Oxygen Anions Research Articles

Carbonized Polymer Dots-Promoted Photocatalytic Activation of Molecular Oxygen for Efficient and Selective Oxidation of Thioethers to Sulfoxides.

Sulfoxides are essential in pharmaceuticals and chemicals, yet traditional thioether oxidation struggles with selectivity and sustainability. This study introduces carbonized polymer dots (CPDs) as effective photocatalysts for ecofriendly thioether to sulfoxide oxidation, using water and ethanol to enhance reaction selectivity and efficiency under 455 nm blue light. These catalysts not only show remarkable efficacy under mild conditions but also display high selectivity for sulfoxide formation, proving versatile across a broad range of substrates. We further elucidated the catalytic mechanism, confirming the predominant roles of singlet oxygen and superoxide anions through both spectroscopic evidence and quenching experiments. The method extends to the synthesis of pharmaceuticals such as oxfendazole, albendazole sulfoxide, and sulindac, highlighting its practical utility. Overall, our findings present a sustainable and efficient avenue for sulfoxide synthesis, thereby broadening the practical utility of CPDs in photocatalytic transformations.

Unveiling the Resistive Switching Mechanism and Low Current Dynamics of Ru‐based Hybrid Synaptic Memristors

AbstractMobile Ru ions in oxide media have been reported as a novel species that offer extremely low switching currents for memristors. However, their bi‐stable resistive‐switching (RS) and low‐switching currents dynamics have not been quantitatively unveiled. Here, the bi‐stable RS mechanism via in‐depth field‐induced atomic migration and chemical bonding state studies is elucidated, showing that the RS of the Ru‐based hybrid memristor (RHM) is possible via the simultaneously controlled hybrid Ru cation and oxygen anion. Additionally, the Ru ion mobility is quantitatively obtained via atomic moving distance and switching time measurements, demonstrating that the lower Ru ion mobility, compared to other conventional mobile species in oxide media, can be the origin of the low‐switching currents. It is found that the current conduction mechanism of the low‐resistance‐state in RHMs has temperature‐range‐dependencies. The direct tunneling conduction mechanism is dominant in relatively low temperatures; however, the ionic transport and thermally activated hopping conduction mechanism govern the current flow in high temperatures. Owing to the low Ru ion mobility, the RHM exhibits highly linear synaptic plasticity with a low‐conductance regime, showing outstanding energy efficiency compared to other memristors in image recognition tasks. These findings can contribute to improving the feasibility of hyper‐scale synaptic cores consisting of RHMs.

Embedding Reverse Electron Transfer Between Stably Bare Cu Nanoparticles and Cation-Vacancy CuWO4.

Cu nanoparticles (NPs) have attracted widespread attention in electronics, energy, and catalysis. However, conventionally synthesized Cu NPs face some challenges such as surface passivation and agglomeration in applications, which impairs their functionalities in the physicochemical properties. Here, the issues above by engineering an embedded interface of stably bare Cu NPs on the cation-vacancy CuWO4 support is addressed, which induces the strong metal-support interactions and reverse electron transfer. Various atomic-scale analyses directly demonstrate the unique electronic structure of the embedded Cu NPs with negative charge and anion oxygen protective layer, which mitigates the typical degradation pathways such as oxidation in ambient air, high-temperature agglomeration, and CO poisoning adsorption. Kinetics and in situ spectroscopic studies unveil that the embedded electron-enriched Cu NPs follow the typical Eley-Rideal mechanism in CO oxidation, contrasting the Langmuir-Hinshelwood mechanism on the traditional Cu NPs. This mechanistic shift is driven by the Coulombic repulsion in anion oxygen layer, enabling its direct reaction with gaseous CO to form the easily desorbed monodentate carbonate.

Dynamic Evolution of Antisite Defect and Coupling Anionic Redox in High-Voltage Ultrahigh-Ni Cathode.

High-voltage ultrahigh-Ni cathodes (LiNixCoyMn1-x-yO2, x≥0.9) can significantly enhance the energy density and cost-effectiveness of Li-ion batteries beyond current levels. However, severe Li-Ni antisite defects and their undetermined dynamic evolutions during high-voltage cycling limit the further development of these ultrahigh-Ni cathodes. In this study, we quantify the dynamic evolutions of the Li-Ni antisite defect using operando neutron diffraction and reveal its coupling relationship with anionic redox, another critical challenge restricting ultrahigh-Ni cathodes. We detect a clear Ni migration coupled with an unstable oxygen lattice, which accompanies the oxidation of oxygen anions at high voltages. Based on these findings, we propose that minimized Li-Ni antisite defects and controlled Ni migrations are essential for achieving stable high-voltage cycling structures in ultrahigh-Ni cathodes. This is further demonstrated by the optimized ultrahigh-Ni cathode, where reduced dynamic evolutions of the Li-Ni antisite defect effectively inhibit the anionic redox, enhancing the 4.5 V cycling stability.

A Type I Photosensitizer-Polymersome Boosts Reactive Oxygen Species Generation by Forcing H-Aggregation for Amplifying STING Immunotherapy.

Activation of the innate immune Stimulator of Interferon Genes (STING) pathway potentiates antitumor immunity. However, delivering STING agonists systemically to tumors presents a formidable challenge, and resistance to STING monotherapy has emerged in clinical trials with diminishing natural killer (NK) cell proliferation. Here, we encapsulated the STING agonist diABZI within polymersomes containing a Type I photosensitizer (NBS), creating a nanoagonist (PNBS/diABZI) for highly responsive tumor immunotherapy. This structure promoted H-aggregation and intersystem crossing of NBS, resulting in a ∼ 3-fold amplification in superoxide anion and singlet oxygen generation. The photodynamic therapy directly damaged hypoxia tumor cells and stimulated the proliferation of NK cells and cytotoxic T lymphocytes, thereby sensitizing STING immunotherapy. A single systemic intravenous administration of PNBS/diABZI eradicated orthotopic mammary tumors in murine models, achieving long-term antitumor immune memory to inhibit tumor recurrence and metastasis and significantly improving long-term tumor-free survival. This work provides a design rule for boosting reactive oxygen species production by promoting the intersystem crossing process, highlighting the potential of Type I photosensitizer-polymer vehicles for augmenting STING immunotherapy.

Investigation of Protective Coatings for Reducing High-Temperature Oxidation of Steels

AbstractOxidation of steel billets during pre-heating at elevated temperatures is a challenge, particularly in the forging industry. There is a need to address this problem by applying effective oxidation-resistant coatings on forging billets. In this investigation, different types of commercially available high-temperature, oxidation-resistant coatings, termed Coating A, B, C, D, E, F, and G, were applied on AISI 4340 low-alloy steel by spraying and dipping at room temperature. The oxidation protection behavior of each coating was studied over a wide range of temperatures and holding times in atmospheric conditions. The weight and height losses caused by oxidation were measured, and the samples were subsequently characterized using XRD and SEM-EDS. The protection mechanisms and anti-oxidation properties of the coatings are discussed in detail. The sample coated with Coating A showed the best protection at all temperatures compared to other coatings. The weight/height loss of Coating A-coated steel samples was reduced by 80–90% compared to an uncoated/bare sample. Coating A not only limited the outward diffusion of iron cations from the substrate but also prevented the inward diffusion of oxygen anions from the atmosphere, resulting in better oxidation resistance. The findings of the study should apply to other steels with similar compositions.

Phonon-Lithium Ion Interactions: A Case Study of LiM(SeO3)2 (M = Al, Ga, In, Sc, Y, and La).

Li ion diffusion is fundamentally a thermally activated ion hopping process. Recently, soft lattice, anharmonic phonon, and paddlewheel mechanism have been proposed to potentially benefit the ion transport, while the understanding of vibrational couplings of mobile ions and anions is still very limited but essential. Herein, we accessed the ionic conductivity, stability, and especially, lattice dynamics in LiM(SeO3)2 (M = Al, Ga, In, Sc, Y, and La) with two different types of oxygen anions within a LiO4 polyhedron, namely, edge-shared and corner-shared with MO6 polyhedra, the prototype of which, LiGa(SeO3)2, has been theoretically reported before with the similar structural features to NASICON and later experimentally synthesized with the room temperature conductivity ∼0.11 mS cm-1. It is interesting to note that LiM(SeO3)2 with a higher Li phonon band center shows higher Li conductivity, which is in contradiction to the conventional understanding of the importance for soft lattice to superionic conductors. The anharmonic and harmonic phonon interactions as well as the couplings between the vibration of the edge-bonded or corner-bonded anion in Li polyanions and the Li ion diffusion have been studied in detail. With transition metal M changing from La, Y, In, Ga, Al, and Sc, anharmonic phonons increase with reduced activation energy for Li diffusion. The phonon modes dominated by the edge-bonded oxygen anions contribute more to the migration of the Li ion than those dominated by the corner-bonded oxygen anions because of the greater atomic interaction between the Li ion and the edge-bonded anions. Thus, rather than the overall lattice softness, attention shall be given to reduce the frequency of the critical phonons contributing to Li ion diffusion as well as to increase the anharmonicity, i.e., through asymmetric Li polyhedra, for the design of Li ion superionic conductors for all-solid-state batteries.

Electrochemical analysis of sol-gel and hydrothermal synthesized mesoporous strontium titanate spherical nanoparticles as electrode material for high-performance flexible supercapacitors

Perovskite oxides with large specific surface areas present a promising avenue for enhancing supercapacitor efficiency. This study investigates the remarkable charge storage capabilities of strontium titanate (SrTiO3, STO) synthesized via sol-gel and hydrothermal techniques for electrochemical energy storage applications. The cubic crystal structure of STO, confirmed from X-ray Diffraction analysis, synthesized at lower temperatures through both methods, provides three-dimensional diffusion channels for oxygen anion movement, which is crucial for improving charge storage capacity. X-ray photoelectron spectroscopy confirmed the elements’ oxidation states and their spin-orbit splitting. The spherical nanoparticle morphology was observed in the FESEM images, BET characterization revealed a high specific surface area contributing to more charge storage and mesoporous nature facilitates excellent mass transfer rates of electrolytic ions. Electrochemical measurements and calculations confirmed that sol-gel and hydrothermally synthesized STO electrodes exhibit maximum specific capacitances of 130 F g−1 and 156 F g−1 at 10 mV s−1, respectively. A fabricated flexible supercapacitor device in an aqueous medium maintains a constant voltage of 1.2 V, capable of powering a digital watch. Hence, this study demonstrates the potential of STO electrode-based supercapacitors for a wide range of electrochemical energy storage applications.

Simultaneous production of singlet oxygen and superoxide anion by thiocarbonyl coumarin for photodynamic therapy

Photodynamic therapy (PDT) is a medical treatment that kills target cells through reactive oxygen species (ROS) generated by photosensitizers (PS) and surrounding oxygen under the stimulus of light. Despite of its popularity in cancer treatment, PDT relys on oxygen and therefore suffers from long response time and low efficiency under low-oxygen situations such as tumor hypoxia. Herein, to improve the usage of oxygen and increase ROS yield, we synthesized six potential PSs termed DC-O, DC-S, DC-BrO, DC-BrS, DC-IO, and DC-IS, by modifying coumarins with thiocarbonyl and bromine/iodine. We found that the thiocarbonyl group induces a significant bathochromic shift of the absorption spectra. In addition, the ROS production was significantly improved, likely because these PSs can simultaneously generate singlet oxygen (1O2) and superoxide anions (O2•−) through different pathways. Among these compounds, DC-BrS produces largest amount of ROS and exhibits strongest cytotoxicity towards cells, the survival rate of B16-F10 cells incubated with DC-BrS was only 20.7 % after irradiation at 460 nm for 10 min, indicating DC-BrS as a strong candidate for photodynamic therapy. Most importantly, this work provides an important direction for the design of PSs in the future.

Selenate oxyanion-intercalated NiFeOOH for stable water oxidation via lattice oxygen oxidation mechanism

Transition metal-based compounds can serve as pre-catalysts to obtain genuine oxygen evolution reaction (OER) electrocatalysts in the form of oxyhydroxides through electrochemical activation. However, the role and existence form of leached oxygen anions are still controversial. Herein, we selected iron selenite-wrapped hydrated nickel molybdate (denoted as NiMoO/FeSeO) as a pre-catalyst to study the oxyanion effect. It is surprising to find that SeO42− exists in the catalyst in the form of intercalation, which is different from previous studies that suggest that anions are doped with residual elements after electrochemical activation, or adsorbed on the catalyst surface. The experiment and theoretical calculations show that the existence of SeO42− intercalation effectively adjusts the electronic structure of NiFeOOH, promotes intramolecular electron transfer and O–O release, and thus lowers the reaction energy barrier. As expected, the synthesized NiFeOOH-SeO only needs 202 and 285 mV to attain 100 and 1000 mA cm−2 in 1 M KOH. Further, the anion exchange membrane water electrolyzer (AEMWE) consisting of NiFeOOH-SeO anode and Pt/C cathode can reach 1 A cm−2 at 1.70 V and no significant attenuation within 300 h. Our findings provide insights into the mechanism, by which the intercalated oxyanions enhance the OER performance of NiFeOOH, thereby facilitating large-scale hydrogen production through AEMWE.

Porous Lithium‐Doped ZnO Nanosheets with Abundant Oxygen Vacancies for Accelerating Li+ Transport in Solid‐State Composite Electrolyte

The flexible Li‐ion conducting solid polymer electrolyte (SPE) endows a stable long‐term cycling to Li‐metal anode to significantly improve the energy density of solid‐state lithium batteries; however, the practical application of the SPE is limited by its low ionic conductivity and small critical current density for dendrite nucleation. Herein, Li+‐doped porous ZnO (LZO) nanosheets are introduced into the poly(ethylene oxide) (PEO)‐based SPE, releasing more mobile Li ions for faster Li‐ion transport due to the enhanced interaction between abundant oxygen vacancies and anions of Li‐salt. As a result, the optimized LZO/PEO composite polymer electrolyte exhibits a high Li‐ion conductivity of 3.3 × 10−4 S cm−1 at 50 °C, 4 times higher than the pure PEO electrolyte. The solid‐state LiFePO4/Li cell shows extraordinarily long‐term stable cycling, up to 1500 cycles with a high average Coulombic efficiency of 99.8%. In addition, the cycling stability of the high‐voltage LiNi0.8Mn0.1Co0.1O2 (NMC811)/Li cell was also obviously improved compared to the nondoped pure PEO electrolyte, indicating the positive contribution of the LZO on interfacial stability.

Lattice dynamics and vibrational properties of scheelite-type alkali-metal perrhenates

The present work provides insight into the structural, vibrational, and elastic properties of scheelite-type alkali-metal perrhenates AReO4(A= Na, K, Rb, and Cs) via first-principles calculations. Sodium, potassium, and rubidium perrhenates are isostructural and crystallize in a tetragonal structure, whereas cesium perrhenate crystallizes in an orthorhombic structure. All the phonon frequencies and their corresponding mode assignments were estimated through the linear response method within density-functional-perturbation theory. The phonon density of states highlights the participation of the oxygen anions and both the A-type and rhenium (Re) cations in the low-frequency range. In contrast, the oxygen and Re atoms make relatively high and moderate contributions to the remaining phonon frequency spectrum. Considerable splitting of the longitudinal and traverse optic modes was observed. Elastic constants and phonon dispersion calculations confirmed the mechanical and dynamic stability of the studied AReO4compounds. A redshift was observed with the frequency of the phonons following the sequence Na→Cs. The low value calculated for the bulk modulus (ranging from 28.36 GPa to 14.15 GPa) and shear modulus indicates the perrhenates have a low resistance to deformation. The values of these moduli decrease in the order of Na→Cs, which correlates with an increase in an ionic radius of the cation. The response to pressure was found to be anisotropic. This characteristic and the ductile nature of the alkali-metal perrhenates were confirmed through elastic analysis.

Progress in Sealed Lithium–Oxygen Batteries Based on the Oxygen Anion Charge Compensation Mechanism

Progress in Sealed Lithium–Oxygen Batteries Based on the Oxygen Anion Charge Compensation Mechanism

Lithium-rich manganese-based layered oxide cathode materials for lithium-ion batteries modified by MoS2 coatings with two-dimensional graphene-like structures

Lithium-rich manganese-based layered oxide cathode materials (LRMCs) have some unique advantages such as high theoretical capacity (≥ 250 mAh g−1) and high energy density. Therefore, they are deemed as a kind of cathode material for lithium-ion batteries with an excellent prospect of application. However, the redox of oxygen anion is able to generate irreversible lattice oxygen loss, leading to irreversible loss of capacity, bringing about a sharp drop of working voltage, and seriously restricting the commercialization of LRMCs. In this paper, MoS2 coating with two-dimensional graphene-like structure was coated on the surface of LRMCs materials for improving the cycling stability and rate performance. The MoS2 coating can provide a two-dimensional diffusion channel for the migration of lithium-ions, which facilitates the fast release of lithium-ions during cycling process. The results show that the first discharge capacity, initial Coulomb efficiency and rate performance of LRMCs are improved. When the current density is 1 C, the first discharge specific capacity of LRMCs@MoS2 reaches 227.69 mAh g−1, and the capacity retention ratio is 84.98 % after 100 cycles. When the current density is 5 C, it can still provide a discharge specific capacity of 137.87 mAh g−1, demonstrating excellent electrochemical performance. This study comes up a simple and practical idea to realize the modification of cathode materials for high performance lithium-ion batteries.

Transforming Element Sulfur to High Performance Closed-Loop Recyclable Polymer via Proton Transfer Enabled Anionic Hybrid Copolymerization.

The utilization of sulfur has been a global issue. Copolymerization of element sulfur (S8) with other monomers is a promising route to convert it to useful materials but is limited by the comonomers. Here, we report anionic hybrid copolymerization of S8 with acrylate and epoxide at room temperature, where S8 does not copolymerize with epoxide in the absence of acrylate. Yet, the proton transfer from the methyne in acrylate to the oxygen anion enables the ring-opening of the cyclic comonomer and hence the copolymerization. The cyclic comonomers can be expanded to lactone and cyclic carbonate. Specifically, the copolymer of S8 with bisphenl A diglycidyl ether and diacrylate displays mechanical properties comparable to those of most common plastics, namely, it has ultimate tensile strength as high as 60.8 MPa and Young's modulus up to 680 MPa. It also exhibits high UV resistance and good transparency. Particularly, it has excellent UV-induced self-healing, reprocessability and closed-loop recyclability due to the abundant dynamic S-S bonds and ester groups. This study provides an efficient strategy to turn element sulfur into closed-loop recyclable polymer with high mechanical and optical performances.

Reversible pH-switchable NIR-II nano-photosensitizer for precise imaging and photodynamic therapy of tumors

Photodynamic therapy (PDT) has attracted widespread attention from researchers as an emerging cancer treatment method. There have been many reports on various types of NIR-II photosensitizers for imaging and treatment of tumor sites. However, there are few reports on the development of NIR-II organic small molecule photosensitizers that have intelligent response to the tumor microenvironment, precise imaging, real-time treatment, and high biocompatibility. In this work, we developed a series of NIR-II photosensitizers (RBTs) with near-infrared excitation, good photostability, and large Stokes shift. Among them, RBT-Br exhibited higher reactive oxygen species (ROS) generation efficiency due to the introduction of halogen heavy atoms to enhance intersystem crossing (ISC). It is noteworthy that RBT-Br can generate singlet oxygen (1O2) and superoxide anion radicals (•O2−) simultaneously under 730 nm laser. Subsequently, we used molecular engineering technology to construct three pH-responsive NIR-II photosensitizers (RBT-pHs) by utilizing the closure of the lactam ring, among which RBT-pH-1 (pKa = 6.78) is able to be directionally activated under the stimulation of tumor micro-acid environment, with its fluorescence emission window reaching 933 nm. Subsequently, RBT-pH-1 NPs encapsulated in DSPE-mPEG5k were applied for PDT treatment of mouse tumors. The results showed that RBT-pH-1 NPs were activated by the acidic tumor microenvironment and generated ROS under laser excitation, exhibiting precise tumor imaging and significant tumor growth inhibition. We look forward to these multifunctional NIR-II organic small molecule photosensitizers providing a more efficient approach for clinical treatment of tumors. Statement of significanceA reversible pH-switchable NIR-II nano-photosensitizer RBT-pH-1 NPs (pKa = 6.76) is developed for precise imaging and PDT therapy of mouse tumors, which can be effectively used for targeted enrichment and activation of tumor micro-acid environments. The results show that this NIR-II photosensitizer generates ROS through tumor micro-acid environment stimulation and laser triggering, showing precise tumor imaging guidance and significant tumor growth inhibition.

Revealing the degradation pathways of layered Li-rich oxide cathodes.

Layered lithium-rich transition metal oxides are promising cathode candidates for high-energy-density lithium batteries due to the redox contributions from transition metal cations and oxygen anions. However, their practical application is hindered by gradual capacity fading and voltage decay. Although oxygen loss and phase transformation are recognized as primary factors, the structural deterioration, chemical rearrangement, kinetic and thermodynamic effects remain unclear. Here we integrate analysis of morphological, structural and oxidation state evolution from individual atoms to secondary particles. By performing nanoscale to microscale characterizations, distinct structural change pathways associated with intraparticle heterogeneous reactions are identified. The high level of oxygen defects formed throughout the particle by slow electrochemical activation triggers progressive phase transformation and the formation of nanovoids. Ultrafast lithium (de)intercalation leads to oxygen-distortion-dominated lattice displacement, transition metal ion dissolution and lithium site variation. These inhomogeneous and irreversible structural changes are responsible for the low initial Coulombic efficiency, and ongoing particle cracking and expansion in the subsequent cycles.

Synergistic enhancement of ion/electron transport by ultrafine nanoparticles and graphene in Li2FeTiO4/C/G nanofibers for symmetric Li-ion batteries

Low-cost Fe-based disordered rock salt (DRX) Li2FeTiO4 is capable of providing high capacity (295 mA h g−1) by redox activity of cations (Fe2+/Fe4+ and Ti3+/Ti4+) and anionic oxygen. However, DRX structures lack transport channels for ions and electrons, resulting in sluggish kinetics, poor electrochemical activity, and cyclability. Herein, graphene conductive carbon network permeated Li2FeTiO4 (LFT/C/G) nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method. Ultrafine Li2FeTiO4 nanoparticles (2 nm) and one-dimensional (1D) structure provide abundant active sites and unobstructed diffusion channels, accelerating ion diffusion. In addition, introducing graphene reduces the band gap and Li+ diffusion barrier and improves the dynamic properties of Li2FeTiO4, thus achieving a relatively mild interfacial reaction and reversible redox reaction. As expected, the LFT/C/1.0G cathode delivers a remarkable discharge capacity (238.5 mA h g−1), high energy density (508.8 Wh kg−1), and excellent rate capability (51.2 mA h g−1 at 1.0 A g−1). Besides, the LFT/C/1.0G anode also displays a high capacity (514.5 mA h g−1 at 500 mA g−1) and a remarkable rate capability (243.9 mA h g−1 at 8 A g−1). Moreover, the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g−1 after 100 cycles at 50 mA g−1. This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.

An Acceptor-Donor-Acceptor Structured Nano-Aggregate for NIR-Triggered Interventional Photoimmunotherapy of Cervical Cancer.

Compared with conventional therapies, photoimmunotherapy offers precise targeted cancer treatment with minimal damage to healthy tissues and reduced side effects, but its efficacy may be limited by shallow light penetration and the potential for tumor resistance. Here, an acceptor-donor-acceptor (A-D-A)-structured nanoaggregate is developed with dual phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), triggered by single near-infrared (NIR) light. Benefiting from strong intramolecular charge transfer (ICT), the A-D-A-structured nanoaggregates exhibit broad absorption extending to the NIR region and effectively suppressed fluorescence, which enables deep penetration and efficient photothermal conversion (η=67.94%). A suitable HOMO-LUMO distribution facilitates sufficient intersystem crossing (ISC) to convert ground-state oxygen (3O2) to singlet oxygen (1O2) and superoxide anions (·O2 -), and catalyze hydroxyl radical (·OH) generation. The enhanced ICT and ISC effects endow the A-D-A structured nanoaggregates with efficient PTT and PDT for cervical cancer, inducing efficient immunogenic cell death. In combination with clinical aluminum adjuvant gel, a novel photoimmunotherapy strategy for cervical cancer is developed and demonstrated to significantly inhibit primary and metastatic tumors in orthotopic and intraperitoneal metastasis cervical cancer animal models. The noninvasive therapy strategy offers new insights for clinical early-stage and advanced cervical cancer treatment.

Achieving High-Capacity Cathode Presodiation Agent Via Triggering Anionic Oxidation Activity in Sodium Oxide.

Compensating for the irreversible loss of limited active sodium (Na) is crucial for enhancing the energy density of practical sodium-ion batteries (SIBs) full-cell, especially when employing hard carbon anode with initially lower coulombic efficiency. Introducing sacrificial cathode presodiation agents, particularly those that own potential anionic oxidation activity with a high theoretical capacity, can provide additional sodium sources for compensating Na loss. Herein, Ni atoms are precisely implanted at the Na sites within Na2O framework, obtaining a (Na0.89Ni0.05□0.06)2O (Ni-Na2O) presodiation agent. The synergistic interaction between Na vacancies and Ni catalyst effectively tunes the band structure, forming moderate Ni-O covalent bonds, activating the oxidation activity of oxygen anion, reducing the decomposition overpotential to 2.8V (vs Na/Na+), and achieving a high presodiation capacity of 710 mAh/g≈Na2O (Na2O decomposition rate >80%). Incorporating currently-modified presodiation agent with Na3V2(PO4)3 and Na2/3Ni2/3Mn1/3O2 cathodes, the energy density of corresponding Na-ion full-cells presents an essential improvement of 23.9% and 19.3%, respectively. Further, not limited to Ni-Na2O, the structure-function relationship between the anionic oxidation mechanism and electrode-electrolyte interface fabrication is revealed as a paradigm for the development of sacrificial cathode presodiation agent.