery applications. Hierarchically structured microparticles are synthesized from nanoscale primary particles by targeted aggregation. Due to their open accessible porosity, they retain the advantages of nanomaterials but can be packed much more densely. However, the intrinsic porosity of the secondary particles leads to limitations in processing properties and increases the overall porosity of the electrode, which must be balanced against the improved rate stability and increased lifetime. This is demonstrated for an established cathode material for lithium-ion batteries (LiNi_0.33Co_0.33Mn_0.33O₂, NCM111). For active materials with low electrical or ionic conductivity, especially post-lithium systems, hierarchically structured particles are often the only way to produce competitive electrodes. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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13 pages, 3379 KiB

Open AccessArticle

Effects of Nickel Impregnation on the Catalytic Removal of Nitric Oxide by Polyimide-Based Activated Carbon Fibers

by Hun-Seung Jeong and Byung-Joo Kim

Nanomaterials 2023, 13(16), 2297; https://doi.org/10.3390/nano13162297 - 10 Aug 2023

Cited by 1 | Viewed by 807

Abstract

Activated carbon fibers (ACFs) are beneficial for adsorbing harmful gases because of the well-developed micropores on their surface. Usually, the physical adsorption of harmful gases by ACFs is limited by their textural properties. In this study, the effect of nickel particle catalyst impregnation [...] Read more.

Activated carbon fibers (ACFs) are beneficial for adsorbing harmful gases because of the well-developed micropores on their surface. Usually, the physical adsorption of harmful gases by ACFs is limited by their textural properties. In this study, the effect of nickel particle catalyst impregnation on the physicochemical removal of nitric oxide (NO) by polyimide (PI)-based ACFs (PI-ACFs) was investigated. Ni(NO₃)₂ was used as the precursor of nickel particle catalysts and impregnated on ACFs as a function of concentrations. The Ni(NO₃)₂/ACFs were then thermally reduced in an argon atmosphere containing 4% hydrogen (400 °C, 1 h). The gases generated during heat treatment were verified using Fourier transform infrared spectroscopy, and the impregnation amount of metallic nickel was also calculated based on the gas amount generated. The specific surface areas of the ACF and Ni-ACFs were determined to be 1010–1180 m²/g, while the nickel impregnation amount was 0.85–5.28 mg/g. The NO removal capacity of the Ni-ACF was found to be enhanced with the addition of Ni catalysts. In addition, metallic nickel particles on the ACFs maintained their chemical molecular structures before and after the NO removal tests.a Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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10 pages, 2437 KiB

Open AccessArticle

Ultrafast-Laser Micro-Structuring of LiNi_0.8Mn_0.1Co_0.1O₂ Cathode for High-Rate Capability of Three-Dimensional Li-ion Batteries

by Minh Xuan Tran, Peter Smyrek, Jihun Park, Wilhelm Pfleging and Joong Kee Lee

Nanomaterials 2022, 12(21), 3897; https://doi.org/10.3390/nano12213897 - 04 Nov 2022

Cited by 12 | Viewed by 1696

Abstract

Femtosecond ultrafast-laser micro-patterning was employed to prepare a three-dimensional (3D) structure for the tape-casting Ni-rich LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) cathode. The influences of laser structuring on the electrochemical performance of NMC811 were investigated. The 3D-NMC811 cathode retained capacities [...] Read more.

Femtosecond ultrafast-laser micro-patterning was employed to prepare a three-dimensional (3D) structure for the tape-casting Ni-rich LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) cathode. The influences of laser structuring on the electrochemical performance of NMC811 were investigated. The 3D-NMC811 cathode retained capacities of 77.8% at 2 C of initial capacity at 0.1 C, which was thrice that of 2D-NMC811 with an initial capacity of 27.8%. Cyclic voltammetry (CV) and impedance spectroscopy demonstrated that the 3D electrode improved the Li⁺ ion transportation at the electrode–electrolyte interface, resulting in a higher rate capability. The diffusivity coefficient D_Li+, calculated by both CV and electrochemical impedance spectroscopy, revealed that 3D-NMC811 delivered faster Li⁺ ion transportation with higher D_Li+ than that of 2D-NMC811. The laser ablation of the active material also led to a lower charge–transfer resistance, which represented lower polarization and improved Li⁺ ion diffusivity. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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16 pages, 4626 KiB

Open AccessArticle

Gallium-Telluride-Based Composite as Promising Lithium Storage Material

by Vo Pham Hoang Huy, Il Tae Kim and Jaehyun Hur

Nanomaterials 2022, 12(19), 3362; https://doi.org/10.3390/nano12193362 - 27 Sep 2022

Cited by 2 | Viewed by 1674

Abstract

Various applications of gallium telluride have been investigated, such as in optoelectronic devices, radiation detectors, solar cells, and semiconductors, owing to its unique electronic, mechanical, and structural properties. Among the various forms of gallium telluride (e.g., GaTe, Ga₃Te₄, Ga [...] Read more.

Various applications of gallium telluride have been investigated, such as in optoelectronic devices, radiation detectors, solar cells, and semiconductors, owing to its unique electronic, mechanical, and structural properties. Among the various forms of gallium telluride (e.g., GaTe, Ga₃Te₄, Ga₂Te₃, and Ga₂Te₅), we propose a gallium (III) telluride (Ga₂Te₃)-based composite (Ga₂Te₃-TiO₂-C) as a prospective anode for Li-ion batteries (LIBs). The lithiation/delithiation phase change mechanism of Ga₂Te₃ was examined. The existence of the TiO₂-C hybrid buffering matrix improved the electrical conductivity as well as mechanical integrity of the composite anode for LIBs. Furthermore, the impact of the C concentration on the performance of Ga₂Te₃-TiO₂-C was comprehensively studied through cyclic voltammetry, differential capacity analysis, and electrochemical impedance spectroscopy. The Ga₂Te₃-TiO₂-C electrode showed high rate capability (capacity retention of 96% at 10 A g⁻¹ relative to 0.1 A g⁻¹) as well as high reversible specific capacity (769 mAh g⁻¹ after 300 cycles at 100 mA g⁻¹). The capacity of Ga₂Te₃-TiO₂-C was enhanced by the synergistic interaction of TiO₂ and amorphous C. It thereby outperformed the majority of the most recent Ga-based LIB electrodes. Thus, Ga₂Te₃-TiO₂-C can be thought of as a prospective anode for LIBs in the future. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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17 pages, 11382 KiB

Open AccessArticle

Modelling and Optimisation of Laser-Structured Battery Electrodes

by Lukas Schweighofer, Bernd Eschelmüller, Katja Fröhlich, Wilhelm Pfleging and Franz Pichler

Nanomaterials 2022, 12(9), 1574; https://doi.org/10.3390/nano12091574 - 06 May 2022

Cited by 8 | Viewed by 2695

Abstract

An electrochemical multi-scale model framework for the simulation of arbitrarily three-dimensional structured electrodes for lithium-ion batteries is presented. For the parameterisation, the electrodes are structured via laser ablation, and the model is fit to four different, experimentally electrochemically tested cells. The parameterised model [...] Read more.

An electrochemical multi-scale model framework for the simulation of arbitrarily three-dimensional structured electrodes for lithium-ion batteries is presented. For the parameterisation, the electrodes are structured via laser ablation, and the model is fit to four different, experimentally electrochemically tested cells. The parameterised model is used to optimise the parameters of three different pattern designs, namely linear, gridwise, and pinhole geometries. The simulations are performed via a finite element implementation in two and three dimensions. The presented model is well suited to depict the experimental cells, and the virtual optimisation delivers optimal geometrical parameters for different C-rates based on the respective discharge capacities. These virtually optimised cells will help in the reduction of prototyping cost and speed up production process parameterisation. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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15 pages, 1975 KiB

Open AccessArticle

Aqueous Manufacturing of Defect-Free Thick Multi-Layer NMC811 Electrodes

by Lukas Neidhart, Katja Fröhlich, Nicolas Eshraghi, Damian Cupid, Franz Winter and Marcus Jahn

Nanomaterials 2022, 12(3), 317; https://doi.org/10.3390/nano12030317 - 19 Jan 2022

Cited by 10 | Viewed by 3315

Abstract

Manufacturing thick electrodes for Li-ion batteries is a challenging task to fulfill, but leads to higher energy densities inside the cell. Water-based processing even adds an extra level of complexity to the procedure. The focus of this work is to implement a multi-layered [...] Read more.

Manufacturing thick electrodes for Li-ion batteries is a challenging task to fulfill, but leads to higher energy densities inside the cell. Water-based processing even adds an extra level of complexity to the procedure. The focus of this work is to implement a multi-layered coating in an industrially relevant process, to overcome issues in electrode integrity and to enable high electrochemical performance. LiNi

_{0.8}

Mn

_{0.1}

Co

_{0.1}

O

_{2}

(NMC811) was used as the active material to fabricate single- and multi-layered cathodes with areal capacities of 8.6 mA h cm⁻². A detailed description of the manufacturing process is given to establish thick defect-free aqueous electrodes. Good inter-layer cohesion and adhesion to the current collector foil are achieved by multi-layering, as confirmed by optical analysis and peel testing. Furthermore, full cells were assembled and rate capability tests were performed. These tests show that by multi-layering, an increase in specific discharge capacity (e.g., 20.7% increase for C/10) can be established for all tested C-rates. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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19 pages, 8146 KiB

Open AccessArticle

Investigation of Fast-Charging and Degradation Processes in 3D Silicon–Graphite Anodes

by Yijing Zheng, Danni Yin, Hans Jürgen Seifert and Wilhelm Pfleging

Nanomaterials 2022, 12(1), 140; https://doi.org/10.3390/nano12010140 - 31 Dec 2021

Cited by 12 | Viewed by 2852

Abstract

The 3D battery concept applied on silicon–graphite electrodes (Si/C) has revealed a significant improvement of battery performances, including high-rate capability, cycle stability, and cell lifetime. 3D architectures provide free spaces for volume expansion as well as additional lithium diffusion pathways into the electrodes. [...] Read more.

The 3D battery concept applied on silicon–graphite electrodes (Si/C) has revealed a significant improvement of battery performances, including high-rate capability, cycle stability, and cell lifetime. 3D architectures provide free spaces for volume expansion as well as additional lithium diffusion pathways into the electrodes. Therefore, the cell degradation induced by the volume change of silicon as active material can be significantly reduced, and the high-rate capability can be achieved. In order to better understand the impact of 3D electrode architectures on rate capability and degradation process of the thick film silicon–graphite electrodes, we applied laser-induced breakdown spectroscopy (LIBS). A calibration curve was established that enables the quantitative determination of the elemental concentrations in the electrodes. The structured silicon–graphite electrode, which was lithiated by 1C, revealed a homogeneous lithium distribution within the entire electrode. In contrast, a lithium concentration gradient was observed on the unstructured electrode. The lithium concentration was reduced gradually from the top to the button of the electrode, which indicated an inhibited diffusion kinetic at high C-rates. In addition, the LIBS applied on a model electrode with micropillars revealed that the lithium-ions principally diffused along the contour of laser-generated structures into the electrodes at elevated C-rates. The rate capability and electrochemical degradation observed in lithium-ion cells can be correlated to lithium concentration profiles in the electrodes measured by LIBS. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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26 pages, 14657 KiB

Open AccessArticle

The Effect of Silicon Grade and Electrode Architecture on the Performance of Advanced Anodes for Next Generation Lithium-Ion Cells

by Alexandra Meyer, Fabian Ball and Wilhelm Pfleging

Nanomaterials 2021, 11(12), 3448; https://doi.org/10.3390/nano11123448 - 20 Dec 2021

Cited by 15 | Viewed by 3159

Abstract

To increase the specific capacity of anodes for lithium-ion cells, advanced active materials, such as silicon, can be utilized. Silicon has an order of magnitude higher specific capacity compared to the state-of-the-art anode material graphite; therefore, it is a promising candidate to achieve [...] Read more.

To increase the specific capacity of anodes for lithium-ion cells, advanced active materials, such as silicon, can be utilized. Silicon has an order of magnitude higher specific capacity compared to the state-of-the-art anode material graphite; therefore, it is a promising candidate to achieve this target. In this study, different types of silicon nanopowders were introduced as active material for the manufacturing of composite silicon/graphite electrodes. The materials were selected from different suppliers providing different grades of purity and different grain sizes. The slurry preparation, including binder, additives, and active material, was established using a ball milling device and coating was performed via tape casting on a thin copper current collector foil. Composite electrodes with an areal capacity of approximately 1.70 mAh/cm² were deposited. Reference electrodes without silicon were prepared in the same manner, and they showed slightly lower areal capacities. High repetition rate, ultrafast laser ablation was applied to these high-power electrodes in order to introduce line structures with a periodicity of 200 µm. The electrochemical performance of the anodes was evaluated as rate capability and operational lifetime measurements including pouch cells with NMC 622 as counter electrodes. For the silicon/graphite composite electrodes with the best performance, up to 200 full cycles at a C-rate of 1C were achieved until end of life was reached at 80% relative capacity. Additionally, electrochemical impedance spectroscopies were conducted as a function of state of health to correlate the used silicon grade with solid electrolyte interface (SEI) formation and charge transfer resistance values. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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16 pages, 4213 KiB

Open AccessArticle

Electrochemical Performance of Thick-Film Li(Ni_0.6Mn_0.2Co_0.2)O₂ Cathode with Hierarchic Structures and Laser Ablation

by Zelai Song, Penghui Zhu, Wilhelm Pfleging and Jiyu Sun

Nanomaterials 2021, 11(11), 2962; https://doi.org/10.3390/nano11112962 - 04 Nov 2021

Cited by 21 | Viewed by 2172

Abstract

The electrochemical performance of lithium-ion batteries is directly influenced by type of active material as well as its morphology. In order to evaluate the impact of particle morphology in thick-film electrodes, Li(Ni_0.6Mn_0.2Co_0.2)O₂ (NMC 622) cathodes with [...] Read more.

The electrochemical performance of lithium-ion batteries is directly influenced by type of active material as well as its morphology. In order to evaluate the impact of particle morphology in thick-film electrodes, Li(Ni_0.6Mn_0.2Co_0.2)O₂ (NMC 622) cathodes with bilayer structure consisting of two different particle sizes were manufactured and electrochemically characterized in coin cells design. The hierarchical thick-film electrodes were generated by multiple casting using NMC 622 (TA) with small particle size of 6.7 µm and NMC 622 (BA) with large particle size of 12.8 µm. Besides, reference electrodes with one type of active material as well as with two type of materials established during mixing process (BT) were manufactured. The total film thickness of all hierarchical composite electrodes were kept constant at 150 µm, while the thicknesses of TA and BA were set at 1:2, 1:1, and 2:1. Meanwhile, three kinds of thin-film cathodes with 70 µm were applied to represent the state-of-the-art approach. Subsequently, ultrafast laser ablation was applied to generate groove structures inside the electrodes. The results demonstrate that cells with thin-film or thick-film cathode only containing TA, cells with bilayer electrode containing TBA 1:2, and cells with laser-structured electrodes show higher capacity at C/2 to 5C, respectively. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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19 pages, 4746 KiB

Open AccessEditor’s ChoiceArticle

Characterization and Laser Structuring of Aqueous Processed Li(Ni_0.6Mn_0.2Co_0.2)O₂ Thick-Film Cathodes for Lithium-Ion Batteries

by Penghui Zhu, Jiahao Han and Wilhelm Pfleging

Nanomaterials 2021, 11(7), 1840; https://doi.org/10.3390/nano11071840 - 16 Jul 2021

Cited by 20 | Viewed by 3234

Abstract

Lithium-ion batteries have led the revolution in portable electronic devices and electrical vehicles due to their high gravimetric energy density. In particular, layered cathode material Li(Ni_0.6Mn_0.2Co_0.2)O₂ (NMC 622) can deliver high specific capacities of about 180 [...] Read more.

Lithium-ion batteries have led the revolution in portable electronic devices and electrical vehicles due to their high gravimetric energy density. In particular, layered cathode material Li(Ni_0.6Mn_0.2Co_0.2)O₂ (NMC 622) can deliver high specific capacities of about 180 mAh/g. However, traditional cathode manufacturing involves high processing costs and environmental issues due to the use of organic binder polyvinylidenfluoride (PVDF) and highly toxic solvent N-methyl-pyrrolidone (NMP). In order to overcome these drawbacks, aqueous processing of thick-film NMC 622 cathodes was studied using carboxymethyl cellulose and fluorine acrylic hybrid latex as binders. Acetic acid was added during the mixing process to obtain slurries with pH values varying from 7.4 to 12.1. The electrode films could be produced with high homogeneity using slurries with pH values smaller than 10. Cyclic voltammetry measurements showed that the addition of acetic acid did not affect the redox reaction of active material during charging and discharging. Rate capability tests revealed that the specific capacities with higher slurry pH values were increased at C-rates above C/5. Cells with laser structured thick-film electrodes showed an increase in capacity by 40 mAh/g in comparison to cells with unstructured electrodes. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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13 pages, 2611 KiB

Open AccessArticle

Effect of Solvent on Fluorescence Emission from Polyethylene Glycol-Coated Graphene Quantum Dots under Blue Light Illumination

by Po-Chih Yang, Yu-Xuan Ting, Siyong Gu, Yasser Ashraf Gandomi, Jianlin Li and Chien-Te Hsieh

Nanomaterials 2021, 11(6), 1383; https://doi.org/10.3390/nano11061383 - 24 May 2021

Cited by 12 | Viewed by 2905

Abstract

To explore aggregate-induced emission (AIE) properties, this study adopts a one-pot hydrothermal route for synthesizing polyethylene glycol (PEG)-coated graphene quantum dot (GQD) clusters, enabling the emission of highly intense photoluminescence under blue light illumination. The hydrothermal synthesis was performed at 300 °C using [...] Read more.

To explore aggregate-induced emission (AIE) properties, this study adopts a one-pot hydrothermal route for synthesizing polyethylene glycol (PEG)-coated graphene quantum dot (GQD) clusters, enabling the emission of highly intense photoluminescence under blue light illumination. The hydrothermal synthesis was performed at 300 °C using o-phenylenediamine as the nitrogen and carbon sources in the presence of PEG. Three different solvents, propylene glycol methyl ether acetate (PGMEA), ethanol, and water, were used for dispersing the PEG-coated GQDs, where extremely high fluorescent emission was achieved at 530–550 nm. It was shown that the quantum yield (QY) of PEG-coated GQD suspensions is strongly dependent on the solvent type. The pristine GQD suspension tends to be quenched (i.e., QY: ~1%) when dispersed in PGMEA (aggregation-caused quenching). However, coating GQD nanoparticles with polyethylene glycol results in substantial enhancement of the quantum yield. When investigating the photoluminescence emission from PEG-coated GQD clusters, the surface tension of the solvents was within the range of from 26.9 to 46.0 mN/m. This critical index can be tuned for assessing the transition point needed to activate the AIE mechanism which ultimately boosts the fluorescence intensity. The one-pot hydrothermal route established in this study can be adopted to engineer PEG-coated GQD clusters with solid-state PL emission capabilities, which are needed for next-generation optical, bio-sensing, and energy storage/conversion devices. Full article

(This article belongs to the Special Issue Functionalized Nanostructures for Novel Energy Storage Systems)

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