Recent advances in intermediate-temperature CO_(2) capture: Materials,technologies and applications

Carbon capture,utilization and storage(CCUS) is widely recognized as a vital strategy for mitigating the impact of human induced climate change.Among various CO_(2) adsorbents,intermediate-temperature solid adsorbents have garnered significant attention due to their potential applications in hydrogen utilization,specifically in the water gas shift,steam reforming and gasification processes.These processes are crucial for achieving carbon neutrality.While laboratory-level studies have showcased the high adsorption capacity of these materials via various synthesis and modification methods,their practical application in complex industrial environments remains challenging,impeding the commercialization process.This review aims to critically summarize the recent research progress made in intermediatetemperature(200-400℃) solid CO_(2) adsorbents,particularly focusing on indicators such as cyclability,gas selectivity,and formability,which play vital roles in industrial application scenarios.Additionally,we provide an overview of laboratory-level advanced technologies specifically tailored for industrial applications.Furthermore,we highlight several industrial-ready advanced technologies that can pave the way for overcoming the challenges associated with large-scale implementation.The insights provided by this review aim to assist researchers in identifying the most relevant research directions for industrial applications.By promoting advances in the application of solid adsorbents,we strive to facilitate the ultimate goal of achieving carbon neutrality.

Investigation and optimization of high-valent Ta-doped SrFeO_(3-δ)as air electrode for intermediate-temperature solid oxide fuel cells

To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells(ITSOFCs),10mol%Ta5+doped in the B site of strontium ferrite perovskite oxide(SrTa_(0.1)Fe_(0.9)O_(3-δ),STF)is investigated and optimized.The effects of Ta^(5+)doping on structure,transition metal reduction,oxygen nonstoichiometry,thermal expansion,and electrical performance are evaluated systematically.Via 10mol%Ta^(5+)doping,the thermal expansion coefficient(TEC)decreased from 34.1×10^(-6)(SrFeO_(3-δ))to 14.6×10^(-6) K^(-1)(STF),which is near the TEC of electrolyte(13.3×10^(-6) K^(-1) for Sm_(0.2)Ce_(0.8)O_(1.9),SDC),indicates excellent thermomechanical compatibility.At 550-750℃,STF shows superior oxygen vacancy concentrations(0.262 to 0.331),which is critical in the oxygen-reduction reaction(ORR).Oxygen temperature-programmed desorption(O_(2)-TPD)indicated the thermal reduction onset temperature of iron ion is around 420℃,which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity curves.At 600℃,the STF electrode shows area-specific resistance(ASR)of 0.152Ω·cm^(2) and peak power density(PPD)of 749 mW·cm^(-2).ORR activity of STF was further improved by introducing 30wt%Sm_(0.2)Ce_(0.8)O_(1.9)(SDC)powder,STF+SDC composite cathode achieving outstanding ASR value of 0.115Ω·cm2 at 600℃,even comparable with benchmark cobalt-containing cathode,Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)(BSCF).Distribution of relaxation time(DRT)analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite cathode.At 650℃,STF+SDC composite cathode achieving an outstanding PPD of 1117 mW·cm^(-2).The excellent results suggest that STF and STF+SDC are promising air electrodes for IT-SOFCs.

Research on Calcium Doped Ceria Used in Intermediate-Temperature SOFCs Anodes

As a mixed ion-electronic conductor, doped ceria, especially rare earth doped ceria, were used as anodes or components of anodes in SOFCs. In this work, calcium doped ceria （CCO） was synthesized to be used in intermediate-temperature SOFCs （IT-SOFCs） anodes in order to reduce the cost of anode-supported SOFCs. Electrical conductivity of 20% calcium doped ceria （20CCO） reached 0.209 S·cm^-1 in hydrogen at 850 ℃, and 0.041 S·cm^-1 in air at 800℃, which is about 0.04 S·cm^-1 lower than that of conventional samaria-doped ceria （0.079 S·cm^-1）. Electrochemical performance of Ni-20CCO cermet as anode was investigated using a fuel cell with 35μm-thick SDC electrolyte and Sm0.5Sr0.5 Co-SDC cathode. Maximum power density was 623 mW·cm^-2 under humidified （3% H2O） hydrogen at 650 ℃, inferring high catalytic activity of the Ni-20CCO anode.

Challenges and perspectives on high and intermediate-temperature sodium batteries

Energy storage systems are selected depending on factors such as storage capacity, available power, discharge time, self-discharge, efficiency, or durability. Additional parameters to be considered are safety, cost, feasibility, and environmental aspects. Sodium-based batteries （Na-S, NaNiC12） typically require operation temperatures of 300-350 ~C. The high operating temperatures substantially increase the operating costs and raise safety issues. This updated review describes the state-of-the-art materials for high-temperature sodium batteries and the trends towards the development and optimization of intermediate and low-temperature devices. Recent advances in inorganic solid electrolytes, glass-ceramic electrolytes, and polymer solid electrolytes are of immense importance in all-solid-state sodium batteries. Systems such as Na~ super ionic conductor （NASICON, Nal^xZr2PB-~SixOl2 （0 -〈 x _〈 3））, glass-ceramic 94Na3PS4＂6Na4SiS4, and polyethylene oxide （PEO）-sodium triflate （NaCF3SO3） are also discussed. Room temperature ionic liquids （RTILs） are also included as novel electrolyte solvents. This update discusses the progress of on-going strategies to enhance the conductivity, optimize the electrolyte/electrode interface, and improve the cell design of emerging technologies. This work aims to cover the recent advances in electrode and electrolyte materials for sodium- sulfur and sodium-metal-halide （zeolite battery research Africa project （ZEBRA）） batteries for use at high and intermediate temperatures.

Phase transition and heterogeneous strengthening mechanism in CoCrFeNiMn high-entropy alloy fabricated by laser-engineered net shaping via annealing at intermediate-temperature

High-entropy alloys(HEAs)have attracted tremendous attention owing to their controllable mechanical properties,whereas additive manufacturing(AM)is an efficient and flexible processing route for novel materials design.However,a profound appraisal of the fundamental material physics behind the strengthening of AM-printed HEAs upon low/intermediate-temperature annealing is essential.In this work,Co CrFe Ni Mn HEAs have been prepared using laser-engineered net shaping(LENS)and subsequently annealed at different temperatures.The Co Cr Fe Ni Mn HEA annealed at intermediate-temperature(873 K)exhibits a strong strain hardening capability,resulting in ultimate strength of 725 MPa and plasticity of 22%.A ternary heterogeneous strengthening mechanism is proposed to explain this phenomenon,in which equiaxed grains,columnar grains,andσprecipitates play different roles during tensile deformation.The resultant excellent strength and ductility can be ascribed to the heterostructure-induced mismatch.The equiaxed grains provide adequate grain boundaries(GBs),which induce dislocation plugging-up and entanglement;the columnar grains induce the onset and arrest of the dislocations for plastic deformation;and theσprecipitates hinder the movement of slip dislocations.The results provide new insights into overcoming the strength-ductility trade-off of LENS-printed HEAs with complex geometries.

Enhanced electrochemical performance of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3−δ)cathode via Ba-doping for intermediate-temperature solid oxide fuel cells

La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)is recognized as one of the most promising cathode materials for the highly-desired intermediatetemperature solid oxide fuel cell(IT-SOFC)technology.However,it is still challenged by polarization losses due to reduced operation temperatures.In this work,a series of Ba^(2+)-doped La0.6-xBaxSr0.4Co0.2Fe0.8O3-δ(LBSCFx,x=0.05,0.10,0.15,and 0.20)materials are successfully synthesized and their electrochemical performances are evaluated as a cathode for IT-SOFC technology.The study shows that,compared to the un-doped LSCF,the Ba^(2+)-doped LBSCF possess higher electrical conductivities at 500-800℃ and display lower polarization resistances to oxygen adsorption/dissociation.As a result,the Ni-SDC|SDC|LBSCF0.20 cell(SDC=samarium-doped cerium,Sm_(0.2)Ce_(0.8)O_(1.9))delivers a high maximum power density of 0.704 W/cm^(2)at 750℃,which is>30%higher than the Ni-SDC|SDC|LSCF cell.This work reveals that Ba^(2+)-doping is effective in enhancing oxygen catalytic activity of LSCF-based cathode materials,demonstrating a new and commercial-feasible strategy in developing high performance cathode materials for the IT-SOFC technology.

Single-phase La_(0.8)Sr_(0.2)Co_(1-x)Mn_(x)O_(3-δ) electrocatalyst as a triple H^(+)/O^(2-)/e^(-) conductor enabling high-performance intermediate-temperature water electrolysis

Hydrogen,especially the“green hydrogen”based on water electrolysis,is of great importance to build a sustainable society due to its high-energy-density,zero-carbon-emission features,and wide-range applications.Today's water electrolysis is usually carried out in either low-temperature(<100℃),e.g.,alkaline electrolyzer,or high-temperature(>700℃)applications,e.g.,solid oxide electrolyzer.However,the low-temperature devices usually suffer from high applied voltages(usually>1.5 V@0.01 A cm^(-2))and high cost;meanwhile,the high-temperature ones have an unsatisfied lifetime partially due to the incompatibility among components.Reasonably,an intermediate-temperature device,namely,proton ceramic cell(PCC),has been recently proposed.The widely-used air electrode for PCC is based on double O^(2-)/e^(-)conductor or composited O^(2-)/e^(-)-H^(+)conductor,limiting the accessible reaction region.Herein,we designed a single-phase La_(0.8)Sr_(0.2)Co_(1-x)Mn_(x)O_(3-δ)(LSCM)with triple H^(+)/O^(2-)/e^(-)conductivity as the air electrode for PCCs.Specifically,the La_(0.8)Sr_(0.2)Co_(0.8)Mn_(0.2)O_(3-δ)(LSCM8282)incorporates 5.8%proton carriers in molar fraction at 400℃,indicating superior proton conducting ability.Impressively,a high current density of 1580 mA cm^(-2) for hydrogen production(water electrolysis)is achieved at 1.3 V and 650℃,surpassing most low-and high-temperature devices reported so far.Meanwhile,such a PCC can also be operated under a reversible fuel cell mode,with a peak power density of 521 mW cm^(-2) at 650℃.By correlating the electrochemical performances with the hydrated proton concentration of single-phase triple conducting air electrodes in this work and our previous work,a principle for rational design of high-performance PCCs is proposed.

Cobalt-free Composite Ba_(0.5)Sr_(0.5)Fe_(0.9)Ni_(0.1)O_(3-δ)-Ce_(0.8)Sm_(0.2)O_(2-δ) as Cathode for Intermediate-Temperature Solid Oxide Fuel Cell

New cobalt-free composites consisting of Ba0.5Sr0.5Fe0.9Ni0.1O3-δ （BSFN） and Ce0.8Sm0.2O2-δ （SDC） were investigated as possible cathode materials for intermediate-temperature solid oxide fuel cell （IT-SOFC）. BSFN, which was synthesized by auto ignition process, was chemically compatible with SDC up to 1100 ℃ as indicated by X-ray diffraction analysis. The electrical conductivity of BSFN reached the maximum value of 57 S.cm-1 at 450 ℃. The thermal expansion coefficient （TEC） value of BSFN was 30.9×10-6 K-1, much higher than that of typical electrolytes. The electrochemical behavior of the composites was analyzed via electrochemical impedance spectroscopy with symmetrical cells BSFN-SDC/SDC/BSFN-SDC. The area specific interracial polarization resistance （ASR） decreased with increasing SDC content of the composite. The area specific interracial polarization resistance （ASR） at 700 ℃ is only 0.49, 0.34 and 0.31 Ω.cm2 when 30, 40, and 50 wt% SDC was cooperated to BSFN, respectively. These results suggest that BSFN-SDC is a possible candidate for IT-SOFC cathode.

Anomalous yield and intermediate temperature brittleness behaviors of directionally solidified nickel-based superalloy

A nickel-based superalloy with good corrosion resistance was fabricated by directional solidification, and its microstructure and tensile properties at elevated temperatures were investigated. Microstructure observations reveal that the γ＇ precipitates are arrayed in the y matrix regularly with some MC, Ni5Hf and M3B2 particles distributed along the grain boundary. The tensile tests exhibit that the tensile properties depend on temperature significantly and demonstrate obvious anomalous yield and intermediate-temperature brittleness （ITB） behavior. Below 650℃, the yield strength decreases slightly but the ultimate tensile strength almost has no change. When the temperature is between 650 ℃ and 750 ℃, the yield and ultimate tensile strengths rise rapidly, and after then they both decrease gradually with temperature increasing further. The elongation has its minimum value at about 700 ℃. The TEM examination exhibits that sharing of the γ＇ by dislocation is almost the main deformation mechanism at low temperatures, but the γ＇ by-pass dominates the deformation at high temperatures. The transition temperature from shearing to by-pass should be around 800 ℃. The anomalous yield and intermediate-temperature brittleness behaviors should be attributed to the high content of γ＇. In addition, the carbides and eutectic structure also contribute some to the ITB behaviors of the alloy.