Energy advances最新文献

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.

This work utilizes a novel approach leveraging the machine learning (ML) technique to predict the electrochemical supercapacitor performance of graphene oxide nano-rings (GONs) as electrode nanomaterials. Initially, the experimental procedure was carried out to synthesize GO via a modified Hummers method, followed by GONs preparation using the water-in-oil (W/O) emulsion technique. High-resolution transmission electron microscopy (HRTEM) analysis reveals the formation of a typical two-dimensional GO nanosheet and multilayer-GO nano-rings. The X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis results show that the GONs possess similar structural and surface chemistry properties as of GO, with a slight reduction in oxygenous functionalities, enhancing the capacitive behaviours through facile electron migration at the electrode surface. The electrochemical assessment of GO and GONs samples indicates outstanding specific capacitances of 164 F g⁻¹ and 294 F g⁻¹ at 1 mV s⁻¹, showcasing capacitive retention of up to 63% and 60% after 2500 cycles. In addition, four different machine learning models were tested to estimate the role of electrochemical parameters in determining the specific capacitance of GONs.

Formamidinium lead iodide (FAPbI₃) is a metal halide perovskite composition that exhibits improved thermal stability and a more favorable band gap compared to the archetypical methylammonium lead iodide (MAPbI₃). However, the photoactive α-phase is not thermodynamically stable at operating temperatures, which is a challenge that must be overcome for the viability of FAPbI₃-based photovoltaics. This study explores the use of the ammonium acid additives 5-ammonium valeric acid iodide (5-AVAI) and 5-ammonium valeric acid chloride (5-AVACl), to stabilize the α-phase of FAPbI₃. While both additives stabilize the photoactive α-phase and suppress the formation of the photoinactive δ-phase, increase grain size, reduce non-radiative recombination, and improve carrier lifetimes, the addition of 5-AVACl results in superior performance. The improvements with 5-AVACl added are possibly due to its unique ability to initiate formation of the α-phase of FAPbI₃ prior to annealing. DFT calculations also show that the growth of moisture-stable (111) facets is more favorable with the addition of 5-AVACl. These property improvements result in a significant increase in the power conversion efficiency of solar cells, from 9.75 ± 0.61% for devices with pristine FAPbI₃ to 13.50 ± 0.81% for devices incorporating 1 mol% 5-AVACl.

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial reactions in energy storage. However, the sluggish rate of these oxidation electrode reactions and the strong dependence of these technologies on precious metal-based electrocatalysts has greatly restricted further progress. In response to this challenge, researchers have widely investigated the preparation of high-performance ORR and OER electrocatalysts using non-precious metals, reporting substantial advancements in the last ten years. This article provides a concise overview of the latest advancements in oxygen electrocatalysts that are not based on precious metals. The review focuses on the benefits and drawbacks of carbon materials, transition metal compounds, and their composite structures. Moreover, the inherent sources of activity in these materials, techniques for enhancing the density and usage of active sites, and novel design approaches and regulation methods rooted in response mechanisms are examined. Then, a statistical examination of documented bifunctional electrocatalysts is carried out to reveal the correlation between composition, structure, and performance. This report provides a comprehensive analysis of catalyst preparation, element selection, and future directions, delivering significant insights to guide future research endeavors.

Lithium–sulfur batteries (LSBs) offer a distinctive advantage over traditional Li-ion batteries with a higher theoretical capacity (1675 mA h g⁻¹) and energy density (2600 W h kg⁻¹). This study focuses on an inexpensive graphite recycled from the spent LIBs as a promising sulfur host for developing sustainable LSBs. A recycled reduced graphene oxide–sulfur (RRGO-S) composite was cast onto a 3D-carbon fiber (CF) electrode (RRGO-S@CF). The flexible and lightweight RRGO-S@CF electrodes at 500 mA g⁻¹ delivered an initial discharge capacity of 552 mA h g⁻¹, and there was no capacity loss in its initial five cycles, maintaining a stable capacity of 390 mA h g⁻¹ till 300 cycles with 73% capacity retention. At a higher current density of 1.675 A g⁻¹, it delivered an improved capacity of 417 mA h g⁻¹. The enhanced electrochemical performance was due to the favorable interaction between the RRGO and lithium polysulfides, reducing the active material loss and polysulfide dissolution. The 3D-CF and RRGO offer a conductive network and Li-ion transport with electrolyte wettability, thereby improving the sulfur utilization and overall electrochemical performance in LSBs. This approach demonstrates the construction of recycled materials from the spent LIBs as an inexpensive source to meet the growing energy demand in the practical development of LSBs.

The manufacturing of battery electrodes is a critical research area driven by the increasing demand for electrification in transportation. This process involves complex stages during which advanced metrology can be used to enhance performance and minimize waste. A key metrological aspect is the rheology of the electrode slurry which can give a wealth of information about the underlying microstructure and the composite slurry materials' chemical and physical properties. Despite the importance, extensive characterization and a comprehensive understanding of the relationships between rheology, microstructure, and material properties are still lacking. This work bridges academic and industrial perspectives, evaluating current advancements in characterisation. It emphasizes the role of formulation and mixing in determining the slurry's behaviour and structural properties. The study concludes with recommendations to improve measurement techniques and interpret slurry properties, aiming to optimize the manufacturing process and enhance the performance of battery electrodes.

Electrochemical energy storage devices, especially supercapacitors, require electrode materials with high specific capacitance, excellent stability, and efficient charge transfer kinetics. This study presents LaMnO₃(LMO)–Co₃O₄ composites as advanced electrode materials designed to enhance specific capacitance for electrochemical applications. The xLMO–(100% − x) Co₃O₄ composites (with wt% x values of 100%, 90%, 70%, 50%, and 0%) were synthesized using an auto-combustion method followed by calcination at 900 °C. X-ray diffraction analysis confirmed the presence of the individual compounds in the intended ratios. N₂ adsorption/desorption measurements revealed that the LMO–Co₃O₄ composites have a mesoporous structure with a high surface area, with the LMO–Co₃O₄ (70%:30%) composites achieving the highest specific surface area of 6.78 m² g⁻¹. The electrochemical performance of these composites was evaluated using cyclic voltammetry, charge–discharge, and electrochemical impedance spectroscopy in a three-electrode system with a 1 M KOH electrolyte. The battery-type LMO–Co₃O₄ (70%:30%) composites exhibited outstanding electrochemical performance, showing a specific capacitance of 1614 F g⁻¹ at a scan rate of 1 mV s⁻¹ and 660 F g⁻¹ at a current density of 0.5 A g⁻¹, along with energy and power densities of 33 W h kg⁻¹ and 203 W kg⁻¹, respectively. This hybridization approach leverages the strengths of each material to enhance overall electrochemical performance.

Greenhouse structures offer the ability to control the microclimate, enabling year-round crop cultivation and precision agriculture techniques. To maintain optimal crop growth conditions, substantial energy is required to heat, light, irrigate, and ventilate the interior greenhouse environment. The term Agrivoltaics is coined from integrating agricultural land management with renewable solar energy systems. Most agrivoltaic research applications have focused on studying opaque silicon photovoltaics, with limited exploration of novel semitransparent photovoltaics such as organic or perovskite devices. By incorporating semitransparent photovoltaic systems onto greenhouse rooftops, farms can partially generate electricity from solar energy while utilizing the remaining rooftop light transmission to nurture greenhouse plant growth below. This review explores the principles and properties of semitransparent organic and perovskite photovoltaic technologies and their potential benefits for greenhouse applications. Additionally, we discuss practical case studies to illustrate their integration and efficacy in agrivoltaic systems. We also address key metrics such as average visible transmittance, average photosynthetic transmittance, light utilization efficiency, power conversion efficiency, and their impact on greenhouse energy production. We conclude with an analysis of device challenges, including stability and toxicity issues, limited experimental results of semitransparent photovoltaics in current greenhouse agrivoltaics, and the prospects for integrating semitransparent organic photovoltaics and semitransparent perovskite photovoltaics into agrivoltaic systems.

Understanding the impact of different compositions of nanocomposites synthesized via in situ incorporation of different ratios of carbon with metal oxides is an important factor for designing efficient electrode materials for high-performance supercapacitors. Here, a series of nanomaterials, NiMoO₄, carbonaceous nanospheres (CNSs), and NiMoO₄/C nanocomposites (NiMoO₄/C (Dx), where, x = 10, 25, 50, and 75 represents the molar ratio of dextrose (D) to Ni²⁺), have been synthesized via an in situ hydrothermal method. The structural and surface analysis revealed the efficient integration of NiMoO₄ and carbon in the NiMoO₄/C (D50) nanocomposite, consisting of 71.1% NiMoO₄ and 28.9% carbon components. The nanocomposite features a graphitic carbon sheet-like structure embedded with NiMoO₄ nanorods, showing increased defects with higher carbon content and enhanced surface area with larger mesoporosity. In three-electrode supercapacitor studies for these electrode materials using 3 M KOH as the electrolyte, the NiMoO₄/C (D50)-based electrode delivered superior specific capacitance (940 F g⁻¹) at a current density of 1 A g⁻¹ compared to bare NiMoO₄ (520 F g⁻¹), CNS (75 F g⁻¹) and NiMoO₄/C (D10, D25 and D75) nanocomposites (436–583 F g⁻¹), with 71% capacity retention up to 5000 cycles. Furthermore, for the fabricated NiMoO₄/C (D50)-based two-electrode supercapacitors at 1 A g⁻¹ using 3 M KOH, the symmetric configuration delivered a doubled specific capacitance (83 F g⁻¹), while the asymmetric configuration led to a doubled performance in both energy density (14.2 W h kg⁻¹) and power density (444 W kg⁻¹), in comparison to each other. The enhanced supercapacitor performance of NiMoO₄/C (D50) can be attributed to the synergistic effect between carbon and NiMoO₄ in the optimized nanocomposites, which improves the electrolyte-philicity by altering the surface composition and properties, leading to more electroactive sites and increased charge storage capacity. Thus, designing new electrode materials via in situ hydrothermal synthesis of different metal oxide/C nanocomposites with optimal composition and choosing different carbon source materials will deliver high-performance supercapacitors in the near future.