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Applying mixed oxygen ionic and electronic conducting (MIEC) oxides as the cathode offers a promising solution to enhance the performance of solid oxide fuel cells (SOFCs). However, the phase instability in CO2-containing air and sluggish oxygen reduction activity of MIEC cathodes remain a long-term challenge for optimizing the electrochemical performance of SOFCs. Herein, a heterovalent co-doping strategy is proposed to enhance the oxygen reduction activity and CO2 tolerance of SOFCs cathodes, which can be demonstrated by developing a novel BaCo0.6Fe0.4O3-δ (BCF)-based MIEC oxide, BaCo0.6Fe0.2Sn0.1Y0.1O3-δ (BCFSY). In addition to improving the stability of BCF-based perovskites, this strategy achieves an optimized balance of ionic mobility and oxygen vacancies due to the synergies between the effects of the co-dopants. Compared with single-doped materials, BCFSY exhibits improved CO2 tolerance and considerably higher ORR activity, which is reflected in a significantly lower polarization resistance of 0.15 Ω cm2 at 600°C. The results of this work provide an efficient tactic for designing electrode materials for SOFCs.

As a state-of-the-art secondary battery, lithium-ion batteries (LIBs) have dominated the consumer electronics market since Sony unveiled the commercial secondary battery with LiCoO2 as the negative electrode material in the early 1990s. The key to the efficient operation of LIBs lies in the effective contact between the Li-ion-rich electrolyte and the active material particles in the electrode. The particle properties of the electrode materials affect the lithium ion diffusion path, diffusion resistance, contact area with the active material, the electrochemical performance and the energy density of batteries. To achieve satisfied comprehensive performance and of LIBs, it is not only necessary to focus on the modification of materials, but also to balance the properties of electrode material particles. Therefore, in this review, we analyze the influence of particle properties on the battery performance from three perspectives: particle size, particle size distribution, and particle shape. A deep understanding of the effect and mechanism of particles on electrodes and batteries will help develop and manufacture practical LIBs.

Ti-doping enhancing the ability of SFM to resist H2S corrosion, the diffusion and surface adsorption process of oxygen and the reaction kinetics have been significantly improved.

More and more attentions have been attracted by lithium-sulfur batteries (Li-S), owing to the high energy density for the increasingly advanced energy storage system.While the poor cycling stability, due to the inherent polysulfide shuttle, seriously hampered their practical application. Recently, some polar hosts, like single metal oxides and sulfides, have been employed as hosts to interact with polysulfide intermediates. However, due to the inherent poor electrical conductivity of these polar hosts, a relatively low specific capacity is obtained. Herein, a spinel-type bimetal sulfide NiCo2S4 through a Prussian blue analogue derived methodology is reported as the novel host of polysulfide, which enables high-performance sulfur cathode with high Coulombic efficiency and low capacity decay. Notably, the Li-S battery with NiCo2S4-S composites cathode still maintains a capacity of 667 mA h g-1 at 0.5 C after 300 cycles, and 399 mA h g-1 at 1 C after 300 cycles. Even after 300 cycles at the current density of 0.5 C, the capacity decays by 0.138% per cycle at high sulfur loading about 3 mg cm-2. And the capacity decays by 0.026% per cycle after 1000 cycles, when the rate is 1 C. More importantly, the cathode of NiCo2S4-S composite shows the outstanding discharge capacity, owing to its good conduction, high catalytic ability and the strong confinement of polysulfides.

Proton conducting solid oxide fuel cell (H-SOFC) is an emerging energy conversion device, with lower activation energy and higher energy utilization efficiency. However, the deficiency of highly active cathode materials still remains a major challenge for the development of H-SOFC. Therefore, in this work, K2NiF4-type cathode materials Pr2−xBaxNi0.6Cu0.4O4+δ (x = 0, 0.1, 0.2, 0.3), single-phase triple-conducting (e−/O2−/H+) oxides, are prepared for intermediate temperature H-SOFCs and exhibit good oxygen reduction reaction activity. The investigation demonstrates that doping Ba into Pr2−xBaxNi0.6Cu0.4O4+δ can increase its electrochemical performance through enhancing electrical conductivity, oxygen vacancy concentration and proton conductivity. EIS tests are carried at 750 °C and the minimum polarization impedances are obtained when x = 0.2, which are 0.068 Ω·cm2 in air and 1.336 Ω·cm2 in wet argon, respectively. The peak power density of the cell with Pr1.8Ba0.2Ni0.6Cu0.4O4+δ cathode is 298 mW·cm−2 at 750 °C in air with humidified hydrogen as fuel. Based on the above results, Ba-doped Pr2−xBaxNi0.6Cu0.4O4+δ can be a good candidate material for SOFC cathode applications.

Carbon-fueled solid oxide fuel cells (CF-SOFCs) can electrochemically convert the chemical energy in carbon into electricity, which demonstrate both superior electrical efficiency and fuel utilisation compared to all other types of fuel cells. However, using solid carbon as the fuel of SOFCs also faces some challenges, the fluid mobility and reactive activity of carbon-based fuels are much lower than those of gaseous fuels. Therefore, the anode reaction kinetics plays a crucial role in determining the electrochemical performance of CF-SOFCs. Herein, the progress of various anodes in CF-SOFCs is reviewed from the perspective of material compositions, electrochemical performance and microstructures. Challenges faced in developing high performance anodes for CF-SOFCs are also discussed.

Intermediate temperature solid oxide fuel cells (IT-SOFCs) have been extensively studied due to high efficiency, cleanliness, and fuel flexibility. To develop highly active and stable IT-SOFCs for the practical application, preparing an efficient cathode is necessary to address the challenges such as poor catalytic activity and CO2 poisoning. Herein, an efficient optimized strategy for designing a high-performance cathode is demonstrated. By motivating the phase transformation of BaFeO3-δ perovskites, achieved by doping Pr at the B site, remarkably enhanced electrochemical activity and CO2 resistance are thus achieved. The appropriate content of Pr substitution at Fe sites increases the oxygen vacancy concentration of the material, promotes the reaction on the oxygen electrode, and shows excellent electrochemical performance and efficient catalytic activity. The improved reaction kinetics of the BaFe0.95Pr0.05O3-δ (BFP05) cathode is also reflected by a lower electrochemical impedance value (0.061 Ω·cm2 at 750 °C) and activation energy, which is attributed to high surface oxygen exchange and chemical bulk diffusion. The single cells with the BFP05 cathode achieve a peak power density of 798.7 mW·cm-2 at 750 °C and a stability over 50 h with no observed performance degradation in CO2-containing gas. In conclusion, these results represent a promising optimized strategy in developing electrode materials of IT-SOFCs.

The design of active cathode catalysts, with abundant active sites and outstanding catalytic activity for CO2 electroreduction, is important to promote the development of solid oxide electrolysis cells (SOECs). Herein, A-site-deficient perovskite oxide (La0.2Sr0.8)0.9Ti0.5Mn0.4Cu0.1O3-δ (LSTMC) is synthesized and studied as a promising cathode for SOECs. Cu nanoparticles can be rapidly and uniformly in situ-exsolved under reducing conditions. The heterostructure formed by the exsoluted Cu and LSTMC provides abundant active sites for the catalytic conversion of CO2 to CO. Combined with the remarkable oxygen-ion transport capacity of the LSTMC substrate, the specially designed Cu@LSTMC cathode exhibits a dramatically improved electrochemical performance. Furthermore, first-principles calculations proposed a mechanism for the adsorption and activation of CO2 by the heterostructure. Electrochemically, the Cu@LSTMC presents a high current density of 2.82 A cm-2 at 1.8 V and 800 °C, which is about 2.5 times higher than that of LSTM (1.09A cm-2).

Effective utilization of carbonaceous fuels is essential to address the economic and environmental challenges in the future. Direct carbon solid oxide fuel cells (DCSOFCs) offer a promising solution, but their performance is hindered by the sluggish anode processes and poor stability. Herein, a novel layered perovskite, (PrBa)0.95Fe1.6Ni0.2Nb0.2O5+δ (PBFNN), is developed as a highly effective anode material for DCSOFCs. FeNi3 nanoparticles on the perovskite substrate are in situ exsolved under the reduction of carbon, and the resulting alloy–perovskite interfaces can promote efficient reverse Boudouard reaction (RBR) by the optimized CO2 capture and RBR activation. Therefore, the carbon fuel can be efficiently converted into CO because of the highly active RBR on the surface of the PBFNN anode, which further promotes the electrochemical oxidation of CO, leading to enhanced electrochemical performance of the anode. An electrolyte-supported DCSOFC employing the PBFNN anode yields superior performances but using additive-free carbon fuels, and delivers a peak power density of 605.1 mW cm−2 at 800 °C and superior stability over 120 h at 750 °C. Our work highlights that PBFNN is a high-performance and robust alternative perovskite anode for DCSOFCs.

A step-wise current-limiting flash sintering process (SCFS process) was proposed to densify La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) electrolyte. Well-densified microstructures of LSGM samples were obtained at 690 °C under an electric field of 100 V cm−1. Compared with the current-limiting flash sintering process, the spike in power dissipation was avoided, the shrinkage rate of LSGM samples was moderate, and the microstructures of LSGM samples were uniform. The conductivity of LSGM samples sintered via SCFS process at 0.9 A for 30 min reached 0.072 S cm−1 at 850 °C, and this was approximately the same as the value of conventionally sintered LSGM samples at 1400 °C for 10 h. These results proved that SCFS process achieved easy controllability, and it is expected that SCFS process can be applied in industry.

In recent years, many researchers have been interested in studying direct carbon-solid oxide fuel cells (DC-SOFCs) because of their simple structure and the highly efficient method for converting t...

Direct carbon fuel cells (DCFCs) demonstrate both superior electrical efficiency and fuel utilization compared to all other types of fuel cells, and it will be the most promising carbon utilization technology if the sluggish anode reaction kinetics that derives from the use of solid fuel can be addressed. Herein, the electrode morphology and fuel particle size are comprehensively considered to fabricate an efficient DCFC anode skeleton. A honeycombed and size-matching anode architecture with dual-scale porous structure is developed by water droplet templating, which demonstrates an efficient strategy to address the challenge of poor carbon reactivity and improve the electrochemical performance of DCFCs. Single cell with this designed anode framework demonstrates excellent performance, and the maximum power density is as high as 765 mW cm

Mixed oxygen ionic and electronic conduction is a vital function for cathode materials of solid oxide fuel cells (SOFCs), ensuring high efficiency and low-temperature operation. However, Fe-based l...

Protonic ceramic fuel cells (PCFCs) are receiving increasing attention because of their high energy conversion efficiency. However, traditional mixed oxygen-ionic and electronic conductors (MOECs) ...

Proton conducting solid oxide fuel cells (H–SOFCs) with BaZr0·1Ce0·7Y0·2O3-δ as electrolyte were fabricated to couple the removal of nitrogen oxides in power generation technology. Specially, a deliberately designed cathode with the composition of La0·3Sr0·7Mn0·8Mg0·2O3−δ was prepared to realize this dual function. The results indicated that the incorporation of Mg ions in La0·3Sr0·7MnO3−δ can improve its ability to adsorb NO and the cathode activity. At 800 °C, when using the NO as oxidant, single cell with La0·3Sr0·7Mn0·8Mg0·2O3−δ cathode was able to obtain peak power density of 48 mW cm−2 and achieve the conversion of NO to N2 more than 48%. These findings suggested that power generation coupling deNO via H–SOFC is possible and La0·3Sr0·7Mn0·8Mg0·2O3−δ was a promising cathode for this application.

The development of highly efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) has great significance in various renewable energy systems. Herein, we report the rational design and synthesis of cobalt nanoparticles encapsulated in nitrogen-doped carbon nanotube-grafted carbon nanosheets (LDH-R@Co(v-Zn)-NCNTs), via the in situ growth of ZnCo bimetallic zeolitic imidazolate frameworks (ZnCo-ZIFs) on the surface of layered double hydroxides (LDHs) and their subsequent reductive calcination. The incorporation of volatile zinc spatially isolates the cobalt atoms, thus suppressing the aggregation of cobalt nanoparticles, while the use of LDHs prevents the aggregation of ZnCo-ZIFs. The optimal composite exhibits good catalytic activity toward the OER in alkaline media, with a small overpotential of 344 mV at 10 mA cm−2 and a low Tafel slope of 75 mV dec−1, values that are superior to those of commercial IrO2. The superior catalytic activity is attributed to the highly sufficient exposure of active sites and the enhanced electron conductibility of the composite. This work demonstrates an effective strategy by which to regulate a nanostructure and develop highly efficient OER catalysts.

Elevating the sluggish oxygen reduction reaction (ORR) activity of the cathode material is crucial to the development and widespread application of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a novel SOFC cathode, with superior ORR activity, is designed by incorporating F anions at O-sites of a double perovskite oxide (Sr2Fe1.5Mo0.5O6−δ, SFM). The resulting F-doped SFM cathode (Sr2Fe1.5Mo0.5O6−x−δFx, SFMF, x = 0, 0.1, 0.2 and 0.3) exhibits improved crystal structure symmetry and enhanced electrocatalytic activity for the ORR. At 800 °C, the polarization resistance of F-doped SFM is significantly decreased to 0.072 Ω cm2, which can be ascribed to the enhanced oxygen reduction capacity. Moreover, F-doping reduces the metal–oxygen bond energy and accelerates the transportation of O-ions during the electrochemical process, resulting in significantly enhanced ORR activity.

The intermediate temperature solid oxide fuel cells (IT-SOFCs) whose operating temperature ranges from 873 K to 1073 K have attracted a lot of attention in recent years because of their decreased c...

As an energy conversion device, Direct carbon solid oxide fuel cell (DC-SOFC) can efficiently convert the chemical energy contained in carbonaceous fuels into electricity. It may be an efficient and clean way to utilize carbon fuels. In this paper, (PrBa)0.95Fe1.7Ti0.2Co0.1O6-δ (PBFTC), a perovskite oxide with A-site ordered layered structure, is successfully prepared via a sol-gel method and it has been studied as the DC-SOFC anode material. Doping of Ti and the ordered layered structure make PBFTC achieve good structural stability. The phase structure of PBFTC remained unchanged after being treated in both H2 and carbon reducing atmosphere so that it can be applied in DC-SOFC anode. Using PBFTC as the anode material, a peak power density as high as 386 mW·cm−2 is achieved at 800 °C when using pure activated carbon as fuel.

Reversible solid oxide cells (RSOCs) present a conceivable potential for addressing energy storage and conversion issues through realizing efficient cycles between fuels and electricity based on the reversible operation of the fuel cell (FC) mode and electrolysis cell (EC) mode. Reliable electrode materials with high electrochemical catalytic activity and sufficient durability are imperatively desired to stretch the talents of RSOCs. Herein, oxygen vacancy engineering is successfully implemented on the Fe-based layered perovskite by introducing Zr4+, which is demonstrated to greatly improve the pristine intrinsic performance, and a novel efficient and durable oxygen electrode material is synthesized. The substitution of Zr at the Fe site of PrBaFe2O5+δ (PBF) enables enlarging the lattice free volume and generating more oxygen vacancies. Simultaneously, the target material delivers more rapid oxygen surface exchange coefficients and bulk diffusion coefficients. The performance of both the FC mode and EC mode is greatly enhanced, exhibiting an FC peak power density (PPD) of 1.26 W cm-2 and an electrolysis current density of 2.21 A cm-2 of single button cells at 700 °C, respectively. The reversible operation is carried out for 70 h under representative conditions, that is, in air and 50% H2O + 50% H2 fuel. Eventually, the optimized material (PBFZr), mixed with Gd0.1Ce0.9O2, is applied as the composite oxygen electrode for the reversible tubular cell and presents excellent performance, achieving 4W and 5.8 A at 750 °C and the corresponding PPDs of 140 and 200 mW cm-2 at 700 and 750 °C, respectively. The enhanced performance verifies that PBFZr is a promising oxygen electrode material for the tubular RSOCs.

In this study, Nb doped double perovskite oxide (Sr2Fe1.4Nb0.1Mo0.5O6-δ) is prepared and tested as symmetrical electrodes for intermediate temperature solid oxide fuel cells. X-ray diffraction demonstrates that Sr2Fe1.4Nb0.1Mo0.5O6-δ maintains more stable cubic perovskite phase structure than its raw material (Sr2Fe1.5Mo0.5O6-δ) under reducing atmosphere. X-ray photoelectron spectrometry shows that Nb doping significantly enhances bond strength of Fe O Fe(Nb) so that Fe ion maintains more stable oxidation states after reducing. At 600 °C, Nb doping also increases the conductivity from 17.62 to 27.61 cm−1 in air and from 11.11 S cm−1 to 15.86 S cm−1 in wet hydrogen (∼3% H2O). Furthermore, Sr2Fe1.4Nb0.1Mo0.5O6-δ exhibits enhanced electrochemical performances in terms of lower polarization resistance under both oxidizing and reducing atmospheres. Peak power densities of 364.93 and 531.49 mW cm−2 at 750 and 800 °C are obtained based on a single symmetrical cell with Sr2Fe1.4Nb0.1Mo0.5O6-δ electrode, which also shows excellent redox stabilities. All of these results confirm that Sr2Fe1.4Nb0.1Mo0.5O6-δ electrode has promising prospects for the symmetrical intermediate temperature solid oxide fuel cells.

FeF2-reduced graphene oxide nanocomposite is in-situ synthesized and assembled into electrode with poly (acrylic acid) binder as a novel sodium ion cathode, which exhibits greatly improved electrochemical performance. The mechanism for the improved performance of the electrode is studied by ex-situ morphology and phase analysis, before and after cycling. The results show that poly (acrylic acid) binder with high adhesion ability can stabilize the electrode structure, thus increase the utilization of active materials. The in-situ hybridization of FeF2 nanoparticles with reduced graphene oxide can confine the sizes of particles, and restrain the particles agglomeration. As a result, the electrode can attain high capacity and stability. The electrode exhibits superior electrochemical performance: high capacity of 175 mAh g−1 at 0.2 A g−1, high rate capability of 78 mAh g−1 at 10 A g−1, and good cycling stability. The results demonstrate the electrochemical performance of metal fluoride electrode can be enhanced by using highly adhesive materials as binders and the nanostructure construction.

One of the biggest challenges on the way to the commercialization of lithium-oxygen (Li-O2) batteries (LOBs) is the exploration of an air electrode with high electronic conductivity, steadily porous architecture, and high-efficiency bifunctional catalytic activity. In this study, nitrogen-doped and iridium decorated carbon spheres with hollow and hierarchical porous structure were successfully fabricated and used as excellent bifunctional electrocatalysts in alkaline aqueous environment as well as in non-aqueous LOBs. This material structure with large pore volume and high specific surface area provides sufficient room and numerous active sites for the deposition of Li2O2 product. Moreover, the in-situ nitrogen doping further enhances the electron conductivity as well as the electrocatalytic activity toward oxygen, yielding a gratifying discharge platform potential of 2.77 V, and a high discharge capacity (6849 mAh g−1). After anchoring with Ir nanoparticles, the resulting composite material presented significantly reduced charge overpotential (0.83 V) and improved reversibility. Meanwhile, owing to the synergistic effect among the porous carbon, nitrogen heteroatom, and Ir nanocrystals, the increased discharge capacity of 8239 mAh g−1 and high discharge plateau of 2.80 V were also achieved. Besides, the excellent stability of the recharged air-cathode architecture was confirmed via ex-situ scanning electron microscopy.

Protonic ceramic fuel cells (PCFCs) have interesting potential to efficiently produce electrical power from fuels in a low-temperature range (

The design of active cathode catalysts, with abundant active sites and outstanding catalytic activity for CO

Intermediate temperature solid oxide fuel cells (IT-SOFCs) have been extensively studied due to high efficiency, cleanliness, and fuel flexibility. To develop highly active and stable IT-SOFCs for the practical application, preparing an efficient cathode is necessary to address the challenges such as poor catalytic activity and CO

Mixed oxygen ionic and electronic conduction is a vital function for cathode materials of solid oxide fuel cells (SOFCs), ensuring high efficiency and low-temperature operation. However, Fe-based layered double perovskites, as a classical family of mixed oxygen ionic and electronic conducting (MIEC) oxides, are generally inactive toward the oxygen reduction reaction due to their intrinsic low electronic and oxygen-ion conductivity. Herein, Zn doping is presented as a novel pathway to improve the electrochemical performance of Fe-based layered double perovskite oxides in SOFC applications. The results demonstrate that the incorporation of Zn ions at Fe sites of the PrBaFe

In this work, we investigate a novel A-site ordered layered perovskite oxide, (PrBa)0.95Fe1.8–xCuxNb0.2O5+δ (PBFCN), as an anode material for hybrid direct carbon fuel cells (HDCFCs). We study the ...