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Theoretical and experimental endeavor were combined to investigate effects of Co-incorporating on crystal structure and oxygen vacancy formation energy and their influence on Sr 2 Co 1 + x Mo 1 − x O 6 − δ electrochemical performance systematically. From the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), it is found that introducing Co decreases the ordering of B-site cations. Most importantly, Co 3 + content increases with the increasing Co, indicating more Co-O*-Co pairs are introduced within the compounds. Additionally note that the electrochemical performance of the materials is improved apparently when more Co is incorporated. Sr 2 Co 1.5 Mo 0.5 O 6 − δ has an area-specific polarization resistance (ASR) as low as 0.030 Ω cm 2 in a symmetrical cell at 800 °C. First-principles calculations found that the sequence of the oxygen vacancy formation energy was Co-O*-Co < Co-O*-Mo, indicating that Co-doping facilitates formation of oxygen vacancy, which coincides well with experimental results. Therefore, Co-incorporating in Sr 2 CoMoO 6 is an efficient way to enhance electrochemical performance of cathode for IT-SOFCs. [ABSTRACT FROM AUTHOR]

From the view point of compatibility of both crystalline and element with the prototypical perovskite-type electrolyte of La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-δ , a series of micro-Mg-doped La 2 NiO 4+δ compounds with compositions of La 2 Ni 1- x Mg x O 4+δ ( x = 0.0, 0.02, 0.05 and 0.10) were successfully synthesized via a traditional sol-gel process and evaluated as cathode for intermediate-temperature solid oxide fuel cells (IT-SOFC). The effects of Mg-doping on crystal structures, bond properties and covalent states were analyzed by X-Ray Diffraction (XRD), Infrared spectra (IR) and X-ray photoelectron spectroscopy (XPS) techniques, respectively. It is found that Mg-doping is benefit for the migration of the interstitial oxygen by weakening the Ni(Mg) O bond. More importantly, we found that Mg doped at the subsurface under the Ni of (001) surface will promote both the O 2 adsorption and decomposition process from the analysis of the oxygen migration dynamics. Considering the balance of electronic conductivity, it was indicated that La 2 Ni 0.98 Mg 0.02 O 4+δ (LNM0.02) manifested the optimal electrochemical property with the lowest area specific resistance of 0.05 Ω cm 2 at 800 °C, and along with a maximum power density of 528 mW cm −2 for an electrolyte supported single cell LNM0.02|LSGM|NiO-SDC at 800 °C with approximately 20% higher than that of the La 2 NiO 4+δ (LN) (∼429 mW cm −2 ) cathode. The results indicate that introducing micro-dose of Mg into Ni-site in La 2 NiO 4+δ compound is an efficient way to obtain an excellent cathode material for IT-SOFCs. [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]

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]

Abstract Layered perovskite oxide LaBa 0.5 Sr 0.25 Ca 0.25 Co 2 O 5+ δ (LBSCaCO) is studied as a potential cathode material for intermediate temperature solid oxide fuel cells (IT-SOCFs). Ca-free sample LaBa 0.5 Sr 0.5 Co 2 O 5+ δ (LBSCO) is also investigated for comparison. The thermal expansion coefficient (TEC) value is reduced from 26.2 × 10−6 K−1 to 20.0 × 10−6 K−1 by Ca doping. The electrical conductivity of LBSCaCO is above 500 S cm−1 from room temperature to 800 °C. Substitution of Sr by Ca can effectively enhance the electrochemical performance. The area specific resistance (ASR) values of LBSCaCO and LBSCO are 0.075 Ω cm2 and 0.084 Ω cm2 at 800 °C, respectively. Moreover, LBSCaCO cathode achieves an excellent outputting of 662 mW cm−2 at 800 °C. Based on these results, Ca doped layered perovskite LBSCaCO can be a cathode candidate material for IT-SOFC application. Graphical abstract LBSCaCO has a tetragonal structure (space group: P 4/ mmm ) and a good performance of 662 mW cm−2 at 800 °C. fx1 Highlights • LBSCO and LBSCaCO double perovskites are studied as IT-SOFC cathodes. • A-site Ca doping for Sr reduces TEC and ASR values of the sample. • A-site Ca doping for Sr increases the electrical conductivities of the sample. • LBSCaCO exhibits good chemical compatibility and electrochemical performance. [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]

Cobalt phosphide is a promising anode material for lithium-ion batteries (LIBs) due to a high theoretical capacity at low potentials when reaction with lithium. While, capacity-decay upon cycling and unsatisfied rate performance limited the practical application in LIBs. Herein, we report the design and synthesis of free-standing electrode composed of CoP/P-C nanofilm and lightweight carbon cloth (denoted as PCC@CoP/P-C) as an anode material for LIBs. The facile and in situ strategy for the synthesis of PCC@CoP/P-C involves phytic acid (PA) complexed with Co2+ and subsequent annealing treatments. Owing to the unique structural merits of CoP/P-C nanofilm and the lightweight PCC, the PCC@CoP/P-C free-standing electrode exhibits an ultrahigh specific stability capacity and nice cycle stability when direct used as anode for LIBs. This work offers an easy and environment friendly method to boost lithium performance for transition metal phosphides anode materials. • The free-standing electrode consists of CoP/P-C nanofilm and porous carbon cloth. • Porous carbon cloth makes electrode lighter in weight and more stable in structure. • The free-standing electrode exhibits outstanding lithium storage performance. • The free-standing electrode is synthesized in a simple and green method. • This work provides an idea for the design of phosphide anode electrodes. [ABSTRACT FROM AUTHOR]