Energy advances最新文献

This study investigates the effects of crosslinking strategies and KOH activation on the multifaceted characteristics of quaternized poly(vinyl alcohol) (QPVA) membranes for anion exchange membrane (AEM) applications. In situ and combined in situ/ex situ crosslinking with glutaraldehyde were evaluated at 5 M, 6 M, and 8 M KOH concentrations. Multifaceted characteristics on the membranes including ionic conductivity, swelling degree, thermal and oxidative stability are studied. Four types of membranes: M1 (in situ crosslinked, heated), M2 (in situ crosslinked, no heating), M1 2x (in situ, heated and ex situ crosslinked), and M2 2x (in situ, no heating and ex situ crosslinked) were synthesized. The M1 5 M KOH membrane (in situ crosslinked, heated activation) demonstrated the highest ionic conductivity (40.93 mS cm⁻¹ before equilibrium, 33.41 mS cm⁻¹ after equilibrium) and moderate oxidative stability (81.10%). Combined crosslinking and higher activation temperatures improved the membrane stability and mechanical properties but reduced the oxidative stability owing to potential alkaline attack on glutaraldehyde crosslinked groups. Oxidative stability is critical for AEMs because they are exposed to reactive oxygen species (ROS) generated during fuel cell operation or electrolysis. Poor oxidative stability can lead to degradation of the membrane, reducing its lifespan and overall performance in these applications. The novelty of this work lies in the dual crosslinking strategy, which significantly enhances the mechanical and thermal properties of QPVA membranes, while also highlighting the impact of KOH activation on crystallinity and ion transport. This study emphasizes the importance of optimizing crosslinking and activation conditions to develop high-performance QPVA membranes for energy conversion and storage applications such as fuel cells and electrolyzers.

Thorough accounting of the climate change impacts of natural gas is crucial to guide the energy transition towards climate change mitigation, as even decarbonization roadmaps project continued natural gas use into the future. The climate change impacts of natural gas extraction have not previously been assessed at the well pad level, accounting for a multitude of geospatial differences between individual pads. Well pads constructed across a varied landscape lead to a range of well pad areas, earth flattening needs, well pad lifetimes, total gas production, and direct land use change (DLUC) effects such as loss of original biomass, soil organic carbon loss, change in net primary productivity, and altering the surface albedo of the site. Using existing well pad data, machine learning techniques, and satellite imagery, the spatial extents of thousands of well pads in New Mexico were delineated for site-specific data collection. A parametric life cycle assessment (LCA) model of natural gas-producing well pads was developed to integrate geospatial differences and DLUC effects, yielding scenario analysis results for each identified well pad. The DLUC effects contributed a median of 14.4% and a maximum of 59.0% to natural gas extraction carbon footprints. The use of well pad-level data revealed that the carbon footprint of natural gas extraction ranges across orders of magnitude, from 0.016 to 46.4 g CO₂eq per MJ. The results highlight the need to quantify the climate change impacts of establishing a well pad and extracting natural gas case-by-case, with geographically specific data, to guide new installations towards lower emissions.

The annealing conditions of the layer-exchange synthesis of multilayer graphene significantly affected its crystallinity and lithium-ion battery anode properties. We demonstrated excellent capacity retention and fast charge–discharge properties in multilayer graphene synthesized at low temperatures (400 °C). These results could contribute to the realization of flexible thin-film batteries.

Lithium-ion batteries (LIBs) are essential for energising portable devices, electric cars, and energy storage systems. Graphite is a frequently utilised anode material; nonetheless, the continual formation of a solid electrolyte interface (SEI) during cycling results in capacity degradation owing to electrolyte depletion. This study tackles this issue by employing alumina coatings on graphite electrodes via the spray coating technique, which is cost-effective and scalable. Electrodes with different alumina concentrations (1 wt%, 4 wt%, and 7 wt%) were assessed for electrochemical performance. The 1 wt% alumina-coated electrode demonstrated enhanced cycling stability, with 94.97% capacity retention after 100 cycles, in contrast to 91.74% for the uncoated graphite. The Al₂O₃ coating functions as a preformed SEI, diminishing electrolyte decomposition and improving the cycling performance and rate capability of electrodes, particularly at elevated C-rates. This research illustrates that using spray-coated alumina is an effective technique for enhancing the durability and performance of graphite anodes in lithium-ion batteries, with the potential for extensive applications in energy storage systems.

Green hydrogen production has been a particular focus in recent times for implementing sustainable fuels in the future energy economy. One of the most effective ways to produce clean and green hydrogen is electrocatalytic overall water splitting. Various researchers with their persistent explorations have made this topic, the research hotspot in understanding the catalysis mechanism and developing new novel materials. As the hydrogen evolution reaction (HER) kinetically limits the overall water splitting reaction, this work demonstrates the L-cysteine assisted synthesis of millerite nickel sulfide dispersed as particles on nickel foam (NS/NF) by a simple one-step hydrothermal process as a self-supported working electrode. The controlled phase of NiS is confirmed by XRD and TEM analysis and the size and morphology of the catalyst are characterised by SEM analysis. XAS analysis further explores the bulk structure and chemical coordination within the crystal system according to the XANES and EXAFS findings. The HER performance of the NS/NF catalyst exhibits superior activity to bare NF, requiring an overpotential of 140 mV to deliver a current density of −10 mA cm⁻² with a Tafel slope of 112.3 mV dec⁻¹. The catalyst demonstrated excellent durability for 50 h with further electro-activation of NS/NF under reduction conditions. In a two-electrode system, NS/NF||RuO₂ required only 1.79 V as the overall cell voltage to generate a current density of 10 mA cm⁻². This study illustrates a simple and facile route for NiS synthesis with extendable electrochemical surface area (ECSA), demonstrating superior HER activity over time, under alkaline conditions.

Composite solid-state electrolytes (CSEs) with multiple phases offer greater flexibility to customize and combine the advantages of single-phase electrolytes, making them promising candidates for commercial all-solid-state batteries (ASSBs). Based on existing investigations, this review provides a comprehensive overview of the recent progress in CSEs. First, we introduce the historical development of solid-state ionic conductors, and then summarize the fundamentals including key materials and mechanisms of lithium-ion transport. Three main types of advanced structures for CSEs are classified and highlighted according to the recent progress, namely composite solid electrolytes with passive fillers, composite solid electrolytes with active fillers, and 3D framework composite solid electrolytes. Finally, the challenges and perspectives of the composite solid-state electrolytes are discussed.

Hydrogen is emerging as an immense source of energy having the potential to at least partly replace fossil fuels. It is an abundant element on earth, but does not mainly exist in free form. Hydrogen can be produced through different technologies and feedstocks, and based on these, it can be categorized into colors with different environmental impacts. This work aimed to review the environmental impacts of the production of gray (from natural gas without carbon capture and storage), brown (from coal gasification), blue (from fossil fuels with carbon capture and storage), green (from renewable energy or biological process), and turquoise (pyrolysis of natural gas) hydrogen and to identify sustainable hydrogen production pathways that minimize environmental impacts. Global warming, acidification, eutrophication, and resource depletion were considered as indicators to assess the environmental impacts. The results showed that brown hydrogen produced via coal gasification had the highest global warming, acidification, and resource depletion impacts among all the options considered. On the other hand, green hydrogen from electrolysis through wind energy had the lowest environmental impacts. However, adopting these hydrogen colors presents different challenges and opportunities. Success depends on effective policy frameworks, international cooperation, and technological readiness to ensure positive contributions to global sustainability goals.

Redox flow batteries (RFBs) fulfill the requirements for long-duration energy storage (LDES), and the use of bromine as a catholyte has garnered substantial interest due to its high availability and low cost. However, at high states of charge, the vapor pressure of bromine presents significant safety concerns within the catholyte tank, while polybromide species have been shown to corrode the metals present in the stack. Traditionally, soluble bromine complexing agents (BCAs) have been employed to mitigate the concentration of free bromine, providing some improvement in safety; however, this has often resulted in significant reductions in power density and durability. In this study, we present the development of a solid BCA incorporated into the catholyte tank of a hydrogen-bromine RFB (HBRFB). The long-term separation of the bromine-rich solid phase from the flowing liquid phases enables sustained high performance for over 250 cycles. The effective complexing-dissociating equilibrium within the electrolyte tank ensures adequate bromine concentration for operation at high current densities. This advancement significantly enhances the viability of bromine-based RFB technology as a dependable solution for long-duration energy storage.

Degradation of low cobalt lithium-ion cathodes was tested using a full factorial combination of upper cut-off voltage (4.0 V and 4.3 V vs. Li/Li⁺) and operating temperature (25 °C and 60 °C). Half-cell batteries were analyzed with electrochemical and microstructural characterization methods. Electrochemical performance was assessed with galvanostatic cycling, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) supported by distribution of relaxation times (DRT) analysis. Electrode microstructure was characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray absorption near edge structure (XANES) imaging. Higher cut-off voltage cycling shows presence of NiO_x formation, a low diffusivity rock-salt phase, in both CV and XRD data. XRD patterns confirmed that the rock-salt phase was beginning to form at the low cut-off voltage at high temperature, but in much lower intensity than at the high cut-off voltage. Higher temperature accelerates degradation processes at both voltages. Degradation factors at high temperature include NiO_x formation, cathode material dissolution, and electrolyte decomposition. SEM analysis suggests that supporting phases may isolate and disconnect active material particles reducing capacity retention and battery life cycle. DRT analysis and XANES imaging show that both high temperature samples revealed a NiO_x phase based on an increased diffusive impedance and a visible shift in the XANES spectra. The low cut-off voltage, high temperature sample showed a split peak and shift to lower energies indicating early formation of the NiO_x phase. The diffusive impedance, which hinders intercalation and deintercalation, is driven by the formation of the NiO_x phase. While primarily driven by cut-off voltage, elevated temperature also contributes to this degradation mechanism.

This review gives an overview of the application of inorganic nanoparticles in the proton exchange membrane (PEM) of direct methanol fuel cells (DMFCs). The effects of the polymer membrane's physical and chemical characteristics after adding nanoparticles are covered. The article also covers how composite membranes can replace expensive, high-methanol-permeable, low chemically stable, and poor-conductive Nafion membranes at high temperatures. The different types of nanomaterials including solid, hollow, one-dimensional-(1D), two-dimensional-(2D) and three-dimensional-(3D) nanomaterials including clay-based composite membranes are discussed. Along with different types of nanoparticle composite membranes, different methods of making membranes such as dip coating, composite membranes and non-woven mats are also included in the article. The research shows that direct inclusion of the nanoparticles in the polymer as well as solution gel techniques require a precise ratio of the polymer and particles, blending time and a controlled drying temperature. The strong interactions of inorganic nanoparticles with polymers not only tune the pore structure of the proton exchange membrane for promoting Grotthuss and vehicular mechanisms but also create a link to hydrophilic functional groups that promote the further refining of these nanoparticles. The tortuous and non-swelled paths created with the inclusion of nanoparticles in the membrane minimize the methanol permeability while maintaining high proton conductivity. This paper also discusses the advancements in inorganic nanoparticle-modified membranes, their application and future improvements for their better application in the membrane of DMFCs.