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19 pages, 5051 KiB

Open AccessArticle

Imidazole-Based Lithium Salt LiHDI as a Solid Electrolyte Interphase-Stabilising Additive for Lithium-Conducting Electrolytes

by Marek Broszkiewicz, Bartosz Brzozowski, Tomasz Trzeciak, Aldona Zalewska, Jacek Ryl and Leszek Niedzicki

Molecules 2024, 29(4), 804; https://doi.org/10.3390/molecules29040804 - 09 Feb 2024

Viewed by 764

Abstract

Lithium salt LiHDI (lithium 4,5-dicyano-2-(n-heptafluoropropyl)imidazolide) is proposed as a solid electrolyte interphase-stabilising additive for lithium-ion batteries, which can be added in a smaller amount than fluoroethylene carbonate (FEC) and vinylene carbonate (VC) additives. Electrolytes containing either lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI) or battery-standard [...] Read more.

Lithium salt LiHDI (lithium 4,5-dicyano-2-(n-heptafluoropropyl)imidazolide) is proposed as a solid electrolyte interphase-stabilising additive for lithium-ion batteries, which can be added in a smaller amount than fluoroethylene carbonate (FEC) and vinylene carbonate (VC) additives. Electrolytes containing either lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI) or battery-standard LiPF₆ were tested with various amounts of LiHDI additive. Chemical stability in the presence of water and the thermal stability of LiHDI are on par with LiTDI. LiHDI additive does not negatively affect the properties of electrolytes. Conductivity measurements of solutions, galvanostatic cycling of graphite-LiFePO₄ cells at room temperature, cells’ cycling at 60 °C, internal cell resistance monitoring during cycling, and XPS analysis of electrodes’ surfaces after cycling have been performed. LiHDI, unlike the FEC-VC mixture, does not negatively affect the properties of the electrolyte. Cycling showed improved capacity retention with LiHDI additive with both graphite and LiFePO₄ as capacity-limiting electrodes over samples without additives. At elevated temperatures, samples with LiHDI exhibited better capacity retention during cycling than those with FEC-VC. Internal cell resistance can be correlated with capacity retention. XPS results show changes in the composition of SEI depending on the composition of the electrolyte and the duration of cycling. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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15 pages, 4993 KiB

Open AccessArticle

In Situ Growth of Sodium Manganese Hexacyanoferrate on Carbon Nanotubes for High-Performance Sodium-Ion Batteries

by Can Guo, Jianxiong Xing, Ali Shamshad, Jicheng Jiang, Donghuang Wang, Xin Wang, Yixuan Bai, Haifeng Chen, Wenwu Sun, Naying An and Aijun Zhou

Molecules 2024, 29(2), 313; https://doi.org/10.3390/molecules29020313 - 08 Jan 2024

Cited by 1 | Viewed by 845

Abstract

Sodium manganese hexacyanoferrate (NaMnHCF) has emerged as a research hotspot among Prussian blue analogs for sodium-ion battery cathode materials due to its advantages of high voltage, high specific capacity, and abundant raw materials. However, its practical application is limited by its poor electronic [...] Read more.

Sodium manganese hexacyanoferrate (NaMnHCF) has emerged as a research hotspot among Prussian blue analogs for sodium-ion battery cathode materials due to its advantages of high voltage, high specific capacity, and abundant raw materials. However, its practical application is limited by its poor electronic conductivity. In this study, we aim to solve this problem through the in situ growth of NaMnHCF on carbon nanotubes (CNTs) using a simple coprecipitation method. The results show that the overall electronic conductivity of NaMnHCF is significantly improved after the introduction of CNTs. The NaMnHCF@10%CNT sample presents a specific capacity of 90 mA h g⁻¹, even at a current density of 20 C (2400 mA g⁻¹). The study shows that the optimized composite exhibits a superior electrochemical performance at different mass loadings (from low to high), which is attributed to the enhanced electron transport and shortened electron pathway. Surprisingly, the cycling performance of the composites was also improved, resulting from decreased polarization and the subsequent reduction in the side reactions at the cathode/electrolyte interface. Furthermore, we revealed the evolution of potential plateau roots from the extraction of crystal water during the charge–discharge process of NaMnHCF based on the experimental results. This study is instructive not only for the practical application of NaMnHCF materials but also for advancing our scientific understanding of the behavior of crystal water during the charge–discharge process. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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15 pages, 2861 KiB

Open AccessArticle

Effect of Calcination Temperature on the Activity of Unsupported IrO₂ Electrocatalysts for the Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolyzers

by Angeliki Banti, Kalliopi Maria Papazisi, Stella Balomenou and Dimitrios Tsiplakides

Molecules 2023, 28(15), 5827; https://doi.org/10.3390/molecules28155827 - 02 Aug 2023

Cited by 2 | Viewed by 1292

Abstract

Polymer electrolyte membrane (PEM) water electrolyzers suffer mainly from slow kinetics regarding the oxygen evolution reaction (OER). Noble metal oxides, like IrO₂ and RuO₂, are generally more active for OER than metal electrodes, exhibiting low anodic overpotentials and high catalytic [...] Read more.

Polymer electrolyte membrane (PEM) water electrolyzers suffer mainly from slow kinetics regarding the oxygen evolution reaction (OER). Noble metal oxides, like IrO₂ and RuO₂, are generally more active for OER than metal electrodes, exhibiting low anodic overpotentials and high catalytic activity. However, issues like electrocatalyst stability under continuous operation and cost minimization through a reduction in the catalyst loading are of great importance to the research community. In this study, unsupported IrO₂ of various particle sizes (different calcination temperatures) were evaluated for the OER and as anode electrodes for PEM water electrolyzers. The electrocatalysts were synthesized by the modified Adams method, and the effect of calcination temperature on the properties of IrO₂ electrocatalysts is investigated. Physicochemical characterization was conducted using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurement, high-resolution transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. For the electrochemical performance of synthesized electrocatalysts in the OER, cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were conducted in a typical three-cell electrode configuration, using glassy carbon as the working electrode, which the synthesized electrocatalysts were cast on in a 0.5 M H₂SO₄ solution. The materials, as anode PEM water electrolysis electrodes, were further evaluated in a typical electrolytic cell using a Nafion^®115 membrane as the electrolyte and Pt/C as the cathode electrocatalyst. The IrO₂ electrocatalyst calcined at 400 °C shows high crystallinity with a 1.24 nm particle size, a high specific surface area (185 m² g⁻¹), and a high activity of 177 mA cm⁻² at 1.8 V for PEM water electrolysis. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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17 pages, 6142 KiB

Open AccessArticle

Electrode Potential-Dependent Studies of Protein Adsorption on Ti₆Al₄V Alloy

by Belma Duderija, Alejandro González-Orive, Christoph Ebbert, Vanessa Neßlinger, Adrian Keller and Guido Grundmeier

Molecules 2023, 28(13), 5109; https://doi.org/10.3390/molecules28135109 - 29 Jun 2023

Viewed by 1036

Abstract

This article presents the potential-dependent adsorption of two proteins, bovine serum albumin (BSA) and lysozyme (LYZ), on Ti₆Al₄V alloy at pH 7.4 and 37 °C. The adsorption process was studied on an electropolished alloy under cathodic and anodic overpotentials, [...] Read more.

This article presents the potential-dependent adsorption of two proteins, bovine serum albumin (BSA) and lysozyme (LYZ), on Ti₆Al₄V alloy at pH 7.4 and 37 °C. The adsorption process was studied on an electropolished alloy under cathodic and anodic overpotentials, compared to the open circuit potential (OCP). To analyze the adsorption process, various complementary interface analytical techniques were employed, including PM-IRRAS (polarization-modulation infrared reflection-absorption spectroscopy), AFM (atomic force microscopy), XPS (X-ray photoelectron spectroscopy), and E-QCM (electrochemical quartz crystal microbalance) measurements. The polarization experiments were conducted within a potential range where charging of the electric double layer dominates, and Faradaic currents can be disregarded. The findings highlight the significant influence of the interfacial charge distribution on the adsorption of BSA and LYZ onto the alloy surface. Furthermore, electrochemical analysis of the protein layers formed under applied overpotentials demonstrated improved corrosion protection properties. These studies provide valuable insights into protein adsorption on titanium alloys under physiological conditions, characterized by varying potentials of the passive alloy. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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20 pages, 4868 KiB

Open AccessArticle

Improving the Energy Storage of Supercapattery Devices through Electrolyte Optimization for Mg(NbAgS)_x(SO₄)_y Electrode Materials

by Haseebul Hassan, Muhammad Waqas Iqbal, Sarah Alharthi, Mohammed A. Amin, Amir Muhammad Afzal, Jacek Ryl and Mohd Zahid Ansari

Molecules 2023, 28(12), 4737; https://doi.org/10.3390/molecules28124737 - 13 Jun 2023

Cited by 14 | Viewed by 1284

Abstract

Electrolytes are one of the most influential aspects determining the efficiency of electrochemical supercapacitors. Therefore, in this paper, we investigate the effect of introducing co-solvents of ester into ethylene carbonate (EC). The use of ester co-solvents in ethylene carbonate (EC) as an electrolyte [...] Read more.

Electrolytes are one of the most influential aspects determining the efficiency of electrochemical supercapacitors. Therefore, in this paper, we investigate the effect of introducing co-solvents of ester into ethylene carbonate (EC). The use of ester co-solvents in ethylene carbonate (EC) as an electrolyte for supercapacitors improves conductivity, electrochemical properties, and stability, allowing greater energy storage capacity and increased device durability. We synthesized extremely thin nanosheets of niobium silver sulfide using a hydrothermal process and mixed them with magnesium sulfate in different wt% ratios to produce Mg(NbAgS)_x)(SO₄)_y. The synergistic effect of MgSO₄ and NbS₂ increased the storage capacity and energy density of the supercapattery. Multivalent ion storage in Mg(NbAgS)_x(SO₄)_y enables the storage of a number of ions. The Mg(NbAgS)_x)(SO₄)_y was directly deposited on a nickel foam substrate using a simple and innovative electrodeposition approach. The synthesized silver Mg(NbAgS)_x)(SO₄)_y provided a maximum specific capacity of 2087 C/g at 2.0 A/g current density because of its substantial electrochemically active surface area and linked nanosheet channels which aid in ion transportation. The supercapattery was designed with Mg(NbAgS)_x)(SO₄)_y and activated carbon (AC) achieved a high energy density of 79 Wh/kg in addition to its high power density of 420 W/kg. The supercapattery (Mg(NbAgS)_x)(SO₄)_y//AC) was subjected to 15,000 consecutive cycles. The Coulombic efficiency of the device was 81% after 15,000 consecutive cycles while retaining a 78% capacity retention. This study reveals that the use of this novel electrode material (Mg(NbAgS)_x(SO₄)_y) in ester-based electrolytes has great potential in supercapattery applications. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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Review

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23 pages, 15008 KiB

Open AccessReview

Review of the Real-Time Monitoring Technologies for Lithium Dendrites in Lithium-Ion Batteries

by Yifang Liang, Daiheng Song, Wenju Wu, Yanchao Yu, Jun You and Yuanpeng Liu

Molecules 2024, 29(9), 2118; https://doi.org/10.3390/molecules29092118 - 03 May 2024

Viewed by 281

Abstract

Lithium-ion batteries (LIBs) have the advantage of high energy density, which has attracted the wide attention of researchers. Nevertheless, the growth of lithium dendrites on the anode surface causes short life and poor safety, which limits their application. Therefore, it is necessary to [...] Read more.

Lithium-ion batteries (LIBs) have the advantage of high energy density, which has attracted the wide attention of researchers. Nevertheless, the growth of lithium dendrites on the anode surface causes short life and poor safety, which limits their application. Therefore, it is necessary to deeply understand the growth mechanism of lithium dendrites. Here, the growth mechanism of lithium dendrites is briefly summarized, and the real-time monitoring technologies of lithium dendrite growth in recent years are reviewed. The real-time monitoring technologies summarized here include in situ X-ray, in situ Raman, in situ resonance, in situ microscopy, in situ neutrons, and sensors, and their representative studies are summarized. This paper is expected to provide some guidance for the research of lithium dendrites, so as to promote the development of LIBs. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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28 pages, 623 KiB

Open AccessReview

Ag(e)ing and Degradation of Supercapacitors: Causes, Mechanisms, Models and Countermeasures

by Xuecheng Chen, Yuping Wu and Rudolf Holze

Molecules 2023, 28(13), 5028; https://doi.org/10.3390/molecules28135028 - 27 Jun 2023

Cited by 5 | Viewed by 1302

Abstract

The most prominent and highly visible advantage attributed to supercapacitors of any type and application, beyond their most notable feature of high current capability, is their high stability in terms of lifetime, number of possible charge/discharge cycles or other stability-related properties. Unfortunately, actual [...] Read more.

The most prominent and highly visible advantage attributed to supercapacitors of any type and application, beyond their most notable feature of high current capability, is their high stability in terms of lifetime, number of possible charge/discharge cycles or other stability-related properties. Unfortunately, actual devices show more or less pronounced deterioration of performance parameters during time and use. Causes for this in the material and component levels, as well as on the device level, have only been addressed and discussed infrequently in published reports. The present review attempts a complete coverage on these levels; it adds in modelling approaches and provides suggestions for slowing down ag(e)ing and degradation. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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32 pages, 26676 KiB

Open AccessReview

Mechanistic Aspects of the Electrochemical Oxidation of Aliphatic Amines and Aniline Derivatives

by Ashwin K. V. Mruthunjaya and Angel A. J. Torriero

Molecules 2023, 28(2), 471; https://doi.org/10.3390/molecules28020471 - 04 Jan 2023

Cited by 16 | Viewed by 3358

Abstract

The electrochemical oxidation of amines is an essential alternative to the conventional chemical transformation that provides critical routes for synthesising and modifying a wide range of chemically useful molecules, including pharmaceuticals and agrochemicals. As a result, the anodic reactivity of these compounds has [...] Read more.

The electrochemical oxidation of amines is an essential alternative to the conventional chemical transformation that provides critical routes for synthesising and modifying a wide range of chemically useful molecules, including pharmaceuticals and agrochemicals. As a result, the anodic reactivity of these compounds has been extensively researched over the past seven decades. However, the different mechanistic aspects of the electrochemical oxidation of amines have never been discussed from a comprehensive and general point of view. This review examines the oxidation mechanism of aliphatic amines, amides, aniline and aniline derivatives, carbamates, and lactams, either directly oxidised at different electrode surfaces or indirectly oxidised by a reversible redox molecule, in which the reactive form was generated in situ. The mechanisms are compared and simplified to understand all possible pathways for the oxidation of amines using only a few general mechanisms. Examples of the application of these oxidation reactions are also provided. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Electrochemistry)

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