Journal of Power Sources Advances最新文献

Herein we report on the charge storage behaviour of a non-porous planar glassy carbon electrode (GCE) in an aqueous electrolyte of 0.5 M Na2SO4 at temperatures in the range 25 °C to 50 °C. Preliminary cyclic voltammetry (CV) data indicate a decrease in electrode performance at increasing temperatures, and this was supported by detailed analysis of step potential electrochemical spectroscopy (SPECS) data. Kinetic analysis of the deconvoluted SPECS data using the Arrhenius equation has indicated that diffusional charge storage is not thermally activated, instead being possibly influenced by thermal scattering of electrolyte ions. Entropimetric analysis of the SPECS data has generated entropy and enthalpy data for charge storage in this system. These results are discussed in terms of charge storage at this interface.

The mechanical durability of our hydrocarbon polymer electrolyte membrane, poly(sulfophenylene quinquephenylene) (SPP-QP) or polyphenylene ionomer, was evaluated in wet/dry cycle tests in fuel cells according to the US-DOE protocol, where the effect of gas diffusion layers (hard or soft GDL) was investigated. The membrane exhibited mechanical failure with the hard GDL and H₂ crossover (permeation through the membrane) jumping from 0.01% to ca. 2% after 4,000 cycles. Post-test analyses indicated that the edge of the membrane under the gasket was the most damaged, where the dimensional change upon humidification/dehumidification was restricted. Use of the soft GDL significantly improved the wet/dry cycle durability of the membrane with no practical changes in the H₂ crossover, even after 30,000 cycles, due to the strong adhesion of the GDL to the catalyst layers. The mechanical durability of the SPP-QP membrane was better than that of our previous aromatic-based ionomer membrane containing ether and ketone groups in the main chain. The loss of molecular weight and the sulfonic acid groups was rather minor for the SPP-QP membrane, indicating chemical robustness of the membrane under the severe wet/dry cycle conditions.

Liquid Organic Hydrogen Carriers (LOHC) offer a promising solution for hydrogen storage in the existing infrastructure for conventional fuels. Within this framework, the isopropanol/acetone couple as a light-LOHC system is used to generate electricity in a direct isopropanol fuel cell (DIFC). This work focuses on the impact of catalyst loading, ionomer content and catalyst support on the performance of DIFCs. We achieve a performance rise from 95 mW cm^-2 to 219 mW cm^-2 under air operation by increasing the anode catalyst loading from 0.5 mg cm^-2 to 4 mg cm^-2, which can be attributed to the increased abundance of active catalyst sites with higher loadings. In contrast, we find that the cathode loading for the oxygen reduction reaction (ORR) plays a minor role in the performance of DIFCs. Therefore, the cathode loading can be minimized to decrease the total amount of platinum-group metals and, consequently, to save cost. It was also found that an ionomer content of 30% on the anode side is optimal. Additionally, different carbon supports were investigated, where advanced high surface area carbon support showed superior performance to Vulcan with an increase of 20% in power density, motivating the development of new carbon supports for DIFCs.

All-solid-state Na–S secondary batteries that use sodium and sulfur, both available in abundance, are the most attractive next-generation batteries. In this study, two types of amorphous MoS₃ (a-MoS₃) were prepared as electrode active materials for use in all-solid-state sodium secondary batteries using the thermal decomposition (TD) of (NH₄)₂MoS₄ and mechanochemical (MC) processes, denoted a-MoS₃ (TD) and a-MoS₃ (MC), respectively. X-ray diffraction, thermogravimetric-differential thermal analysis, and X-ray photoelectron spectroscopy (XPS) analyses revealed that a-MoS₃ (TD) and a-MoS₃ (MC) had different local structures. The a-MoS₃ (TD) and a-MoS₃ (MC) electrodes showed high reversible capacities of 310 mAh g⁻¹ and 260 mAh g⁻¹, respectively, for five cycles in all-solid-state sodium secondary batteries. XPS analysis of the discharge–charge products suggested that the dissociation and formation of disulfide bonds occurred during the discharge–charge reaction. The results show that a-MoS₃ is a promising active electrode material for all-solid-state sodium batteries.

Energy storage systems as lithium-ion batteries (LIBs) have become an essential part of our lives, powering on-the-go technologies we use every day. Until recently, immense attention was paid to designing and synthesizing advanced active materials for LIBs to enhance the battery characteristics. However, not the least crucial part of the battery, the current collector, was left unattended for a long time. Therefore, it is not surprising that the batteries reached their limits in power and energy densities, leaving the battery progress equal to an almost flat line. The only way to go ahead with the battery technology would be to design new architectures or to investigate new materials. Changing the battery current collector from planar to three-dimensional (3D) would offer dimensionality to the electrodes meaning short diffusion length for Li-ions, which will boost power density, more active material, and mechanical stability. Herein, in this review, various 3D architecture current collectors will be summarized, and recent advances in synthesis routes will be discussed to point out the importance of 3D structures. In addition, the correlation between the electrochemical performances of batteries and current collector architecture will be reviewed. More than 50 research publications related to the synthesis and performance of different 3D current collectors were reviewed and compared. The review results suggest that despite the outstanding performance, currently used technologies to obtain 3D current collectors make them unacceptable in the commercial sphere, and cheaper, faster and simple synthesis routes are desired to be explored.

Nickel-rich cathode active materials (CAMs) and silicon-graphite composite anodes promise substantial lithium-ion battery (LIB) performance increases over state-of-the-art technologies. In order to compete with current LIB technologies, however, they must also be producible at a cost competitive with that of their predecessors. In this paper, full pouch cells based on state-of-the-art and prospective future CAMs are modeled using both graphite and silicon-graphite composite anodes to examine each technology's performance. Current open-market material costs are then utilized to estimate the costs of producing each cell. The two are then related to determine each cell's value on a USD kWh⁻¹ basis. Future nickel-rich CAMs are shown to provide a strong performance advantage over current technologies, especially if their laboratory-scale performance can be replicated at a commercial scale. Silicon-graphite anodes likewise display performance gains, though these are shown to be highly dependent on cell chemistry and design. The collected current open-market prices of the materials needed to produce these technologies, however, are shown to be too high to result in a value improvement. Cost reductions necessary to achieve value parity with current technologies are thus calculated and possible future developments are discussed.

The simplified gravimetric intermittent titration technique (GITT) model, which was first proposed by Weppner and Huggins in 1977, remains a popular method to determine the solid-state diffusion coefficient ($D_1$) and the electrochemical kinetic rate constant ($k$). This is despite the model having been developed on the premise of a single-slab electrode and other gross simplification which are not applicable to modern-day porous battery electrodes. Recently however, more realistic and conceptually descriptive models have emerged, which make use of the increased availability of computational power. Chief among them is the P2D model developed by Newman et al., which has been validated for various porous battery electrodes. Herein, a P2D GITT model is presented and coupled with grid search optimization to determine state-of-charge (SOC) dependent $D_1$ and $k$ parameters for a sodium-ion battery (SIB) cathode. Using this approach, experimental GITT steps could be well fitted and thus validated at different SOC points. This work demonstrates the first usage of the P2D GITT model coupled with optimization as an analytical method to derive and validate physically meaningful parameters. The accurate knowledge of $D_1$ and $k$ as a function of the SOC gives further insight into the SIB intercalation dynamics and rate capability.

An accurate analysis of ion transportation in an all-solid-state battery is crucial to improve and estimate performance. For an all-solid-state battery using sulfide solid electrolytes, coupling the stress and electric field simulations is required because the battery is pressurized, this affects the void space, which then affects ion transportation. In this paper, we propose a new method to analyze the ionic conductivity in a pressurized all-solid-state battery by coupling nonlinear stress analysis and electric field analysis. The nonlinear stress analysis can estimate the stress distribution of solid electrolyte and it was found that nonlinear stress-strain characteristics that originate from the voids diminished with increased pressure. The numerical results based on a model-electrode were nearly identical to the experimental results.

A novel and commercially available electrocatalyst is characterised and used as cathode catalyst in an anion-exchange membrane fuel cell (AEMFC). The catalyst material is prepared using VariPore™ method by Pajarito Powder, LLC, and as dopants iron and nitrogen are used, making it a mesoporous transition metal-nitrogen-carbon type catalyst. The physico-chemical characterisation shows the success of doping as well as almost completely mesoporous structure (average pore size of approximately 7 nm) with high specific surface area. The initial assessment of the oxygen reduction reaction (ORR) activity by the rotating ring-disc electrode method reveals that the material exhibits a very good electrocatalytic performance in alkaline media having a half-wave potential of 0.89 V. The catalyst material is employed as an anion exchange membrane fuel cell cathode and it shows AEMFC performance as good as that of the Pt-based material. The high ORR electrocatalytic activity of this material is due to the synergy of nitrogen-moieties, namely pyrrolic-N, pyridinic-N and graphitic-N, with iron as well as the highly mesoporous nature.