Future Directions and Challenges

Endres, Frank; Abbott, Andrew P.; MacFarlane, Douglas R.

doi:10.1002/9783527682706.ch14

Cited by 28 publications

(53 citation statements)

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“…The quantitative validity of the here presented CV curves, therefore, is limited, which always has to be considered when using pseudo-reference electrodes. [65][66][67] CVs of the solutions of CoO, Co 3 O 4 and LiCoO 2 (Figure 7, solid lines) show a cathodic current increase within the electrochemical window of the IL which we attribute to the reduction of cobalt(II). The cathodic onset potential ranges from À 1.3 V to À 1.6 V. Oxidation peaks with maxima ranging from À 0.6 V to À 0.9 V are attributed to cobalt stripping.…”

Section: Electrodeposition Of Cobaltmentioning

confidence: 85%

“…However, in preliminary experiments with ferrocene‐containing solutions, we observed shifting ferrocene/ferrocenium oxidation and reduction potentials, indicating that the potential of the platinum pseudo‐reference electrode is also not entirely stable. The quantitative validity of the here presented CV curves, therefore, is limited, which always has to be considered when using pseudo‐reference electrodes [65–67] …”

Section: Resultsmentioning

confidence: 99%

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Cobalt Deposition from Ionothermally Dissolved Cobalt Oxides

2023

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Owing to the environmental problems of numerous metal production processes, there is a growing need for more energyefficient approaches. Cobalt is considered a strategic element that is extracted not only from ores but also from spent Li-ion batteries. One promising new approach is ionometallurgy, which is the extraction of metal oxides by ionic liquids (ILs). This study concerns new investigations into ionometallurgical processing of CoO, Co 3 O 4 , and LiCoO 2 in the IL betainium bis(trifluoromethylsulfonyl)imide, [Hbet][NTf 2 ]. Three crystal structures of cobaltÀ betaine complex compounds and combined spectroscopic and diffraction studies provide insights into the dissolution process. In addition, an optimized dissolution procedure for metal oxides is presented, avoiding the previously reported decomposition of the IL. Subsequent cobalt electrodeposition is only possible from cationic complex species, highlighting the importance of a thorough understanding of the complex equilibria. The presented method is also compared to other recently reported approaches.

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Section: Electrodeposition Of Cobaltmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Cobalt Deposition from Ionothermally Dissolved Cobalt Oxides

2023

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“…ILs, salts in the liquid state, have been widely used as extractive solvents or directly as extractants due to the distinctive and unique properties they possess, such as negligible vapor pressure, wide solubility range, and flame-retardant property, as well as their tunable nature by simple variation of the building anions and cations. , In addition, in the field of recycling, mainly of platinum group metal catalysts (PGMs), ILs have been successfully used for the extraction of metal ions but also for the dissolution of metals from various solutions and supports. − Particularly, phosphonium-based ionic liquids have been reported to be effective candidates for the extraction and separation of PGMs. − …”

Section: Introductionmentioning

confidence: 99%

Direct Extraction of Platinum Nanoparticles from Fuel Cells with Ionic Liquids: Part 1. Implementation and Optimization of the Process Parameters

Coudray

Billy

Mendil‐Jakani

et al. 2023

Ind. Eng. Chem. Res.

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The cost of proton-exchange membrane fuel cells (PEMFCs) comes mainly from platinum nanoparticles, which are used as a catalyst; it represents 40% of the stack price for large-scale production. It is thus crucial to reduce their cost to produce cheaper devices, which could compete with fossil energy on the industrial market. One way to reach this goal would be to recover the Pt catalyst from the membrane electrode assembly (MEA) for further recycling. For now, current end-of-life (EoL) technologies are mainly based on hydrometallurgical and pyro-hydrometallurgical processes for recovering platinum, which are identified to be energy-demanding and generate high amounts of toxic liquids and gaseous effluents. To meet sustainability and circular economy criteria in the recycling of noble metals, our approach was based on the use of ionic liquids (ILs) to both extract and stabilize platinum in the form of metallic nanoparticles (Pt NPs), thus avoiding the use of strong acids and the emissions of hydrofluoric acid (HF), which make the waste management of conventional processes complicated. Thirteen different ILs were selected to investigate how their structural composition as well as their physicochemical properties may affect the extent of Pt extraction, and their ability to stabilize detached nanoparticles. This screening study showed that ionic liquids could interact with all of the elements of the active layer and allowed us to delineate the key parameters that ILs should possess to achieve the best extraction performance: hydrophilicity, hydrogen bonding ability, and the coordinating ability of the anions. The best result was obtained with trihexyltetradecylphosphonium chloride (P 66614 Cl, commercial Cyphos IL 101; 120 °C and 6 h), which not only led to an extraction extent up to >90% of the Pt present initially on the catalytic layer but also allowed in a single step to detach the Pt NPs from the carbon support. The metallic Pt NPs suspended in P 66614 Cl were found stable with diameters of around 2−3 nm, as evidenced by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) analyses. Compared to conventional processes, this safer and convenient route to recover Pt catalysts from MEAs directly in their metallic form by simple immersion of the electrode in the appropriate IL opens up new perspectives in terms of rare earth metal recycling from material composites.

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“…Room-temperature ionic liquids (RTILs), liquid salts at ambient temperature, have received significant interest as promising electrolyte materials. Their wide electrochemical windows are advantageous for various applications such as batteries, supercapacitors, plating, and CO 2 reduction. − The low vapor pressure and nonflammable nature enable safe use in such applications without explosion or deformation of devices and, in addition, open a way to operations at high-temperature environments (up to 200–250 °C).…”

Section: Introductionmentioning

confidence: 99%

Origin of Temperature-Dependent Overpotential of Co Electrodeposition in an Ionic Liquid

Motobayashi,

Nakagawa,

Shibamura

et al. 2023

J. Phys. Chem. C

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Electrodeposition in ionic liquids is a promising process for surface functionalization as well as material recycling with a high current efficiency. For metal electrodeposition in ionic liquids, overpotentials, which were problematically high at room temperature (RT), significantly decreased with elevating temperatures. To reveal the microscopic origin of such a remarkable temperature dependence, we investigated the interfacial structures of 1-propyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)amide [C 3 mpyr][TFSA] under Co electrodeposition reaction on an Au electrode by using surface-enhanced infrared absorption spectroscopy (SEIRAS) at various temperatures. In situ interfacial observation indicated that the onset potentials of anion-to-cation replacement in the first ionic layer showed a more positive onset at higher temperatures. Even with such a modification, the onsets of the first ionic layer replacement still agree with those of Co electrodeposition in the entire temperature range between RT and 370 K. This agreement validates that the interfacial structure dependence of the electrodeposition reactivity is the origin of the high electrodeposition overpotential, as previously discussed at RT.

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Future Directions and Challenges

Cited by 28 publications

References 0 publications

Cobalt Deposition from Ionothermally Dissolved Cobalt Oxides

Cobalt Deposition from Ionothermally Dissolved Cobalt Oxides

Direct Extraction of Platinum Nanoparticles from Fuel Cells with Ionic Liquids: Part 1. Implementation and Optimization of the Process Parameters

Origin of Temperature-Dependent Overpotential of Co Electrodeposition in an Ionic Liquid

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