Nanoscale Probing of Voltage Activated Oxygen Reduction/Evolution Reactions in Nanopatterned (LaxSr1‐x)CoO3‐δ Cathodes

Bias‐dependent mechanisms of reversible and irreversible electrochemical processes on a (La_0.5Sr_0.5)₂CoO_4±δ modified (La_xSr_1‐x)CoO₃‐ surface are studied using dynamic electrochemical strain microscopy (D‐ESM). The reversible oxygen reduction/evolution process is activated at voltages as low as 3–4 V and the degree of transformation increases linearly with applied bias. The irreversible processes associated with static surface deformation become apparent above 10–12 V. Post‐mortem focused‐ion milling combined with atomic resolution scanning transmission electron microscopy and electron energy loss spectroscopy is used to establish the mechanisms of irreversible transformations and attribute it to amorphization of the top layer of material. These studies both establish the framework for probing irreversible electrochemical processes in solids and illustrate rich spectrum of electrochemical transformations underpinning electrocatalytic activity in cobaltites.     

Interface‐Engineered All‐Solid‐State Li‐Ion Batteries Based on Garnet‐Type Fast Li+ Conductors

All‐solid‐state Li‐ion batteries based on Li₇La₃Zr₂O₁₂ (LLZO) garnet structures require novel electrode assembly strategies to guarantee a proper Li⁺ transfer at the electrode–electrolyte interfaces. Here, first stable cell performances are reported for Li‐garnet, c‐Li_6.25Al_0.25La₃Zr₂O₁₂, all‐solid‐state batteries running safely with a full ceramics setup, exemplified with the anode material Li₄Ti₅O₁₂. Novel strategies to design an enhanced Li⁺ transfer at the electrode–electrolyte interface using an interface‐engineered all‐solid‐state battery cell based on a porous garnet electrolyte interface structure, in which the electrode material is intimately embedded, are presented. The results presented here show for the first time that all‐solid‐state Li‐ion batteries with LLZO electrolytes can be reversibly charge–discharge cycled also in the low potential ranges (≈1.5 V) for combinations with a ceramic anode material. Through a model experiment, the interface between the electrode and electrolyte constituents is systematically modified revealing that the interface engineering helps to improve delivered capacities and cycling properties of the all‐solid‐state Li‐ion batteries based on garnet‐type cubic LLZO structures.     

Low‐Temperature Micro‐Solid Oxide Fuel Cells with Partially Amorphous La0.6Sr0.4CoO3‐δ Cathodes

Partially amorphous La_0.6Sr_0.4CoO_3‐δ (LSC) thin‐film cathodes are fabricated using pulsed laser deposition and are integrated in free‐standing micro‐solid oxide fuel cells (micro‐SOFC) with a 3YSZ electrolyte and a Pt anode. A low degree of crystallinity of the LSC layers is achieved by taking advantage of the miniaturization of the cells, which permits low‐temperature operation (300–450 °C). Thermomechanically stable micro‐SOFC are obtained with strongly buckled electrolyte membranes. The nanoporous columnar microstructure of the LSC layers provides a large surface area for oxygen incorporation and is also believed to reduce the amount of stress at the cathode/electrolyte interface. With a high rate of failure‐free micro‐SOFC membranes, it is possible to avoid gas cross‐over and open‐circuit voltages of 1.06 V are attained. First power densities as high as 200–262 mW cm^?2 at 400–450 °C are achieved. The area‐specific resistance of the oxygen reduction reaction is lower than 0.3 Ω cm² at 400 °C around the peak power density. These outstanding findings demonstrate that partially amorphous oxides are promising electrode candidates for the next‐generation of solid oxide fuel cells working at low‐temperatures.     

Modifying La0.6Sr0.4MnO3 Perovskites with Cr Incorporation for Fast Isothermal CO2‐Splitting Kinetics in Solar‐Driven Thermochemical Cycles

Perovskites are promising oxygen carriers for solar‐driven thermochemical fuel production due to higher oxygen exchange capacity. Despite their higher fuel yield capacity, La_0.6Sr_0.4MnO₃ perovskite materials present slow CO₂‐splitting kinetics compared with state‐of‐the‐art CeO₂. In order to improve the CO production rates, the incorporation of Cr in La_0.6Sr_0.4MnO₃ is explored based on thermodynamic calculations that suggest an enhanced driving force toward CO₂ splitting at high temperatures for La_0.6Sr_0.4Cr_xMn_1?xO₃ perovskites. Here, reported is a threefold faster CO fuel production for La_0.6Sr_0.4Cr_0.85Mn_0.15O₃ compared to conventional La_0.6Sr_0.4MnO₃, and twofold faster than CeO₂ under isothermal redox cycling at 1400 °C, and high stability upon long‐term cycling without any evidence of microstructural degradation. The findings suggest that with the proper design in terms of transition metal ion doping, it is possible to adjust perovskite compositions and reactor conditions for improved solar‐to‐fuel thermochemical production under nonconventional solar‐driven thermochemical cycling schemes such as the here presented near isothermal operation.     

Double Columnar Structure with a Nanogradient Composite for Increased Oxygen Diffusivity and Reduction Activity

The cathodic performances that can be achieved in solid oxide fuel cells (SOFCs), particularly in terms of oxygen diffusion, need to be improved so that high power densities can be produced at intermediate temperatures. Here, to improve the cathodic performance, a double columnar functional interlayer (DCFL) consisting of Sm_0.2Ce_0.8O_2?δ (SDC) and Sm_0.5Sr_0.5CoO_3?δ (SSC) is fabricated between a La_0.9Sr_0.1Ga_0.8Mg_0.2O_3?δ electrolyte film and a SSC cathode film with pulsed laser deposition. The DCFL has a rough surface morphology consisting of nanosized grains (with diameters less than 5 nm), and it is formed of small columns that grow at an angle of ca. 45° from the substrate. Inserting the DCFL causes the electrical conductivity of the cathode to increase significantly, and the power density obtained by using it in a metal‐supported SOFC is increased. Atomic resolution scanning transmission electron microscopy (TEM) images and density functional theory calculations confirm that the samarium atoms in the SDC columns and cobalt atoms in the SSC columns are located at the interfaces between SDC and SSC columns. Therefore, it is possible a SmCoO_3?δ nanogradient is formed, which may cause lattice distortions. The ¹⁸O₂ concentration is actually much higher in the DCFL than in either of SSC or SDC films.     

Perovskite Oxyfluoride Electrode Enabling Direct Electrolyzing Carbon Dioxide with Excellent Electrochemical Performances

Solid oxide electrolysis cells (SOECs) can efficiently convert the greenhouse‐gas CO₂ to valuable fuel CO at the cathodes. Herein, fluorine is doped into mixed ionic–electronic conducting Sr₂Fe_1.5Mo_0.5O_6‐δ (SFM), to evaluate its potential use as a cathode for CO₂ reduction reaction (CO₂‐RR). SFM retains its cubic structure after doped with fluorine, forming perovskite oxyfluoride Sr₂Fe_1.5Mo_0.5O_6‐δF_0.1 (F‐SFM). The substitution of oxygen by fluorine increases CO₂ adsorption by a factor of ≈2, bulk oxygen vacancy concentration by 35–37% at 800 °C, and consequently enhances the surface reaction rate constant for CO₂‐RR and chemical bulk diffusion coefficient by factors of 2–3. The faster kinetics are also reflected by a lower polarization resistance of 0.656 Ω cm² for F‐SFM than 1.130 Ω cm² for SFM at 800 °C in symmetrical cells. Furthermore, the single cell with F‐SFM cathode exhibits the best CO₂ electrolysis performance among the reported perovskite electrodes, achieving current density of 1.36 A cm^?2 at 1.5 V and excellent stability over 120 h at 800 °C under harsh conditions. The theoretical computations confirm that fluorine doping is energetically favorable to CO₂ adsorption and dissociation. The present work provides a promising strategy for the design of robust cathodes for direct CO₂ electrolysis in SOECs.     

Exceptionally High Performance Anode Material Based on Lattice Structure Decorated Double Perovskite Sr2FeMo2/3Mg1/3O6−δ for Solid Oxide Fuel Cells

A novel double perovskite Sr₂FeMo_2/3Mg_1/3O_6?δ is prepared and characterized as an anode material for solid oxide fuel cells (SOFCs). X‐ray diffraction refinement reveals that Mg and Mo cations locate separately in two different B sites (B and B′ in A₂BB′O₆) while Fe occupies both B and B′ sites, forming the lattice structure with the form of Sr₂(Mg_1/3Fe_2/3)(Mo_2/3Fe_1/3)O_6?δ. The inactive element Mg doping not only endows the material with excellent redox structural stability but also triggers the creation of antisite defects in the crystal lattice, which provide the material with excellent electrochemical activity. The anode performance of Sr₂FeMo_2/3Mg_1/3O_6?δ is characterized in an La_0.8Sr_0.2Ga_0.8Mg_0.2O_3?δ electrolyte supported cell with La_0.58Sr_0.4Fe_0.8Co_0.2O_3?δ cathode. A peak power density of 531, 803, 1038, and 1316 mW cm^?2 at 750, 800, 850, and 900 °C, respectively, is achieved in humidified H₂. The Sr₂FeMo_2/3Mg_1/3O_6?δ shows suitable thermal expansion coefficient (16.9(2) × 10^?6 K^?1), high electrical conductivity, and good tolerance to carbon deposition and sulfur poisoning. First‐principle computations demonstrate that the presence of Fe_B? O? Fe_B′ bonds can promote the easy formation and fast migration of oxygen vacancies in the lattice, which are the key to affecting the anode reaction kinetics. The excellent overall performance of Sr₂FeMo_2/3Mg_1/3O_6?δ compound makes it a promising anode material for SOFCs.     

Synthesis and Characterization of High‐Energy,High‐Power Spinel‐Layered Composite Cathode Materials for Lithium‐Ion Batteries

Spinel‐layered composites, where a high‐voltage spinel is incorporated in a layered lithium‐rich (Li‐rich) cathode material with a nominal composition x{0.6Li₂MnO₃ · 0.4[LiCo_0.333Mn_0.333Ni_0.333]O₂} · (1 – x) Li[Ni_0.5Mn_1.5]O₄ (x = 0, 0.3, 0.5, 0.7, 1) are synthesized via a hydroxide assisted coprecipitation route to generate high‐energy, high‐power cathode materials for Li‐ion batteries. X‐ray diffraction patterns and the cyclic voltammetry investigations confirm the presence of both the parent components in the composites. The electrochemical investigations performed within a wide potential window show an increased structural stability of the spinel component when incorporated into the composite environment. All the composite materials exhibit initial discharge capacities >200 mAh g^–1. The compositions with x = 0.5 and 0.7 show excellent cycling stability among the investigated materials. Moreover, the first cycle Coulombic efficiency achieve a dramatic improvement with the incorporation of the spinel component. More notably, the composite materials with increased spinel component exhibit superior rate capability compared with the parent Li‐rich material especially together with the highest capacity retention for x = 0.5 composition, making this as the optimal high‐energy high‐power material. The mechanisms involved in the symbiotic relationship of the spinel and layered Li‐rich components in the above composites are discussed.     

Electronic Activation of Cathode Superlattices at Elevated Temperatures – Source of Markedly Accelerated Oxygen Reduction Kinetics

Solid‐oxide fuel cells are an attractive energy conversion technology for clean electric power production. To render them more affordable, discovery of new cathode materials with high reactivity to oxygen reduction reaction (ORR) at temperatures below 700 °C is needed. Recent studies have demonstrated that La_0.8Sr_0.2CoO₃/(La_0.5Sr_0.5)₂CoO₄ (LSC_113/214) hetero‐interfaces exhibit orders of magnitude faster ORR kinetics compared with either single phase at 500 °C. To obtain a microscopic level understanding and control of such unusual enhancement, we implemented a novel combination of in situ scanning tunneling spectroscopy and focused ion beam milling to probe the local electronic structure at nanometer resolution in model multilayer superlattices. At 200–300 °C, the LSC₂₁₄ layers are electronically activated through an interfacial coupling with LSC₁₁₃. Such electronic activation is expected to facilitate charge transfer to oxygen, and concurrent with the anisotropically fast oxygen incorporation on LSC₂₁₄, quantitatively explains the vastly accelerated ORR kinetics near the LSC_113/214 interface. Our results contribute to an improved understanding of oxide hetero‐interfaces at elevated temperatures and identify electronically coupled oxide structures as the basis of novel cathodes with exceptional performance.     

Influence of Electrical Resistivity and Machining Parameters on Electrical Discharge Machining Performance of Engineering Ceramics

Engineering ceramics have been widely used in modern industry for their excellent physical and mechanical properties, and they are difficult to machine owing to their high hardness and brittleness. Electrical discharge machining (EDM) is the appropriate process for machining engineering ceramics provided they are electrically conducting. However, the electrical resistivity of the popular engineering ceramics is higher, and there has been no research on the relationship between the EDM parameters and the electrical resistivity of the engineering ceramics. This paper investigates the effects of the electrical resistivity and EDM parameters such as tool polarity, pulse interval, and electrode material, on the ZnO/Al₂O₃ ceramic''s EDM performance, in terms of the material removal rate (MRR), electrode wear ratio (EWR), and surface roughness (SR). The results show that the electrical resistivity and the EDM parameters have the great influence on the EDM performance. The ZnO/Al₂O₃ ceramic with the electrical resistivity up to 3410 Ω·cm can be effectively machined by EDM with the copper electrode, the negative tool polarity, and the shorter pulse interval. Under most machining conditions, the MRR increases, and the SR decreases with the decrease of electrical resistivity. Moreover, the tool polarity, and pulse interval affect the EWR, respectively, and the electrical resistivity and electrode material have a combined effect on the EWR. Furthermore, the EDM performance of ZnO/Al₂O₃ ceramic with the electrical resistivity higher than 687 Ω·cm is obviously different from that with the electrical resistivity lower than 687 Ω·cm, when the electrode material changes. The microstructure character analysis of the machined ZnO/Al₂O₃ ceramic surface shows that the ZnO/Al₂O₃ ceramic is removed by melting, evaporation and thermal spalling, and the material from the working fluid and the graphite electrode can transfer to the workpiece surface during electrical discharge machining ZnO/Al₂O₃ ceramic.     

Luminescence in Sr4Al14O25:Ce3+ aluminate phosphor

Cerium‐doped Sr₄Al₁₄O₂₅ phosphor is prepared using a single‐step combustion synthesis and its X‐ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) properties are characterized. XRD reveals the formation of the desired phase in the prepared sample. SEM micrographs of the prepared Sr₄Al₁₄O₂₅ phosphor show that the particle size is 10 µm. The prepared Sr₄Al₁₄O₂₅, along with Sr₄Al₁₄O₂₅:Ce_x (x = 0.5–5 mol%) shows a PL emission peak at 314 nm under UV excitation of 262 nm wavelength due to 5d → 4f transition. The phosphor is suitable for higher concentrations of Ce ions. The TL glow peak reveals three clearly visible distinct peaks at temperatures around 130, 231 and 336ºC. The three peaks are separated by deconvolution and kinetic parameters calculated using Chen's peak shape method. The calculation shows that the reaction follows second‐order kinetics with activation energy (E) values of 0.52, 0.81 and 1.12 eV, and frequency factor (s) values of 5.58 × 10⁵, 4.53 × 10⁷ and 4.57 × 10⁸ s^‐1 for the three individual peaks. Copyright © 2014 John Wiley & Sons, Ltd.     

Solid Solution Domains at Phase Transition Front of LixNi0.5Mn1.5O4

Nickel‐substituted manganese spinel LiNi_0.5Mn_1.5O₄ (LNMO) is a promising 5 V class positive electrode material for lithium‐ion batteries. As micron‐sized LNMO particles show high rate capability in its two‐phase coexistence regions, the phase transition mechanism is of great interest in understanding the electrode behavior at high rates. Here, the phase transition dynamics of Li_xNi_0.5Mn_1.5O₄ is elucidated on high rate charging–discharging using operando time‐resolved X‐ray diffraction (TR‐XRD). The TR‐XRD results indicate the existence of intermediate states, in addition to the thermodynamically stable phases, and it is shown that the origin of such intermediate states is ascribed to the solid‐solution domains at the phase transition front, as supported by the analysis using transmission electron microscopy coupled with electron energy‐loss spectroscopy. The phase transition pathways dependent on the reaction rate are shown, together with possible explanation for this unique transition behavior.     

Insight of a Phase Compatible Surface Coating for Long‐Durable Li‐Rich Layered Oxide Cathode

Li‐rich layered oxides (LLOs) can deliver almost double the capacity of conventional electrode materials such as LiCoO₂ and LiMn₂O₄; however, voltage fade and capacity degradation are major obstacles to the practical implementation of LLOs in high‐energy lithium‐ion batteries. Herein, hexagonal La_0.8Sr_0.2MnO_3?y (LSM) is used as a protective and phase‐compatible surface layer to stabilize the Li‐rich layered Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ (LM) cathode material. The LSM is Mn? O? M bonded at the LSM/LM interface and functions by preventing the migration of metal ions in the LM associated with capacity degradation as well as enhancing the electrical transfer and ionic conductivity at the interface. The LSM‐coated LM delivers an enhanced reversible capacity of 202 mAh g^?1 at 1 C (260 mA g^?1) with excellent cycling stability and rate capability (94% capacity retention after 200 cycles and 144 mAh g^?1 at 5 C). This work demonstrates that interfacial bonding between coating and bulk material is a successful strategy for the modification of LLO electrodes for the next‐generation of high‐energy Li‐ion batteries.     

All‐In‐One Perovskite Catalyst: Smart Controls of Architecture and Composition toward Enhanced Oxygen/Hydrogen Evolution Reactions

A conventional water electrolyzer consists of two electrodes, each of which is embedded with a costly and rare electrocatalyst, typically IrO₂/C for oxygen evolution reaction (OER) and Pt/C for hydrogen evolution reaction (HER), respectively. HER and OER electrocatalysts usually require very different pH values to keep them stable and active. Thus, the development of earth‐abundant nonprecious metal catalysts for both HER and OER is of great importance to practical applications. This work reports the results of integrated water electrolysis using the hybrids of electrospun La_0.5(Ba_0.4Sr_0.4Ca_0.2)_0.5Co_0.8Fe_0.2O_3–δ (L‐0.5) perovskite nanorods attached to reduced graphene oxide (rGO) nanosheets as bifunctional electrodes. Via rationalizing the composition and morphology of L‐0.5/rGO nanohybrids, excellent catalytic performance and stability toward OER and HER are achieved in alkaline media. The operating voltage of integrated L‐0.5/rGO electrolyzer is tested to be 1.76 V at 50 mA cm^–2, which is close to that of the commercially available IrO₂/C‐Pt/C couple (1.76 V @ 50 mA cm^–2). Such a bifunctional electrocatalyst could be extended toward practical electrolysis use with low expanse and high efficiency. More generally, the protocol described here broadens our horizons in terms of the designs and the diverse functionalities of catalysts for use in various applications.     

Superassembly of Porous Fetet(NiFe)octO Frameworks with Stable Octahedron and Multistage Structure for Superior Lithium–Oxygen Batteries

Promising lithium–oxygen batteries (LOBs) with extra‐high capacities have attracted increasing attention for use in future electric devices. However, the challenges facing this complicated battery system still limit their practical applications. These challenges mainly consist of inefficient product evolution and low‐activity catalysts. In present work, a cation occupying, modified 3D‐architecture NiFeO cubic spinel is constructed via superassembly strategy to achieve a high rate, stable electrocatalyst for LOBs. The octahedron predominant spinel provides a stable polycrystal structure and optimized electronic structure, which dominates the discharge/charge products evolution with multiformation kinetics of crystal Li₂O₂ and Li_2?xO₂ at low and high rate conditions and energetically favors the mass transport between the electrode/electrolyte interface. Simultaneously, the porous NiFeO framework provides adequate spaces for Li₂O₂ accommodation and complex channels for sufficient electrolyte, oxygen, and ion transportation, which dramatically alter the cathode catalysis for an unprecedented performance. As a consequence, a large specific capacity of 23413 mAh g^?1 and an excellent cyclability of 193 cycles at a high current of 1000 mA g^?1, and 300 cycles at a current of 500 mA g^?1, are achieved. The present work provides intrinsic insights into designing high‐performance metal oxide electrocatalysts for Li–O₂ batteries with fine‐tuned electronic and frame structure.     

Solvent‐Free Synthesis of Thin,Flexible, Nonflammable Garnet‐Based Composite Solid Electrolyte for All‐Solid‐State Lithium Batteries

Thin solid‐state electrolytes with nonflammability, high ionic conductivity, low interfacial resistance, and good processability are urgently required for next‐generation safe, high energy density lithium metal batteries. Here, a 3D Li_6.75La₃Zr_1.75Ta_0.25O₁₂ (LLZTO) self‐supporting framework interconnected by polytetrafluoroethylene (PTFE) binder is prepared through a simple grinding method without any solvent. Subsequently, a garnet‐based composite electrolyte is achieved through filling the flexible 3D LLZTO framework with a succinonitrile solid electrolyte. Due to the high content of garnet ceramic (80.4 wt%) and high heat‐resistance of the PTFE binder, such a composite electrolyte film with nonflammability and high processability exhibits a wide electrochemical window of 4.8 V versus Li/Li⁺ and high ionic transference number of 0.53. The continuous Li⁺ transfer channels between interconnected LLZTO particles and succinonitrile, and the soft electrolyte/electrode interface jointly contribute to a high ambient‐temperature ionic conductivity of 1.2 × 10^?4 S cm^?1 and excellent long‐term stability of the Li symmetric battery (stable at a current density of 0.1 mA cm^?2 for over 500 h). Furthermore, as‐prepared LiFePO₄|Li and LiNi_0.5Mn_0.3Co_0.2O₂|Li batteries based on the thin composite electrolyte exhibit high discharge specific capacities of 153 and 158 mAh g^?1 respectively, and desirable cyclic stabilities at room temperature.     

Hybrid Polymer Electrolyte Encased Cathode Particles Interface-Based Core–Shell Structure for High-Performance Room Temperature All-Solid-State Batteries

A smooth interfacial contact between electrode and electrolyte, alleviation of dendrite formation, low internal resistance, and preparation of thin electrolyte (<20 µm) are the key challenging tasks in the practical application of Li₇La₃Zr₂O₁₂ (LLZO)-based solid-state batteries (SSBs). This paper develops a unique strategy to reduce interfacial resistance by designing an interface-based core–shell structure via direct integration of Al-LLZO ceramic nanofibers incorporated poly(vinylidene fluoride)/LiTFSI on the surface of a porous cathode electrode (HPEIC). This yields an ultrathin solid polymer electrolyte with a thickness of 7 µm. The integrated HPEIC/Li SSB with LiFePO₄/C exhibits an initial specific capacity of 166 mAh g⁻¹ at 0.1 C and 159 mAh g⁻¹ with capacity retention of 100% after 120 cycles at 0.5 C (25 °C). The HPEIC/Li SSB with LiNi_0.8Mn_0.1Co_0.1O₂ cathode delivers a good discharge capacity of 134 mAh g⁻¹ after 120 cycles at 0.5 C. The rational design of interface-based core–shell structure outperforms the conventional assembly of solid-state cells using free-standing solid electrolytes in specific capacity, internal resistance, and rate performance. The proposed strategy is simple, cost-effective, robust, and scalable manufacturing, which is essential for the practical applicability of SSBs.     

Synthesis,characterization, and electrocatalytic behaviour of hydrothermally grown nanostructured La2O3 and La2O3/K-complex

Rare earth metals play a conspicuous role in magnetic resonance imaging (MRI) for detecting cancerous cells. The alkali metal potassium is a neurotransmitter in the sodium–potassium pump in biomedical sciences. This unique property of rare earth metals and potassium drew our attention to carry forward this study. Therefore, in this work, previously synthesized potassium (K) complexes formed by the reflux of 4-N,N-dimethylaminobenzoic acid (DBA) and potassium hydroxide in methanol, and named [(μ2–4-N,N-dimethylaminobenzoate-κO)(μ2–4-N,N-dimethylaminobenzoic acid-κO)(4-N,N-dimethylaminobenzoic acid-κO) potassium(I) coordination polymer)] were treated hydrothermally with La₂O₃ nanomaterials to obtain a nanohybrid La₂O₃/K-complex. After that, the K-complex was analyzed using single-crystal X-ray diffraction and ¹H and ¹³C NMR spectroscopy. In addition, the structural and morphological properties of the as-prepared nanostructured La₂O₃/K-complex were also characterized, which involved an investigation using X-ray diffraction (XRD)spectroscopy, Fourier transform infrared (FTIR) spectroscopy, atomic force spectroscopy (AFM), transmission electron microscopy (TEM), and energy dispersive X-ray (EDX) analysis. After this, the electrochemical redox behaviour of the synthesized nanohybrid material was studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Therefore, the results from these studies revealed that the as-prepared material was a La₂O₃/K-complex that has a promising future role in sensing various analytes, as it showed effective electrocatalytic behaviour.     

High‐Temperature Treatment of Li‐Rich Cathode Materials with Ammonia: Improved Capacity and Mean Voltage Stability during Cycling

Li‐rich electrode materials of the family x Li₂MnO₃·(1?x )LiNi_a Co_b Mn_c O₂ (a + b + c = 1) suffer a voltage fade upon cycling that limits their utilization in commercial batteries despite their extremely high discharge capacity, ≈250 mA h g^?1. Li‐rich, 0.35Li₂MnO₃·0.65LiNi_0.35Mn_0.45Co_0.20O₂, is exposed to NH₃ at 400 °C, producing materials with improved characteristics: enhanced electrode capacity and a limited average voltage fade during 100 cycles in half cells versus Li. Three main changes caused by NH₃ treatment are established. First, a general bulk reduction of Co and Mn is observed via X‐ray photoelectron spectroscopy and X‐ray absorption near edge structure. Next, a structural rearrangement lowers the coordination number of Co? O and Mn? O bonds, as well as formation of a surface spinel‐like structure. Additionally, Li⁺ removal from the bulk causes the formation of surface LiOH, Li₂CO₃, and Li₂O. These structural and surface changes can enhance the voltage and capacity stability of the Li‐rich material electrodes after moderate NH₃ treatment times of 1–2 h.     

Morphological and Structural Properties of Cathode Compound Material for Lithium-Ion Battery

The combustion method for preparation of compound material like Li Co _0.5 Ni _0.45 Ag_0.05 O₂ cathodes is widely selected because it has the virtue of simplicity and lower cost. It was prepared by firing a mixture of stoichiometric amounts lithium nitrate (LiNO₃), cobalt nitrate (Co(NO₃)₂.6H₂O), nickel nitrate (Ni(NO₃)₂. 6H₂O) and silver nitrates (AgNO₃₎. The as-synthesized material was subjected to (TGA/DSC) analysis to determine the optimum range of annealing temperatures at 800, 900, and 1000 °C for 8 h. The effect of annealing on the structural and morphological features can be represented by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive scattering (EDS), and transmutation electric microscopy (TEM), powders data from this method showed the coexistence of cubic Li Ni₂O₄ spinel structures at 400 °C. The optimum annealing result at 900 °C with constant duration 8 hours showed a single rhombohedra layered type Li Co _0.5 Ni _0.45 Ag_0.05 O₂ and polycrystalline structures.