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Herein, a new type of perovskite oxide PrBaCo2O5+δ (PBCO) was synthesized and optimized by cooperating with carbon nanotubes (CNT) or carbon nanoparticles (BP2000), which was further applied into Li–O2 battery cathode as a bi-functional cathode catalyst, achieving a high discharge capacity of 15.1 mA h, the number of which is over four times than that of single PBCO or CNT cathode, and seven times than single BP2000 cathode. Furthermore, a significantly enhanced stability was achieved as sustained more than 290 cycles at a fixed capacity, the number of which exceeds most carbon-based and even other perovskite catalytic Li–O2 batteries. The charge transfer resistance (Rct) of PBCO was reduced 46.6% after cooperating with carbon materials, which is almost half of single PBCO. All these results demonstrated that the big defect of PBCO can be remedied through the surface decorating with electronic conductors, such as, carbon nano-materials, and thus resulting in a substantially enhanced cathodic performance.

Li–CO2 batteries are regarded as promising electrochemical devices to simultaneously capture CO2 and deliver electric energy. Although efforts are made to exploring reaction routes and developing e...

We proposed a prototype which can directly be powered by portable electricity for the catalytic removal of formaldehyde and CO. A compact air cleaner equipped with a conductive Ag–SnO2 catalyst and the corresponding reaction system were assembled, featuring a circuit to allow electric current to pass through the catalyst with Joule heating. The removal performances were superior to the thermal heating counterpart and the electricity was found to suppress CO poisoning, which was preliminarily attributed to the electron transport between Ag and SnO2.

Emerging graphene quantum dots (GQDs) materials have attracted worldwide attention in biological, optoelectronic and energy-related applications because of their unique features. Herein, we successfully synthesized glucose-derived GQDs through a hydrothermal process, which were further employed as an efficient cathodic catalyst in non-aqueous lithium–oxygen batteries for the first time. The GQDs possessed an average size of about 3 nm (less than 10 layers), and exhibited excellent water/ethanol solubility, which was beneficial for the impregnation process. The distinct G band in the Raman spectrum of the GQDs demonstrated their crystalline core, and their unique optical properties suggested the existence of a self-passivated layer outside their core. Furthermore, a GQDs-impregnated cathode was fabricated, which delivered an ultrahigh capacity of 68 900 mA h g−1 under a current density of 1400 mA g−1 in a 1 M LiTFSI/TEGDME electrolyte system. Moreover, the GQDs-impregnated cathode showed a quite good stability under a current density of 2000 mA g−1. Under a limited capacity of 1000 mA h g−1, it could cycle for 300 cycles without obvious decay. These results strongly suggest that the GQDs materials have good application prospect in lithium–oxygen battery systems as a superior cathodic catalyst.

In this study, we report an eco-friendly and cost-efficient cathode based on sucrose-derived active carbon (SDAC). Ni(NO3)2 is then co-impregnated into the cathode, which is designed to form a hierarchical pore architecture inside the SDAC that takes into account both the mass transport process of O2/Li+ and the accommodation of discharge product (Li2O2). Another feature of the cathode is binder-free that circumvents the aggregation of the cathodic active materials and the three-phase boundaries loss. This study is aimed to provide a feasible reference plan to give common cathode substrates an additional capability to catalyze electrochemical reactions without destroying its pristine structure and mission. A lithium–oxygen battery with the cathode delivers a high capacity of 24500 mAh g−1 at 200 mA g−1 in a 1 M LiTFSI/TEGDME electrolyte system. Moreover, the cathode exhibits a pretty good stability in a long-term round-trip test of 1000 cycles. These results suggest that the SDAC with a hierarchical pore structure has the potential to be used in next-generation lithium–oxygen batteries in a facile and cost-efficient manner, moreover, the proposed convenient method is worth applying and popularizing as it can transform even the most mundane into the spectacular.

Herein, a new type of perovskite oxide PrBaCo2O5+δ was synthesized and innovatively applied into Li-O2 battery (LOB) system as a cathode catalyst, obtained a specific capacity of over 8000 mAh g−1 and sustained more than 1000 cycles at a fixed capacity of 1000 mAh g−1, the number of which approaches and even exceeds most carbon-based Li-O2 batteries. The charge transfer resistance (Rct) was tested and resulted in 71 Ω, which was obvious lower than that of BP2000, i.e., 145 Ω. The charging voltage of the PBCO cathode was less than 4 V, resulting in substantially enhanced voltage and energy efficiencies. All these results demonstrated that PrBaCo2O5+δ can be a potential bi-functional catalyst in LOB systems.

Direct carbon solid oxide fuel cells (DC-SOFCs) with the novel perovskite La0.3Sr0.7Fe0.7Ti0.3O3–δ (LSFT) electrodes are evaluated by using biochar derived from some one-time toothpicks made of wood as fuel in different discharging modes. The constant current (CC) mode and constant resistance (CR) mode are compared with same fuel cell configuration and fuel loading. The results show that the fuel discharged in CR mode possesses larger fuel utilization (39.7%) than that in CC mode (34.5%). The biochar fuels obtained from the wood pyrolysis in Ar atmosphere for 1 h at 400 °C, 500 °C, 600 °C and 700 °C present the efficiencies of fuel utilization are 26.3%, 34.1%, 38.6% and 39.6%, respectively. A special discharging mode is employed in this paper for DC-SOFC to test cell performance and improve fuel utilization simultaneously as well.

The solid-state batteries have received widespread attention due to their excellent stability and safety, however, the low ionic conductivity and weak interface contact always restricted its performance. In this work, we propose an in situ thermally cross-linked and solidified polymer electrolyte with polyethylene glycol diacrylate (PEGDA) as scaffold in which succinonitrile (SN) and lithium bis-trifluoromethanesulfonimide (LiTFSI) were further introduced to improve the ionic conductivity. Herein, the composite gel was served as not only solid-solid interface material but also solid-state electrolyte. Different with conventional polymer gels, the solvent evaporation could not happen for this composite material during the solidification process, and therefore resulting in good interface contact without inside bubbles. We further present the investigation on transport principle of Li+ in the solid-state electrolyte and the effect of molecular chain on ionic conductivity. The conductivity of the solid-state electrolyte can reach 1.76 × 10−4 S cm−1 at room temperature without any assistance of liquid electrolytes, which is attributed to the short molecular chain of PEGDA. Electrochemical window of the solid-state electrolyte can reach 5.2 V after cross-linking treatment. And the lithium-oxygen battery using this solid-state electrolyte can stably cycle for more than 1100 cycles with a current density of 200 mA g−1 and a limit capacity of 200 mAh g−1 at room temperature.

Actually, Li-O2 batteries can be served as flexible power sources with extremely high specific energy densities to meet the rising demand for flexible and wearable electronic devices. In this work, the electrochemical performance and flexibility of a Li-O2 battery are demonstrated to be significantly enhanced by introducing a KH550–NH4Cl-treated, KOH-activated, CNTs-grafted cotton fabrics cathode. The as-fabricated flexible cathode exhibits superior electrochemical performance, including a high specific capacity (22.4 mAh cm−2 at 0.15 mA cm−2), an excellent rate capability, and a good cyclic performance for more than 250 cycles.

These years, Li O2 batteries attract wide interest because of its high theoretical energy density. However, the catalytic activity and porous structure of cathode remains a great challenge. In this work, we developed a hierarchical porous graphene foam to serve as a battery cathode, which has much richer active sites for cathodic reaction and channels for Li+ transfer and O2 diffusion. The cathode exhibits a superior specific capacity as high as 9559 mAh g−1 at 57 mA g−1 and remains a high-rate capability of 3988 mAh g−1 at an increased current density of 285 mA g−1. Benefiting from the well-designed cathode structure, the battery can be stably operated for 150 cycles with a stable voltage profile and voltage efficiency up to 65%. The well-designed graphene has a potential to be a superior free-standing cathode to other carbon-based materials due to its good combination of its hierarchical and porous structure, large surface area, abundant defects and excellent mechanical stability.

Double perovskite oxide GdBaCo2O5+δ (GBCO) is widely investigated as promising cathode for solid oxide fuel cells (SOFCs), but it remains unclear whether GBCO is suitable for application in solid oxide electrolysis cells (SOECs) anode. In this study, the effect of anodic polarization on electrochemical activity and microstructure of GBCO electrode are investigated under SOECs operation conditions. Both polarization and impedance spectra results clearly demonstrate that anodic bias treatment leads to substantial performance degradation and higher anodic current passage causes more serious activity loss. The deactivation behavior can be mainly ascribed to the formation of surface BaO precipitates in harsh oxidation atmosphere, as revealed by microstructural observation. Our study suggests that GBCO oxide is not suitable for SOECs anode application, but significant change of surface chemistry enables it a good model electrode for segregation related studies.

Here, we report a high performance biomass-derived cathode material. Compared to traditional carbon materials, biomass-derived carbon, prepared through the pyrolysis of yeast followed by activation with KOH, shows a great improvement in both catalytic activity and stability. A lithium–oxygen battery that uses the yeast-derived carbon as its cathode presents a discharge capacity of 22,100 mAh g−1 at 570 mA g−1, and sustains more than 500 cycles at a fixed capacity of 1360 mAh g−1. Moreover, the rate capability reaches as high as 3390 mA g−1, a value which is nearly an order of magnitude higher than that of conventional lithium–oxygen batteries. This work will provide a new direction for choosing cathode material for energy conversion and storage.

Sr-doped LaMnO3 (LSM)/MnO2 composites show different electrochemical performance and thus indicate that LSM has a positive effect on the capacitance of MnO2 electrode. A typical LSM(10 wt%)/MnO2 electrode presents a higher capacitance of 287.8 F g−1 in 1.0 M Na2SO4 aqueous solution, comparing to the pristine MnO2 electrode, 251.7 F g−1. More interesting, LSM can evidently improve the capacitance of MnO2 electrode under the high rate discharging condition. Compared with the pristine MnO2, LSM(10 wt%)/MnO2 shows excellent capacitance improvement of 11% at low scan rate of 2 mV s−1, 33% at intermediate scan rate of 50 mV s−1 and 47.1% at a high scan rate of 200 mV s−1, respectively. The higher the discharge rate is, the better capacitance improvement can be obtained. Moreover, LSM/MnO2 composite electrode also exhibits excellent cycle performance even after 1000 cycles. These characteristics suggest that LSM/MnO2 composites are promising electrode materials for supercapacitor with high performance.

A novel La2NiO4+δ-La3Ni2O7−δ-Ce0.55La0.45O2−δ (L2N1-L3N2-LDC) ternary composite with a weight ratio of 0.3:2.5:2.2 was prepared by a one-step co-synthesis method and employed as cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs). X-ray diffraction (XRD) profiles confirmed the successful synthesis of the composite consisted of L2N1, L3N2 and LDC phases, without any other impurity. Compared with the cathode prepared by the physical mixing method, the co-synthesized composite cathode possessed a porous microstructure with the smaller particle size and more uniform distribution of various elements. The ternary composite cathode on Sm0.2Ce0.8O1.9 (SDC) electrolyte revealed improved electrochemical performance, achieving the polarization resistance value of 0.06 Ω cm2 at 800° C in stationary air. Electrochemical impedance spectra under various oxygen partial pressures indicated the charge transfer process was the rate limiting step for oxygen reduction reaction. Furthermore, a SDC electrolyte (about 350 μm) supported single cell with L2N1-L3N2-LDC as cathode and Ni-SDC as anode demonstrated a maximum power density of 253 mW cm−2 at 800° C. These results confirmed that L2N1-L3N2-LDC ternary composite prepared by co-synthesized method is a very promising cathode material for IT-SOFCs.

In this paper, a composite cathode material consisted of 70 wt % La 2 NiO 4+δ and 30 wt % Ce 0.55 La 0.45 O 2-δ (LNO-LDC) was synthesized by co-synthesized method. The LNO-LDC composite cathode was coated on Sm 0.2 Ce 0.8 O 1.9 electrolyte and its electrochemical performance was evaluated. The co-synthesized LNO-LDC cathode showed excellent electrochemical performance, demonstrating a polarization resistance of 0.06 Ω cm 2 at 800 °C, which is significantly lower than that of physically mixed LNO-LDC composite cathode under the same operating condition. The enhanced electrochemical performance was mainly due to the reduced particle size and improved dispersion uniformity of the two phases, leading to increase of the two phase boundary (2 PB) and triple-phase boundary (3 PB). Furthermore, impedance spectra under various oxygen partial pressure determined that the rate-determining step of the co-synthesized LNO-LDC cathode is the charge transfer process. The obtained results indicated that co-synthesized method is a simple and effective method to fabricate high-performance LNO-LDC composite for intermediate temperature solid oxide fuel cells (IT-SOFCs).

Pr and Ti co-doped strontium ferrite oxide Pr0.3Sr0.7Ti0.3Fe0.7O3−δ (PSTF) has been examined as a hydrogen electrode for solid oxide electrolysis cell (SOEC). X-ray diffraction analysis shows that the PSTF material maintains phase stability during 20 hours of treatment under 5%H2/N2 conditions. An SOEC with a configuration of PSTF||SDC|YSZ||LSM-YSZ operates under various H2O concentrations and current densities. As can be observed from the AC impendence spectra of the PSTF electrode, H2O/H2 adsorption desorption or surface diffusion process is the main rate-limiting step for steam electrolysis reaction. The low-frequency arc RL obviously depends on the H2O concentration and the electrolysis current density. Steam starvation in hydrogen electrode occurs at low H2O concentration and large current density. A maximum current density of 302 mA cm−2 is obtained at an electrolysis voltage of 1.46 V in Ar/H2/60%H2O at 800 °C. The corresponding polarization resistance of PSTF electrode is as small as 0.25 Ω cm2. This study demonstrates that Pr0.3Sr0.7Ti0.3Fe0.7O3−δ is a promising hydrogen electrode material of SOEC for H2O electrolysis.

Sulfur poisoning and subsequent oxidative regeneration of La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3−δ (LSCrM) anode by pure O 2 were studied using a model solid oxide fuel cell with yttria-stabilized zirconia (YSZ) electrolyte. Utilization of H 2 fuel containing 50 ppm (v) of H 2 S was found to result in increasing polarization resistance of LSCrM anode and degradation of overall cell performance, mainly due to absorption of sulfur and formation of metal sulfides. The electrochemical performance of the cell can be recovered after first two poisoning-oxidative regeneration cycles. Oxidative treatment made it possible to remove the absorbed sulfur and to oxidize metal sulfide. Progressing microstructure changes in LSCrM anode with increasing number of alternative poisoning-regeneration cycles lead however to irreversible degradation.

(La0.75Sr0.25)0.95MnO3-δ (LSM)/MnO2 composite for supercapacitor (SC) electrode is successfully synthesized via a facile hydrothermal method. The LSM/MnO2 composite shows a flower-like structure and possesses numerous active sites and better conductivity. The as-prepared LSM/MnO2 electrode exhibits a larger specific capacitance of 437.2 F g−1, much better than that of pure MnO2. Furthermore, the composite electrode also has a higher rate capability (capacitance improvement can reach to 70%) and better cycling stability. It is believed that the present results provide an efficient electrode materials design and a novel composite for the future practical application of high-performance supercapacitor.

Due to the development needs of electric transportation as well as sustainability and physical health, lithium-oxygen batteries (LOBs) have attracted much attention with its superior theoretical specific energy density. In this study, we report our findings on a biomass material, oak-derived carbon (ODC), which is served as an efficient cathodic catalyst in LOBs system for the first time. In contrast to traditional commercial carbon catalysts, biomaterials are abundant in heteroatoms, such as N, P and S, leading to a substantial increase in electrochemical activity of cathodes. Compared with functional doped carbon, natural biomass carbon with abundant and uniform heteroatoms is easy to obtain and low in price. In this work, LOBs with the optimized ODC cathodes present the highest discharge capacity of 37000 mAh g−1, the number of which is among the best, and the batteries keep stable over 400 cycles, suggesting a great prospect.

Herein, we report a binder-free, low-cost and high performance cathode for lithium-oxygen batteries based on carbon black BP2000 decorated Ni(OH)2 nanoflakes array on Ni foam. The Ni(OH)2 nanoflakes array is fabricated by hydrothermal treatment of Ni foam in acidic medium without nickel salt. The highly organized structure of Ni(OH)2 nanoflakes array provides a more uniform distribution of catalysts and discharge products, resulting in high capacity with a relatively stable cycling voltage profile. The cathode outputs a discharge capacity as high as 12400 mAh gcarbon −1 at 160 mA gcarbon −1, which is 244% higher than that of BP2000 decorated Ni foam electrode without Ni(OH)2 nanoflakes array. The cathode can sustain 100 cycles under a capacity limitation of 320 mAh gcarbon −1 with high energy efficiency (∼67%). Our work points out the key issues and suggests an effective method for the surface modification technology.

Most non-aqueous lithium-air batteries reported in the literature are limited to operating with pure oxygen. To practically operate the battery in ambient air, understanding how the battery’s performance varies with humidity of moist air is essential. Here we study the effects of moist air on the cycling performance through operating a non-aqueous lithium-air battery with a stable anode and a nano-structured RuO2/NiO cathode at various relative humidities. Results show that in the dry air, the discharge and charge terminal voltages are around 2.51 and 4.12 V, respectively, but change to 2.79 and 3.87 V when the relative humidity reaches 84%. The energy efficiencies corresponding to the dry air and the relative humidity of 84% are 66.2% and 73.8%, respectively. The improved performance is found to be mainly due to the increased fraction of LiOH among the discharge products at high relative humidities. The discharge voltage for the formation of LiOH is higher than that for the formation of Li2O2, while the charge voltage for the decomposition of LiOH is lower than that for the decomposition of Li2O2. The results suggest that to enable a non-aqueous lithium-air battery to operate in moist air, in addition to protecting the lithium anode from water, designing a cathode with electrocatalytic activities for the decomposition of both Li2O2 and LiOH is required.

In this work, we synthesize inexpensive Vulcan XC-72 carbon supported Fe 2 O 3 nanoparticles (Fe 2 O 3 /XC) as an oxygen evolution reaction (OER) catalyst for non-aqueous lithium-oxygen batteries. It is demonstrated that the battery with the Fe 2 O 3 /XC cathode exhibits a charge voltage plateau of 4.01 V at a current density of 200 mA g −1 , which is 0.43 V lower than that with the pure XC carbon cathode. The battery also presents an outstanding rate capability, giving a charge voltage plateau of 3.99, 4.01 and 4.15 V at the current density of 100, 200 and 400 mA g −1 , respectively. Furthermore, the battery can be operated for 50 cycles at a fixed capacity of 500 mA h g −1 without obvious degradation, showing its superior cycling stability. The results suggest that the iron oxide is a cost-effective catalyst for non-aqueous lithium-oxygen batteries.

In this work, we present a simple and cost-effective method to form a dual-scale porous electrode by KOH activation of the fibers of carbon papers. The large pores (∼10 μm), formed between carbon fibers, serve as the macroscopic pathways for high electrolyte flow rates, while the small pores (∼5 nm), formed on carbon fiber surfaces, act as active sites for rapid electrochemical reactions. It is shown that the Brunauer-Emmett-Teller specific surface area of the carbon paper is increased by a factor of 16 while maintaining the same hydraulic permeability as that of the original carbon paper electrode. We then apply the dual-scale electrode to a vanadium redox flow battery (VRFB) and demonstrate an energy efficiency ranging from 82% to 88% at current densities of 200–400 mA cm−2, which is record breaking as the highest performance of VRFB in the open literature.

Novel perovskite-type La0.3Sr0.7Fe0.7Ti0.3O3 (LSFT) oxide is investigated as both anode and cathode materials in a symmetrical solid oxide electrolysis cell (SOEC) for direct electrolysis of pure CO2 at 800 °C. The current density is 521 mA cm−2 at an applied voltage of 2.0 V. The lowest polarization resistance Rp of this symmetrical SOEC is obtained at 2.0 V with a value of as low as 0.08 Ω cm2, which is much lower than that of other perovskite and Ni-cermet cathode. LSFT cathode also shows excellent durability in pure CO2 electrolysis, especially at high voltage of 2.0 V. Our results indicate that the LSFT is a promising alternative electrode material for CO2 electrolysis. Keywords: Solid oxide electrolysis cell, CO2 reduction, Symmetrical cell, Titanium-substituted lanthanum strontium ferrite

Ceramic lithium-oxygen batteries that use non-flammable and non-volatile electrolyte have the potential to store a large amount of energy in a relatively safe way. However, the performance of this type of battery has been extremely low due primarily to the large ohmic-resistance from a thick electrolyte and the limited triple-phase boundaries (TPBs) in conventional cathodes. In this work, we fabricate a seamless electrolyte-electrode structure by one-step sintering a rather thin Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte layer (20 µm thick) onto a porous LATP substrate. A hierarchical carbon is then grown in the pores of the porous LATP, uniquely forming three-dimensional pathways for the transport of lithium-ions, electrons, and oxygen throughout the entire cathode. It is found that the cathodic TPBs are 330 times larger than those of conventional solid-state lithium-oxygen batteries. As a result, the battery is capable of operating in O2 for over 1174 cycles (~150 days) and for over 450 cycles (75 days) with degradation of

In this study, a carbon–air battery based on a solid oxide fuel cell (SOFC) is demonstrated to continuously generate electric power through a direct oxidation of the biomass wastes. Due to inevitable poisoning gases such as H2S, SO2, CO2 in wastes, more stable La0.75Sr0.25Cr0.5Mn0.5O3–δ (LSCM) instead of Ni is used as the anode material for SOFC. Nano– and/or micro–particles of LSCM are prepared onto a 3D porous yttria–stabilized zirconia (YSZ) scaffold via an infiltration process, in which YSZ backbone provides rich pathways for O2− which can remedy the major defect of the LSCM, negligible O2− conductivity, and thus expanding the triple–phase boundary (TPB) to the whole anode. When falling leaves are tucked into the anode chamber, an attractive performance of 330 mW cm−2 can be reached for the battery at 800 °C, which is among the best in the published open literature. There is no visible degradation in cell performance during stability-test for 1000 min. This work provides a novel waste fed SOFC system that has a wide range of application potentials due to its unique advantages of low cost, low emission and high efficiency.

Manganese dioxide (MnO 2 ) has been recognized as an effective catalyst for the oxygen reduction and oxygen evolution reactions in non-aqueous lithium-oxygen batteries. However, a further improvement in battery performance with the MnO 2 catalyst is limited by its low electronic conductivity and catalytic activity, which strongly depend on the morphology and composition. In this work, we develop a carbon- and binder-free MnO 2-x nanosheets/stainless steel (SS) cathode via a simple and effective electrodeposition-solvothermal route. The created Mn(III) and oxygen vacancy in MnO 2-x nanosheets allows an significant increase in the electronic conductivity and catalytic activity. It is experimentally shown that the use of the present nanostructure MnO 2-x /SS cathode in a non-aqueous lithium-oxygen battery results in a rechargeable specific capacity of 7300 mAh g −1 at a current density of 200 mA g −1 , which is 39% higher than that with the MnO 2 /SS cathode. In addition, the specific capacities at 400 mA g −1 and 800 mA g −1 reach 5249 mAh g −1 and 2813 mAh g −1 , respectively, which are over 30% higher than that with the MnO 2 /SS cathode. Furthermore, the discharge/charge cycle test shows no degradation for 120 cycles. All the results show that the present nanostructure MnO 2-x /SS cathode is a promising candidate for high-performance lithium-oxygen batteries.

The use of a dense film to modify perovskite is a new approach to develop highly stable cathode for solid oxide fuel cell (SOFC). Here, we report that La0.8Sr0.2MnO3 (LSMO) surface decoration led to markedly enhanced stability and activity of conventional Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF). This novel cathode architecture has a potential to make effective use of the desirable properties of two different materials: the high oxygen ionic conductivity of a BSCF backbone and the excellent stability and high catalytic activity of an LSMO film-coating. An optimized impregnation technology was used to prepare a uniform and continuous LSMO nano-film into BSCF porous cathode.

In this study, we report a kind of highly efficient and environmentally friendly cathode based on yeast derived hydrothermal carbon. Different hydrothermal conditions are explored in order to obtain the optimal hydrothermal carbon based cathode. Then a kind of one-step synthesis method of yeast based cathode is developed to simplify the experimental scheme. The yeast derived hydrothermal carbon is rich in various atoms including N, P, S, which could provide amounts of active sites for electrochemical reactions in the cathode. Another feature of the hydrothermal carbon based cathode is the mild preparation process in which there is no need of introduction of other surfactants and catalysts. This study is aimed to provide a feasible plan to utilize the biomass derived hydrothermal carbon with unique microstructures, higher heat value, higher carbon content, lower ash content as well as green and inexpensive access. A lithium–oxygen battery with the cathode delivers a high capacity of 21,000 mAh g−1 at 185 mA g−1 in a 1 M LiTFSI/TEGDME electrolyte system. Moreover, the cathode exhibits a good oxygen reduction reaction and oxygen evolution reaction activity. These results suggest that the yeast derived hydrothermal carbon can be efficiently optimized for efficient electrocatalytic reactions in lithium–oxygen batteries.

Rechargeable nonaqueous lithium–oxygen batteries with a high theoretical capacity of 3.86×10 Ahkg¢1 and energy density of 1.14×10 Whkg¢1 have been regarded as one of the most promising power sources for next-generation electric vehicles and portable devices. However, the system is complex and certain issues need to be addressed before this technology can be brought into practical use. The system suffers from many problems such as low practical capacity, low energy efficiency, and short cycle life, all of which are highly dependent on the surface and structural properties of the cathode. Efforts have been made to optimize catalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) and the design of porous electrodes that can enhance the transport of oxygen, lithium ions, and electrons. For conventional lithium–oxygen batteries, carbon materials have been applied widely as catalysts or supports in air cathodes because of their comparably simple preparation method, large specific surface area, appropriate pore size and volume, good reaction activities, and economic merits. With these benefits, carbon materials exhibit a good discharge performance in nonaqueous lithium–oxygen batteries. For example, hierarchical micron-sized mesoporous/macroporous graphene has been used as a cathode material in nonaqueous lithium–oxygen batteries and delivered an excellent specific discharge capacity of 13700 mAhg¢1.[5] In addition, many other carbon-based materials have been used for cathodes, which include carbon powder, carbon nanotubes, and ordered carbons. However, recent detailed studies of nonaqueous lithium–oxygen batteries suggested the serious instability issue of carbon-based materials: carbon can react with the discharge product Li2O2, [9] promote electrolyte decomposition during discharge–charge cycles, and even decompose at charge voltages higher than 3.5 V. This instability will lead to the formation of the irreversible product lithium carbonate (Li2CO3) on the electrode surface. This product is an insulator and will increase the electron transport resistance to lead to a deterioration of the round-trip efficiency and a shorter cycle life. Therefore, carbon materials are assessed to be unfavorable for long-term operation in nonaqueous lithium–oxygen batteries. In contrast, noncarbon materials can fundamentally avoid the formation of Li2CO3 on the product–electrode interface. As a result, the exploration of a suitable alternative non-carbon cathode is important to develop a lithium–oxygen battery with a long cycle life. Recent research has reported on numerous non-carbon cathodes for nonaqueous lithium–oxygen batteries. For example, Ni-supported cathodes were developed with directly grown hierarchical porous Co3O4 films, [13] vertically grown Co3O4 nanowire (NW) arrays, [14] tunable nanoarchitectures of Co3O4, [15] and porous noble metals. The application of these cathodes was reported to reduce overvoltage and improve stability caused by the suppression of the decomposition caused by carbon electrodes. In addition, other kinds of metal oxides and metal carbides have also been used to fabricate non-carbon cathodes. Conventional non-carbon electrodes are typically formed by coating catalyst materials onto a substrate/current collector, which decreases the practical gravimetric specific capacity caused by the added weight of substrate/current collecThe development of non-carbon electrodes for nonaqueous lithium–oxygen batteries has become a recent focus as carbon electrodes were found to be unstable. Conventional non-carbon electrodes are typically formed with a substrate/ current collector, which will decrease the practical capacity. Here, we propose an integrated porous electrode made of LaNiO3 that does not require a substrate/current collector. The porous structure allows the formation of nanosized pores on the walls of microsized pores, which facilitates the transport of both oxygen and lithium ions. Importantly, all the surfaces of the porous structure are catalytically active for electrochemical reactions. Experimental results show that the adoption of the electrode in the battery enables a capacity of 1.064 mAhcm¢2 at a current density of 0.05 mAcm¢2. Furthermore, it is demonstrated that the battery can be cycled for at least 25 cycles at a fixed capacity of 0.3 mAhcm¢2, and the electrode shows no degradation after the cycles.

In this study, comparison experiments are conducted based on yttria-stabilized zirconia (YSZ) electrolyte supported single solid oxide fuel cells (SOFCs) with pure La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3−δ (LSCrM) or Ni/CeO 2 impregnated LSCrM anodes. The single cells are tested in dry H 2 and H 2 /H 2 S (50 ppm) mixture, respectively. Compared with the pure LSCrM anode, the cell with Ni/CeO 2 impregnated LSCrM presents a significant performance improvement when the pure H 2 is fueled to the anode, and shows a good stability during a constant-current discharge testing (398 mA cm −2 ). When the fuel is switched to H 2 /H 2 S mixture, the cell with Ni/CeO 2 impregnated LSCrM anode still shows a remarkable constant-current discharge (120 mA cm −2 ) performance compared with pure LSCrM anode. The Ni/CeO 2 impregnation can improve the electrochemical performance of the LSCrM anode without any sacrifice of sulfur tolerance ability. The Ni/CeO 2 impregnated LSCrM might be a potential anode material for solid oxide fuel cell operating in sulfur-containing fuels. The XRD and XPS results demonstrate that the anode poisoning product is composed of adsorbed sulfur, metal sulfides and sulfate radical. The mass spectrum result confirms that the poisoning mechanism involves the reaction of sulfur with anode rather than the direct reaction between H 2 S gas and anode.

YSZ (Y2O3-stabilized ZrO2)/SDC (Sm-doped CeO2) bilayer electrolyte film was successfully fabricated on NiO/YSZ anode substrate using stepwise sintering processing by screen-printing technique. OCVs (open-circuit voltages) of 1.06 V, 1.05 V and 0.88 V were achieved at 750 °C for single cells with bilayer electrolyte of 12 μm-SDC/8 μm-YSZ, 12 μm-SDC/5 μm-YSZ, and 12 μm-SDC/2 μm-YSZ, respectively. Interdiffusion of ions at YSZ/SDC interface and formation of YSZ–SDC solid solution after sintering at 1400 °C for 2 h was investigated. The EDX result suggested that the region for the interdiffusion in a YSZ/SDC bilayer structure was 2.0 μm from the YSZ/SDC interface into the YSZ layer for Sm and Ce, and 0.5 μm into the SDC layer for Zr and Y. The YSZ–SDC solid solution exhibited a low electrical conductivity, which negatively affected the performance of single cell. After two thermal cycles, the maximum power density of the single cell exhibited a significant decrease. The destruction of YSZ/SDC bilayer electrolyte structure was not observed during the thermal cycles.

Most researchers usually adopt laboratory experimental methods when studying the effects of water level variations on the concentrations of pollutants. In this study, the data from routine monitoring sites in the city of Luoyang, China, are collected and analyzed to verify the results of previous laboratory experiments and to examine whether variations in the water level affect the concentration of pollutants in different locations, particularly that of nitrates. Statistical studies conducted between 2007 and 2011 show a significant variation in the groundwater depth in the Luoyang area. This depth variation clearly affected the groundwater environment in the soil system. This study uses field data to investigate the effects of water table fluctuation on the nitrate content of groundwater. Hydrogeological information and land management data are collected from five monitoring points in Luoyang. The significance of and correlation between the environmental indicators of groundwater depth and soil–water systems are then analyzed using SPSS and Origin software. The results show that the redox potential (E h) and nitrate nitrogen content are strongly correlated with groundwater depth. Significantly negative correlations were found between nitrate nitrogen and ammonium nitrogen concentration, between E hand ammonium nitrogen concentration, and between pH and nitrate nitrogen concentration. These results indicate that water table fluctuation affects the soil–water physicochemical properties and further exerts a significant effect on nitrate movement across soil sola.

A high internal resistance and limited triple-phase boundaries are two critical issues that limit the performance of conventional solid-state Li–O2 batteries. In this work, we propose and fabricate a novel solid-state Li–O2 battery with an integrated electrolyte and cathode structure. This design allows a thin electrolyte layer (about 10% of that in conventional batteries) and a highly porous cathode (78% in porosity), both of which contribute to a significant reduction in the internal resistance, while increasing triple-phase boundaries. As a result, the battery outputs a discharge capacity as high as 14 200 mA h gcarbon−1 at 0.15 mA cm−2, and can sustain 100 cycles at a fixed capacity of 1000 mA h gcarbon−1. The novel integrated electrolyte and cathode structure represents a significant step toward the advancement of Li–O2 batteries.

In this paper, the surface properties of the (001) surface in PrMnO3 are investigated using the projector augmented plane wave (PAW) methods within the spin-polarization generalized gradient approximation (GGA+U), where U is on-site Coulomb interaction correction. The result of the total density of states shows a half-metallic ground state for PrMnO3 in GGA+U treatment. The optimized structure parameters of both cubic and orthorhombic bulk phases are obtained. The electronic properties of the cubic PrMnO3 (001) surface with PrO- and MnO2-terminations are discussed. Based on the results of the calculated surface energies, we predict the surface energies of three low-index surfaces follows the sequence of (001)

(1− x wt%) La 0.6 PrSr 0.4 NiO 4 – ( x wt%) Ce 0.8 Pr 0.2 O 2 ( x = 0, 10, 20, 30, 40, 50), abbreviated as LPSN- x CPO, were prepared and used as composite cathode for intermediate temperature solid oxide fuel cell (IT-SOFC). XRD result suggested that no chemical reaction occurred between LPSN and CPO after sintering at 1200 °C for 4 h. Electrical conductivity of LPSN- x CPO decreased with x . LPSN-40CPO exhibited the best performance on cathode impedance spectra under open-circuit condition. At 700 °C, Exchange current density of LPSN-40CPO and LPSN was 50.1 and 15.8 mA cm −2 , respectively, and the polarization resistance R P of LPSN-40CPO was 0.22 Ω cm 2 , which is about one-eighth of that of LPSN. The OCV of the cell with LPSN-40CPO as cathode was about 0.78 V, and the maximum of power density was about 88 mW cm −2 . LPSN-40CPO can be a promise candidate for cathode in IT-SOFC.