Journal of Power Sources Advances最新文献

Flow battery is a promising energy storage technology for facilitating utilization of renewable resources. While new types of flow batteries have been explored toward high energy density, hampering the power density due to high electrolyte viscosity and sluggish reaction kinetics. Discovery of an aqueous electrolyte with multi-electron transfer reaction is thus favorable for both high energy and power densities due to its multiple charge stored at the same concentration. Both criteria are crucial to improve the flexibility of cell design and widen the application potential. Herein, bismuth is pioneered as negative electrolyte (negolyte) for hybrid flow battery owing to its three-electron reaction and the significantly increased solubility in methanesulfonic acid. In conjunction with cerium electrolyte, a volumetric energy density of 90 Wh L⁻¹ is achieved and simultaneously a high power density of 295 mW cm⁻² at 90% state-of-charge is demonstrated using low-cost carbon electrode. Furthermore, a high volumetric capacity of 120 Ah L⁻¹ is reached via adopting graphite felt, which is 100% of the theoretical specific capacity of 1.5 M bismuth negolyte.

High-pressure in situ X-ray computational tomography measurements of sulfide solid electrolyte were conducted to elucidate the behavior of a single particle. Chlorine in Li₆PS₅Cl solid electrolyte was replaced by iodine to obtain high-contrast X-ray computational tomography measurements, and the behavior of a single particle under high pressure was successfully visualized. The experimental results were statistically analyzed to extract the generalized behavior of a solid electrolyte particle. The results show that pressurization increased the contact area and sphericity of a solid electrolyte particle and suppressed the voids between and within the solid electrolyte particles, thereby enhancing ionic conductivity.

Freshly assembled proton exchange fuel cells (PEMFC) require conditioning to reach maximum power density. This process may last up to tens of hours and adds to the cost of commercial fuel cell technology. We present an accelerated conditioning procedure involving starving the cathode of oxidant. In single cells, this procedure conditions a membrane electrode assembly (MEA) within 40 min, without compromising durability. The performance and durability of MEAs conditioned using this technique are compared with US Department of Energy (DOE) and European Union (EU) harmonized protocols, and to an amperometric conditioning protocol. The time to reach peak power density using cathode starvation conditioning is <10% of the time required for DOE, EU, and amperometric protocols. Conditioned MEAs were subjected to accelerated degradation by cycling the cell voltage between 0.6 V and open-circuit voltage under low relative humidity. Degradation was found to be caused by loss of electrochemical surface area of the cathode, which in turn increases the charge transfer resistance of the MEA. MEAs conditioned using cathode starvation experienced only a 15% loss in performance; in contrast to 19, 17 and 17% losses in performance caused by the DOE, EU, and amperometric protocols, respectively.

Materials with low cost, environmentally benign, high structural stability and high Mg content are of considerable interest for the construction of rechargeable Mg-ion batteries. In the present study, atomistic simulations are used to provide insights into defect and diffusion properties of garnet type Mg₃Fe₂Si₃O₁₂. Calculations reveal that the Mg–Fe anti-site defect cluster (0.44 eV/defect) is the lowest energy intrinsic defect process. Three dimensional Mg-ion migration pathway with the activation energy of 2.19 eV suggests that Mg-ion diffusion in this material is slow. Favourable isovalent dopants are found to be Mn²⁺, Ga³⁺ and Ge⁴⁺ on the Mg, Fe and Si sites respectively. While the formation of Mg interstitials required for the capacity is facilitated by Al doping on the Si site, Mg vacancies needed for the vacancy assisted Mg-ion diffusion are enhanced by Ge doping on the Fe site. The electronic structures of favourable dopants are calculated and discussed using density functional theory.

Metal halide perovskites have been recently proposed as hopeful materials for energy storage applications. Besides, the quite important electrochemical characteristics of these materials, all the perovskite-based anodes are synthesized at high temperatures (90–150 °C) and with reaction durations of the order of tens of hours. In this work, it has been particularly shown that the direct growth of all-inorganic, metal halide microcrystals free of ligands, provides high-performance and stable electrodes for Li-air batteries. We describe a very simple and rapid method to synthesize well-crystalline and ultra-stable, at both ambient and aqueous conditions, CsPbBr₃ microcubes, exhibiting prominent electrochemical performance. In particular, it is shown that during the successive scans in which the Li-ions intercalate and deintercalate, the microcubes-based anodes showed a high specific capacity of 549 mAh·g⁻¹ and operation durability up to 1500 cycles. The large interfacial area between the perovskite electroactive material and the electrolyte along with the increase of the active sites on the exposed microcubes facets favor the Li-ions intercalation. It is concluded that the anodes presented here demonstrate the best electrochemical features among the nano- and microparticulate lead halide perovskite anodes used for Li-air batteries, to date.

The growing needs for electrochemical storage systems are pushing the research community to explore alternatives to Li-ion technology. Ca-based chemistry is attracting more and more attention and expectation. However, the unsuitability of Ca metal as counter and reference electrodes limits the research activity on the topic. Herein we propose a simple electrochemical cell configuration employing activated carbon as counter and reference electrodes, which is suitable for positive electrode screening. The feasibility of this cell configuration has been confirmed by evaluating the electrochemical activity of bilayered-V₂O₅ in the Ca-ion system.

Ni/NiFe₂ dual-layer coating is fabricated on SUS 430 stainless steel by magnetron sputtering for solid oxide fuel cells (SOFCs) interconnect application. Ni/NiFe₂ coated steels are exposed to air at 800 °C for duration of up to 10 weeks in comparison with NiFe₂ coated steels. Ni/NiFe₂ coating is thermally converted to an oxide structure with an inner NiO layer and an outer NiFe₂O₄ spinel layer. NiO/NiFe₂O₄ oxide layer is more effective in blocking Cr migration and reducing oxidation rate during long-term exposure than a single NiFe₂O₄ layer converted from NiFe₂ coating. Enhancements on oxidation resistance and Cr-blocking capability are attributed to NiO layer serving as a diffusion barrier between Cr₂O₃ and NiFe₂O₄.

An in situ accelerated mechanical stress test (ΔP-AMST) that applies relative humidity (RH) cycling combined with a pressure differential (ΔP) at a high temperature is proposed to accelerate mechanical degradation in all types of reinforced membranes used in fuel cells and obtain mechanical failure in a relatively short time. For validation, ePTFE reinforced membranes are mechanically degraded by RH cycling accelerated by means of a ΔP applied from cathode to anode using a custom designed polycarbonate spacer. Reinforced membrane failure detected by ΔP loss is reached within ∼10 to 10,000 RH cycles using this method, depending on the level of applied ΔP. The ΔP-AMST protocol is hence demonstrated as a fast, economical in situ alternative compared to existing methods for evaluating the mechanical fatigue durability of advanced fuel cell membranes.

Solid oxide fuel cell systems (SOFCs) are able to convert biogas from e.g. waste water plants highly efficiently into electricity and heat. An efficiency study of industrial sized solid oxide fuel cell systems installed at a waste water treatment plant is presented. The site consist of a biogas cleaning unit, two Convion C50 SOFC systems and a heat recovery section. The electric and total efficiencies of the systems are analyzed as a function of the electric net power output. The two systems achieved consistently high electric (50–55%) and total (80–90%) efficiencies in an electric net power output range between 25 kW and 55 kW. The study also shows that the high system efficiencies are independent of the CH₄ content in the biogas. The results indicate that fuel cell systems are able to perform power modulation according to the power demand, while achieving constant high efficiencies. This is a clear benefit in comparison to micro turbines and combustion engines which are normally used for converting biogas into electricity and heat.

Mass transfer is of paramount importance for an efficient operation of liquid metal batteries. We show for the first time that electrodynamically driven flow can indeed improve mixing of liquid electrodes, and reduces concentration polarisation substantially. Simulating the discharge of a realistic Li$\left|\right|$Bi cell at 1 A/cm², the corresponding overpotential reduces by up to 62%. Moreover, the formation of intermetallic phases is delayed, which improves capacity usage. Finally, we demonstrate that vertical magnetic fields – which are originating from external sources – change the flow structure entirely, and will homogenise the positive electrode even better.