Frontiers in Energy最新文献

The increasing emission of carbon dioxide (CO₂) has intensified global efforts toward its conversion and utilization. Electrocatalytic CO₂ reduction reaction (CO₂RR) has emerged as a promising sustainable strategy to address interconnected energy and environmental challenges. Among the various products of CO₂ reduction, methanol has attracted significant research attention as both an essential chemical feedstock and a promising renewable energy carrier. This review comprehensively summarizes recent advances in the electrocatalytic conversion of CO₂ to methanol, with systematic discussions on fundamental reaction mechanisms and pathways, innovative reactor configurations, diverse catalysts, and auxiliary optimization strategies. Particular emphasis is placed on categorizing and evaluating various catalysts, including mono-/bimetallic catalysts, molecular catalysts, enzyme catalysts, and carbon-based materials, while exploring their structure-activity relationships and performance enhancement strategies for improving methanol selectivity. Furthermore, the techno-economic viability of current processes is analyzed, assessing the cost-effectiveness and commercial potential of electrocatalytic methanol production. Finally, based on current research progress and existing challenges, key research directions are outlined to advance the development of commercially feasible electrocatalytic CO₂-to-methanol systems, providing practical guidance for future investigations.

The development of low-cost platinum-free electrocatalysts for the oxygen reduction reaction (ORR) is essential for the sustainable energy technologies. In this work, spinel-type LiMn₂O₄ was chemically modified via proton exchange to systematically investigate the effects of protonation on crystal structure, electronic configuration, and ORR performance. Experimental results reveal that proton exchange not only regulates the lattice parameters and Mn oxidation states, but also enhances surface hydrophilicity and oxygen adsorption capacity, leading to a significant improvement in ORR activity with at a half-wave potential of 0.81 V for pure Mn-based oxide. Physical characterizations and theoretical calculations reveal that protonation optimizes the surface electronic structure by mitigating the over-stabilization of oxygen intermediates on LiMn₂O₄, thus facilitating the rate-determining step *OH adsorption and improving reaction kinetics. This work establishes proton exchange as a versatile strategy for the construction of Mn-based oxide electrocatalysts containing alkali metals, offering valuable insights for the rational design of nonprecious metal catalysts in energy conversion applications.

Compressed carbon dioxide (CO₂) energy storage (CCES) has emerged as a promising large-scale energy storage technology, characterized by high energy density, moderate critical temperature, and operational flexibility. Concurrently, carbon capture, utilization and storage (CCUS) technology represents a critical pathway toward carbon neutrality for energy systems. The integration of CCES with CCUS is attracting growing research interests due to its unique potential to synergize energy and carbon flows within a closed-loop framework. This paper provides a comprehensive literature review of technological advancements in CCES and offers a perspective on its integration with CCUS. First, the fundamental working principle, system configurations, key performance indicators, and emerging demonstration projects of CCES are introduced. Subsequently, cutting-edge research and key challenges of CCES system are reviewed, focusing on optimization of CO₂-based mixed working media, efficient liquefaction of low-pressure CO₂, development of low-cost and safe CO₂ storage facilities, enhancement of system performance through integration, and evaluation of dynamic behaviors. A central focus is placed on the integration of CCES with CCUS, highlighting how this synergy transforms CCES from a pure storage technology into a multi-functional tool for carbon management. This integration enables infrastructure sharing, dual-function storage (for energy and CO₂), and improved economics. Finally, this review identifies key directions for future research, including advancing efficient system integration, developing high-precision transient simulation models and dynamic control algorithms, ensuring long-term safety of geological reservoirs under cyclic injection-extraction operations, and establishing multi-objective optimization and multi-criteria assessment frameworks to support the commercial deployment of integrated CCES-CCUS systems.

With the rapid development of electric vehicles and energy storage systems (ESSs), accurate state-of-health (SOH) estimation for lithium-ion batteries has become crucial for ensuring safety and optimizing performance. However, SOH estimation under dynamic operating conditions remains challenging, as non-monotonic voltage profiles and irregular current patterns reduce the effectiveness of conventional measurement methods. This paper proposes a comprehensive approach that combines health feature extraction with a parallel deep learning architecture for robust SOH estimation. First, the method extracts four highly correlated health features (K, b, σ_ΔQ, and σ_δΔQ) from dynamic measurement data collected by sensors, with correlation coefficients between these features and the actual SOH exceeding 0.95. These extracted features are then processed through a novel parallel Temporal Convolutional Networks (TCN)-Transformer hybrid architecture: the TCN captures multi-scale local temporal patterns, while the Transformer models global dependencies. An attention-gated fusion module dynamically integrates complementary feature representations from the two branches and adaptively weights different paths based on degradation features. Experimental validation on three standardized battery datasets (MIT, CALCE, Oxford) shows that the method achieves an estimation accuracy with a root mean square error (RMSE) below 1% under all operating conditions, representing an 8%–70% improvement over conventional methods. Attention weight analysis reveals correlations with aging mechanisms, providing interpretability for model decisions. The proposed method enables practical real-time battery health assessment in dynamic environments.

Solid-state electrolytes are crucial for developing next-generation batteries with enhanced safety and energy density. Among them, the polymethyl methacrylate (PMMA)-based gel polymer electrolytes (GPEs) have emerged as promising materials for high-performance battery systems. However, PMMA-based electrolytes suffer from intrinsically low ionic conductivity. While blending with quaternary ammonium salts offers an effective solution, it often leads to salt deposition during cycling, compromising long-term stability. In this work, a novel GPE is developed by grafting long-chain quaternary ammonium salt (C₁₆DMAAC) onto the PMMA backbone. This molecular design simultaneously regulates polymer chain disorder and immobilizes free anions, enabling a high Li-ion transfer number of 0.59, ionic conductivity of 7.23 × 10⁻⁴ S/cm, and an expanded electrochemical stability window of 4.9 V. Moreover, the incorporated ammonium cations in the C₁₆DMAAC segment optimize the Li⁺ solvation structure, promoting the formation of a robust, inorganic-rich solid electrolyte interphase (SEI). The excellent cycling stability is demonstrated by the Li∥NCM811 full cell, which retains 92% of its initial capacity over 200 cycles at 0.5 C, and 80% retention after 300 cycles at 2 C. This work presents a promising strategy for designing novel electrolyte structures by grafting quaternary ammonium salts into polymer chains to improve battery stability and lifespan.

The widespread commercial adoption of fuel cells requires continued improvements in cost-effectiveness, performance, and durability. A tree-like nitrogen-doped carbon (T-NC) support structure was developed for low-platinum (Pt) loaded fuel cells. Carbon nanotubes serve as the conductive backbone, while ZIF-8-derived carbon, synthesized from 2-methylimidazole zinc salt, forms the branches that provide attachment sites for platinum group metals (PGMs). In cathodes with a Pt loading of 0.1 mg_Pt/cm², this novel Pt/T-NC electrode exhibited a remarkable 30% reduction in concentration loss at 2.0 A/cm² and a 12.7% increase in peak power density, compared to conventional Pt/C electrodes. Additionally, the corrosion resistance of the electrode was improved. Following 5000 cycles of accelerated durability testing (ADT) for carbon corrosion, the fuel cell retained 50.8% of its original performance, while conventional electrodes retained only 38%. The T-NC structure is broadly applicable for supporting various advanced PGM catalysts. This advancement offers a promising approach to bridge the gap between theoretical catalytic activity and practical output, leading to substantial improvements in both performance and durability of fuel cells.

Polyanionic silicate-based cathode materials have attracted considerable attention due to their intrinsic structural stability, strong thermal and chemical resistance, and ability to achieve high operating voltages through the inductive effects of polyanion groups. In this study, atomistic simulations were conducted to explore the energetics of intrinsic point defect formation, Na-ion migration pathways, and dopant incorporation in Na₂FeSiO₄, providing key insights into its viability as a cathode material for sodium-ion batteries (SIBs). Among the native defects, the Na Frenkel pair exhibited the lowest formation energy, suggesting a natural preference for vacancy-mediated Na-ion migration. The calculated migration energy barriers of 0.38 and 0.41 eV further support the material’s capability for efficient sodium-ion transport. Doping analysis identified K, Zn, and Ge as the most favorable isovalent dopants at the Na, Fe, and Si sites, respectively, while Ga showed a strong tendency to substitute at Fe sites and facilitate Na-vacancy formation. Furthermore, Al substitution at the Si site was found to increase the overall sodium content in the lattice. The electronic structure of these promising dopants was further investigated using density functional theory (DFT), offering deeper insights into their influence on the electrochemical behavior of Na₂FeSiO₄.

This paper presents a techno-economic assessment (TEA) combined with an environmental life cycle assessment (LCA) of various hydrogen delivery options within Europe, aiming to identify the most sustainable and cost-effective methods for transporting renewable hydrogen. Five hydrogen carriers—compressed hydrogen, liquid hydrogen, ammonia, methanol, and a liquid organic hydrogen carrier—are compared, assuming that hydrogen is produced via renewable electrolysis in Portugal and transported to the Netherlands by either ship or pipeline. The findings align with much of the existing literature, indicating that the most economically and environmentally sustainable options for long-distance hydrogen delivery are shipping liquid hydrogen and transporting compressed hydrogen via pipeline. Chemical carriers tend to involve higher costs and environmental impacts, largely due to the additional energy and materials (e.g., extra solar panels) required in hydrogen conversion steps (i.e., packing and unpacking). While the findings offer valuable insights for policymakers, further research is needed to address the limitations of multi-criteria assessments for emerging hydrogen technologies, particularly the uncertainties associated with the early development stages of processes along the hydrogen value chain. Future research should also focus on extending the scope of sustainability assessments and enhancing model reliability, especially for underrepresented environmental and social impact categories.