Energy advances最新文献

The potential use of several ecofriendly nitrogen-doped 2D graphene-like derivatives (N-2D GDs) with various graphitic structural features as electrode materials for symmetric 2-electrode supercapacitor devices was explored. The N-2D GDs were synthesized via a novel, facile, ecofriendly, economic and scalable technique. The synthesis technique is simply a single-step hydrothermal treatment of glucose using traces of cetyltrimethylammonium bromide (CTAB) and ammonia as structure-directing agents. Graphitic structural characteristics were controlled by manipulating hydrothermal process temperature and CTAB dose. Electrochemical energy storage performance was found to be strongly dependent on the oxidation level, doped-N content and configuration, density of graphitic surface-capping by CTAB, morphological architecture and graphitic structural order of N-2D GD-based electrodes. Interestingly, such graphitic structural parameters influenced overall charge-storage capacitance through EDLC and pseudocapacitance mechanisms in a competitive manner. An N-2D GD sample synthesized at a hydrothermal temperature of 270 °C and CTAB/glucose molar ratio of 1/6 (NG-HCD270) exhibited the best energy storage capacitive performance in a symmetric 2-electrode supercapacitor system owing to the almost pure well-ordered N-doped graphene. It showed excellent electrochemical energy storage performance as compared to other 2D graphene derivatives reported in the literature synthesized via toxic conventional methods, with a specific capacitance of 553 F g⁻¹, energy density of 84.5 W h kg⁻¹, power density of 550.2 W kg⁻¹ and 88.5% capacitance retention after 5000 cycles. Thus, the NG-HCD270 graphitic sample can be considered a promising ecofriendly and cost-effective electrode material for high-performance supercapacitors, which can benefit the substantial development of electrical energy storage industry and, hence, electrical power production from renewable energy sources at competitive costs.

In the dynamic realm of energy storage devices, supercapacitors (SCs) stand out as promising options. Among the various materials considered for SC electrodes, layered substances like Ti₃C₂ have drawn attention due to their outstanding electrochemical qualities, especially their impressive volumetric capacitance. This study focuses on assessing the predictive abilities of three machine learning models: Bayesian ridge regression (BRR), K-nearest neighbors (KNN), and artificial neural network (ANN) in estimating specific capacitance in Ti₃C₂-based supercapacitors. BRR offered reliable predictions with an R-squared (R²) value of 0.759 and a low root mean square error (RMSE) of 0.074. KNN excelled in predicting supercapacitor performance with an impressive R² of 0.928 and a minimal RMSE of 0.040. However, the ANN model stood out as it could reveal the significance of various inputs much like the human brain's intricate functioning. It achieved a high R² of 0.8929 with a low RMSE of 0.0493, demonstrating its proficiency in capturing complex relationships in the dataset. The precise tuning of hyperparameters further enhanced its accuracy. The use of SHAP (SHapley Additive exPlanations) values emphasized cation mobility, and scan rates as key contributing factors. These findings provide a strong foundation for utilizing machine learning to predict specific capacitance in Ti₃C₂-based supercapacitors. Researchers can benefit from these versatile tools for precise predictions, facilitating systematic supercapacitor design and enhancing our understanding of electrode materials.

Among the diverse range of modern renewable energy storage technologies, electrochemical energy storage devices have been rapidly adopted across various applications owing to their superior characteristics, including high coulombic efficiency, elevated energy and power densities, scalability, modularity, and rapid response capabilities. Conjugated conducting polymers have recently attracted significant attention in electrochemical energy storage devices due to their unique pseudocapacitive behavior, hybrid ionic/electronic conduction, rapid doping/de-doping dynamics, bulk intercalation of ionic species, high specific capacity, and exceptional structural and thermal stability. Conducting polymers exhibit pseudocapacitance through reversible redox reactions coupled with doping/de-doping processes, facilitating the movement of counterion dopants and ionic species between the polymer matrix and the electrolyte. The size and nature of counterion dopants significantly influence the electrochemical performance of these polymers. Small counterion dopants like chloride enhance redox exchange with the electrolyte and broaden the electrochemical potential window, which is advantageous for electrochemical energy storage devices. The pseudocapacitive properties can be further enhanced by increasing the semi-crystalline characteristics and attaining longer polymer chains. This review article focuses on the fabrication methods, fundamental aspects of ionic and electrical conductivity, and pseudocapacitance characteristics of conjugated conducting polymers, as well as their applications in Li–ion batteries, supercapacitors, and redox flow batteries.

Waste heat, particularly of low-grade (lower than 100 °C), represents a considerable amount of energy loss across different industries and areas of human development. In recent years, different ways of harvesting heat have been the focus of extensive research, with the thermally regenerative electrochemical cycle (TREC) being of particular interest due to its promising results, derived from using the temperature coefficient of electrolytes to obtain more efficient charging and discharging battery cycles. While studies have shown groundbreaking results by trial-and-error-based combinations of different redox couples, these studies have been mostly isolated from one another, possibly missing unseen potentials of unexplored redox couple combinations. Therefore, a wider view of these combinations is explored in this work to screen them for the TREC battery applications. Herein, we present a comprehensive survey of the redox couples used in the literature to highlight the untapped potential of a TREC cell. Furthermore, strategic guidelines on choosing the efficient redox couples for the TREC with engineering remarks and insights for their practical heat-to-electricity conversion applications are presented.

This article provides a comprehensive insight into Germany's transition to climate neutrality, bringing together the political framework of Germany's Climate Protection Act (CPA), the funding strategy of its key pillar, namely the “Wasserstoffstrategie” and the technical dimensions for non-technical stakeholders through a case study of Germany's largest current hydrogen user, the chemical industry. Increasing complexity of our modern economy and society and a lack of clarity in reporting contribute to misleading conclusions and can facilitate polarised views. To overcome that gap, we aim to draw a clear picture of these complex scientific topics and make them also accessible to non-technical stakeholders. This paper reviews Germany's climate policy, emphasizing the federal constitutional court's pivotal role. By calculating prospective GHG-reduction paths for Germany, we illuminate the gap between aspirational targets and practical strategies, emphasizing the need to translate global targets into actionable national plans. Taking the crucial, often-overlooked CO₂-budget into account, potential shortcomings are revealed, even when annual emission goals are met by Germany. Shifting focus of this paper to the German hydrogen strategy, a core part of the Climate Protection Program, we reveal a strong emphasis on international collaboration. This involves a global hydrogen ramp-up and facilitation of hydrogen imports, offering trade opportunities but also introducing dependencies and potential price increases. A scale estimation case study on green hydrogen production for the German chemical industry underscores the rationale behind prioritising imports over domestic production. Calculating a demand of 7840 windmills (78.37 TW h) that require 168 000 football pitches (7000 m² per pitch) of space, it provides easy to grasp insights into the necessary actions for a climate neutral Germany. This perspective frames Germany's climate goals, the Wasserstoffstrategie, and the technical scale of implementing renewables by conducting a case study on green hydrogen. Hereby, it highlights the magnitude of the climate problem and the immense scale of solutions required for a sustainable technical transition in a clear and sound manner.

Developing an artificial solid electrolyte interphase (SEI) with high Li ion flux is vital to improve the cycling stability of lithium metal batteries, especially under a high rate. In this work, a novel artificial SEI film was prepared via in situ deposition of a lithium-doped cesium lead chloride perovskite (Li–CsPbCl₃). Benefiting from its ultra-high thickness (0.45 μm), high mechanical modulus (5.9 GPa), high lithium-ion migration number (0.57), and unique highly oriented framework, the Li–CsPbCl₃ SEI film could promote the rapid transport and uniform deposition of lithium ions, enhancing the stability of lithium deposition and stripping. As a result, Li/Li symmetric cells based on the Li–CsPbCl₃ protective film could cycle stably for 1300 hours under high current density of 10 mA cm⁻². In addition, the Li/LiFePO₄ battery using the Li–CsPbCl₃ SEI film showed an impressive cycling stability with a capacity retention rate of up to 91.4% after 230 cycles at a high current rate of 3C.

Volumetrically unbalanced compositionally symmetric cell cycling with potentiostatic (CV) or galvanostatic-with-potential-hold (CCCV) protocols is a rigorous technique for evaluating the calendar lifetime of reactants for redox flow batteries. Here, we evaluate the influence of reactant crossover through the membrane on symmetric cell cycling behavior. We tested symmetric cells of anthraquinone disulfonic acid (AQDS) with Nafion membranes of varied thickness and manufacture (NR211, NR212, N115, and N117, ranging 25–183 μm). Membranes were tested both as-received and pretreated with a common procedure of soaking in water at elevated temperature and then in dilute hydrogen peroxide. We found no significant difference in capacity fade rates of symmetric cells with any of the membranes as-received, indicating a negligible influence of crossover. However, we observed increased capacity fade with increased permeability through pretreated membranes. Supported by zero-dimensional modeling and operando UV-vis spectrophotometry, we propose a mechanism for net crossover in AQDS symmetric cells based on a higher time-averaged concentration of quinhydrone dimers in the non-capacity limiting side (NCLS) compared to the capacity limiting side (CLS), driving net crossover of AQDS reactants out of the CLS. Further, we illustrate other hypothetical scenarios of net crossover using the zero-dimensional model. Overall, many membrane–electrolyte systems used in symmetric cell studies have sufficiently low crossover flux as to avoid the influence of crossover on capacity fade, but under conditions of higher crossover flux, complex interactions of crossover and chemical reactions may result in diverse capacity fade trajectories, the mechanisms of which may be untangled with operando characterization and modeling.

Polyethylene oxide (PEO)-based solid composite electrolytes (SCEs), with inorganic fillers, are studied extensively due to their effective balance between mechanical and electrochemical properties. The correlation between the composition of SCEs and their electrochemical behavior has been studied extensively, primarily focusing on the type of polymer matrix with a bias towards high lithium (Li) salt. In this study, we examine the changes in the properties of SCEs at two low EO : Li ratios, 43 : 1 and 18 : 1, in the PEO-LiTFSI matrix (with and without 10 wt% of 5 μm LLZTO) and evaluate their impact on Li stripping and plating reactions. Although higher salt concentration (18 : 1) results in substantially higher ionic conductivity (by approximately an order of magnitude), interestingly we observe that lower salt concentration (43 : 1) exhibits up to 3 times longer Li cycling life. Notably, electrolytes with low salt concentration (43 : 1) are much stiffer, with compressive modulus more than twice as high as the 18 : 1 counterpart. Although the ionic conductivity of the electrolyte is often the most immediate concern in the electrolyte design process, these findings accentuate the equal importance of mechanical properties in order to ensure successful electrolyte performance throughout prolonged Li cycling.

Developing low cost and highly efficient electrocatalysts for the oxygen evolution reaction (OER) is highly desired for renewable energy production. Ni-based electrocatalysts have been widely investigated as candidates for the OER, but developing a low-cost, easily synthesized electrocatalyst with high activity and good stability remains elusive. Herein, we report the facile electrodeposition of triethanolamine-decorated Ni oxide on carbon paper (Ni/CP-TEA) as an efficient electrocatalyst for water oxidation. Structural and experimental analyses reveal that the electrode surface is modified by triethanolamine (TEA) through Ni–N coordination bonding. The leaching of TEA drives rapid in situ surface reconstruction, facilitating the generation of high-valence Ni (Ni³⁺) species, thereby accelerating the OER performance. The Ni/CP-TEA exhibits enhanced electrocatalytic OER performance with a low overpotential of 320 mV at 10 mA cm⁻² and good long-term stability. This work presents a simple route for the rational design of cost-effective and highly efficient OER catalysts.

In many cases, batteries used in light e-mobility vehicles such as e-bikes and e-scooters do not have an active thermal management system. This poses a challenge when these batteries are stored in sub-zero temperatures and need to be charged. In such cases, it becomes necessary to move the batteries to a warmer location and allow them to acclimatize before charging. However, this is not always feasible, especially for batteries installed permanently in vehicles. In this work, we present an internal high-frequency AC heater for a 48 V battery, which is used for light electric vehicles of EU vehicle classes L1e and L3e-A1 for a power supply of up to 11 kW. We have taken advantage of the features of a damped oscillating circuit to improve the performance of the heater. Additionally, only a small inductor was added to the main current path through a cable with three windings. Furthermore, as the power electronics of the heater is part of the battery main switch, fewer additional parts inside the battery are required and therefore a cost and space reduction compared to other heaters is possible. For the chosen setup we reached a heating rate of up to 2.13 K min⁻¹ and it was possible to raise the battery temperature from −10 °C to 10 °C using only 3.1% of its own usable capacity.