VOCl3 Research Articles

Vanadium pentoxide nanowires preparation via kinetic control of vanadium oxytrichloride catalytic oxidation with APCVD

Vanadium pentoxide nanowires were successfully fabricated using vanadium oxytrichloride oxidation with copper oxide nanoparticles serving as catalysts via atmospheric pressure chemical vapor deposition. Kinetic parameters such as temperature and flow velocity were proved to play important roles in the morphologic control of as-deposited product. Vanadium pentoxide nanowires with an average length of ∼10 μm and a diameter of 50–100 nm, were obtained under the optimum conditions. A root growth mechanism of nanowires was proposed that precursor was readily captured by catalyst nanoparticles at the beginning of deposition, forming nucleation sites. Subsequently, the anisotropic growth of vanadium pentoxide is primarily governed by energy minimization under the reaction rate limited conditions. The presence of oxygen vacancies in the nanowires was confirmed by Raman, XPS and photoluminescence characterization, indicating promising applications in functional materials manufacture. The novel route for preparing vanadium pentoxide nanowires provides an alternative pathway for transitioning traditional vanadium industry towards advanced functional materials development.

A congruent-melting rubidium zinc vanadium oxychloride exhibiting strong mid-infrared second-harmonic generation and high laser-induced damage threshold

A novel mid-infrared (MIR) nonlinear optical (NLO) crystal Rb4ZnV5O15Cl (RZVC) has been designed and sythesized by the aliovalent substitution strategy based on the parent structure Rb2(VO)(V2O7). Modification of square pyramidal VO5 units through introduction of chlorine ion and zinc metal caion significantly enhanced the dipole moments in a unit cell from 1.653 D for Rb2(VO)(V2O7) to 6.559 D for RZVC. Consequently, polycrystalline RZVC exhibits strong SHG responses of 12.5 × KDP @1064 nm and 1.2 × AGS @2 μm. Furthermore, RZVC features a congruent melting property, an ultra-high LIDT value (62 × AGS @1064 nm), and a deep IR transparency cutoff edge (10 μm). Most importantly, RZVC can achieve full-wavelength phase matching in a very wide MIR transparency range of 1.69–10 μm, completely covering the important atmospheric window (3–5 μm) through NLO processes. Because of its many outstanding properties, RZVC can be a highly desirable candidate for practical MIR NLO applications.

Short-Process Preparation of High-Purity V2O5 from Shale Acid Leaching Solution via Chlorination

The conventional V2O5 preparation processes include ion exchange, chemical precipitation, solvent extraction, and other processes. Given the long process and complex operation nature of traditional V2O5 production methods, we herein developed a short-process, low-temperature, and convenient operation method of isolating vanadium (in the form of V2O5) from shale acid leaching solution. The acid leaching solution was oxidized with NaClO3 and pH-adjusted with NaOH to form a vanadium-containing precipitate, which was mixed with AlCl3 (V:AlCl3 = 1:5, mol/mol) and roasted for 120 min at 170 °C to afford vanadium oxytrichloride (VOCl3) with a purity of 99.59%. In addition, the vanadium-containing precipitate was mixed with AlCl3 and NaCl (V:AlCl3:NaCl = 3:12:8, mol/mol/mol) and roasted for 120 min at 170 °C to afford VOCl3 with a purity of 99.94%. VOCl3 (purity of 99.94%) was dissolved in ultrapure water, and the solution (32 gvanadium/L) was treated with NH3·H2O (NH3:V = 1.34, mol/mol) at 50 °C for 120 min. The obtained precipitate (vanadium precipitation rate = 99.28%) was roasted at 550 °C for 3 h to afford high-purity vanadium pentoxide (V2O5) with a purity of 99.86%. Compared with the traditional hydrometallurgical method of V2O5 preparation, our method avoided solvent extraction and other undesired processes and the overall process flow is greatly shortened, thus having high practical value.

High purity vanadium pentoxide preparation via gas phase oxidation of vanadium oxytrichloride in fluidized bed reactor

With the increasing demand for high purity vanadium pentoxide for manufacturing of all-vanadium redox flow batteries (VRFBs), production of high purity vanadium pentoxide by chlorination process is an efficient and clean approach. However, oxidation of vanadium oxytrichloride is the controlling step. In the present work, gaseous vanadium oxytrichloride oxidation and vanadium pentoxide deposition behavior on particle substrates in a fluidized bed reactor were investigated. Results showed that the thermodynamic equilibrium conversion of oxidation gradually decreased with increasing temperature above 400 °C, while the kinetic limitation was predominant at low temperatures. Subsequently, oxidation experiments were conducted to investigate the influences of parameters on the conversion efficiency. Under optimized reaction conditions, the conversion of vanadium oxytrichloride and the deposition rate of vanadium pentoxide could achieve 68.52 % and 0.48 g/(h·g), respectively. It was more preferable than previous works that the purity of deposited vanadium pentoxide products reached 99.99 wt%, while impurities that would greatly affect electrochemical performance of the VRFBs were undetectable. This novel method provides an efficient route for the preparation of high purity vanadium pentoxide along with the recycling of chlorine gas for the chlorination process, which would be a promising method for green and sustainable development of the vanadium industry.

Spectroscopic investigations, ab-initio DFT calculations, molecular docking and in-vitro assay studies of novel oxovanadium(V)chalcone complexes as potential antidiabetic agents

A series of four novel oxovanadium(V)chalcone complexes ([VO(LI-IV)2Cl]; where HLI=1-(2-Hydroxy-phenyl)-3-phenyl-propenone, HLII=1-(1-Hydroxy-naphthalen-2-yl)-3-phenyl-propenone, HLIII = 1-(2-Amino-phenyl)-3-phenyl-propenone, HLIV = 4-Hydroxy-6-methyl-3-(3-phenyl-acryloyl)-pyran-2-one) were designed and synthesized by performing chemical reaction between VOCl3 and respective chalcone derivatives in 1:2 molar ratio. Their formation as well as chemical structures were confirmed by FTIR, UV-Visible, 1H-NMR, SEM, EDS, and mass spectrometry spectroscopic techniques. The geometry of the synthesized complexes was purposed to be octahedral on the basis of the characterization. Further computational and structural parameters of the synthesized complexes were determined in order to establish their thermodynamic stability/chemical reactivity of the synthesized complexes. Density Functional Theory (DFT) method was employed to calculate the molecular geometry and vibrational frequencies of the synthesized complexes using B3LYP hybrid functional at 6-31G* level of basis set. Further, Spartan'20 V1.0.0 program package was used to calculate the 1H-NMR spectra with (DFT/ B3LYP) in the gaseous phase to validate the structure of oxovanadium(V) complexes. The experimentally obtained results were found to be well correlated with theoretical results with a correlation value > 0.96. Global reactivity descriptors helps to explain the bioactivity of complexes hence, were calculated from the HOMO-LUMO energies. The enzymatic assay experiments indicated that all the four synthesized complexes have significant to moderate inhibition potential against α-glucosidase, and α-amylase enzymes. Among all the oxovanadium(V)chalcone complexes, complex 4showed excellent and superior inhibition potency almost equivalent to the commercially available Acarbose drug and even better in case of α-amylase. The observed IC50 value of complex 4 for the inhibition of α-amylase and α-glucosidase was calculated to be 16.36 µg/mL and 57.27 µg/mL, respectively. The Kinetic parameters calculated from the Lineweaver-Burk plot showed that complex 4 were uncompetitive and mixed inhibitor of α-amylase and α-glucosidase respectively. Thereafter,the antiradical activity of synthesized vanadium(V)chalcone complexes was assessed with the help of DPPH radical scavenging assay. The results demonstrated that all the complexes were remarkable free radical scavengers for the DPPH. The complex 1 was observed to be best among them with the 0.03 µg/mL IC50 value. The AutoDockTools-1.5.6 software was used to examine structure-activity relationship and the binding interactions between oxovanadium(V) complexes and protein target alpha-amylase, alpha-glucosidase, and Myeloperoxidase respectively. The in-vitro as well as in-silico biological activity studies showed significant and major improvements after complexation of chalcone derivatives with vanadium oxychloride (VOCl3). Thus, oxovanadium(V)chalcone complexes were found to be potent inhibitors of the α-glucosidase and α-amylase enzyme.

Chemical Exfoliation toward Magnetic 2D VOCl Monolayers.

The diversification of magnetic two-dimensional (2D) materials holds the key to the further development of advanced technologies, such as spintronic devices and efficient data storage. However, the search for intrinsic magnetism down to the 2D limit is severely limited by the ability to reliably exfoliate large, air-stable nanosheets. Chemical exfoliation, a relatively underutilized method for delamination, offers many advantages, including a high degree of adaptability and higher yields of uniformly exfoliated materials. van der Waals (vdW) materials, in particular the family of transition-metal oxyhalides, are ideal candidates for chemical exfoliation due to their large interlayer spacing and the wide variety of interesting magnetic properties they exhibit. In this study, we employ a chemical exfoliation method to delaminate the layered antiferromagnet vanadium oxychloride (VOCl) down to the monolayer limit. The resulting nansoheets have lateral sizes of up to 20 μm, are air-stable, and can be easily isolated. Magnetic characterization was performed throughout the exfoliation process, tracking the changes in magnetic behavior among bulk VOCl, its lithiated intercalate, and the restacked nanosheet pellet. The results from this work demonstrate the potential of chemical exfoliation, along with illustrating the effects of low dimensionality on magnetic properties.

High Purity Vanadium Pentoxide Preparation Via Gas Phase Oxidation of Vanadium Oxytrichloride in Fluidized Bed Reactor

High Purity Vanadium Pentoxide Preparation Via Gas Phase Oxidation of Vanadium Oxytrichloride in Fluidized Bed Reactor

Chlorination behaviors for green and efficient vanadium recovery from tailing of refining crude titanium tetrachloride

The refined tailing, generated from refining of titanium tetrachloride (TiCl4) for vanadium (V) removal, is a hazardous material to environment due to the high content of V. Aiming at effective and selective extraction of V from the refined tailing, a fluidized chlorination process was proposed in present work. The chlorination behaviors of the refined tailing which determine the efficiency and selectivity of V extraction were emphatically investigated. A resultant 96.36% of V and 4.23% of Ti can be synchronously extracted from the tailing at the optimum conditions of 800 °C for 60 min, with the pressure fraction of chlorine [P(Cl2)/P(Cl2 +N2)] = 0.5 and the mass fraction of petroleum coke in raw materials for chlorination at 10 wt%. High purity vanadium oxytrichloride (VOCl3, higher than 99.99 wt%) can be finally obtained via further simple purification of the collected chloride product. Moreover, the chlorination residue containing concentrated TiO2 has the potential to be further utilized for Ti extraction. Thus the process provides a new prospect for effective, clean and comprehensive utilization of the refined tailing, which can solve the hazardous waste recycle and environmental concerns simultaneously.

Graphene vanadic acid (GVA) as a novel heterogeneous catalyst for highly selective benzene hydroxylation under mild conditions

In the present study, Graphene Vanadic Acid (GVA) is introduced as a novel catalyst for high-efficiency hydroxylation of benzene to phenol using hydrogen peroxide at ambient conditions. Graphene oxide as a famous carbon support has converted to a high-performance catalyst through the functionalization using vanadium oxytrichloride (VOCl3). This new carbon compound is regarded as the efficient catalyst due to the prominent advantages such as high-recativity and reusability, facile preparation, active Lewis and Bronsted acid sites, high potential for development of various oxidation reactions, and high thermal, chemical, and physical stability due to the regular carbon structure. GVA progressed the benzene oxidation toward the phenol formation as a useful raw material. Cause of the considerable reactivity of the synthesized catalyst, a minimum amount of hydrogen peroxide was required and the benzene oxidation carried out using an equimolar ratio of benzene/H2O2, and phenol obtained with a remarkable yield (28.2%) as the sole product.

Optimizing the Optoelectronic Properties of Face‐On Oriented Poly(3,4‐Ethylenedioxythiophene) via Water‐Assisted Oxidative Chemical Vapor Deposition

AbstractEngineering the texture and nanostructure to improve the electrical conductivity of semicrystalline conjugated polymers must address the rate‐limiting step for charge carrier transport. In highly face‐on orientation, the charge transport between chains within a crystallite becomes rate‐limiting, which is highly sensitive to the π–π stacking distance and interchain charge transfer integral. Here, face‐on oriented semicrystalline poly(3,4‐ethylenedioxythiophene) (PEDOT) thin films are grown via water‐assisted (W‐A) oxidative chemical vapor deposition (oCVD). Combining W‐A with the volatile oxidant, antimony pentachloride, yields an optimized electrical conductivity of 7520 ± 240 S cm−1, a record for PEDOT thin films. Systematic control of π–π stacking distance from 3.50 Å down to 3.43 Å yields an electrical conductivity enhancement of ≈1140%. The highest electrical conductivity also corresponds to minimum in Urbach energy of 205 meV, indicating superior morphological order. The figure of merit for transparent conductors, σdc/σop, reaches a maximum value of 94, which is 1.9× and 6.7× higher than oCVD PEDOT grown without W‐A and utilizing vanadium oxytrichloride and iron chloride oxidizing agents, respectively. The W‐A oCVD is single‐step all‐dry process and provides conformal coverage, allowing direct growth on mechanical flexible, rough, and structured surfaces without the need for complex and costly transfer steps.

Highly active and thermo‐stable iminopyridyl vanadium oxychloride catalyzed isoprene polymerization

AbstractStereoregular polymerizations are of high importance, which disclosing the relationships between microstructures and physical properties of polymers. In this contribution, a series of iminopyridyl vanadium oxychloride complexes V1–V8 (R = H, R1 = CH2Ph for V1; R = H, R1 = CHPh2 for V2; R = H, R1 = octamyl for V3; R = H, R1 = Ph for V4; R = H, R1 = 4‐OMe‐C6H4 for V5; R = H, R1 = 4‐CF3C6H4 for V6; R = H, R1 = 2,4,6‐Ph3C6H2 for V7 and R = Me, R1 = Ph for V8) have been prepared, and were investigated for their catalytic capacity of isoprene polymerization. A single crystal structure of V7′ was reported, which was reduced from V(v) to V(iv) in the oxidation state of vanadium central atom. The catalytic activity was up to 408 kg (mol V)−1 hr−1, when V4 was used. The catalyst V6 was found to be highly thermo‐stable with excellent activity even at 100°C. Most importantly, resultant polymers mainly possessed cis‐1,4 units (up to 75%) with 25% side‐chain 3,4 functional group, which is particularly important component to enhance the application of these synthetic rubbers.

A spiral shaped regenerative microfluidic fuel cell with Ni‐C based porous electrodes

Microchannel geometry, electrode surface area, and better fuel utilization are important aspects of the performance of a microfluidic fuel cell (MFC). In this communication, a membraneless spiral-shaped MFC fabricated with Ni as anode and C as a cathode supported over a porous filter paper substrate is presented. Vanadium oxychloride and dilute sulfuric acid solutions are used as fuel and electrolyte, respectively, in this fuel cell system. The device generates a maximum open-circuit voltage of ~1.2 V, while the maximum energy density and current density generated from the fuel cell are ~10 mW cm−2 and ~51 mA cm−2, respectively. The cumulative energy density generated from the device after five cycles are measured as ~200 mW after regeneration of the fuel by applying external voltage. The spiral design of the fuel cell enables improved fuel utilization, rapid diffusive transport of ions, and in-situ regeneration of the fuel. The present self-standing spiral-shaped MFC will eliminate the challenges associated with two inlet membrane-less fuel cells and has the potential to scale up for commercial application in portable energy generation.

Vanadium oxychloride as cathode for rechargeable aluminum batteries

Vanadium oxychloride (VOCl) with layered structure may be a potential cathode material for rechargeable aluminum batteries (RABs) due to its large interlayer spacing and high theoretical capacity. Herein, the VOCl material is employed as the cathode material of RABs for the first time. The corresponding electrochemical performance and mechanisms of the VOCl cathode are investigated. The VOCl cathode after the first charge delivers a high reversible discharge capacity of 124.7 mAh g−1, which is ascribed to the AlCl4− deintercalation and the subsequent Al3+ intercalation. However, the discharge capacity fades to 41.5 mAh g−1 after 100 cycles, which is mainly caused by the irreversible AlCl4− intercalation/deintercalation during cycling. The electrochemical capacity of the VOCl cathode in the RAB is dominated by the Al3+ intercalation/deintercalation after the first cycle, as confirmed by the electrochemical tests, energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). In addition, it is found that there is no evident lattice expansion when the AlCl4− or Al3+ is intercalated into the interlayers of VOCl.

High-purity, low-Cl V2O5 via the gaseous hydrolysis of VOCl3 in a fluidized bed

Present-day all-vanadium redox flow batteries (VRFBs) generally require high purity vanadium oxide as a raw ingredient. The chlorination procedure presents distinct technical advantages with regard to preparing high purity vanadium pentoxide (V2O5) using vanadium oxytrichloride (VOCl3) as a highly pure intermediate. To efficiently prepare high purity V2O5 from VOCl3, a single-step fluidized bed chemical vapor deposition (FBCVD) method was explored in the present work. Based on thermodynamic analyses, the direct and complete conversion of VOCl3 to V2O5 is difficult, and may result in a small amount of residual Cl in the product. Consequently, the effects of temperature and the H2O/VOCl3 molar ratio on the quantity of residual Cl were assessed. The Cl concentration was found to decrease with increasing temperature or increasing H2O/VOCl3 molar ratios. Additionally, Cl was determined to be present only in the form of ClV bonds, while ClH and ClCl bonds were not detected in a V2O5 product made at 200°C with a H2O/VOCl3 molar ratio of 18. A Cl concentration of less than 0.05wt% was obtained under the optimal synthesis conditions, demonstrating that the FBCVD method is a viable means of preparing high purity V2O5 via the gaseous hydrolysis of VOCl3.

Electroactive and Conformal Coatings of Oxidative Chemical Vapor Deposition Polymers for Oxygen Electroreduction

Polymer from 3,4-ethylenedioxythiophene (EDOT) was synthesized using oxidative chemical vapor deposition (oCVD). To enable the synthesis of PEDOT, two different oxidants, antimony pentachloride (SbCl5) and vanadium oxytrichloride (VOCl3), were utilized. The effect of deposition temperature on the polymer electroactivity and conductivity was evaluated by measuring the overpotential for the oxygen reduction reaction and film electrical conductivity, respectively. PEDOT films with conductivity values of ∼2000 S/cm were deposited in a single step coating and doping process. X-ray photoelectron spectroscopy revealed that the residual metalloid within polymer films, in the case of SbCl5, is contributing to the hole conductivity. The electrocatalytic activity of deposited material in oxygen reduction reaction (ORR) was studied; the results indicate a direct relationship between the conductivity values and the electrocatalytic activities of the deposited films. The unique potential offered by oCVD to coat PEDOT conformally enabled us to apply a coat of electroactive polymers on complex structures of a gas diffusion layer fabric, carbon cloth. Using our approach, we imparted stable electrocatalytic activity to carbon cloth electrodes and fabricated all-organic electrodes for ORR.

Lithium-Magnesium Hybrid Battery with Vanadium Oxychloride as Electrode Material

Metallic magnesium represents a promising solution for next generation electrochemical energy storage devices because of its dendrite-free electrodeposition, higher theoretical volumetric energy density, abundancy and safety compared to lithium technology. Nevertheless, Mg2+ is strongly polarized, which slows down its diffusion during discharging/charging. An electrochemical energy storage device containing a metallic Mg anode, a Li intercalation cathode and a Li/Mg-electrolyte can be regarded as a solution to circumvent the intrinsic drawbacks linked to both Li- and Mg-electrochemistry. In this contribution, we report on the performance of a VOCl/Mg cell containing a Li−Mg hybrid electrolyte. The cell delivered 195 mA h g−1 at 100 mA g−1 with a coulombic efficiency of 97.5%. At 200 mA g-1, after 150 cycles, 107 mA h g−1 was measured with 99.5% coulombic efficiency. At 500 mA g−1, after 800 cycles, the cell still produced 75 mA h g−1 with 99.8% coulombic efficiency. Lithium reacted with VOCl first via an intercalation reaction and then in a conversion reaction to LiCl and VO. The co-deposition of Li at the anode, Li−Mg alloy formation or contributions from side reactions could be ruled out.

Preparation and Electrochemical Properties of High Purity Mixed-Acid Electrolytes for High Energy Density Vanadium Redox Flow Battery

All-vanadium redox flow battery (VRFB) is a large-scale electrochemical energy storage technology with numerous potential applications because of its inherent safety and long service life. In previous years, a novel mixed-acid electrolyte system, vanadium electrolytes with mixture of sulfuric acid and hydrochloric acid, has been developed by the Pacific Northwest National Laboratory (PNNL) to increase vanadium solubility, which can effectively raise the electrolyte energy density from 25 Wh/L to 40 Wh/L. To further improve mixed-acid VRFBs, in present work, high purity mixed-acid electrolytes were prepared using a novel direct dissolution - electrochemical reduction process from high purity vanadium oxytrichloride (VOCl3). And the purity and electrochemical properties were investigated, comparing with common mixed-acid electrolytes and regular sulfate electrolytes prepared from metallurgical grade vanadium pentoxide. It was found that the novel process demonstrated a great potential for the low cost and high efficiency production of high purity electrolytes with excellent electrochemical properties for mixed-acid VRFBs. Comparing the traditional high purity electrolytes preparation process, the present novel method will dramatically cut the cost by more than 90 percent, which will considerably facilitate the commercial application of high performance and high density VRFBs.

Selective hydrolysis of trace TiCl 4 from VOCl 3 for preparation of high purity V 2 O 5

Abstract Given the strong demands for high purity vanadium products dedicated for all-vanadium redox flow battery (VRFB), numerous preparation technologies have been developed. One of them, the chloride process that using vanadium oxytrichloride (VOCl3) as purification intermediate presents distinct technical advantages. The intermediate is readily purified via distillation process to remove most of the impurities. However, the trace titanium tetrachloride (TiCl4) is difficult to be removed, due to close saturated vapor pressures. In present work, based on thermodynamic calculation and analyses, we found that TiCl4 reacts with water significant preferentially to form the corresponding oxide, compared with VOCl3. Then we proposed a novel method to remove trace TiCl4 from VOCl3 by selective hydrolysis – distillation. The related experiments were conducted and validated the feasibility of the innovative process. Vanadium pentoxide (V2O5) with purity higher than 99.99 wt% (4N) was further prepared from the purified VOCl3 by precipitation – calcination.

Chlorination and purification of vanadium pentoxide with anhydrous aluminum chloride

Abstract A novel chlorination process was investigated to prepare high-purity vanadium pentoxide (V2O5). Anhydrous aluminum chloride (AlCl3) instead of toxic and corrosive chlorine (Cl2) was used as the chlorination agent. The chlorination temperature was decreased as low as 160 °C–170 °C. By adding sodium chloride (NaCl) into the chlorination system, the reaction rate and purity of the intermediate product, vanadium oxytrichloride (VOCl3) were both remarkably improved. Additionally, hydrolysis conditions were also discussed. It was found that the precipitation rate reached 93.56% under the conditions of vanadium concentration of 13.4–68.8 (V2O5)g/L and the ammonium adding coefficient of 0.8–1.0. Based on the optimal conditions, V2O5 with a purity of 99.95 wt% at least was obtained, the content of Fe, Al, Si, K, Na, Zn, P and other impurities were effectively reduced. Compared with the preparation method currently used in the industrial process, the novel chlorination method proposed is an environmently-friendly process with the low cost, high selectivity, and simplified operation advantages. Therefore, the novel chlorination method exhibits a competitive potential in industrial application.

Interlayer‐Expanded Vanadium Oxychloride as an Electrode Material for Magnesium‐Based Batteries

AbstractMg‐based batteries, which use the Mg2+ shuttle, theoretically offer several advantages compared to the Li technology, such as higher theoretical volumetric capacity (3833 mA h cm−3) of the Mg‐metal anode, the possibility to be safely handled in air, and dendrite‐free electrodeposition. In this study, vanadium oxychloride was employed as an electrode material in a Mg‐based battery. As the cell delivered just 45 mA h g−1 in the first cycle, we tried to improve the delivered capacity through preliminary cycling of the VOCl electrode with Li. The strategy is based on the ability of VOCl to expand its interlayer spacing upon intercalation of ions or molecules within them. In fact, a VOCl electrode with expanded interlayer spacing should facilitate the intercalation of Mg2+, thus leading to higher specific capacities. The Li pretreatment was able to promote the specific capacity by a factor of four (170 mA h g−1) after the first discharge at 298 K. Over 130 mA h g−1 was retained at 5 mA g−1 after 70 cycles. Structural and electrochemical characterization was carried out by means of galvanostatic charge/discharge tests, cyclic voltammetry, ex situ X‐ray photoelectron spectroscopy, X‐ray diffraction, transmission electron microscopy coupled with energy‐dispersive X‐ray spectroscopy, and electron energy loss spectroscopy. Inductively coupled plasma optical emission spectrometry was used to determine the concentration of lithium in the electrode.