• Energy Research

AbstractAluminum–metal batteries show great potential as next‐generation energy storage due to their abundant resources and intrinsic safety. However, the crucial limitations of metallic Al anodes, such as dendrite and corrosion problems in conventional aluminum–metal batteries, remain challenging and elusive. Here, we report a novel electrodeposition strategy to prepare an optimized 3D Al anode on carbon cloth with an uniform deposition morphology, low local current density, and mitigatory volume change. The symmetrical cells with the 3D Al anode show superior stable cycling (>450 h) and low‐voltage hysteresis (~170 mV) at 0.5 mA cm−2. High reversibility (~99.7%) is achieved for the Al plating/stripping. The graphite | | Al‐4/CC full batteries show a long lifespan of 800 cycles with 54 mAh g−1 capacity at a high current density of 1000 mA g−1, benefiting from the high capacitive‐controlled distribution. This study proposes a novel strategy to design 3D Al anodes for metallic‐Al‐based batteries by eliminating the problems of planar Al anodes and realizing the potential applications of aluminum–graphite batteries.

Abstract In this study, a novel interlaced microchannel with a “cold water-hot water-cold water” counterflow arrangement was designed. The influences of microchannel configurations on the thermal and hydraulic performance were studied by comparing the proposed microchannel configuration with parallel and traditional spiral configurations. The results showed that the effective heat transfer area of the interlaced microchannel was 6.4 and 8.4 times that of the parallel and spiral configurations, respectively. For interlaced microchannels, the maximum temperature difference between the cross sections was 0.07 °C, and the temperature rise along the flow direction was only 6 °C. When the Reynolds number was 492, the Nusselt number of the interlaced microchannels was 2 and 10 times that of the parallel and spiral microchannels, respectively. The heat transfer performance of interlaced microchannels was improved by 83.46% compared with that in the literature. The influence of microchannel configurations on the pressure drop and the entrance length were negligible. The interlaced microchannel exhibited its lowest thermal resistance of 0.015 °C/W and lowest entropy production of 22.6 W/ °C at a Reynolds number of 492. The heat transfer enhancement coefficient of the interlaced microchannel and parallel microchannel were 5 and 2.8 times that of the traditional spiral microchannel, respectively. The maximum heat load of loop heat pipe was enhanced by 4 times with the integration of interlaced microchannel as the condenser.

It is challenging to develop highly efficient and stable multifunctional electrocatalysts for improving the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the oxygen reduction reaction (ORR) for sustainable energy conversion and storage systems such as water-alkali electrolyzers (WAEs) and hybrid sodium-air batteries (HSABs). In this work, sub-nm Pt nanoclusters (NCs) on defective NiFe layered double hydroxide nanosheets (NixFe LDHs) are synthesized by a facile electrodeposition method. Due to the synergistic effect between Pt NCs and abundant atomic M(II) defects, along with hierarchical porous nanostructures, the Pt/NixFe LDHs catalysts exhibit superior trifunctional electrocatalytic activity and durability toward the HER/OER/ORR. A WAE fabricated with Pt/NixFe LDHs electrodes needs 1.47 V to reach a current density of 10 mA cm-2, much lower than that of the mixed 20% Pt/C and 20% Ir/C catalysts. An HSAB assembled by Pt/NixFe LDHs as a binder-free air cathode displays a high open-circuit voltage, a narrow overpotential gap, and remarkable rechargeability. This work provides a feasible strategy for constructing freestanding efficient trifunctional electrocatalysts for sustainable energy conversion and storage systems.

A consumption-free electrochemical desalination method is demonstrated to work based on a light-driven photocathode with a Pt/CdS/CZTS/Mo architecture.

Abstract To provide and improve national energy security and low-carbon green energy economy, as a government-supported research institute related to developing new and renewable energy technologies, including energy efficiency, Korea Institute of Energy Research (KIER) needs to establish a long-term strategic energy technology roadmap (ETRM) in the hydrogen economy sector for sustainable economic development. In this paper, we establish a strategic ETRM for hydrogen energy technologies in the hydrogen economy considering five criteria: economic impact (EI), commercial potential (CP), inner capacity (IC), technical spin-off (TS), and development cost (DC). As an extended research, we apply the integrated two-stage multi-criteria decision-making approach, including the hybrid fuzzy analytic hierarchy process (AHP) and data envelopment analysis (DEA) model, to assess the relative efficiency of hydrogen energy technologies in order to scientifically implement the hydrogen economy. Fuzzy AHP reflects the vagueness of human thought with interval values, and allocates the relative importance and weights of four criteria: EI, CP, IC, and TS. The DEA approach measures the relative efficiency of hydrogen energy technologies for the hydrogen economy with a ratio of outputs over inputs. The result of measuring the relative efficiency of hydrogen energy technologies focuses on 4 hydrogen technologies out of 13 hydrogen energy technologies. KIER has to focus on developing 4 strategic hydrogen energy technologies from economic view point in the first phase with limited resources. In addition, if energy policy makers consider as some candidates for strategic hydrogen technologies of the other 9 hydrogen energy technology, the performance and productivity of 9 hydrogen energy technologies should be increased and the input values of them have to be decreased. With a scientific decision-making approach, we can assess the relative efficiency of hydrogen energy technologies efficiently and allocate limited research and development (R&D) resources effectively for well-focused R&D.

Abstract To replace the traditional electric heating mode and increase methanol steam reforming reaction performance in hydrogen production, methanol catalytic combustion was proposed as heat-supply mode for methanol steam reforming microreactor. In this study, the methanol catalytic combustion microreactor and self-thermal methanol steam reforming microreactor for hydrogen production were developed. Furthermore, the catalytic combustion reaction supports with different structures were designed. It was found that the developed self-thermal methanol steam reforming microreactor had better reaction performance. Compared with A-type, the △Tmax of C-type porous reaction support was decreased by 24.4 °C under 1.3 mL/min methanol injection rate. Moreover, methanol conversion and H2 flow rate of the self-thermal methanol steam reforming microreactor with C-type porous reaction support were increased by 15.2% under 10 mL/h methanol-water mixture injection rate and 340 °C self-thermal temperature. Meanwhile, the CO selectivity was decreased by 4.1%. This work provides a new structural design of the self-thermal methanol steam reforming microreactor for hydrogen production for the fuel cell.

Abstract One-step assembled CdSe/CdS (core/shell) quantum dots (QDs) were deposited onto ZnO nanowires (NWs) and characterized for their structure, morphology and optical analyses. As deposited ZnO NWs array were wurtzite in structure. During a single hydrothermal cycle a layer of ∼4 nm CdSe/CdS QDs was formed onto ZnO NWs and overgrowth evidenced with an additional 2–5 layers due to which, (a) absorbance density, and (b) Raman Shift of 1LO mode (from 286 cm −1 to 296 cm −1 ) increased and (c) the photoluminescence intensity of the near band-edge emission peak at ∼379 nm decreased. Due to more accumulation of CdSe/CdS, photoelectrochemical cells of ZnO-based photoelectrodes designed for 1–4 cycles of CdSe/CdS onto indium-tin-oxide substrate demonstrated increasing power conversion efficiency trend from 0.18% to 1.29% whereas, for 5th cycle power conversion efficiency, due to an increased series resistance, decreased to 1.12% on account of an accumulation of several QDs.

The performance of multimetal-(Cu, Cr, Zn, Ni, and Co)-ion-exchanged zeolite A prepared from both a commercial-grade sample and one produced from coal fly ash in methane emissions abatement was evaluated in this study. The ion-exchange process was used to load the metal ions in zeolite A samples. The methane conversion efficiency by the samples was studied under various parameters including the amount of metal loading (7.3-19.4 wt%), reaction temperature (25-500 degrees C), space velocity (8400-41 900 h(-1)), and methane concentration (0.5-3.2 vol %). At 500 degrees C, the original commercial-grade zeolite A catalyzed 3% of the methane only, whereas the addition of different percentages of metals in the sample enhanced the methane conversion efficiency by 40-85%. Greater methane conversion was observed by increasing the percentage of metals added to the zeolite even though the BET surface area of the zeolite consequently decreased. Higher percentage methane conversion over the multi-ion-exchanged samples was observed at lower space velocities indicating the importance of the mass diffusion of reactants and products in the zeolite. Compared to the multi-ion-exchanged zeolite A prepared from the commercial-grade zeolite, the one produced from coal fly ash demonstrated similar performances in methane emissions abatement, showing the potential use of this low cost recycled material in gaseous pollutant treatment.