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Ca-doped perovskite oxides PrBa 1- x Ca x CoCuO 5+ δ (PBCCCO, x = 0–0.2) were prepared and investigated as SOFC cathode materials. PBCCCO samples are single perovskite structure with P4/mmm space group. Pr, Cu and Co ions in PBCCCO samples exist in the form of Pr3+/Pr4+, Cu2+/Cu+ and Co3+/Co4+ multi-valence states. The average TECs of PBCCCO samples were reduced from 17.4 × 10−6 K−1 (x = 0) to 16.7 × 10−6 (x = 0.1) and 16.1 × 10−6 K−1 (x = 0.2) whin RT-900°С. The electrical conductivity and electrochemical catalytic activity of PBCCCO perovskites was enhanced obviously by Ca doping. The ASR values decreased by 60.1% (@650 °C), 68.9% (@700 °C), 71.0% (@750 °C) and 72.8% (@800 °C) respectively when Ca doping content increased from x = 0 to 0.2. These results suggest PBCCCO sample with Ca doing content x = 0.2 can be a promising cathode for IT-SOFC. [ABSTRACT FROM AUTHOR]

Bismuth doped La 2- x Bi x NiO 4+ δ (x = 0, 0.02 and 0.04) oxides are investigated as SOFC cathodes. The effects of Bi doping on the phase structure, thermal expansion, electrical conduction behavior as well as electrochemical performance are studied. All the samples exist as a tetragonal Ruddlesden-Popper structure. Bi-doped LBNO-0.02 and LBNO-0.04 have good chemical and thermal compatibility with LSGM electrolyte. The average TEC over 20–900°С was 13.4 × 10−6 and 14.2 × 10−6 K−1 for LBNO-0.02 and LBNO-0.04, respectively. The electrical conductivity was decreasing with the rise of Bi doping content. EIS measurement indicates Bi doping can decrease the ASR values. At 750 °C, the obtained ASR for LBNO-0.04 is 0.18 Ωcm2, which is 56% lower than that of the sample without Bi doping, suggesting Bi doping is beneficial to the electrochemical catalytic activity of LBNO cathodes. [ABSTRACT FROM AUTHOR]

Addressing challenges in oxygen reduction efficiency and CO 2 endurance is essential for advancing the electrochemical energy conversion performance of solid oxide fuel cells (SOFCs). This investigation introduces an innovative strategy by employing Ce doping to enhance the oxygen reduction kinetics and CO 2 resistance of NdBaCoFeO 5+ δ (NBCF) cathodes. Ce doping effectively regulates the oxygen vacancy content, the ratio of Co3+/Co4+ and Fe3+/Fe4+ in NBCF, leading to substantial improvements in oxygen exchange, lattice diffusion, and charge transfer processes. Consequently, a significant enhancement in the oxygen reduction reaction catalytic activity and CO 2 endurance is achieved. At 800 °C, the introduction of 10 mol% Ce doping results in a 65.3% reduction in Rp, reaching 0.024 Ω cm2. Simultaneously, the power density experiences a 50.8% enhancement, reaching 1.0 W cm−2. The current investigation presents a novel avenue towards the advancement of next-generation high-efficiency and stable cathode materials for SOFCs. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of the oxygen reduction reaction (ORR) and susceptibility to CO 2 poisoning present significant challenges in the application of intermediate temperature solid oxide fuel cells (IT-SOFCs). In this study, bismuth (Bi) was introduced as a dopant for the first time to enhance both the ORR activity and CO 2 tolerance of PrBaCoCuO 5+ δ (PBCCO) cathode. Bi doping serves to concurrently modulate the oxygen vacancy content and carrier concentration. This dual regulation enhances the processes of oxygen adsorption, dissociation, and charge transfer, as evidenced by the distribution of relaxation time (DRT) technique. Furthermore, PBBCCO demonstrates exceptional CO 2 tolerance and remarkable performance recovery following exposure to CO 2 -induced degradation. At 800 °C, the polarization resistance (R p) and maximum power density (MPD) of PBBCCO were 0.026 Ω cm2 and 631 mW cm−2, respectively. Notably, R p was reduced by 52.45%, and MPD exhibited an improvement of 45.11% at 800 °C. These findings highlight the significant impact of Bi doping on the performance of the PBCCO double perovskite cathode, underscoring its crucial importance for future developments of novel cathode materials. [ABSTRACT FROM AUTHOR]

Abstract Nb and W co-doped SrFeO 3- δ perovskite SrNb 0.1 W 0.1 Fe 0.8 O 3- δ (SNWF) is exploited as a novel cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). SNWF has a cubic structure with Pm 3 ¯ m space group. Its thermal, electrical and electrochemical properties were examined in detail. Nb/W co-doping increased the oxygen vacancy density of SNWF in comparison with that of Nb and W single-doped SrNb 0.2 Fe 0.8 O 3 -δ (SNF) and SrW 0.2 Fe 0.8 O 3 -δ (SWF) perovskites. Nb/W co-doping resulted in the decrease of electrical conductivity and the enhancement of thermal expansion coefficients (TECs) as well as the electrochemical performance. The average TEC value during 30–1000 °С is 19.6 × 10−6 K−1 for SNWF. At 750 °C, the area specific resistance (ASR) and the maximum power density are 0.113 Ω cm2 and 832 mW cm−2 for the cells based on SNWF electrode and La 0.8 Sr 0.2 Ga 0.8 Mg 0.1 O 3 (LSGM) electrolyte. Good ORR activity and output performance indicate SNWF can be a good alternative cathode material for IT-SOFC. [ABSTRACT FROM AUTHOR]

The development of cathode materials with high oxygen reduction reaction (ORR) activity is crucial to realize the wide application of solid oxide fuel cells. Nd-doped SrFeO 3-δ (SNF) two-phase nanocomposite was fabricated by a dopant-induced in situ self-assembly process. The SNF nanocomposite comprises 63.4 wt% perovskite main phase (P–SNF) and 36.6 wt% Ruddlesden-Popper second phase (RP-SNF). The average thermal expansion coefficient (TEC) of SrFeO 3-δ is reduced by 36.5 % and down to 13.9 × 10−6 K−1. At 750 °C, SNF demonstrates an impressive output power of 779 mW cm−2, which is twice that of the single-phase SrFeO 3-δ. The superior performance stems from the heterointerface effect of the in situ self-assembled two phases. This effect increases the content of oxygen vacancies, thereby enhancing both chemical oxygen surface exchange coefficient and bulk diffusion coefficient. Moreover, the SNF composite exhibits excellent CO 2 tolerance than the single-phase SrFeO 3-δ. This work presents a promising avenue for exploring multifunctional materials through interface engineering, offering new possibilities for future energy conversion devices. [ABSTRACT FROM AUTHOR]

Layered perovskite oxides with and without Ca-doped NdBa 0.5 Sr 0.25 Ca 0.25 Co 2 O 5+ δ (NBSCaCO) and NdBa 0.5 Sr 0.5 Co 2 O 5+ δ (NBSCO) are studied to investigate the effects of Ca doping on the crystal structure, thermal behavior, electrical and electrochemical properties. Both NBSCO and NBSCaCO are tetragonal structure with P 4 /mmm space group. The average thermal expansion coefficient (TEC) value is reduced from 23.3 × 10 −6 K −1 to 19.8 × 10 −6 K −1 during 30–800 °C. The electrical conductivities are increased by Ca doping. Both electrical conductivities of NBSCO and NBSCaCO are higher than 600 S·cm −1 over 30–800 °C. Substitution of Sr with Ca can effectively improve the electrochemical properties of NBSCaCO. From 650 °C to 800 °C, the area specific resistance (ASR) of NBSCaCO are decreased from 0.62 to 0.062 Ω cm 2 and the corresponding output power density are increased from 258 to 812 mW cm −2 . On the basis of these results, Ca doped layered perovskite NBSCaCO can be a good cathode candidate material for SOFC application. [ABSTRACT FROM AUTHOR]

Bi-doped La 2- x Bi x Cu 0.5 Mn 1.5 O 6 (LBCM- x , x = 0, 0.1 and 0.2) were synthesized as potential cathode materials for intermediate-temperature solid oxide fuel cells. The effects of 6s 2 lone pair electrons on the electrical and electrochemical properties of LBCMs were investigated. The results reveal that Bi 3+ affects the properties of LBCMs in two ways. First, Bi doping can promotes the formation of oxygen vacancies, which is consistent with the results of first-principles calculations. The formation of oxygen vacancies can increase the amount of Mn 3+ /Mn 4+ pairs for the hopping of electrons and accelerate the oxygen transportation. Second, Bi doping can affect the microstructure of LBCMs and make LBCM-0.1 has the smallest grain size. The dual effects of Bi doping result in the highest electrical conductivity (143.91 Scm −1 ) as well as the lowest polarization resistance (0.101 Ωcm 2 ) of LBCM-0.1 at 850 °C and make it a superior cathode candidate for solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

A series of novel composite electrolytes based on 20 mol% Gd doped CeO 2 with varying amounts of (Li/Na) 2 SO 4 have been synthesized. X-ray diffraction, thermogravimetry and differential scanning calorimetry, scanning electron microscope and transmission electron microscope were applied to characterize the phase components and microstructures of the composite electrolytes. Their ionic conductivities were determined by AC impedance spectroscopy. It has been found that the optimum sintering temperature and sulphate content for the composite electrolyte is 870 °C and 20 wt% (Li/Na) 2 SO 4 , respectively. Above 550 °C, a sharp increase in conductivity occurred, which can be interpreted as superionic phase transitions in the interface phases between GDC and sulphates. Both the high ionic conductivities above the transition temperature, 0.191, 0.298 and 0.372 S cm −1 at 550, 650 and 750 °C respectively, and low activation energy (0.303 eV) highlight composite GDC-20 wt% (Li/Na) 2 SO 4 a promising electrolyte candidate for application in intermediate temperature solid oxide fuel cells. [ABSTRACT FROM AUTHOR]

• Ba-deficient PrBa 0.5- x Sr 0.5 Co 2 O 5+ δ perovskites were studied as IT-SOFC cathode. • Introduction of Ba deficiency promotes the formation of oxygen vacancies. • PB 0.5- x SCO oxides have good chemical compatibility with LSGM electrolyte. • Ba deficiency is beneficial to the electrochemical performance of PB 0.5- x SCO. Ba-deficient PrBa 0.5- x Sr 0.5 Co 2 O 5+ δ (PB 0.5- x SCO, x = 0, 0.04 and 0.08) perovskites are synthesized. The effects of Ba deficiency on the phase structure, thermal expansion, electrical and electrochemical characteristics of PB 0.5- x SCO are investigated. PB 0.5- x SCO samples are chemically compatible with LSGM electrolyte at 1000 °С. Slightly decrement of TECs with the rise of Ba deficiency content in PB 0.5- x SCO is observed. The introduction of Ba deficiency promotes the formation of additional oxygen vacancies, which is responsible for the decrement of electrical conductivity and improvement of electrochemical performance of PB 0.5- x SCO samples. The electrical conductivity is higher than 580 Scm−1 for PB 0.5- x SCO perovskites within 50–800 °C. The electrochemical performance is promoted significantly by introducing Ba deficiency in PB 0.5- x SCO. The ASRs of the Ba-deficient PB 0.5- x SCO decreased by more than 60% in comparison with the sample without Ba-deficiency, indicating the introduction of Ba deficiency is an effective way to improve the electrochemical characteristic of PB 0.5- x SCO cathodes. [ABSTRACT FROM AUTHOR]

• Novel anion doping strategy is used to enhance the catalysis of NiCo 2 O 4. • NCOF demonstrates enhanced performance as an electrode for both SOFCs and LIBs. • NCOF shows a 61.5 % reduction in R p at 750 °C in SOFCs. • NCOF exhibits outstanding discharge specific capacity and rate capability in LIBs. The advancement of electrode materials exhibiting high catalytic activity is crucial for the application of solid oxide fuel cells (SOFCs) and lithium-ion batteries (LIBs). Herein, the anion substitution strategy is used to enhance the electrochemical catalytic activity of spinel oxide NiCo 2 O 4. For the first time, F-doped NiCo 2 O 3 F (NCOF) was synthesized and systematically studied as the electrode for both SOFCs and LIBs. The results demonstrate a noticeable increase in both the content of oxygen vacancies and the unit cell free volume after F doping. Simultaneously, there is a reduction in the band gap width, consequently significantly enhancing the conductivity of NCO. These changes are beneficial to the oxygen reduction reaction (ORR) process. At 750 °C, the R p of NCOF is 0.05 Ω cm2, exhibiting a reduction of 61.5 % compared to NCO. F doping accelerates the process of charge transfer and the adsorption/dissociation of oxygen. At 800 °C, NCOF exhibits an output performance of 0.85 W cm2, which is 46.6 % higher than that of NCO. Simultaneously, the initial discharge specific capacity of NCOF-based LIB reaches 1395 mAh/g at a current density of 100 mA g−1. F doping demonstrates a noteworthy improvement in both insertion potential and cycling performance. As a result, the NCOF electrode exhibits exceptional rate capability, highlighting its enhanced ability to efficiently handle charging and discharging processes over multiple cycles. These findings suggest that NCOF holds significant potential as an advanced electrode material for both SOFC and LIBs. This study introduces fresh perspectives for designing and developing high catalytic activity multifunctional electrodes for energy conversion and storage devices in the future. [ABSTRACT FROM AUTHOR]

Cathodes demonstrating elevated electrochemical catalysis and CO 2 endurance are fundamental for solid oxide fuel cells (SOFCs). Herein, Ta/Cu co-doped SrCo 0.8 Ta 0.1 Cu 0.1 O 3- δ (SCTC) and Nb/Cu co-doped SrCo 0.8 Nb 0.1 Cu 0.1 O 3- δ (SCNC) perovskite oxides were prepared and comparative studied as high-performance SOFC cathodes. Due to the synergistic effects of Ta/Cu and Nb/Cu, the oxygen vacancy content, the ratio of Co3+/Co4+, the average bonding energy and the critical radius in the material are well regulated, resulting in the reduction of TEC and enhanced electrochemical catalytic activity in SCTC and SCNC. At 800 °C, SCTC exhibits an ASR of 0.033 Ω cm2, while it is 0.038 Ω cm2 for SCNC. Additionally, SCTC demonstrates a considerable output performance of 0.89 W cm-2, representing a 15.65% improvement over SCNC. This work offers a highly effective approach to developing materials for next-generation energy transformation devices. [ABSTRACT FROM AUTHOR]

A series of perovskite oxides have been investigated as excellent potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this paper, we take the La 0.75 Sr 0.25 Cu 0.5− x Co x Mn 0.5 O 3− δ (LSCCM, x = 0, 0.25 and 0.5) system as subject, with Cu/Mn and/or Co/Mn on B-site and 25% Sr-substituted La ions on A-site, to investigate their structures, thermal stability and electrochemical properties. Pure rhombohedral crystal with space group R 3 ¯ c (no. 167) is identified by Rietveld refinement of X-ray diffraction data (XRD). It is found that the thermal expansion coefficient (TEC) is manageable when Co ion is incorporated, and the low TEC value ranges from 12.7 × 10 −6 to 15.4 × 10 −6 K −1 that are well compatible with prototypical electrolytes Zr 0.84 Y 0.16 O 1.92 (YSZ) and Ce 0.8 Sm 0.2 O 2− δ (SDC). The dc-conductivity is significantly enhanced from 36.5, 90.5 to 173.7 S cm −1 at 850 °C with the increasing Co percent, and accordingly, polarization resistance (R p ) is determined as 0.1291, 0.0835 and 0.0486 Ω cm 2 at 800 °C. The high electrical conductivities and low resistances can be attributed to the strong B O bond hybridization and oxygen vacancy formation at elevated temperatures with the introduction of Co ion, which is consistent with the results of first-principles calculation and thermogravimetric analysis. All these results demonstrate that LSCCM series are promising cathodes with controllable TEC for IT-SOFCs. [ABSTRACT FROM AUTHOR]

As a mixed oxygen ionic and electronic conductor, SrFe0.8Mo0.2O3-δ is confirmed to be a good cathode material for intermediate-temperature solid-state fuel cells (IT-SOFCs). The sample of SrFe0.8Mo0.2O3-δ is synthesized by a solid-state reaction method. Pure cubic SrFe0.8Mo0.2O3-δ perovskite, with space group of Pm-3m (no. 221) and lattice parameter a =3.9120(1) Å, is determined via Powder X-ray Rietveld refinements. X-ray photoelectron spectroscopy testifies the existence of mixed oxidation states Fe2+/3+/4+ and Mo5+/6+ in the crystal. Thermogravimetry analysis consistently shows that the SrFe0.8Mo0.2O3-δ begins to the loss of lattice oxygen at about 450°C, which overlaps to the inflection temperature of the electrical conductivity profile. The maximum electrical conductivity obtained is about 50.20Scm−1 at 450°C, and the impedance 0.11 Ω cm2 at 850°C. The performance demonstrates that SrFe0.8Mo0.2O3-δ is a potential candidate as a cathode material for IT-SOFCs. [ABSTRACT FROM AUTHOR]

• A novel Co 3 O 4 @Fe 2 O 3 composite with nanosheet morphology can improve the electron transfer in the catalytic process. • The electronic interaction between Co 3 O 4 and Fe 2 O 3 in the heterostructure region can obtain the more catalytic active site. • The Co 3 O 4 @Fe 2 O 3 composite produces better ORR/OER bifunctional catalytic activity and fast charge transfer. • The interface between Co 3 O 4 and Fe 2 O 3 can promote the reversible formation and decomposition of Li 2 O 2. Lithium-oxygen battery (LOB) has attracted wide attention owing to its high specific energy and environmental protection advantages. However, LOB also has many problems, such as the discharge products accumulated around the pore size to block the oxygen diffusion channel. In this work, a Co 3 O 4 @Fe 2 O 3 nanosheet composite catalytic material is designed, which can effectively improve the electron transfer in the catalytic process. Furthermore, due to the electronic interaction between Co 3 O 4 and Fe 2 O 3 in the heterostructure region, the optimal active sites for the adsorption and activation of the reactant molecules can be obtained so as to produce better ORR/OER bifunctional catalytic activity. Besides that, the interface between Co 3 O 4 and Fe 2 O 3 can stimulate more electrons to participate in the redox reaction and promote the reversible formation and decomposition of Li 2 O 2. When Co 3 O 4 @Fe 2 O 3 nanosheet composite as cathode catalyst, LOB can achieve a high discharge specific capacity of 5585 mAh/g with 141 stable charge and discharge cycles. [Display omitted] [ABSTRACT FROM AUTHOR]

• A novel Si@SiC nanowire is synthesized via a facile vacuum direct current arc method. • The pores between crosslinked nanowires can provide more space for the volume expansion. • SiC with strong Si-C bond force embedded in nanowires can buffer the volume change of Si active material. • Phenol resin coating Si@SiC nanowires can improve the conductivity and stability. • The material is loose and porous with a large specific surface area, which is conducive to the transport of ions and electrons. Owing to the volume expansion of silicon-based materials during the lithium insertion and de-insertion process, it has been restricted in the commercial advancement of lithium-ion batteries. Herein, 1D crosslinked Si and SiC nanowires are successfully prepared via a facile vacuum DC arc method and embedded into the pyrolyzed amorphous carbon of phenolic resin (PF) so as to form a novel Si@SiC@PF nanocomposite anode for lithium-ion batteries. Vacuum DC arc method generates instantaneous high temperatures during the reaction process, so the reactant can be ionized into a plasma state and grows into nanomaterials with a specific morphology and stable structure during the condensation. The crosslinked nanowires structure provides sufficient pores and SiC serving as a buffer owing to its high Si-C bond energy can slow down the volume expansion of silicon active material during the electrochemical reaction process. And embedding it into amorphous carbon can improve the conductivity and cycle stability. The electrochemical performance shows the specific discharge capacity after 300 cycles of Si@SiC with PF mass ratio to 1:4 anode can be stable at 1132 mAh·g−1 at the 0.2 A·g−1 current density and has more superb rate capabilities. [Display omitted] [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li–S) batteries are considered to be promising next-generation rechargeable system. However, the shuttle effect for lithium polysulfides (LiPSs) and slow sulfur reaction kinetics due to multistep phase transitions severely limit the practical application of Li–S batteries. Herein, via dual-strategy of heterogeneous interface and defect engineering, a cocklebur-like sulfur host with the TiO 2 -VO x heterostructure (CTVHs) for long-life Li–S batteries is fabricated, and atomic-level clarification of the chemical interaction between the substrate and LiPSs from a theoretical viewpoint is achieved. Benefiting from the heterostructure, the high adsorption energy heterojunction interface works as capturing centers to trap LiPSs which ensures rapid diffusion to VO x. In addition, the defect-rich spiny VO x is endowed with high catalytic activity towards LiPSs and fast lithium-ion migration so as to effectively implement one-step adsorption diffusion transformation. DFT calculations show that the introduction of a heterostructure can change the electronic structure, thereby improving the adsorption capacity of CTVHs. Electrochemical measurements reveal favorable kinetics for Li 2 S deposition, better cyclability, and an outstanding discharge capacity. The CTVHs/S cathode delivers a slow capacity decay rate of 0.029% per cycle and achieves nearly 100% coulombic efficiency (CE) at 0.5 C over 1400 cycles. This proposed strategy provides broad prospects to promote the adsorption-conversion of LiPSs for long-life Li–S batteries. [ABSTRACT FROM AUTHOR]

The perovskite oxides, La 1− x Sr x Ni 0.5 Mn 0.5 O 3− δ (LSNM, x = 0.0, 0.05, 0.1, and 0.15), have been evaluated as promising cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The polycrystalline LSNM nanoparticles are synthesized by a glycine-nitrate combustion method. The Rietveld refinements to X-ray diffraction patterns indicate that LaNi 0.5 Mn 0.5 O 3− δ (LS 0.0 NM) is within the mixed P b n m and R 3 ¯ c phases. However, the Sr-doping strategy initially makes the product only be R 3 ¯ c phase when x = 0.05, which is considered to be closely relevant to its high oxygen vacancy concentration. The R 3 ¯ c phase is also identified in x = 0.1 and 0.15 compounds. The electrochemical performance of LSNM has been performed by the electrochemical impedance spectra technique, and the La 0.9 Sr 0.1 Ni 0.5 Mn 0.5 O 3− δ (LS 0.1 NM) demonstrates the optimal electrochemical property as evidenced by the lowest area specific resistance (ASR) of 0.12 Ω cm 2 at 800 °C. Compared to the cobalt-containing cathode materials, the average thermal expansion coefficient (TEC) of LS 0.1 NM is about 11.33 × 10 −6 K −1 , matching well with the prototypical electrolyte La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3− δ below 850 °C. The maximum power densities of the electrolyte-support single cell with the configuration of LS 0.1 NM|LSGM|NiO-SDC reach 440 and 331 mW cm −2 at 850 and 800 °C, respectively. Therefore, LS 0.1 NM could be considered as a novel potential cathode candidate for IT-SOFCs. [ABSTRACT FROM AUTHOR]

A series of novel perovskites LaM 0.25 Mn 0.75 O 3− δ (M = Fe, Co, Ni, Cu) are considered as promising cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Polycrystalline powders of LaM 0.25 Mn 0.75 O 3− δ are synthesized by a modified Pechini method. Powder X-ray Rietveld refinements reveal that LaM 0.25 Mn 0.75 O 3− δ series are in the orthorhombic perovskite structure within Pnma (no. 62) space group at room temperature. In situ high temperature X-ray diffractions indicate the existence of phase transformation from the orthorhombic Pnma phase to a higher symmetrical rhombohedral phase at elevated temperatures without any second phase formation for all these compounds. Multivalent states of M (Fe, Co, Ni and Cu) and Mn ions are testified by X-ray photoelectron spectroscopy measurement (XPS). The electrical conductivity are measured to be 39.6, 85.3 and 48.1, 99.4 S cm −1 for M = Fe, Co, Ni and Cu, respectively and the corresponding impedance are 0.131, 0.106, 0.107 and 0.0634 Ω cm 2 at 850 °C. Among these compounds, LaCu 0.25 Mn 0.75 O 3 −δ exhibits the highest electrical conductivity and the lowest electrode polarization resistances, which is consistent with its calculated smallest band gap and lowest oxygen vacancy formation energy. Moreover, they all exhibit excellent chemical compatibility with prototypical electrolyte Ce 0.8 Sm 0.2 O 2−δ (SDC). While the overall electrochemical properties of LaM 0.25 Mn 0.75 O 3 −δ (M = Fe, Co, Ni) are high enough to fulfill the practical applications. Thus, these LaM 0.25 Mn 0.75 O 3− δ (M = Fe, Co, Ni, Cu) compounds are potential cathode materials for IT-SOFCs. [ABSTRACT FROM AUTHOR]

The synthesis, crystal structure, and dielectric properties of the titled compounds were described. The structural symmetry was determined to be monoclinic P 2 1 / n (No. 14) space group. Based on the highly ordered array of alternating MgO 6 and SbO 6 octahedra, these double perovskites exhibited significant octahedral tilting distortion according to the Glazer's notation system a − a − c + . As the result of substituting different rare earth ions from La 3+ to Nd 3+ , both the tolerance factor ( t ) and coordination number (CN) were reduced simultaneously and the B-site lattice distorted more heavily with the increase in chemical pressure by adopting smaller Ln 3+ ion. For the investigation of dielectric properties, all the samples consistently presented weak frequency dependent characteristic with relatively low dielectric constant ( ε ') and low tangent loss (tan δ ). With the shrinkage of the Ln 3+ ion size, the corresponding ε ' decreased remarkably and the dispersive tan δ peaks around 300 K shifted to low temperature, indicating that the space-charge-hopping mechanism dominated permittivity property can be tuned by controlling the degree of lattice distortion via substituting different Ln 3+ ions. [ABSTRACT FROM AUTHOR]

Abstract: To date great efforts have been devoted to the development of solid oxide fuel cell (SOFC) devices that is able to run at intermediate temperature (IT) and to retain good electrochemical performance as in the high temperature regime. To this end, Tantalum (Ta) is doped into Sr2Fe1.5Mo0.5−x Ta x O6−δ (0.0 ≤ x ≤ 0.15) to further improve the electrochemical performance as the cathode materials for IT-SOFC. Pure orthorhombic Sr2Fe1.5Mo0.5−x Ta x O6−δ (0.0 ≤ x ≤ 0.15) samples, with space group Pnma (no. 62), are synthesized by a two-step method and identified via the powder X-ray Rietveld refinements. X-ray photoelectron spectroscopy and thermogravimetry results consistently show that the number of oxygen vacancy increases with the increasing of Ta content. The thermal expansion compatibility of the samples is found to match the electrolyte of La0.9Sr0.4Ga0.1Mg0.2O3−δ (LSGM) better than that of cobalt-containing electrode compounds. Finally, the higher oxygen vacancy concentration leads to the enhanced ionic conductivity although electrical conductivity is slightly decreased due to the oxygen vacancy blocking. Therefore, Ta-doped Sr2Fe1.5Mo0.5O6−δ is proved to be a promising candidate for future cathode materials of IT-SOFC. [Copyright &y& Elsevier]

A sulfur composite active material for lithium-sulfur batteries with a highly active interface structure can display excellent electrochemical performances. For this reason, in this paper, we design a type of V 2 O 5-x /TiO 2 active interface structure with high polysulfide adsorption energy as a high-performance sulfur-wrapped matrix. Physical property characterization indicates this interface is constructed from circular anatase structure TiO 2 and anoxic vanadium oxide structure composed of V4+ and V5+. After sulfur wrapping, Ti-S and S-S bond structures are produced by chemical and physical adsorption. Density functional theory calculations show that the V 2 O 5-x /TiO 2 interface has very high adsorption energy (-5.93 eV) with lithium polysulfide (Li 2 S 6). After sulfur wrapping as a cathode active material, it displays low electrochemical charge transfer resistance (31.89 Ω) and high lithium-ion transfer efficiency (3.50 × 10−12). In addition, it has rather high discharge specific capacities of 1466.47, 963.84 and 801.16 mAh.g−1 at 0.1, 0.2 and 0.5 C, respectively. After 500 cycles, the discharge capacity retention at 0.5 C is up to 76.11% corresponding to 0.048% capacity decay rate per cycle. This is the reason that the V 2 O 5-x /TiO 2 active interface has very strong adsorption to polysulfide and can effectively suppress the shuttle effect (Q low /Q high =1.44 at 0.2 C). [ABSTRACT FROM AUTHOR]