Aluminum Chloride Complexes Research Articles

Unlocking Four-electron Conversion in Tellurium Cathodes for Advanced Magnesium-based Dual-ion Batteries.

Magnesium (Mg) batteries hold promise as a large-scale energy storage solution, but their progress has been hindered by the lack of high-performance cathodes. Here, we address this challenge by unlocking the reversible four-electron Te0/Te4+ conversion in elemental Te, enabling the demonstration of superior Mg//Te dual-ion batteries. Specifically, the classic magnesium aluminum chloride complex (MACC) electrolyte is tailored by introducing Mg bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2), which initiates the Te0/Te4+ conversion with two distinct charge-storage steps. Te cathode undergoes Te/TeCl4 conversion involving Cl- as charge carriers, during which a tellurium subchloride phase is presented as an intermediate. Significantly, the Te cathode achieves a high specific capacity of 543 mAh gTe -1 and an outstanding energy density of 850 Wh kgTe -1, outperforming most of the previously reported cathodes. Our electrolyte analysis indicates that the addition of Mg(TFSI)2 reduces the overall ion-molecule interaction and mitigates the strength of ion-solvent aggregation within the MACC electrolyte, which implies the facilized Cl- dissociation from the electrolyte. Besides, Mg(TFSI)2 is verified as an essential buffer to mitigate the corrosion and passivation of Mg anodes caused by the consumption of the electrolyte MgCl2 in Mg//Te dual-ion cells. These findings provide crucial insights into the development of advanced Mg-based dual-ion batteries.

Unlocking Four‐electron Conversion in Tellurium Cathodes for Advanced Magnesium‐based Dual‐ion Batteries

AbstractMagnesium (Mg) batteries hold promise as a large‐scale energy storage solution, but their progress has been hindered by the lack of high‐performance cathodes. Here, we address this challenge by unlocking the reversible four‐electron Te0/Te4+ conversion in elemental Te, enabling the demonstration of superior Mg//Te dual‐ion batteries. Specifically, the classic magnesium aluminum chloride complex (MACC) electrolyte is tailored by introducing Mg bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2), which initiates the Te0/Te4+ conversion with two distinct charge‐storage steps. Te cathode undergoes Te/TeCl4 conversion involving Cl− as charge carriers, during which a tellurium subchloride phase is presented as an intermediate. Significantly, the Te cathode achieves a high specific capacity of 543 mAh gTe−1 and an outstanding energy density of 850 Wh kgTe−1, outperforming most of the previously reported cathodes. Our electrolyte analysis indicates that the addition of Mg(TFSI)2 reduces the overall ion‐molecule interaction and mitigates the strength of ion‐solvent aggregation within the MACC electrolyte, which implies the facilized Cl− dissociation from the electrolyte. Besides, Mg(TFSI)2 is verified as an essential buffer to mitigate the corrosion and passivation of Mg anodes caused by the consumption of the electrolyte MgCl2 in Mg//Te dual‐ion cells. These findings provide crucial insights into the development of advanced Mg‐based dual‐ion batteries.

SYNTHESIS AND MOLECULAR STRUCTURE OF TETRA-3-(4-CYCLOHEXYLPHENOXY)PHTHALOCYANINE ALUMINUM CHLORIDE COMPLEX

This work is devoted to the synthesis and study of the molecular structure of the tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride complex. The synthesis of tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride was carried out by the "nitrile" method. The complex was purified by M60 silica gel column chromatography, eluting with the chromophore. IR-spectroscopy and mass-spectrometry (MALDI-TOF) were used for the identification of the obtained compound. The electronic absorption spectrum was obtained in tetrahydrofurane and interpreted by quantum-chemical calculations in TDDFT approximation. The conformational search was performed utilizing the CREST program and GFN2-xTB approximation, followed by DFT calculations of the “single-point” energies of the found conformations. For each configuration, "single-point" energy calculations were carried out in the B3LYP-D3/dgdzvp approximation and the most energetically favorable structure was identified. It has been established that the most energetically favorable structure of the tetra-3-(4-cyclohexylphenoxy)phthalocyanine aluminum chloride molecule is characterized by a helical mutual arrangement of bulky substituents on the same side of the macrocyclic plane. The interpretation of the electronic absorption spectrum was made on the basis of TDDFT calculations in the B3LYP-D3/def2-TZVP and CAM-B3LYP/def2-TZVP approximations with and without solvent (tetrahydrofuran, THF) within the C-PCM continuum solvation model. For both approximations, taking into account the solvent leads to a shift of the long-wavelength absorption maximum by 25–33 nm towards the experimental value (704 nm). The best agreement with experiment is achieved with the [PCM] CAM-B3LYP/def2-TZVP method.The simulated electronic spectrum is compared with the previously obtained spectra for complexes of Al(Cl) with tetrabenzoporphyrin (ClAlTBP) and tetrapyrazinoporphyrazine (ClAlTPyzPA).

Utilisation of a dianionic pentadentate ligand in group 13 chemistry

Using the pentadentate tetrapyrazolylpyridyl diborate (B2Pz4Py) ligand allowed for the isolation of overall seven group 13 complexes, which have been fully characterised and whose solid-state structures were obtained by single-crystal X-ray diffraction analysis. The aluminium chloride (1) and bromide (2) complexes as well as the gallium chloride (3) and iodide (4) complexes are accessible by deprotonation of the ligand precursors [B2Pz4LiPyH]2 with lithium hexamethyldisilazide and subsequent reaction with aluminium and gallium trihalides. Using indium(I) chloride instead gives rise to the indium(III) bis(trimethylsily)amide complex 5. Chloride abstraction from the aluminium(III) complex 1 using a combination of TlBArF24 and TlPF6 affords the related aluminium(III) fluoride complex 6 while using the gallium(III) complex 3 yields the dinuclear cationic PF2O2-bridged gallium(III) complex 7.

Toward High-Performance Mg/S Batteries with M4-Assisted Mg(AlCl4 )2 /PYR14TFSI/DME Electrolyte and MoS2 @CMK/S Cathode.

Rechargeable magnesium batteries (RMBs) are considered as one of the most promising candidates for next-generation batteries. However, the popularization of RMBs is seriously plagued due to the lack of suitable non-nucleophilic electrolytes and the passivation of Mg anode. Herein, a novel non-nucleophilic electrolyte is developed by introducing (s)-1-methoxy-2-propylamine (M4) into themagnesium aluminum chloride complex (MACC)-like electrolyte. The as-synthesizes Mg(AlCl4 )2 -IL-DME-M4 electrolyte enables robust reversible cycling of Mg plating/stripping with low overpotential, high anodic stability, and ionic conductivity (8.56mScm-1 ). These features should be mainly attributed to the in situ formation of an MgF2 containing Mg2+ -conducting interphase, which dramatically suppresses the passivation and parasitic reaction of Mg anode with electrolyte. Remarkably, the Mg/S batteries assemble with as-synthesize electrolyte and a new type MoS2 @CMK/S cathode deliver unprecedented electrochemical performance. Specifically, the Mg/S battery exhibited the highest reversible capacity up to 1210mAhg-1 at 0.1C, excellent rate capability and satisfactory long-term cycling stability with a reversible capacity of 370mAhg-1 (coulombic efficiency of ≈100%) at 1.0C for 600 cycles. The study findings provide a novel strategy and inspiration for designing efficient non-nucleophilic Mg electrolyte and suitable sulfur-host materials for practical Mg/S battery applications.

Mechanistic Studies on Aluminum-Catalyzed Ring-Opening Alternating Copolymerization of Maleic Anhydride with Epoxides: Ligand Effects and Quantitative Structure-Activity Relationship Model.

Previous work has indicated that aluminum (Al) complexes supported by a bipyridine bisphenolate (BpyBph) ligand exhibit higher activity in the ring-opening copolymerization (ROCOP) of maleic anhydride (MAH) and propylene oxide (PO) than their salen counterparts. Such a ligand effect in Al-catalyzed MAH-PO copolymerization reactions has yet to be clarified. Herein, the origin and applicability of the ligand effect have been explored by density functional theory, based on the mechanistic analysis for chain initiation and propagation. We found that the lower LUMO energy of the (BpyBph)AlCl complex accounts for its higher activity than the (salen)AlCl counterpart in MAH/epoxide copolymerizations. Inspired by the ligand effect, a structure-energy model was further established for catalytic activity (TOF value) predictions. It is found that the LUMO energies of aluminum chloride complexes and their average NBO charges of coordinating oxygen atoms correlate with the catalytic activity (TOF value) of Al complexes (R2 value of 0.98 and '3-fold' cross-validation Q2 value of 0.88). This verified that such a ligand effect is generally applicable in anhydride/epoxide ROCOP catalyzed by aluminum complex and provides hints for future catalyst design.

The influence of polyguanidin on the direction of biochemical processes in wheat (Triti- cum L.) plants.

Modern crop production requires a balance of high and sustainable productivity with maximum safety for the environment, consumers and agricultural workers. The well-known chemical compound polyguanidine, which was previously used as a disinfectant, surfactant and complexing agent, has recently become widely used as a plant growth and development stimulant. Despite the increasing use of polyguanidine preparations as a growth stimulant, there is no data in the literature on its mechanism of action on plants. There are many studies that try to determine whether the effect of biostimulants on plant productivity is a direct or indirect response, for example, through the soil or microbiome. In many cases, biostimulants are considered in terms of their effects on various plant regulatory and functional systems (signaling, metabolic, uptake and transport mechanisms, etc.). But, in general, these modes of action are very diverse and may include activation of nitrogen metabolism or release of phosphorus from soils, general stimulation of soil microbial activity, or stimulation of root growth and increased plant nutrition. The effect of polyguanidin on the physiological parameters of wheat plants was studied under vegetation and laboratory conditions. Seeds of winter wheat variety Bogdana were used for the study. For the determination of flavonoids, a spectrophotometric method based on the measurement of their absorption with aluminum chloride complex was used. It was proved that the treatment of wheat in the tillering and earing phases with polyguanidin had the greatest effect on the protein content in winter wheat grain, which ensured the formation of this indicator at the level of 11.0–13.4% compared to the control. The treatment of wheat seeds with a preparation based on polyguanidine increased the amount of chlorophyll a by almost two times, while the content of chlorophyll b and carotene increased somewhat less. Thus, the use of polyguanidine contributes to the efficient functioning of the photosynthetic apparatus of plants, which will increase their productivity. Since the energy basis of photosynthesis is the absorption of solar radiation by photosynthetic pigments, which are used to form organic matter, there is a direct link between chlorophyll content and plant productivity. Therefore, we decided to check the content of the main photosynthetic pigments in plants after treatment with polyguanidine. At the first stage of our research, plants at the early stages of ontogenesis were analyzed. Thus, we have shown that the treatment of wheat seeds with a polyguanidine-based preparation increases the amount of chlorophyll a almost twice. Evaluation of flavonoid content in wheat plants showed a decrease in their amount after treatment with polyguanidin. That is, after the treatment, the plants, on the contrary, reduced their adaptive potential, because at the biochemical stage it was believed that there were no unfavorable factors in the environment. The analysis of the free proline content showed an increase in its concentration after treatment with the test substance almost doubled both after the first and after the second treatment. Also, it should be noted that reducing the concentration of the drug to 0.15 liters per 200 liters of the working solution increases the level of proline after the first treatment. The increase in proline, in this case, can lead to an increase in stress resistance, which is provided by metabolic and physiological changes. Consequently, its accumulation and conversion into other amino acids due to changes in the activity of proline oxidase contributes to an increase in the protein content in the grain.

Determination of total phenolic and flavonoid content of Ghontoghe (Kleinhovia hospita L.) leaves: in vitro antioxidant study

The Ghontohge plant (Kleinhovia hospita L.) has been used as a traditional medicine to treat scurvy, lice, eye pain, jaundice and hepatitis, cholesterol, diabetes, hypertension and treat pneumonia. Therefore, it is possible that plants can be used as antioxidants and redox signalling sourced from natural materials. The purpose of this study was to investigate the antioxidant potential and evaluate the total phenolic and flavonoid content of Ghontoghe leaves and investigate the most potent fraction as an antioxidant from the extract and fractions of Ghontoghe leaves. Ghontoghe leaf powder was extracted using the maceration method. Antioxidant activity was evaluated using 2,2-diphenyl-1-picryhidrazyl (DPPH) and 2,2-Azinobis 3-ethyl benzothiazoline 6-sulfonic acid radicals (ABTS). The total phenolic content was determined using the Folin-Ciocalteau method. Meanwhile, the total flavonoid content was determined using the aluminium chloride complex colourimetric method. The ethyl acetate fraction showed the strongest antioxidant activity on both DPPH radicals and ABTS radicals with IC50 values of 6.253±0.008 g/mL and 6.486±0.023 g/mL, respectively. The ethyl acetate fraction also showed high phenolic and flavonoid content with values of 26.92±0.10 mg GAE/g sample and 95±0.69 mg QE/g sample, respectively. The ethyl acetate fraction has the potential to be used as a source of natural antioxidants and has the potential to be used as a functional food.

INTERRELATION BETWEEN MITOCHONDRIAL ENZYME ACTIVITY AND ANTIOXIDANT ACTIVITY OF SECONDARY POLYPHENOL NATURE METABOLITES IN HEMIPARASITE VISCUM ALBUM L. LEAVES

Antioxidants are widely used in practical medicine. Not only the search for new plant antioxidants, but also the study of the factors affecting their accumulation in plants, are relevant.The aim is to study the interrelation between the activity of mitochondrial enzymes and the antioxidant activity of the secondary polyphenolic nature metabolites in hemiparasite Viscum Album L. leaves.Materials and methods. The sampling material was Viscum album L. leaves, collected in winter from a host tree, Malus domestica Borkh. The extraction of biologically active substances was carried out with ethyl alcohol of various concentrations (90%, 70% and 50%), or purified water. The amount of total antioxidants was estimated by the amperometric method. The amount of total phenols was evaluated in the reaction with the Folin-Ciocalteu reagent. The concentration of total flavonoids was estimated by the change in the optical density of the rutin with aluminum (III) chloride complex. The antioxidant properties of the analyzed extracts were determined in vitro in the induced lipid peroxidation test. The activity of aconitase was assessed by a conjugated aconitase-isocitrate dehydrogenase reaction, citrate synthase – by changing the color intensity of the Ellman reagent solution, succinate dehydrogenase were determined in the reaction of succinate-dependent oxidation of 2,6-dichlorophenolindophenol.Results. The carried out study showed that the maximum amount of total phenols (2.39±0.05%) is observed in a 50% ethanol extract from Viscum album L. leaves, with the content of total flavonoids equal to 1.83±0.04%, and the antioxidants equal to 0.503±0.007 mg/g (a quercetin equivalent) and 0.322±0.006 mg/g (a gallic acid equivalent). A 50% ethanol extract suppressed lipid peroxidation in the model mixture with IC50=106.3±1.09 µg/ml. In Viscum album L. leaves, a high activity of aconitase which strongly correlated (r=0.88416) with changes in the concentration of flavonoids, has been notified.Conclusion. The optimal extractant for obtaining extracts with a high antioxidant activity is 50% ethyl alcohol. The analysis of the mitochondrial enzymes activity showed that in Viscum album L. leaves collected in winter, a high activity of aconitase strongly correlated with changes in the concentration of flavonoids (r=0.88416).

Antioxidant activity assay and determination of phenolic and flavonoid content of Libho (Ficus Septica Burm. F) fruits

Background: One of the plants used in Indonesian traditional medicine Libho (Ficus Septica Burm. F) is traditionally used to treat some diseases, including malaria, diarrhea, diabetes, analgesic, antifungal, dysentery, anthelmintic, antioxidant, hemostatic and anti-inflammatory. Purpose: The purpose of the study is to investigate the potential in vitro antioxidant activity assay and phytochemical content of Libho fruits. Methods: Libho leaves powder was extracted with the maceration method Antioxidant activity was evaluated using ABTS cation and CUPRAC radicals. Total phenolic content was determined using the Folin-Ciocalteau method. Meanwhile, the total flavonoid content was determined using the aluminum chloride complex colorimetric method; Results: Extract and fraction of Ficus Septica Burm. F fruits have the strongest antioxidant potential. The ethyl acetate fraction showed the strongest antioxidant activity on both ABTS and CUPRAC radicals with IC50 values of 6.33 ± 0.01 µg/mL and 11.64 ± 0.28 µg/mL, respectively. Ethyl acetate fraction also showed high phenolic and flavonoid content with values of 28 ± 0.05 mg GAE/100 mg sample and 43.08 ± 0.48 mg QE/100 mg sample, respectively. Conclusion: Ethyl acetate fraction has the potential to be used as a source of natural antioxidants and has the potential to be used as a nutraceutical.

Preliminary Screening and Quantification of Flavonoids in Selected Seeds of Apiaceae by UV-Visible Spectrophotometry with Evaluation Study on Different Aluminium Chloride Complexation Reaction

Background : The objective of the study includes a preliminary phytochemical screening of selected plant seeds of Apiaceae for flavonoid content and developing a suitable method of quantification by a UV-Visible spectrophotometer and validation of the same. Methods: Selected dry seeds of Apiaceae were extracted using 70% ethanol at 60◦C for 1h in the shaker. Procedures of different chemical compositions were designed to evaluate flavonoid-Aluminium chloride complexation reaction to determine the best suitable method for the quantification of total flavonoid content by UV-Visible spectrophotometer. The antioxidant activity was investigated by the phosphomolybdenum method and DPPH radical scavenging method. The developed method was validated by considering the parameters such as linearity, accuracy, precision, and limit of detection and quantification. Findings: The concentration of flavonoid varied from 246 mg QE/g - 2856 mg QE/g among the selected dry seeds of Apiaceae and showed promising antioxidant activities with IC50 values varying between 9.64- 249.75 mg/ml. Evaluation study on different aluminum chloride complexation reactions involved in the flavonoid quantification analysis revealed that procedure 3 developed by the researcher was the accurate and suitable method. The developed method was showed to be the simple and rapid method compared to previously published methods. The developed method showed to be linear (R2 = 0.999), precise (R.S.D. < 2%), accurate (recovery of 103.03%), and inexpensive. Novelty: The extracts were shown to contain a significant amount of flavonoid and displayed promising antioxidant activity and can therefore be a potential source of flavonoid and natural antioxidant agents. This article data could serve as a reference against the improper use of AlCl3 chelation methods for the quantification of flavonoids in food and plant samples. Keywords: Apiaceae; Quercetin; Total Flavonoid Content; Antioxidant Activity; Flavonoid and Aluminium chloride Complex; UV-Visible spectrophotometer

Determination of antiradical activity and phenolic and flavonoid contents of extracts and fractions of jackfruit (Artocarpus heterophyllus Lamk) seeds

Jackfruit (Artocarpus heterophyllus Lamk) is a plant from the Moraceae family that is widespread in Indonesia. Empirically, jackfruit can be used to cure hypertension, diabetes, cancer, asthma, dermatosis, coughs, wounds, acne, and diarrhea. The bioactive compounds in jackfruit include phenolics and flavonoids, which function as natural antioxidants. This research investigated the antiradical activity of jackfruit seed extracts and fractions using DPPH (2-2-diphenyl-1-picrylhydrazyl) and examined the total phenolic and flavonoid contents which may be developed as functional medicines and foods. The jackfruit seed powder was extracted using the maceration method. Radical scavenging activities were measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Total phenolic contents were determined using the Folin-Ciocalteu method. Meanwhile, the contents of flavonoids were determined using the aluminum chloride complex colorimetric method. The IC50 value of ethyl acetate fraction, methanol extract, n -hexane fraction, and water fraction was 5.435±0.064 µg/mL, 5.639±0.302 µg/mL, 7.201±0.475 µg/mL, and 9.134±0.2911 µg/mL, respectively. The phenolic and flavonoid contents of ethyl acetate fraction, methanol extract, n-hexane fraction, and water fraction were 49.597±1.589, 47.949±1.966, 41.214±4.354 and 35.504±0.913 g GAE/100 g of sample, respectively for phenolic, and 70.199±0.458, 65.228±0.615, 59.907±0.719, and 54.234±0.351 g of quercetin equivalent/100 g of sample, respectively of flavonoids, with a correlation value (R2 ) to antiradical power of 0.4582 for phenolic and 0.5281 for flavonoids. The ethyl acetate fraction of jackfruit seeds can be further developed as an anti -radicals and functional food.

Combining experimental and theoretical vibrational spectroscopy to study magnesium aluminum chloride complex electrolytes

Measurements of the Far-IR and Raman spectra of 1:1 MACC-ether electrolytes were carried out. [(μ-Cl)2Mg2]2+ is the major dimer in DME solution and the bands at 250 and 222 cm−1 may be used as markers in the respective IR and Raman spectra. On the other hand, [MgCl]+ stands out in the THF-based electrolyte, where an IR band at 286 cm−1 is here reported for the first time in the literature and may be employed as sensor. The [(μ-Cl)3Mg2]+ dimer, which is usually formed at the 2:1 MACC-THF electrolyte and deemed the electrochemically active species on the electrode, is also identified at the 1:1 ratio. AIMD-simulated IR spectra of the dimer and monomer are in good agreement with the experimental data and were pivotal to characterize the [MgCl(THF)5]+ complex. QC calculations helped assign a few bands in the Raman spectra and Gibbs free energies explained the preferential formation of Mg species in each medium.

A Review of Magnesium Aluminum Chloride Complex Electrolytes for Mg Batteries

AbstractDeveloping suitable electrolytes with high oxidation decomposition potential, low cost, and good compatibility with electrode materials has been a critical challenge in realizing practical magnesium batteries. The emerging magnesium aluminum chloride complex (MACC) electrolytes based on inorganic chloride salts exhibit high Coulombic efficiencies for magnesium batteries. This review summarizes recent studies of MACC electrolytes, focusing on the synthesis, characterization, and chemical environment of Mg species, electrolytic conditioning of electrolytes, and their application in typical magnesium batteries. The electrolyte evolution and influencing factor of electrolytic conditioning are discussed, and several kinds of conditioning‐free MACC electrolytes are further introduced. Finally, future trends and perspectives in this field are discussed.

Cycloaddition of carbon dioxide to epoxides by highly active constrained aluminum chloride complexes.

The transformation of carbon dioxide (CO2) and epoxides to cyclic carbonates has gained much interest due to its low cost, abundance, low toxicity, and renewability. Therefore, novel constrained aluminum chloride complexes were developed based on bis(salicylimine) ligands for epoxides/CO2 coupling reactions. The five-membered rings attached to the aromatic rings were designed to enlarge the coordination pocket around the aluminum center as demonstrated by single-crystal X-ray crystallography. Addition of propylene oxide (PO) to a mixture of an aluminum chloride complex and tetrabutylammonium bromide (TBAB) rapidly gave (ligand)Al-OCH(Me)CH2Cl and (ligand)Al-OCH(Me)CH2Br in similar quantities. The anion exchange between (ligand)Al-Cl and TBAB was found to be faster than the ring-opening of PO. From a series of catalyst screening and optimization, the combination of catalyst 2g having no substituent on the aromatic rings and TBAB displayed very high activity (TOF up to 10 800 h-1) for the PO/CO2 coupling reaction. This catalyst system was extended to eleven more examples of epoxides. Moreover, excellent selectivity for cyclic carbonate production was observed for both terminal and internal epoxides.

Activating Magnesium Electrolytes through Chemical Generation of Free Chloride and Removal of Trace Water.

Mg batteries are attractive next-generation energy storage systems due to their high natural abundance, inexpensive cost, and high theoretical capacity compared to conventional Li-ion based systems. The high energy density is achieved by electrodeposition and stripping of a Mg metal anode and requires the development of effective electrolytes enabled by a mechanistic understanding of the charge-transfer mechanism. The magnesium aluminum chloride complex (MACC) electrolyte is a good model system to study the mechanism as the solution phase speciation is known. Previously, we reported that minor addition of Mg(HMDS)2 to the MACC electrolyte causes significant improvement in the Mg deposition and stripping voltammetry resulting in good Coulombic efficiency on cycle one and, therefore, negating the need for electrochemical conditioning. To determine the cause of the improved electrochemistry, here we probe the speciation of the electrolyte after Mg(HMDS)2 addition using Raman spectroscopy, 27Al nuclear magnetic resonance spectroscopy, and 1H-29Si heteronuclear multiple bond correlation spectroscopy on MACC + Mg(HMDS)2 at various Mg(HMDS)2 concentrations. Mg(HMDS)2 scavenges trace H2O, but it also reacts with MACC complexes, namely, AlCl4-, to form free Cl-. We suggest that although both the removal of H2O and the formation of free Cl- improve electrochemistry by altering the speciation at the interface, the latter has a profound effect on electrodeposition and stripping of Mg.

Facile Modification of LiAlCl4 Electrolytes for Mg–Li Hybrid Batteries by the Conditioning-Free Method

Lithium aluminum chloride complexes (LACCs) are excellent electrolyte candidates for Mg–Li hybrid batteries (MgHBs) because they can simultaneously conduct electrochemical reactions both at Mg anod...

Composition dependence on the spectral behavior of magnesium aluminum chloride complex electrolytes

A composition-dependent study is presented for 1:1 and 2:1 MgCl2:AlCl3 (MACC)-tetrahydrofuran (THF) electrolytes and the findings very well support electrochemical data reported in the literature. Quantitative Raman analyses in the region characteristic of the νCC and νCO modes of THF at around 915 cm−1 were performed and correlated with the low wavenumber region. The νAl-O and νMg-O vibrations are reported for the first time and are in excellent agreement with the solvates identified in the IR and Raman spectra. Although AlCl3.xTHF (x = 1–2) are present in these solutions, the systems are governed by the [AlCl4]− anion. In light of our spectroscopic results, [Mg (THF)6]2+ is the major species and responsible for the lower electrochemical performance of the 1:1 electrolyte, whereas [MgCl2 (THF)4] and [(μ-Cl)3Mg2(THF)6]+ are the complexes related with the higher electrochemical activity of the 2:1 proportion.

Conditioning-Free MgCl2/AlCl3 Electrolyte for Magnesium Batteries By Chemical Formation of Solvated Chloride

Mg metal is a promising alternative anode material that offers higher theoretical specific capacity than conventional Li-ion batteries (LIBs), and the high natural abundance of Mg makes it more economically appealing than other post-LIB anode materials. The greater energy density hinges on a Mg-metal anode, and reversible Mg electrodeposition and stripping require an effective Mg electrolyte. Various electrolyte systems that support reversible have been introduced, but many of them contain drawbacks, such as narrow electrochemical window, reactivity with electrode materials, or poor Coulombic efficiency. In addition, challenges remain in understanding the relationship between electrochemistry at the Mg anode and the electrolyte composition due to the complicated interface of Mg metal and the electrolyte.To probe the effect of the interface on Mg electrodeposition, an electrolyte with a known solution phase composition, the magnesium aluminum chloride complex (MACC) electrolyte, is explored. The MACC electrolyte undergoes electrolytic conditioning to support reversible Mg electrodeposition and stripping. During conditioning, free Cl- is released electrolytically while Al3+ is irreversibly deposited, and the concentration of the active species [Mg2(µ−Cl)3·6(THF)]+ increases, activating the MACC electrolyte.Here, we show that a small concentration of Mg(HMDS)2 to the MACC electrolyte suppresses Al3+ deposition and promotes reversible Mg electrodeposition and stripping on the first cycle. Such a drastic change from a small concentration suggests that changes are localized at the electrode-electrolyte interface. We show spectroscopically that Mg(HMDS)2 scavenges trace water in the solution. Spectroscopic results also suggest that Mg(HMDS)2 reacts with AlCl4 - in the MACC electrolyte to form free Cl-. Based on the spectroscopic and electrochemical results, we suggest that the formation of Cl- is the primary cause for improved behavior on cycle one, highlighting the role of Cl- in Mg deposition and stripping.

Conditioning-Free Mg Electrolyte by the Minor Addition of Mg(HMDS)2.

Mg-based batteries are an attractive next-generation energy storage chemistry due to the high natural abundance and inexpensive cost of Mg, along with the high theoretical energy density compared to that of conventional Li-ion chemistry. The greater energy density is predicated on a Mg metal anode, and pathways to achieving reversible Mg electrodeposition and stripping are reliant on the development of Mg electrolytes. Although Mg electrolyte chemistry has advanced significantly from the reactive Grignards of the 1920s to the carboranes of this decade, there remains significant challenges in correlating the Mg metal anode electrochemistry with the composition of the electrolyte salts as a result of the complicated interface of Mg metal and the electrolyte. To probe the effect of the interface on Mg electrodeposition, we turn to an electrolyte with a known solution-phase composition: the magnesium aluminum chloride complex (MACC) electrolyte. The MACC electrolyte requires electrolytic conditioning to support reversible Mg electrodeposition and stripping. Here, we show that a small concentration (2-5 mM) of Mg(HMDS)2 with respect to the MACC electrolyte salts suppresses Al3+ deposition and promotes reversible Mg electrodeposition and stripping in the first cycle. The significant effect of a small concentration of additive is attributed to changes to the electrode interface. The impact of the Mg interface on the observed electrochemical performance is discussed.