NaCl Molten Salt Research Articles

Hot corrosion of sputtered nanocrystalline coating with and without preoxidation and arc ion plating coating on a Ni-based single-crystal superalloy

Hot corrosion of the N5 nanocrystalline coating with 0.5 wt% Y addition with and without preoxidation under 75 wt% Na2SO4 + 25 wt% NaCl molten salts at 900 °C was investigated, in comparison with that of the NiCrAlY coating under the same condition. The results showed that the nanocrystalline coating with nano-columnar structure suffered more severe corrosion than NiCrAlY coating. The high density of grain boundaries in the nanocrystalline coating facilitated inward penetration of the corrosive medium and accelerated the destruction of the scale. Preoxidation significantly enhanced the corrosion resistance of the nanocrystalline coating by forming an exclusive Al2O3 scale on the surface that could prevent molten salt from accessing the coating surface. The coating preoxidized at 1000 °C exhibited the highest corrosion resistance with the least internal corrosion. Y stabilized Ta and/or S during preoxidation and subsequent corrosion process, improving the purity and stability of the scale. The coating preoxidized at 1100 °C performed worse than that at 1000 °C. The inferior corrosion resistance was attributed to the more Ta oxides segregation and faster consumption of Al at the higher preoxidation temperature, accelerating scale destruction during hot corrosion.

Effect of Cr on the high-temperature corrosion of dissimilar AISI 904L and Inconel 625 joints employed in the coal-fired thermal power plant tubes

ABSTRACT The hot corrosion behaviours of 5-mm-thick plates of dissimilar AISI 904L and Inconel 625 weldments produced by continuous current gas tungsten arc welding process using Ni-Cr-Mo-enriched filler wires (ERNiCrMo-4 and ERNiCrCoMo-1) were investigated. Optical microscopy was used to examine the microstructure of these weldments. The corrosion performance of the weldments and base metals was determined in the mixture of K2SO4 + 60% NaCl molten salt (MS) and air oxidation conditions at 700°C for 50 cycles. The thermogravimetric plots derived the corrosion kinetics of the weldments. The microstructure and the elemental analysis of the scales formed on the corroded samples were evaluated by scanning electron microscopy and energy-dispersive spectroscopy. The phases developed on the oxide layers during the corrosion were analysed using X-ray diffraction. The fusion zones of ERNiCrCoMo-1 weldment and AISI 904L base metal were vulnerable to degradation in the MS environment, causing severe cracks and spallation compared to ERNiCrCoMo-1 weldment.

An investigation on hot corrosion behavior of Al0.4MnCrCoFeNi high entropy alloy in different molten salts at 750 °C

The hot corrosion behavior of Al0.4MnCrCoFeNi high entropy alloy in different molten salts at 750 °C was investigated. The high entropy alloy was synthesized by vacuum melting and casting. The hot corrosion tests were performed in 75%Na2SO4 + 25%NaCl, 75%Na2SO4 + 20%NaCl + 5%V2O5, 75%Na2SO4 + 5%NaCl + 10%V2O5, and 60%Na2SO4 + 40%V2O5 mixture salts. Microstructural characterizations were carried out using a field emission scanning electron microscope equipped with an X-ray energy dispersive (EDS) analyzer. X-ray diffraction method with CuKα radiation was also used for phase analysis of corrosion products. The results indicated that Al0.4MnCrCoFeNi alloy had relatively good resistance to hot corrosion in 75%Na2SO4 + 25%NaCl molten salt compared to the other salts due to the formation of a protective layer consisting of Mn, Cr, and Al oxides. The addition of V2O5 to the mixture salt promoted the dissolution of the oxide layer in the molten salt and hence decreased the resistance of the alloy to hot corrosion. The mechanisms of hot corrosion were oxidation-sulfidation and fluxing. The least resistance to hot corrosion was observed in 60%Na2SO4 + 40%V2O5 mixture salt because the oxide scale was destroyed seriously, resulting in accelerated propagation of hot corrosion.

Corrosion of Yb2SiO5/Yb2Si2O7/Si EBCs against Na2SO4 + 25 wt%NaCl molten salt at 1350 ℃

The reaction behaviors and corrosion mechanisms of tri-layer Yb2SiO5/Yb2Si2O7/Si EBCs were explored in Na2SO4 + 25 wt%NaCl molten salt environment at 1350 °C. Results showed that the molten salt rapidly penetrated the Yb2SiO5 layer and then reacted with the Yb2Si2O7 layer to form SiO2-riched Na-Yb-Si-O glass phase. The reaction product of glass phase diffused to the EBCs surface through the cracks and reacted with Yb2SiO5 to form Yb2Si2O7. The reaction of Yb2Si2O7 caused the development of transverse cracks, which eventually led to the failure of the EBCs. Moreover, the Yb2SiO5 layer exhibited better corrosion resistance than the Yb2Si2O7 layer.

The formation mechanism of NaLiTi3O7 and its effect on Li4Ti5O12 prepared by the NaCl molten salt flux method

Octahedral single-crystal Li4Ti5O12 materials with {111} crystalline surfaces exposed are prepared in NaCl flux, but the presence of NaLiTi3O7 in the product deteriorates the electrochemical performance of Li4Ti5O12 materials. Herein, the formation mechanism of NaLiTi3O7 in the product was discussed, and it was suggested that the impurity content is affected by the diffusion of the raw materials in the NaCl molten salt flux. The more NaCl is present, the more NaLiTi3O7 is generated. Because Li2O and TiO2 are separated by the salt, and both reactants should diffuse a much longer distance to react. Once the ratio of Li2O and TiO2 reaches 1:3, NaLiTi3O7 will form immediately; otherwise, if the ratio reaches 2:5, Li4Ti5O12 forms. Based on this hypothesis, NaLiTi3O7 will form because there is not enough Li2O to react with TiO2 to form Li4Ti5O12. Therefore, the content of Li2CO3 in the material preparation process was increased, allowing more Li2O to come into contact with TiO2 in the NaCl flux, thereby increasing the probability of Li4Ti5O12 formation and reducing the generation of NaLiTi3O7. Two modification strategies have been proposed to inhibit the generation of impurities. It was found that increasing the amount of Li2CO3 to 15 wt % in excess can reduce impurities of NaLiTi3O7, and further increasing its amount will cause the occurrence of new impurities. Adding a small amount of LiCl to the precursor mixtures can also inhibit NaLiTi3O7 generation in the prepared LTO materials and improve their electrochemical performances.

Electrochemical corrosion and high temperature hot corrosion behavior of NbTaTiV and CrNbTaTiV high entropy alloy

NbTaTiV and CrNbTaTiV were fabricated by arc melting and effect of Cr element on electrochemical and high temperature hot corrosion behavior were compared. Electrochemical corrosion investigations revealed that Laves phase at grain boundaries of CrNbTaTiV would underwent galvanic corrosion, resulting in a marginal reduction in corrosion resistance. The results of high temperature hot corrosion showed that within Na2SO4 + 25 wt% NaCl molten salt environment, the oxide film formed by Cr element effectively improved the surface stability, reduced the formation of unprotected loose corrosion products and the generation of low melting point chlorides with strong volatility, which improved the resistance of molten salt corrosion.

Engineering Electronic Structure of Nitrogen-Carbon Sites by sp3 -Hybridized Carbon and Incorporating Chlorine to Boost Oxygen Reduction Activity.

Development of efficient and easy-to-prepare low-cost oxygen reaction electrocatalysts is essential for widespread application of rechargeable Zn-air batteries (ZABs). Herein, we mixed NaCl and ZIF-8 by simple physical milling and pyrolysis to obtain a metal-free porous electrocatalyst doped with Cl (mf-pClNC). The mf-pClNC electrocatalyst exhibits a good oxygen reduction reaction (ORR) activity (E1/2 =0.91 V vs. RHE) and high stability in alkaline electrolyte, exceeding most of the reported transition metal carbon-based electrocatalysts and being comparable to commercial Pt/C electrocatalysts. Likewise, the mf-pClNC electrocatalyst also shows state-of-the-art ORR activity and stability in acidic electrolyte. From experimental and theoretical calculations, the better ORR activity is most likely originated from the fact that the introduced Cl promotes the increase of sp3 -hybridized carbon, while the sp3 -hybridized carbon and Cl together modify the electronic structure of the N-adjacent carbons, as the active sites, while NaCl molten-salt etching provides abundant paths for the transport of electrons/protons. Furthermore, the liquid rechargeable ZAB using the mf-pClNC electrocatalyst as the cathode shows a fulfilling performance with a peak power density of 276.88 mW cm-2 . Flexible quasi-solid-state rechargeable ZAB constructed with the mf-pClNC electrocatalyst as the cathode exhibits an exciting performance both at low, high and room temperatures.

Tuning the carbon morphology by pyrolysis in AlCl3–NaCl molten salt from coal tar pitch

Pitch-based carbon materials (PCMs) such as carbon microspheres and carbon fibers have gained great attention and obtained many applications. However, how to prepare PCMs via a simple route and modulate PCMs morphology is still a big challenge. In this study, we found and systematically elucidate the transition from carbon microspheres to fibrous carbons (FCs) in AlCl3–NaCl molten salt (ANMS) using coal tar pitch as the carbon precursor, and investigated the associated transition mechanism based on morphological analysis. Based on this mechanism and dispersion state analysis of pitch in molten salt, we achieved pitch-based carbon microspheres and FCs through a simple one-step approach using the ANMS as reaction medium. It was found that the reaction temperature and the ANMS formulation determines the morphology of PCMs. Spherical PCMs with the mean diameter of 4 μm were obtained when the molten salt is in liquid phase. Fibrous carbon are obtained when the molten salt coexists in gas-liquid two-phases. We propose a method to manipulate the reaction temperature and the composition of ANMS to control the static or dynamics of the reaction system, enabling the successful synthesis of carbon microspheres and FCs. Furthermore, our carbon microspheres maintain a specific capacity of 350mAh/g after 400 cycles, reaching the level of commercial MCMB. Our work further perfects the structure and morphology mechanism of PCMs in molten salt and provides new insights for a simple and shape-controllable method to design and develop the competitive PCMs.

Single-Crystal Growth of P2-Type Layered Oxides with Increased Exposure of {010} Planes for High-Performance Sodium-Ion Batteries.

An increase in the size of single-crystal particles can effectively reduce the interfacial side reactions of layered oxides for sodium-ion batteries at high voltages but may result in sluggish Na+ transport. Herein, single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 with increased proportions of {010} planes is synthesized by adding low-cost NaCl as the molten salt. With the assistance of a NaCl molten salt, the median diameter (D50) of single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 increases to 10.46 μm relative to that of the comparison sample without NaCl (6.57 μm). Electrolyte decomposition on the surface of single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 is considerably suppressed, owing to a decrease in the specific surface area. Moreover, the increased exposure of {010} planes is favorable for improving the Na+ transport kinetics of single-crystal particles. Therefore, at 100 mA g-1, single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 exhibits a high-capacity retention of 96.6% after 100 cycles, which is considerably greater than that of the comparison sample (86.8%). Moreover, the rate performance of single-crystal Na0.66Ni0.26Zn0.07Mn0.67O2 (average discharge capacity of 81.2 mAh g-1) is superior to that of the comparison sample (average discharge capacity of 61.2 mAh g-1) at 2000 mA g-1. This work provides a new approach for promoting the single-crystal growth of layered oxides for highly stable interfaces at high voltages without compromising Na+ transport kinetics.

Towards high-entropy alloys with high-temperature corrosion resistance and structural stability

Complex component alloys (CCAs) consisting of multiple principal elements potentially encompass superior mechanical properties and good corrosion resistance. Eutectic high-entropy alloys (EHEAs) stand out from CCAs as the desired candidates for high-temperature (HT) applications due to the combined advantages of HEA alloys and unique equilibrium eutectic structure. This work first explores the thermodynamic calculation route toward HEAs with eutectic structure. Series of pseudo-binary diagrams of transition metal (TM) CCAs were calculated with the Calphad approach to locate the potential eutectic points. The representatives of a CrFeCoNi2.2Al alloy with eutectic structure and a non-eutectic CrFeCoNiCu alloy were cast, and their HT performance was further evaluated by hot corrosion with Na2SO4 + 25 wt% NaCl molten salts at 700, 800 and 900 °C, respectively. The HT degradation mechanism was explicitly revealed from a comprehensive thermodynamic perspective. Relationships between the HT performance and the inherent physicochemical properties of the constituent phases and the alloying components were addressed for the first time. It was found that the mixing enthalpy (ΔHmix) and valance electron concentration (VEC) played more decisive roles in the hot corrosion resistance than the mixing entropy (ΔSmix) of CCAs. A strategy for tailoring and developing HEAs for HT application by modulating alloy chemistry and microstructural features was proposed.

Thermal Stability and Hot Corrosion Performance of the AlCoCrFeNi2.1 High-Entropy Alloy Coating by Laser Cladding.

Both crack-free AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) and Y and Hf co-doping AlCoCrFeNi2.1 EHEA (YHf-EHEA) coatings were prepared by laser cladding. The solidification microstructure, thermal stability, and hot corrosion performance of the coatings at 900 °C under 75% Na2SO4 + 25% NaCl molten salts were investigated. The experimental results showed that the structure of the as-deposited coatings consisted of FCC and BCC/B2 phases. After heat treatment, an Al-rich L12 phase was precipitated in the FCC phase of all coatings. The grain sizes of the EHEA and YHf-EHEA coatings after heat treatment at 900 °C for 10 h increased by 27.5% and 15.7%, respectively, compared to the as-deposited coatings. Meanwhile, after hot corrosion, the spallation areas of the YHf-EHEA and EHEA coatings accounted for 14.98% and 5.67% of the total surface area, respectively. In this study, the Y and Hf co-doping did not change the microstructure morphology and phase structure of the coatings but did improve the thermal stability and resistance of the hot corrosion oxide scale spallation, providing a certain amount of data and theoretical support for the application of EHEA coatings as high-temperature protective coatings.

Influence of Nb on the Hot Corrosion Behaviors of a Fe–Cr–Ni Heat-Resistant Steel Weld Metal in the Na2SO4–NaCl Molten Salt at 700 °C

Influence of Nb on the Hot Corrosion Behaviors of a Fe–Cr–Ni Heat-Resistant Steel Weld Metal in the Na2SO4–NaCl Molten Salt at 700 °C

Molecular dynamics simulations of CaCl2–NaCl molten salt based on the machine learning potentials

Molecular dynamics simulations of CaCl2–NaCl molten salt based on the machine learning potentials

Na+ Lattice Doping Induces Oxygen Vacancies to Achieve High Capacity and Mitigate Voltage Decay of Li-Rich Cathodes.

In this work, we synthesized 1D hollow square rod-shaped MnO2, and then obtained Na+ lattice doped-oxygen vacancy lithium-rich layered oxide by a simple molten salt template strategy. Different from the traditional synthesis method, the hollow square rod-shaped MnO2 in NaCl molten salt provides numerous anchor points for Li, Co, and Ni ions to directly prepare Li1.2Ni0.13Co0.13Mn0.54O2 on the original morphology. Meanwhile, Na+ is also introduced for lattice doping and induces the formation of oxygen vacancy. Therefrom, the modulated sample not only inherits the 1D rod-like morphology but also achieves Na+ lattice doping and oxygen vacancy endowment, which facilitates Li+ diffusion and improves the structural stability of the material. To this end, transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, X-ray photoelectron spectroscopy, and other characterization are used for analysis. In addition, density functional theory is used to further analyze the influence of oxygen vacancy generation on local transition metal ions, and theoretically explain the mechanism of the electrochemical performance of the samples. Therefore, the modulated sample has a high discharge capacity of 282 mAh g-1 and a high capacity retention of 90.02% after 150 cycles. At the same time, the voltage decay per cycle is only 0.0028 V, which is much lower than that of the material (0.0038 V per cycle) prepared without this strategy. In summary, a simple synthesis strategy is proposed, which can realize the morphology control of Li1.2Ni0.13Co0.13Mn0.54O2, doping of Na+ lattice, and inducing the formation of oxygen vacancy, providing a feasible idea for related exploration.

Hot Corrosion Behavior of Fe–Cr–Ni-Based Austenitic Heat-Resistant Steel Weld Metal in Na2SO4–NaCl Molten Salts at Different Temperatures

The hot corrosion behavior of the austenitic heat-resistant steel weld metal produced by multi-pass gas tungsten arc welding was investigated. A bilayer oxide scale formed on the surface of the weld metal by the selective oxidation of the element Cr and Fe, and the dissolution of the oxide film occurred at elevated temperatures due to the existence of the molten salt. Morphologies and structures of the oxide scale were characterized by electron microscopy and X-ray diffraction techniques, and then the underlying reason for the hot corrosion of the nonequilibrium weld metal was identified. The interdendritic region could act as the shortcut path for the oxygen, which promotes the internal oxide distribution in chains, and a large internal oxidation zone appears under the bilayer oxide scale.

Hot corrosion effect of the vacuum arc melted (a2/γ)Ti-48Al-2Nb-0.7Cr-0.3Si alloy under an environment of NaCl-Na2SO4 salt

The Ti-48Al-2Nb-0.7Cr-0.3Si alloy comprising of α2-Ti3Al and γ-TiAl phases was successfully fabricated using vacuum arc melting. To study its hot corrosion behaviour, the alloy was subjected to cyclic thermal loading under a Na2SO4 + 25wt.%NaCl molten salt mixture at 900 °C for up to 60 h. Mass change per unit surface was measured to determine the corrosion kinetics of the alloy. The alloy experienced severe hot corrosion attacks up to -50.94 mg/cm2. SEM indicated the formation of a mixture of TiO2/Al2O3 scales on the alloy's surface. XRD confirmed the presence of hot corrosion products such as Na2Ti3O7, TiO2, Al2O3, and Cr2O3. The presence of chlorine gas in the hot corrosion environment resulted in the delamination of the protective scale on the surface, indicating its detrimental effect.

Oxidation and Hot Corrosion Behaviour of Ni-Based Superalloy 825 and AISI 321 Dissimilar Laser Weldment in K2SO4–60% NaCl Molten Salt Environment at 650°C

Oxidation and Hot Corrosion Behaviour of Ni-Based Superalloy 825 and AISI 321 Dissimilar Laser Weldment in K2SO4–60% NaCl Molten Salt Environment at 650°C

Effect of Cathode Physical Properties on the Preparation of Fe3Si0.7Al0.3 Intermetallic Compounds by Molten Salt Electrode Deoxidation.

As a new process, molten salt electrolysis is widely used in the preparation of metal materials by in situ reduction in solid cathodes. Therefore, it is meaningful to study the influence of the physical properties of solid cathodes on electrolysis products. In this paper, mixed oxides of Fe2O3-Al2O3-SiO2 were selected as raw materials, and their particle size distribution, pore size distribution, specific surface area, and other physical properties were investigated by mechanical ball milling at different times. The CaCl2-NaCl molten salt system was selected to electrolyze the sintered cathode solid at 800 °C and a voltage of 3.2 V. The experimental results show that with the prolongation of ball-milling time, the particle size of mixed oxide raw materials gradually decreases, the specific surface area gradually increases, the distribution of micropores increases, and the distribution of mesopores decreases. After sintering at 800 °C for 4 h, the volume and particle size of the solid cathode increased, the impedance value gradually decreased, and the pores first increased and then decreased. The electrolysis results showed that the prolongation of the ball-milling time hindered the electrolysis process.

Multi-cationic molten salt electrolyte of high-performance sodium liquid metal battery for grid storage

Multi-cationic molten chloride salt mixtures such as LiCl–KCl–NaCl are promising molten salt electrolytes for sodium liquid metal batteries (Na-LMBs). In this work, the melting temperature of LiCl–KCl–NaCl was determined with Differential Scanning Calorimetry (DSC), assisted by FactSage™ simulation and confirmed by a melting point apparatus OptiMelt™. It is founded that the eutectic LiCl–KCl–NaCl can be considered as a pseudo-binary system with LiCl–KCl eutectic (59.2–40.8 mol.%) as the solvent and NaCl as the solute. When NaCl is not more than 9 mol.%, the eutectic LiCl–KCl–NaCl salt mixture has a melting temperature of ∼350 °C as that of LiCl–KCl eutectic. In addition, the exchange reactions between anode Na metal with LiCl–KCl–NaCl molten salt electrolyte were studied at the temperature of 400–500 °C quantitatively. The equilibrium constants of the exchange reactions were determined by chemical analysis on the salt and metal phases with Ion Chromatography (IC). A one ampere-hour (Ah) Na-LMB test cell shows promising energy storage performance. Moreover, the phenomena in the cell test can be explained convincingly, combining the results of exchange reactions and the pseudo-binary-system theory. The findings on the multi-cationic molten salt electrolytes for Na-LMBs in this work could support further development of other liquid metal batteries.

Sulfur Composite Cathodes for High-Capacity Aluminum Metal Anode Rechargeable Batteries

Recently, needs to rechargeable batteries have been diversified into various kinds due to expansion of their application range. Not only future high-performance batteries exceeding Li-ion batteries (LiBs), but also new concept ones, which are composed solely of common elements and have performance comparable to current LiBs, have become one of the important recent research targets in this area. Focusing rich abundance and very-high theoretical capacity (2980 mAh g-1, 8046 mAh cm-3) of aluminum (Al) metal, we have created new concept rechargeable batteries with the following anode reaction in chloroaluminate ionic liquids (ILs):1,2 4[Al2Cl7]- + 3e- ⇌ Al + 7[AlCl4]- Many research groups have also reported similar Al metal anode batteries.3 Herein, some sulfur (S) composite cathodes that enable the use of S(IV)/S electrode reaction are designed to greatly enhance the capacity of Al metal anode battery.The preparation and purification processes for 60.0-40.0 mol% AlCl3–[C2mim]Cl and 61.0-26.0-13.0 mol% AlCl3–NaCl–KCl IL electrolytes were identical with those described in our previous articles.1,2 Three types of cathode active materials, S-coated multi-walled carbon nanotube (S-MWCNT), sulfurized polyethylene glycol (SPEG),4 and sulfurized polyacrylonitrile (SPAN),5 were employed. All the S composite electrodes were prepared by pressing the mixtures of 50 wt% S-based cathode active materials, 45 wt% conductive additive (MWCNT), and 5 wt% polytetrafluoroethylene onto Mo plate current collectors. Al metal plate was employed as the anode active material. Electrochemical experiments were carried out with a commonly used three-electrode cell or a two-electrode sealed cell in an Ar gas-filled glove box with O2 and H2O < 1 ppm.Figure 1 shows multiple cyclic voltammograms recorded at a S-MWCNT composite electrode in a three-electrode cell with 60.0-40.0 mol% AlCl3–[C2mim]Cl at 298 K. When the potential scan was initiated from the rest potential to the negative direction, a pair of reduction and oxidation waves appeared with large over potential. These waves gradually varied with an increase in the number of cycles. Considering the article reported by Gao et al.,6 the redox waves observed in Fig. 1a can be regarded to be the following electrochemical reaction (S/S2-):3S + 8[Al2Cl7]- + 6e- ⇌ Al2S3 + 14[AlCl4]- As for the positive scan from the rest potential (Fig. 1b), several oxidation and reduction waves were observed. Overpotential obviously diminished compared to that for the S/S2-. Similar electrode behavior for S in a Lewis acidic 63-37 mol% AlCl3–NaCl molten salt is reported by Marassi, et al.7 Given that the electrochemical reaction process is the same, the number of electrons involved in the reaction is estimated to be 4. Then, the electrochemical reaction (S(IV)/S) is:[SCl3]+ + 3[Al2Cl7]- + 4e- ⇌ S + 6[AlCl4]- If we can apply this S(IV)/S reaction to the Al metal anode-S cathode rechargeable battery, S cathode capacity becomes double and higher working voltage is expected relative to conventional S/S2- one. Unfortunately, the redox waves for the reaction decrease sharply with increase in the cycle number. The waves almost disappeared at the 5th cycle. Analogous results were also obtained in the 61.0-26.0-13.0 mol% AlCl3–NaCl–KCl. We concluded that the electrode reaction for S(IV)/S on the S-MWCNT composite cathode is not suitable for battery application. However, the use of S-combined active materials, SPEG and SPAN, substantially improved the electrode reaction in the 61.0-26.0-13.0 mol% AlCl3–NaCl–KCl IL at 393 K. Thus, we carried out the charge-discharge test for the Al | SPEG and Al | SPAN batteries with the inorganic IL electrolyte using both S/S2- and S(IV)/S electrode reactions. If SPEG was used, the discharge capacity was ca. 1050 mAh (g-S)-1 at 50th cycle. When using only S/S2- reaction, such high capacity was not attained.2 The S(IV)/S electrode reaction should be directly involved in the capacity increase. Interestingly, the use of SPAN made further improvement possible. One of the typical results is shown in Fig. 2. At the first cycle, the discharge capacity reached ca. 4700 mAh (g-S)-1 and showed ca. 2600 mAh (g-S)-1 even after 50th cycle. These results suggest that the S-combined active material, i.e., SPEG and SPAN, composite electrodes can work as the high-capacity cathodes for Al metal anode rechargeable battery.This research was supported by JST-MIRAI program (JPMJMI17E9). SPAN was provided by ADEKA corporation. References Tsuda, et al., J. Electrochem. Soc., 161, A908 (2014).Tsuda, et al., Chem. Commun., 58, 1518 (2022).Ru, et al., J. Mater. Chem. A, 7, 14391 (2019).Kojima, et al., ECS Trans., 75, 201 (2017).S. Ahmed, et al., Adv. Sci., 8, 2101123 (2021).Gao, et al., Angew. Chem. Int. Ed., 55, 9898 (2016).Marassi, et al., J. Electrochem. Soc., 126, 231 (1979). Figure 1