Reaction Of Anion Research Articles

Manganese-Based Tunnel and Layered Oxide Cathodes for Secondary Alkali-Ion Batteries

Designing new cathode materials remains crucial in developing (post) Li-ion batteries. Mn-based oxide cathodes have received wide attention due to their sustainable nature, low cost, elemental abundance, structural diversity/polymorphism, and rich oxidation states (2+ to 7+), offering tunable redox potential [1]. Here, we have investigated different oxide-based cathode insertion compounds for secondary metal-ion batteries.i) We have demonstrated tunnel-type sodium insertion material Na44MnO2(NMO) as an intercalation host for Li-ion and K-ion batteries. The solution combustion synthesized Na0.44MnO2 assuming an orthorhombic structure (space group Pbam), exhibited rod-like morphology. After electrochemical ion exchange from NMO, we obtained Na0.11K0.27MnO2 (NKMO) and Na0.18Li0.51MnO2 (NLMO) cathodes for K-ion batteries and Li-ion batteries, respectively [2]. These new compositions, NKMO and NLMO, showed excellent cycling stability with capacities of ∼74 and 141 mAh g–1 (first cycle, C/20 current rate). The underlying mechanistic features concerning charge storage and structural modifications in these cathode compositions were probed by combining ex-situ structural, spectroscopy, and electrochemical tools [3].ii) Using composite formation, we have tried to improve the P2-type layered material. Here, the stable Na7(Li1/18Mn1/18Ni3/18Fe2/18χ1/18)O2–xNa2MoO4 biphasic composite was synthesized using Mo doping. Overall, the redox chemistry was investigated using various spectroscopy techniques to prove the net capacity resulted from both cationic and anionic redox reactions [4]. Keywords: energy storage; batteries; cathode; manganese oxides; intercalation; doping

Reactivity of hydrogen sulfide toward organic compounds with sulfur-sulfur bonds

The presence of organic molecules containing sulfur-sulfur bonds was documented in the water columns and sediments of the natural aquatic systems as well as in fossil fuels. These compounds range from small molecules of volatile organic compounds to polysulfide cross-linked macromolecules in the sediments. While processes leading to formation of these compounds were intensively studied during the last decades, kinetics and mechanisms of reactions which lead to their decomposition are poorly understood. In this work, the kinetics and products of the reactions of dimethyl disulfide, dimethyl trisulfide, and cyclic polysulfide lenthionine (1,2,3,5,6-pentathiepane) with hydrogen sulfide at the environmental pH and temperature ranges were studied. It was shown that at pH ≥ 5, the reaction of bisulfide anion (HS–) rather than that of hydrogen sulfide controls the overall reaction rates. The activation energy and the order of the reaction with respect to bisulfide anion is dimethyl disulfide– < dimethyl trisulfide < lenthionine, while the order of the reaction with respect to organosulfur compounds is lenthionine < dimethyl trisulfide < dimethyl disulfide. The obtained results suggest that bisulfide anion is responsible for fast decomposition of organosulfur compounds in aphotic natural aquatic systems. This observation leads to the conclusion that sulfurization of sedimentary organic matter during the early diagenesis is not an unidirectional but a dynamic process, and concentrations of organic compounds with sulfur-sulfur bonds are controlled by the polysulfide to sulfide sulfur concentrations ratio in the sedimentary pore waters. In addition, the cyclic polysulfides were shown to be more stable than their linear analogs that results in preferential preservation of these compounds during the maturation process.

Study on the Superlubricity Behavior of Ions under External Electric Fields at Steel Interfaces.

Realizing macroscopic superlubricity in the presence of external electric fields (EEFs) at the steel interfaces is still challenging. In this work, macroscopic superlubricity with a coefficient of friction value of approximately 0.008 was realized under EEFs with the lubrication of LiPF6-based ionic liquids at steel interfaces. The roles of cations and anions in the superlubricity realization under EEFs were studied. Based on the experimental results, the macroscopic superlubricity behavior of Li(PEG)PF6 under EEFs at steel interfaces is attributed to the strong hydration effect of Li+ cations and the complete reactions of anions that contributed to the formation of a boundary film on the appropriate surface. Moreover, the reduction in the number of iron oxides in the boundary film on the disc was beneficial for friction reduction. We also provide a calculation model to describe the relationship between the hydration effect and the optimal voltage position, at which the lowest friction might occur. Ultimately, this work proves that macroscopic superlubricity can be realized under EEFs at steel interfaces and provides a foundation for engineering applications of superlubricity in an electrical environment.

In‐situ Polymerized Single Lithium‐ion Conducting Binder as an Integrated Strategy for High Voltage LNMO Electrodes

AbstractHigh voltage spinel LiNi0.5 Mn1.5O4 (LNMO) is a promising material for next generation lithium‐Ion batteries. However, its reactivity near 5 V possess stability and cycling challenges. In this study, a novel integrated approach is employed using a single lithium‐ion conducting polymer binder (SLICPB) to prevent interactions with reactive anions and create a protective layer against electrolyte decomposition. The proposed SLICPB in‐situ polymerization in the LNMO electrodes simplifies the preparation process, reducing costs. SLICPB properties effectively decrease polarization by concentration. For instance, at a discharge capacity of 68 mAh g−1, the voltage hysteresis difference is 0.31 V, enabling higher capacity at 1 C (a 38 % increase) compared to traditional binder electrodes. Notably, this integrated strategy completely replaces the traditional binder without any need for additives, thus avoiding any extra weight in the electrode preparation. Furthermore, SLICPB properties successfully decreasereactivity and diminish the leaching of Mn2+, as evaluated through differential electrochemical mass spectrometry and electron paramagnetic resonance, respectively.

Brønsted-Lowry Acid-Based Aqueous Eutectic Electrolyte for Practical Zinc Batteries.

Aqueous highly concentrated electrolytes (AHCEs) have recently emerged as an innovative strategy to enhance the cycling stability of aqueous Zinc (Zn) batteries (AZB). Particularly, thanks to high Zn Chloride (ZnCl2) solubility in water, AHCEs based on ZnCl2 feature remarkable Zn anode stability. However, due to their inherently acidic pH and Cl- anion reactivity, these electrolytes face compatibility challenges with other battery components. Here, an aqueous eutectic electrolyte (AEE) based on Brønsted-Lowry concept is reported-allowing the usage of cheap and abundant salts, ZnCl2, and sodium acetate (NaAc). The reported, pH buffered, AEE displays a higher coordination of water at an even lower salt concentration, by simply balancing the acceptor-donor H─bonding. This results in impressive improvement of electrolyte properties such as high electrochemical stability, high transport properties and low glass transition temperature. The developed AEE displays higher compatibility with vanadium oxide-based cathode with a 50% increase in capacity retention in comparison to sat. ZnCl2. More importantly, the pH buffered AEE solves the incompatibility issues of ZnCl2 toward commonly used aluminium (Al) current collector as well as cellulose separator. This work presents an efficient, simple, and low-cost strategy for the development of aqueous electrolytes for the practical application of Zn batteries.

Sulfur-Assisted Surface Modification of Lithium-Rich Manganese-Based Oxide toward High Anionic Redox Reversibility.

Energy storage via anionic redox provides extra capacity for lithium-rich manganese-based oxide cathodes at high voltage but causes gradual structural collapse and irreversible capacity loss with generation of On - (0 ≤ n < 2) species upon deep oxidation. Herein, the stability and reversibility of anionic redox reactions are enhanced by a simple sulfur-assisted surface modification method, which not only modulates the material's energy band allowing feasible electron release from both bonding and antibonding bands, but also traps the escaping On - via an as-constructed SnS2- x - σ Oy coating layer and return them to the host lattice upon discharge. The regulation of anionic redox inhibits the irreversible structural transformation and parasitic reactions, maintaining the specific capacity retention of as-modified cathode up to 94% after 200 cycles at 100mA g-1 , along with outstanding voltage stability. The reported strategy incorporating energy band modulation and oxygen trapping is promising for the design and advancement of other cathodes storing energy through anion redox.

Diastereoselective Access to anti-β-Hydroxy Sulfoxides from ­Chiral Epoxides and Prochiral Sulfenate Anions: Mechanistic ­Insights, Scope, and Limitation

AbstractReported herein is a stereoselective route to anti-β-hydroxy sulfoxides through the reaction of epoxides with sulfenate anions. Extensive experimental/computational studies revealed the dual special roles of MgBr2·OEt2, serving to generate the bromohydrin alkoxide intermediate, which undergoes nucleophilic attack on the prochiral sulfenate in a diastereoselective manner. The present study has opened a general stereoselective synthetic route to anti-β-hydroxy sulfoxides.

Electronic States Tailoring and Pinning Effect Boost High-Power Sodium-Ion Storage of Oriented Hollow P2-Type Cathode Materials.

Fierce phase transformation and limited sodium ion diffusion dynamics are critical obstacles that hinder the practical energy storage applications of P2-type layered sodium transition metal oxides (NaxTMO2). Herein, a synergistic strategy of electronic state tailoring and pillar effect was carefully implemented by substituting divalent Mg2+ into Na0.67Ni0.33Mn0.67O2 material with unique oriented hollow rodlike structures. Mg2+substitution can not only facilitate the anionic oxygen redox reactions and electronic conductivity through increasing the electronic states at Femi energy but also act as pillars within TMO2 layers to alleviate the severe phase transformation to improve structure stability. Moreover, the oriented hollow structure incorporating sufficient buffer spaces and rationally exposed electrochemically active facets effectively alleviates the stresses induced by low volume changes of 8% and provides more open channels for Na+ ion diffusion without crossing multiple grain boundaries. Hence, the Na0.67Mg0.08Ni0.25Mn0.67O2 cathode showed a superior rate capability with high energy density and cycling stability for sodium-ion storage. The underlying mechanisms of these achievements were deciphered through diversified dynamic analysis and the first principle calculations, providing new insights into P2-type NaxTMO2 cathodes for the infinite prospect as an alternative to lithium-ion batteries.

The aluminum chemistry involved redox mechanisms in transition metal dichalcogenides

Transition metal dichalcogenides (TMDs) featured an open framework structure and versatile electronic properties are attractive for their higher capacitance when used as cathodes for aluminum-ion batteries (AIBs). However, the inexhaustive understanding of cell chemistry involving complicated charge transfer stalls the deployment of this type AIBs electrode materials. Here the sulfide materials of MS2 (M = Fe, Ni, Co) served as emblematic conversion-type electrodes are taken as models to shed light on the regularity among the Al storage mechanisms in TMDs cathodes. To explain such chemistry, we therefore interrogate the redox mechanisms between MS2 (M = Fe, Ni, Co) from a broad range of experimental and mechanistic characterization perspectives. Remarkably, as indicated by characterization results, the detailed Al insertion and removal processes occurring in MS2 (M = Fe, Ni, Co) cathodes are revealed, accompanied by the anionic-redox reaction of sulfide anion (S2−), whereas the valence state transitions of the metal element in CoS2 (Co2+∼Co3+) also occur simultaneously during the insertion/extraction of Al3+. Using theoretical calculations, we further clarify the essential reasons for the mechanistic discrepancy, and discuss the energy storage regularity in TMDs. These foundations not only contribute to a profound understanding for the charge storage mechanisms in TMDs but also expand the palette of property boosting electrode materials for practical AIBs.

Understanding Lattice Oxygen Redox Behavior in Lithium‐Rich Manganese‐Based Layered Oxides for Lithium‐Ion and Lithium‐Metal Batteries from Reaction Mechanisms to Regulation Strategies

AbstractLithium‐rich manganese‐based layered oxides (LMLOs) are considered to be one type of the most promising materials for next‐generation cathodes of lithium batteries due to their distinctive anionic redox processes contributing ultrahigh capacity and energy density. Unfortunately, their practical applications are still plagued by several challenges such as undesirable interfacial reactions and structural evolution, as well as voltage hysteresis/recession, in which irreversible anionic redox behavior bears the brunt as the primacy factor. Undoubtedly, a deep understanding of anionic redox reaction mechanisms and irreversible behavior of oxygen species is crucial in order to provide essential guidance for modification strategies for LMLOs. In this paper, the fundamental understanding of intricate anionic redox reaction mechanisms from thermodynamics models to kinetic anionic redox reaction pathways is comprehensively reviewed, and the existing challenges of LMLOs related with irreversible oxygen reaction behavior are analyzed. Furthermore, numerous representative modification strategies for overcoming these challenges, coupled with their underlying mechanisms for regulating anionic redox reversibility are summarized. In addition, the aspects of multi‐scale structural modifications, integration of interdisciplinary technologies, and application in quasi‐/all‐solid‐state battery systems are given some emphasis in terms of further improvement of LMLOs‐based cathode materials for advanced lithium batteries‐based energy storage systems.

Synergistic Activation of Nitrite and Thiocarbonyl Compounds Affords NO and Sulfane Sulfur via (Per)thionitrite (SNO- /SSNO- ).

(Per)thionitrite (SNO- /SSNO- ) intermediates play vital roles in modulating nitric oxide (NO) and hydrogen sulfide (H2 S) dependent bio-signalling processes. Whilst the previous preparations of such intermediates involved reactive H2 S/HS- or sulfane sulfur (S0 ) species, the present report reveals that relatively stable thiocarbonyl compounds (such as carbon disulfide (CS2 ), thiocarbamate, thioacetic acid, and thioacetate) react with nitrite anion to yield SNO- /SSNO- . For instance, the reaction of CS2 and nitrite anion (NO2 - ) under ambient condition affords CO2 and SNO- /SSNO- . A detailed investigation involving UV/Vis, FTIR, HRMS, and multinuclear NMR studies confirm the formation of SNO- /SSNO- , which are proposed to form through an initial nucleophilic attack by nitrite anion followed by a transnitrosation step. Notably, reactions of CS2 and nitrite in the presence of thiol RSH show the formation of organic polysulfides R-Sn -R, thereby illustrating that the thiocarbonyls are capable of influencing the pool of bioavailable sulfane sulfurs. Furthermore, the availability of both NO2 - and thiocarbonyl motifs in the biological context hints at their synergistic metal-free activations leading to the generation of NO gas and various reactive sulfur species via SNO- /SSNO- .

Synergistic Activation of Nitrite and Thiocarbonyl Compounds Affords NO and Sulfane Sulfur via (Per)thionitrite (SNO−/SSNO−)

Abstract(Per)thionitrite (SNO−/SSNO−) intermediates play vital roles in modulating nitric oxide (NO) and hydrogen sulfide (H2S) dependent bio‐signalling processes. Whilst the previous preparations of such intermediates involved reactive H2S/HS− or sulfane sulfur (S0) species, the present report reveals that relatively stable thiocarbonyl compounds (such as carbon disulfide (CS2), thiocarbamate, thioacetic acid, and thioacetate) react with nitrite anion to yield SNO−/SSNO−. For instance, the reaction of CS2 and nitrite anion (NO2−) under ambient condition affords CO2 and SNO−/SSNO−. A detailed investigation involving UV/Vis, FTIR, HRMS, and multinuclear NMR studies confirm the formation of SNO−/SSNO−, which are proposed to form through an initial nucleophilic attack by nitrite anion followed by a transnitrosation step. Notably, reactions of CS2 and nitrite in the presence of thiol RSH show the formation of organic polysulfides R‐Sn‐R, thereby illustrating that the thiocarbonyls are capable of influencing the pool of bioavailable sulfane sulfurs. Furthermore, the availability of both NO2− and thiocarbonyl motifs in the biological context hints at their synergistic metal‐free activations leading to the generation of NO gas and various reactive sulfur species via SNO−/SSNO−.

The reaction of glutathione-derived dinitrosyl iron complex and superoxide radical anion - the detection and quantitation of peroxynitrite

The reaction of glutathione-derived dinitrosyl iron complex and superoxide radical anion - the detection and quantitation of peroxynitrite

Boosting the Reversibility and Kinetics of Anionic Redox Chemistry in Sodium-Ion Oxide Cathodes via Reductive Coupling Mechanism.

Activating anionic redox chemistry in layered oxide cathodes is a paradigmatic approach to devise high-energy sodium-ion batteries. Unfortunately, excessive oxygen redox usually induces irreversible lattice oxygen loss and cation migration, resulting in rapid capacity and voltage fading and sluggish reaction kinetics. Herein, the reductive coupling mechanism (RCM) of uncommon electron transfer from oxygen to copper ions is unraveled in a novel P2-Na0.8Cu0.22Li0.08Mn0.67O2 cathode for boosting the reversibility and kinetics of anionic redox reactions. The resultant strong covalent Cu-(O-O) bonding can efficaciously suppress excessive oxygen oxidation and irreversible cation migration. Consequently, the P2-Na0.8Cu0.22Li0.08Mn0.67O2 cathode delivers a marvelous rate capability (134.1 and 63.2 mAh g-1 at 0.1C and 100C, respectively) and outstanding long-term cycling stability (82% capacity retention after 500 cycles at 10C). The intrinsic functioning mechanisms of RCM are fully understood through systematic in situ/ex situ characterizations and theoretical computations. This study opens a new avenue toward enhancing the stability and dynamics of oxygen redox chemistry.

Hydroxyl Radical vs. One-Electron Oxidation Reactivities in an Alternating GC Double-Stranded Oligonucleotide: A New Type Electron Hole Stabilization.

We examined the reaction of hydroxyl radicals (HO•) and sulfate radical anions (SO4•-), which is generated by ionizing radiation in aqueous solutions under anoxic conditions, with an alternating GC doubled-stranded oligodeoxynucleotide (ds-ODN), i.e., the palindromic 5'-d(GCGCGC)-3'. In particular, the optical spectra of the intermediate species and associated kinetic data in the range of ns to ms were obtained via pulse radiolysis. Computational studies by means of density functional theory (DFT) for structural and time-dependent DFT for spectroscopic features were performed on 5'-d(GCGC)-3'. Comprehensively, our results suggest the addition of HO• to the G:C pair moiety, affording the [8-HO-G:C]• detectable adduct. The previous reported spectra of one-electron oxidation of a variety of ds-ODN were assigned to [G(-H+):C]• after deprotonation. Regarding 5'-d(GCGCGC)-3' ds-ODN, the spectrum at 800 ns has a completely different spectral shape and kinetic behavior. By means of calculations, we assigned the species to [G:C/C:G]•+, in which the electron hole is predicted to be delocalized on the two stacked base pairs. This transient species was further hydrated to afford the [8-HO-G:C]• detectable adduct. These remarkable findings suggest that the double-stranded alternating GC sequences allow for a new type of electron hole stabilization via delocalization over the whole sequence or part of it.

Investigation on the Origin of Sluggish Anionic Redox Kinetics in Cation-Disordered Cathode

Cation-disordered rock salt (DRX) cathodes exhibit high specific capacity due to the simultaneous use of anionic and cationic redox reactions. However, DRX systems face severe challenges that limit their practical applications; a most important challenge is their poor rate performance. In this work, the structure and morphology of Li1.17Ti0.58Ni0.25O2 (LTNO) were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), etc. In combination with various electrochemical characterizations, we found that the sluggish kinetics of anionic redox within LTNO can be the key reason for the inferior rate performance. By sample relaxation at moderate temperature and X-ray absorption near edge structure (XANES), the ligand-to-metal charge transfer process is verified to occur between O and Ni and exhibits a prolonged characteristic time of 113.8 min. This time-consuming charge transfer process is verified to be the very fundamental origin of the slow kinetics of oxygen oxidation and reduction. This claim is further supported by the galvanostatic intermittent titration technique (GITT) at different temperatures. These findings provide essential guidance for understanding and further optimizing cathodes with anion redox reactions not only in the context of DRX cathodes but also conventional Li-rich cathodes.

Regulating interfacial reaction through electrolyte chemistry enables gradient interphase for low-temperature zinc metal batteries

In situ formation of a stable interphase layer on zinc surface is an effective solution to suppress dendrite growth. However, the fast transport of bivalent Zn-ions within the solid interlayer remains very challenging. Herein, we engineer the SEI components and enable superior kinetics of Zn metal batteries under harsh conditions through regulating the sequence of interfacial chemical reaction. With the differences in chemical reactivity of trimethyl phosphate co-solvent and trifluoromethanesulfonate anions in the Zn2+-solvation shell, Zn3(PO4)2 and ZnF2 are successively generated on Zn metal surface to form a gradient ZnF2–Zn3(PO4)2 interphase. Mechanistic studies reveal the outer ZnF2 facilitates Zn2+ desolvation and inner Zn3(PO4)2 serves as channels for fast Zn2+ transport, contributing to long-term cycling at subzero temperatures. Impressively, the gradient SEI enables a high lifespan over 7000 hours in Zn symmetric cell and a capacity retention of 86.1% after 12000 cycles in Zn–KVOH full cell at –50 °C.

Cationic–Anionic Redox Chemistry in Multivalent Metal‐Ion Batteries: Recent Advances, Reaction Mechanism, Advanced Characterization Techniques, and Prospects

AbstractRechargeable multivalent metal‐ion batteries (MMIBs) have garnered a surge of attention as competitive candidates for large‐scale energy storage applications owing to their high capacity, abundant resources, and good security. However, their practical implementation is still stuck at the prototype stage, mainly plagued with the lack of suitable cathode materials capable of reversible insertion/extraction of multivalent ions and the intrinsically complicated redox reaction mechanism. Recently, anionic redox chemistry has shown to be an effective strategy to increase energy density, providing a new research direction for the next generation of high‐energy rechargeable batteries. Unfortunately, anion redox chemistry has not received sufficient attention in MMIBs so far. Here, the fundamental principle and mechanism of anionic redox reactions in MMIBs are discussed and the recent advances regarding cathode materials based on cooperative cationic–anionic redox (CCAR) mechanism are summarized. Additionally, various advanced characterization techniques for studying the anionic redox process are highlighted, aiming to effectively illustrate the underlying reaction mechanism. Finally, challenges and perspectives for the future research on cationic–anionic redox chemistry in MMIBs are proposed. Insight into the significance of CCAR chemistry is provided here in MMIBs, presenting a new avenue for the development of high‐energy‐density cathode materials for MMIBs.

Reactivity of Open-Shell Metallofullerene Anions: Synthesis, Crystal Structures, and Electrochemical Properties of Benzylated Gd@C2v-C82

The reactivity of the open-shell Gd@C2v-C82 with different charge states towards benzyl bromide was investigated. [Gd@C2v-C82]3− exhibited enhanced activity relative to Gd@C2v-C82 and [Gd@C2v-C82]−. The structural characterizations, including MALDI-TOF MS, UV-vis-NIR, and single crystal X-ray diffraction, indicate the formation of isomeric benzyl monoadducts of Gd@C2v-C82. All three monoadducts contain 1:1 mirror-symmetric enantiomers. Additionally, the addition of the benzyl group and its specific position result in distinct electrochemical behavior of the products compared to the parent Gd@C2v-C82. Theoretical studies demonstrate that only [Gd@C2v-C82]3− has a HOMO energy level that matches well with the LUMO energy level of the PhCH2 radical, providing a rationalization for the observed significantly different reactivity.

Trivinylphosphine Oxide: Synthesis, Characterization, and Polymerization Reactivity Investigated Using Single-Crystal Analysis and Density Functional Theory.

Organophosphorus chemicals are versatile and important in industry. Trivinylphosphine oxide (TVPO), for example, exhibited a promising precursor as a flame-retardant additive for industrial applications. Density functional theory (DFT) simulations were used to explore the kinetic and thermodynamic chemical processes underlying the nucleophilic addition reactions of TVPO in order to better understand their polymerization mechanisms. An experimental X-ray single-crystal study of TVPO supported this work's theory based on its computed findings. TVPO was prepared using POCl3 and VMB in a temperature-dependent reaction. TVPO, the thermodynamically favourable product, is preferentially produced at low temperatures. The endothermic anionic addition polymerization reaction between TVPO and VMB begins when the reaction temperature rises. An implicit solvation model simulated TVPO and piperazine reactions in water, whereas a hybrid model modelled VMB interactions in tetrahydrofuran. The simulations showed a pseudo-Michael addition reaction mechanism with a four-membered ring transition state. The Michael addition reaction is analogous to this process.