Effects of the structural characteristics of carbon cathode on the initial voltage delay in Li/SOCl2 battery

The study investigates electrochemical behaviors of Li/SOCl₂ batteries based on structural features of carbon cathodes to find out solutions of initial voltage delay, a natural problem of the batteries. The structural features of the carbon cathodes in the Li/SOCl₂ batteries are directly related to the transient minimum voltage (TMV) and the initial voltage delay, the inevitable fault in the batteries, and the study confirms possibilities to solve inherent problems of the batteries by structurally adjusting carbon cathodes. Low density of carbon cathodes inhibits the TMV increase, the initial voltage delay more than high density. The operating voltage of the battery may rise with increasing electronic conductivity of the carbon cathode, however, it fails to improve the TMV and the delay. The study shows that expanding carbon cathode volume shrinks a gap between the lithium and the carbon cathode, pressurizing and destroying passivation films, and improving the TMV and the initial voltage delay. Based on this, it is expected to manufacture excellent Li/SO₂Cl₂ batteries by improving the initial voltage delay as adjusting aging lapse and pressed density.     

Room temperature discharge characteristics of Li/NH4NO3−LiNO3-amide cells using silver salts as active cathode materials

The discharge characteristics of cells using lithium anodes in conjunction with nitrate-amide melt electrolytes and silver salt cathodes are presented. The use of insoluble or sparingly soluble silver salts as active cathode materials for ambient temperature galvanic cell cathodes can allow higher rate discharges than otherwise possible using melt reduction as the cathode reaction. The cathode materials studied were: Ag₂CrO₄, Ag₂MoO₄, Ag₂WO₄, Ag₂PO₄, Ag₂SO₄, AgIO₃, AgIO₄, AgF, AgCl, AgBr, AgI, Ag₄RbI₅ and Ag₂O. The reduction characteristics of silver ions added to natrate-amide melts are also presented.     

On the use of vinylene carbonate (VC) as an additive to electrolyte solutions for Li-ion batteries

Vinylene carbonate (VC) was tested as an additive to electrolyte solutions for Li-ion batteries. For the model electrodes, synthetic graphite was chosen as the anode material, while LiMn₂O₄ spinel and LiNiO₂ were chosen as the cathode materials. The test solution was 1 M LiAsF₆ in a 1:1 mixture of ethylene and dimethyl carbonates (EC-DMC). Cyclic voltammetry (CV), chronopotentiometry, impedance spectroscopy, electrochemical quartz crystal microbalance (EQCM), FTIR and X-ray photoelectron spectroscopies have been used in this study. It was found that VC is a reactive additive that reacts on both the anode and the cathode surfaces. The influence of this additive on the behavior of Li-graphite anodes is very positive, since it improves their cyclability, especially at elevated temperatures, and reduces the irreversible capacity. The spectroscopic studies indicate that VC polymerizes on the lithiated graphite surfaces, thus forming poly alkyl Li-carbonate species that suppress both solvent and salt anion reduction. The presence of VC in solutions reduces the impedance of the LiMn₂O₄ and LiNiO₂ cathodes at room temperature. However, we have not yet found any pronounced impact of VC on the cycling behavior of the cathodes, either at room temperature or at elevated temperatures. Thus, VC can be considered as a desirable additive for the anode side in Li-ion batteries, one which has no adverse effect on the cathode side.     

Microwave- or conventional–hydrothermal synthesis of Co-based materials for electrochemical energy storage

Crystalline Co₃O₄ and Co(OH)₂ were synthesized using Co(NO₃)₂ as a precursor by conventional–hydrothermal and microwave–hydrothermal routes, respectively. The Co₃O₄ phase showed cubic morphologies while the β-Co(OH)₂ phase exhibited plate-like shapes. The electrochemical performances of Co₃O₄ and Co(OH)₂ phases were evaluated as electrode materials for lithium-ion battery anodes, cathodes and supercapacitors. Both Co₃O₄ and Co(OH)₂ phases showed pseudocapacitive performances in Li₂SO₄ and KOH electrolytes. The Co₃O₄ and Co(OH)₂ phases were found to be more promising as anodes than as cathodes in lithium-ion batteries. The Co(OH)₂ electrodes showed higher specific capacitances than those of Co₃O₄ materials.     

Enhanced cycling performance of Li ion batteries based on Ni-rich cathode materials with LaPO4/Li3PO4 co-modification

The recent development of Li-ion batteries based on Ni-rich cathodes with high specific capacity has generated considerable interest. However, cathodes with a sufficiently high Ni concentration suffer from rapid capacity decay and poor thermal stability during charge/discharge cycling, which represents a substantial challenge toward commercialization. While the application of a coating layer has been demonstrated to be an effective means of solving this issue, this typically increases the complexity and expense of cathode material fabrication. The present work addresses this issue by applying a LaPO₄/Li₃PO₄ (LP) layer on the surface of LiNi_0.83Co_0.11Mn_0.06O₂ cathode materials using a facile in situ coating method. This simple method functions concurrently with the high-temperature solid-state method employed for fabricating the cathode materials using Ni_0.83Co_0.11Mn_0.06(OH)₂ as a precursor with added ammonium dihydrogen phosphate (NH₄H₂PO₄) and lanthanum nitrate (La(NO₃)₃). The modified cathode material reacts with residual Li, and forms a LP layer on the Ni-rich cathode surface, while a proportion of the La³⁺ diffuses into the layered LiNi_0.83Co_0.11Mn_0.06O₂ structure during the modification process. Experimental investigation indicates that the LP layer not only eliminates the residual Li, but also deters the formation of microcracks, and thereby inhibits reactions with the electrolyte during charge/discharge cycling. The LP-modified LiNi_0.83Co_0.11Mn_0.06O₂ sample is demonstrated to attain a capacity retention of 94% and 79.8% after 100 and 500 charge/discharge cycles conducted at 1C, respectively.     

Four coordination polymers derived from 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole and copper sulfate

The reaction of 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-bpt) with copper sulfate in EtOH/H₂O solvent yields four coordination polymers [Cu(3-bpt)(H₂O)₄](SO₄)·H₂O (1), [Cu(3-bpt)(H₂O)₄][Cu(3-bpt)(H₂O)₃(SO₄)](SO₄)·7H₂O (2), [Cu(3-bpt)(H₂O)₃(SO₄)]·2H₂O (3) and [Cu(3-bpt)(H₂O)(SO₄)] (4), showing one-dimensional undulated chain, zigzag chain and two-dimensional network. The formations of compounds 1, 2 and 3 are controlled by the EtOH/H₂O ratio. The synthesis of compound 4 may be controlled by the EtOH/H₂O ratio and the temperature because it is prepared under solvothermal condition. The thermal properties have been investigated.     

Stabilizing structure and voltage decay of lithium-rich cathode materials

A major challenge in the discovery of high-energy lithium-ion batteries (LIBs) is to control the voltage stability and Li⁺ kinetics in lithium-rich layered oxide (LrLO) cathode materials. Although these materials can provide a higher specific capacity compared to the current industrially used cathodes, the substantial voltage decay and low Li⁺ diffusion during long term cycling is a serious reason for hindering their practical applications. In order to suppress the voltage decay in lithium-rich cathode materials, herein we introduce the Ti doping into Li_1.2Mn_0.56Ni_0.17Co_0.07O₂ cathodes. Also, the influence of Ti doping on the crystalline internal structure, surface chemistry, cycling retention, and Li⁺ kinetics of Li_1.2Mn_0.56Ni_0.17Co_0.07O₂ cathodes have been focused in this work. The Ti doping effectively enhances the structural/interfacial stability of the cathode and accelerates the Li⁺ kinetics by expanding the lattice, thereby significantly realizing its voltage/cycling stability and high-rate capability. Experimental results show that Ti-doped LrLO (1% Ti) has achieved high electrochemical kinetics as the discharge cycle retention increased from 61.58% (pristine) to 80.0% after 180 cycles at 1 C, with 150.3 mAh g^?1 showing superior high-rate performance at 5C. Ex-situ XRD results confirmed the better structural stability of Ti-doped LrLO after high-rate electrochemical cycling. Our findings provide a suitable element doping strategy for regulating the voltage decay and cycle retention of LrLO, thus promoting their real-world application in future batteries.     

Bi1.4Er0.6O3‐(La0.74Bi0.10Sr0.16) MnO3‐δ Cathodes Fabricated By Ion‐impregnating Method For IT‐SOFCs

Bi_1.4Er_0.6O₃‐(La_0.74Bi_0.10Sr_0.16)MnO_3‐δ (ESB‐LBSM) composite cathodes were fabricated by impregnating the ionic conducting ESB matrix with the LBSM electronic conducting materials. The ion‐impregnated ESB‐LBSM cathodes were beneficial for the O₂ reduction reactions, and the performance of these cathodes was investigated at temperatures below 700 °C by AC impedance spectroscopy and the results indicated that the ion‐impregnated ESB‐LBSM system had an excellent performance. At 700 °C, the lowest cathode polarisation resistance (R_p) was only 0.07 Ω cm² for the ion‐impregnated ESB‐LBSM system. For the performance testing of single cells, the maximum power density was 1.0 W cm^–2 at 700 °C for a cell with the ESB‐LBSM cathode. The results demonstrated that the unique combination of the ESB ionic conducting matrix with electronic conducting LBSM materials was a valid method to improve the cathode performance, and the ion‐impregnated ESB‐LBSM was a promising composite cathode material for the intermediate‐temperature solid oxide fuel cells.     

Hydrothermal Crystal Growth,Structures and Thermal Properties of Co(II)-4,4′-bipyridine-Based Coordination Polymeric Materials

Hydrothermal synthetic parameters were studied and optimized for the preparation of new coordination polymeric materials based on Co(II) and 4,4′-bipy. A new polymeric compound, [Co₂(H₂O)₂(OH)₂(4,4′-bipy)₈](NO₃)₂·2(4,4′-bipy) 10(H₂O) (1), was prepared and structurally characterized by single crystal experiment. The framework of (1) is made up of two different one-dimensional substructures, i.e., the neutral chain A and positively charged chain B, both of which share the same nodes and node linkers. This is rarely found, especially from a one-pot crystal growth technique. Two other crystals were also identified, i.e., [Co(SO₄)(H₂O)₃(4,4′-bipy)]·2(H₂O), and K₂Co(H₂O)₆(SO₄)₂. The optimization of synthetic parameters apparently favors the formation of different polymeric structures, and this can be experimentally fine tuned. The influences of these parameters on phase formation, purity and crystal growth are discussed. The complicated thermogravimetric property of the new compound is also reported.     

Preparation of composite cathode material by using the extracted lead (Pb) of waste lead acid battery for LT-SOFC

The extraction of Pb from the waste lead acid batteries offers the conservation of energy resources and reduction of pollution load in the environment. The recycling of waste lead acid batteries than discarding by conventional methods is the best way. In the present studies, for LT-SOFC, three composite cathode materials (Pb_0.1Fe_0.4Co_0.5O_4-δ, Pb_0.2Fe_0.3Co_0.5O_4-δ and Pb_0.3Fe_0.2Co_0.5O_4-δ) were produced by extracting Pb from the waste lead acid batteries, cobalt nitrate [Co(NO₃)₃.6H₂O] and iron nitrate [Fe(NO₃)₃.9H₂O] using standard solid state reaction method. Thermal stability, morphological and structural characteristics were studied by TGA, SEM and XRD analyses. FTIR spectra were used to investigate the types of metal oxide bonding in the prepared ceramic composite cathode materials. Fuel cell testing and DC four probes were used to investigate electrochemical properties. The measurement of average crystalline size of the composites was found to be in the range of 12–37 nm.Scanning electron microscopy (SEM) images showed that composite materials are porous and suitable to diffuse the gases. The maximum conductivities of 1.6 Scm^?1, 2.05 Scm^?1 and 2.6 Scm^?1 have been obtained for Pb_0.1Fe_0.4Co_0.5O_4-δ, Pb_0.2Fe_0.3Co_0.5O_4-δ and Pb_0.3Fe_0.2Co_0.5O_4-δ, respectively. At 600 °C, the high OCV (0.95V) and the maximum power density (439 mW/cm²) have been achieved using hydrogen as the fuel. Lower value of activation energy (0.36ev) of Pb_0.3Fe_0.2Co_0.5O_4-δ confirms that it is the efficient material to convert electrochemically hydrogen fuel into valuable electricity.     

Spectroscopic properties and conduction mechanism of KAl(SO4)2:xSm: A multifunctional materials for optical and electrochemical applications

Anhydrous α-alum materials doped with the trivalent samarium oxide Sm₂O₃ and denoted as KAl(SO₄)₂:xSm (x = 0; 0.5; 1; 1.5; 2; 2.5% mol.) are prepared by the solid-state reaction method at 350 °C. The resulting phases are crystallized in a simple hexagonal structure with space group P321. Powder X-ray diffraction (XRD), Infrared (IR), and Raman spectroscopies confirmed a high purity of phases with variation in lattice parameters according to the amount of doping.Optical measurements through absorption and fluorescence spectroscopies in the ultra-violet and visible regions prove the different electronic transitions between excited levels and ⁶H_5/2 ground state of Sm³⁺, the incorporation of samarium in the crystal structure, and suggest the quenching phenomenon.The materials presented in the study showed an ionic semiconductor behavior with an increase in their conductivity as a function of the doping level. A 1D conduction is made according to the Correlated Barrier Hopping CBH model by cations mobility in crystalline sites under the effect of thermal agitation in the [170–250 °C] region. KAl(SO₄)₂: xSm (x = 1.5% mol.) with its lower activation energy value, is suggested as a suitable cathode material for aluminum-based batteries.     

Study of vanadium(IV) species and corresponding electrochemical performance in concentrated sulfuric acid media

The vanadium(IV) ion is found to form the [VO(SO₄)(H₂O)₄]·H₂O complex, as well as the dimer, [VO(H₂O)₃]₂(μ-SO₄)₂, in concentrated H₂SO₄ media. Their formation mechanisms were investigated by UV–Visible spectroscopy (UV–Vis), Raman spectroscopy, X-ray diffraction (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). UV–Vis spectroscopy study showed that [VO(SO₄)(H₂O)₄]·H₂O concentration in H₂SO₄ solution was proportional to concentrations of VO²⁺ and SO₄²⁻. The increased deviation from the near centrosymmetry of the octahedral complexes is due to the replacement of an equatorial water oxygen in [VO(H₂O)₅]SO₄ by a sulfate oxygen in [VO(SO₄)(H₂O)₄]·H₂O. The dimer shows symmetrical structure, which correlates very well with non-activity in UV–Vis spectroscopic analysis. Structural information on both vanadium(IV) species can be confirmed by Raman and XRD measurements of crystals from the supersaturated solution of VOSO₄ in 1 M, 6 M and 12 M sulfuric acid. A solution of vanadium(IV) (0.05 M) in 12 M H₂SO₄, in which the vanadium(IV) species is [VO(H₂O)₃]₂(μ-SO₄)₂, exhibits a reversible redox behavior near 1.14 V (vs. SCE) on the carbon paper electrode.     

Hydrothermal synthesis and rate capacity studies of Li3V2(PO4)3 nanorods as cathode material for lithium-ion batteries

It is an effective method by synthesizing one-dimensional nanostructure to improve the rate performances of cathode materials for Li-ion batteries. In this paper, Li₃V₂(PO₄)₃ nanorods were successfully prepared by hydrothermal reaction method. The structure, composition and shape of the prepared were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scan electron microscope (SEM) and transmission electron microscope (TEM), respectively. The data indicate the as-synthesis powders are defect-rich nanorods and the sizes are the length of several hundreds of nanometers to 1 μm and the diameter of about 60 nm. The preferential growth direction of the prepared material was the [1 2 0]. The electrodes consisting of the Li₃V₂(PO₄)₃ nanorods show the better discharge capacities at high rates over a potential range of 3.0-4.6 V. These results can be attributed to the shorter distance of electron transport and the fact that ion diffusion in the electrode material is limited by the nanorod radius. All these results indicate that the resulting Li₃V₂(PO₄)₃ nanorods are promising cathode materials in lithium-ion batteries.     

Reactivity between carbon cathode materials and electrolyte based on industrial and laboratory data

Interaction between electrolyte and carbon cathodes during the electrolytic production of aluminium decreases cell life. This paper describes the interaction between carbon cathode materials and electrolyte, based on industrial and laboratory data. It also reports on the degree of expansion of semi-graphitic and graphitised materials when exposed to a sodium rich environment. Phase relations in the slow cooled bath electrolyte, spent industrial cathodes and laboratory scale cathode samples were similar: all contained Na₃AlF₆, NaF, CaF₂ and NaAl₁₁O₁₇. Al₄C₃, AlN and NaCN were only detected in the spent industrial cathodes. The inability to locate Al₄C₃ in the laboratory scale samples could be due to very low concentrations of Al₄C₃ which could not be detected by XRD, or to the limited direct contact between the produced aluminium and carbon material. X-ray diffraction analysis confirmed that sodium intercalation into graphite did not take place. Wear of the examined carbon cathodes proceeded due to penetration of electrolyte and sodium into the cathode, followed by reactions with carbon and N₂ whereby AlN and NaCN formed. Once electrolysis started the carbon cathodes expanded rapidly, but slowed down after approximately an hour. Sodium expansion decreased with degree of graphitisation of the carbon cathode material.     

Stable interfaces constructed by concentrated ether electrolytes to render robust lithium metal batteries

Lithium metal batteries (LMBs) are highly considered as promising candidates for next-generation energy storage systems.However,routine electrolytes cannot tolerate the high potential at cathodes and low potential at anodes simultaneously,leading to severe interfacial reactions.Herein,a highly concentrated electrolyte (HCE) region trapped in porous carbon coating layer is adopted to form a stable and highly conductive solid electrolyte interphase (SEI) on Li metal surface.The protected Li metal anode can poten-tially match the high-voltage cathode in ester electrolytes.Synergistically,this ingenious design promises high-voltage-resistant interfaces at cathodes and stable SEI with abundance of inorganic components at anodes simultaneously in high-voltage LMBs.The feasibility of this interface-regulation strategy is demonstrated in Li | LiFePO4 batteries,realizing a lifespan twice as long as the routine cells,with a huge capacity retention enhancement from 46.4％ to 88.7％ after 100 cycles.This contribution proof-of-concepts the emerging principles on the formation and regulation of stable electrode/electrolyte inter-faces in the cathode and anode simultaneously towards the next-generation high-energy-density batteries.     

X-ray absorption fine structure spectroscopy and X-ray diffraction study of cementitious materials derived from coal combustion by-products

Cementitious materials derived from coal combustion by-products have been investigated by means of X-ray diffraction (XRD) and S and Ca K-edge X-ray absorption fine structure (XAFS) spectroscopy. The XRD analysis revealed that these materials are a complex mixture of a small amount of quartz [SiO₂] and three calcium-bearing compounds: hannebachite [CaSO₃·1/2H₂O], gypsum [CaSO₄·2H₂O] and ettringite [(Ca₆(Al(OH)₆)₂(SO₄)₃·26H₂O)]. Analysis of the S XAFS data focused on deconvolution of the X-ray absorption near-edge structure (XANES) regions of the spectra. This analysis established that sulfate and sulfite are the two major sulfur forms, with a minor thiophenic component contained in unburned carbon in the fly ash. Increasing sulfate and decreasing sulfite correlated well with increasing gypsum and ettringite and decreasing hannebachite content in the samples. Different calcium compounds were identified primarily through simple comparison of the Ca K-edge XANES and radial structure functions (RSFs) of the cementitious samples with those of reference compounds. Because of the complex coordination chemistry of calcium in these materials, it was difficult to obtain detailed local atomic environment information around calcium beyond the first CaO peak. Analysis of the extended X-ray absorption fine structure (EXAFS) and the RSF gave average CaO distances in the range 2.44-2.5 Å, with each calcium atom surrounded roughly by eight oxygen atoms. In certain samples, the average CaO distances were close to that in ettringite (2.51 Å), suggesting that these samples have higher ettringite content. The results of S and Ca K-edges XAFS and the XRD data were in reasonable agreement.     

First-principles insights on anion redox activity in NaxFe1/8Ni1/8Mn3/4O2: Toward efficient high-energy cathodes for Na-ion batteries

In the search for high-energy cathode materials for Na-ion batteries (NIBs), Fe-doped layered transition metal oxides have been recently proposed as promising systems that can ensure improved reversible capacity at high working voltage. Exploiting the anionic redox chemistry in this class of materials represents a great advance for the energy storage community, but uncontrolled oxidation process can lead to the formation of unbound molecular oxygen, with detrimental effects on overall capacity and stability upon cycling. The higher TM–O covalency provided by Fe doping seems to prevent oxygen loss and ensure full capacity recovery. Understanding anionic processes and the underlying mechanism with atomistic details can reinforce the experimental efforts and help to outline rational design strategies for novel high-performing NIB cathodes. To this end, we present a state-of-the-art first-principles study on the P2-type Na_xTMO₂ (TM = Fe, Ni, and Mn—NFNMO) oxide. We compare structural and electronic features of stoichiometric (Na_xFe_0.125Ni_0.125Mn_0.75O₂) and Mn-deficient (Na_xFe_0.125Ni_0.125Mn_0.68O₂) NFNMO to identify and discuss the contribution of each element sublattice on charge compensation processes. Although Mn deficiency is predicted to increase the cathode working voltage, we find the charge compensation being mostly exerted by the Ni and Fe sublattices. Oxygen redox is unfold via the formation of superoxide species at low Na loads with a preferential breaking of more labile Ni–O bonds and binding to Fe atoms. Our calculations predict no release of molecular O₂ upon desodiation, thus highlighting the key role of Fe dopant that provides a good TM–O bond strength, preventing oxygen loss while still enabling anionic redox reactions at high voltages with extra reversible capacity.     

A robust carbon coating strategy toward Ni-rich lithium cathodes

The surface coating strategy provide a facile and effective means of improving the electrochemical behavior of lithium-ion batteries (LiBs) since it can prevent cathodes/anodes from contacting moisture and improve the thermal stability and cyclability of LiBs. However, to date, few studies have focused on carbon coating Ni-rich cathodes due to the moisture sensitivity of cathode materials. Herein, poly (vinylidene fluoride)/n-vinyl-2-pyrrolidinone (PVDF/NMP) solution was employed as the carbon source to coat LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) spheres for the first time. The coating process mainly includes two steps under moisture-free conditions: (1) wetting NMC811 using PVDF/NMP solution and (2) heat treatment of NMC811/PVDF under inert circumstances. The thickness of the obtained carbon layer can be controlled easily by adjusting the solution concentration. A 2.5 wt% PVDF containing solution can coat a carbon layer of ~4 nm on NMC811 spheres, which significantly improved the integral Li⁺ storage performance. The discharge capacity of the resulting carbon-coated NMC811 showed only a 1.26% decrease after 100 cycles at a 0.2 C rate, while pristine NMC811 lost 6.85% of its initial reversible capacity. This work highlights that carbon coating offers a facile yet effective approach to achieve high-performance cathodes materials for LIBs.     

Characterization of structure and electrochemical properties of lithium manganese oxides for lithium secondary batteries hydrothermally synthesized from δ-KxMnO2

Lithium manganese oxides have attracted much attention as cathode materials for lithium secondary batteries in view of their high capacity and low toxicity. In this study, layered manganese oxide (δ-K_xMnO₂) has been synthesized by thermal decomposition of KMnO₄, and four lithium manganese oxide phases have been synthesized for the first time by mild hydrothermal reactions of this material with different lithium compounds. The lithium manganese oxides were characterized by powder X-ray diffraction (XRD), inductively coupled plasma emission (ICPE) spectroscopy, and chemical redox titration. The four materials obtained are rock salt structure Li₂MnO₃, hollandite (BaMn₈O₁₆) structure α-MnO₂, spinel structure LiMn₂O₄, and birnessite structure Li_xMnO₂. Their electrochemical properties used as cathode material for secondary lithium batteries have been investigated. Of the four lithium manganese oxides, birnessite structure Li_xMnO₂ demonstrated the most stable cycling behavior with high Coulombic efficiency. Its reversible capacity reaches 155 mAh g⁻¹, indicating that it is a viable cathode material for lithium secondary batteries.     

Development of potassium ferrate(VI) cathode material stabilized with yttria doped zirconia coating for alkaline super-iron battery

To improve the stability of potassium ferrate(VI) (K₂FeO₄) cathode and its properties of charge transfer in alkaline battery system, K₂FeO₄ cathodes are coated by yttria (Y₂O₃) doped zirconia (ZrO₂) composites, denoted as Y₂O₃–ZrO₂ composite coatings. These composite coatings are derived from the conversion of yttrium nitrate (Y(NO₃)₃·6H₂O) and Zirconium oxychloride (ZrOCl₂·6H₂O) in ether medium. Examinations by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) show that K₂FeO₄ cathodes are coated by Y₂O₃–ZrO₂ overlayer. Alternatively, results of discharge properties and electrochemical impedance spectroscopes (EIS) indicate that when the molar ratio between Y₂O₃ and ZrO₂ is 0.09, denoted as Y₂O₃ (9 mol%)–ZrO₂, the stability and charge transfer of Y₂O₃ (9 mol%)–ZrO₂ coated K₂FeO₄ cathodes are improved greatly compared to that of uncoated or ZrO₂ coated K₂FeO₄ cathodes. Therefore, Y₂O₃–ZrO₂ composite coatings are a potential choice to improve the stability and charge transfer of K₂FeO₄ cathodes in alkaline electrolyte.