Frontiers in Energy最新文献

Proton exchange membrane fuel cells (PEMFCs) have attracted significant attention as sustainable energy technologies due to their efficient energy conversion and fuel flexibility. However, several challenges remain, such as low catalytic activity of fuel cell membrane electrode assembly (MEA), insufficient mass transfer performance, and performance degradation caused by catalyst deactivation over long period of operation. These issues are especially significant at high current densities, limiting both efficiency and operational lifespan. Mesoporous carbon materials, characterized by a high specific surface area, tunable pore structure, and excellent electrical conductivity, are emerging as crucial components for enhancing power density, mass transfer efficiency, and durability of PEMFCs. This review first discusses the properties and advantages of mesoporous carbon and outlines various synthetic strategies, including hard template, soft template, and template-free approaches. It then comprehensively examines the applications of mesoporous carbon in PEMFCs, focusing on their effects on the catalyst and gas diffusion layer. Finally, it concludes with future perspectives, emphasizing the need for further research to fully exploit the potential of mesoporous carbon in PEMFCs.

Aqueous zinc metal batteries (ZMBs) are regarded as strong contenders in secondary battery systems due to their high safety and abundant resources. However, the cycling performance of the Zn anode and the overall performance of the cells have often been hindered by the formation of Zn dendrites and the occurrence of parasitic side reactions. In this paper, a surface electron reconfiguration strategy is proposed to optimize the adsorption energy and migration energy of Zn²⁺ for a better Zn²⁺ deposition/stripping process by adjusting the electronic structure of ceric dioxide (CeO₂) artificial interface layer with copper atoms (Cu) doped. Both experimental results and theoretical calculations demonstrate that the Cu₂Ce₇O_x interface facilitates rapid transport of Zn²⁺ due to the optimized electronic structure and appropriate electron density, leading to a highly reversible and stable Zn anode. Consequently, the Cu₂Ce₇O_x@Zn symmetric cell exhibits an overpotential of only 24 mV after stably cycling for over 1600 h at a current density of 1 mA/cm² and a capacity of 1 mAh/cm². Additionally, the cycle life of Cu/Zn asymmetric cells exceeds 2500 h, with an average Coulombic efficiency of 99.9%. This paper provides a novel approach to the artificial interface layer strategy, offering new insights for improving the performance of ZMBs.

Thermo-mechanical energy storage (TMES) technologies have attracted significant attention due to their potential for grid-scale, long-duration electricity storage, offering advantages such as minimal geographical constraints, low environmental impact, and long operational lifespans. A key benefit of TMES systems is their ability to perform energy conversion steps that enable interaction with both thermal energy consumers and prosumers, effectively functioning as combined cooling, heating and power (CCHP) systems. This paper reviews recent progress in various TMES technologies, focusing on compressed-air energy storage (CAES), liquid-air energy storage (LAES), pumped-thermal electricity storage (PTES, also known as Carnot battery), and carbon dioxide energy storage (CES), while exploring their potential applications as extended CCHP systems for trigeneration. Techno-economic analysis indicate that TMES-based CCHP systems can achieve roundtrip (power-to-power) efficiencies ranging from 40% to 130%, overall (trigeneration) energy efficiencies from 70% to 190%, and a levelized cost of energy (with cooling and heating outputs converted into equivalent electricity) between 70 and 200 $/MWh. In general, the evolution of TMES-based CCHP systems into smart multi-energy management systems for cities or districts in the future is a highly promising avenue. However, current economic analyses remain incomplete, and further exploration is needed, especially in the area “AI for energy storage,” which is crucial for the widespread adoption of TMES-based CCHP systems.

The utilization of solar energy to address energy and environmental challenges has a seen a significant growth in recent years. Metal halides, which offer unique advantages such as tunable bandgaps, high light absorption efficiencies, favorable product release rates, and low exciton binding energies, have emerged as excellent photocatalysts for energy conversion. This paper reviews the recent advancements in both all-inorganic and organic-inorganic hybrid metal halide photocatalytic materials, including the fundamental mechanisms of photocatalytic CO₂ reduction, various synthesis strategies for metal halide photocatalysts, and their applications in the field of photocatalysis. Finally, it examines the current challenges associated with metal halide materials and explores potential solutions for metal halide materials, along with their future prospects in photocatalysis applications.

The use of porous skeletons for encapsulating phase change materials (PCMs) is an effective approach to addressing issues such as leakage, low thermal conductivity, and poor photothermal conversion efficiency. Inspired by the hollow skeletal structure found in birds in nature, high-quality 3D interconnected hollow diamond foam (HDF) was fabricated using a series of processes, including microwave plasma chemical vapor deposition (CVD), laser perforation, and acid immersion. This HDF was then used as a scaffold to encapsulate PEG2000. The results demonstrate that HDF significantly reduces the supercooling degree and latent heat discrepancy of PEG2000. Compared to pure PEG2000, the thermal conductivity of the HDF/PEG increased by 378%, while its latent heat reached 111.48 J/g, accompanied by a photothermal conversion efficiency of up to 86.68%. The significant performance improvement is mainly attributed to the combination of the excellent properties of the diamond with the inherent advantages of the 3D interconnected structure in HDF, which creates a high-conductivity transport network inside. Moreover, the HDF/PEG composite extends the temperature cycling time of electronic components by 4 times for heating and 2.3 times for cooling, thereby prolonging the operational lifetime of electronic devices. HDF/PEG offers an integrated solution for solar energy collection, photothermal conversion, heat dissipation in electronic components, and thermal energy transfer/storage. This innovative approach provides innovative ideas for the design and fabrication of composite PCMs and has great application potential, such as solar energy utilization, thermal management, and thermal energy storage.

Carbon dioxide energy storage (CES) is an emerging compressed gas energy storage technology which offers high energy storage efficiency, flexibility in location, and low overall costs. This study focuses on a CES system that incorporates a high-temperature graded heat storage structure, utilizing multiple heat exchange working fluids. Unlike traditional CES systems that utilize a single thermal storage at low to medium temperatures, this system significantly optimizes the heat transfer performance of the system, thereby improving its cycle efficiency. Under typical design conditions, the round-trip efficiency of the system is found to be 76.4%, with an output power of 334 kW/(kg·s⁻¹) per unit mass flow rate, through mathematical modeling. Performance analysis shows that increasing the total pressure ratio, reducing the heat transfer temperature difference, improving the heat exchanger efficiency, and lowering the ambient temperature can enhance cycle efficiency. Additionally, this paper proposes a universal and theoretical CES thermodynamic intrinsic cycle construction method and performance prediction evaluation method for CES systems, providing a more standardized and accurate approach for optimizing CES system design.

Existing swirling combustion technology, which relies on faulty coal, is unable to meet deep peak shaving demands without auxiliary methods. This paper developed a deep peak regulation burner (DPRB) to achieve stable combustion at 15%–30% of the boiler’s rated load without auxiliary support. Gas-particle tests, industrial trials, and transient numerical simulations were conducted to evaluate the burner’s performance. At full rated load, the DPRB formed a central recirculation zone (RZ) with a length of 1.5d and a diameter of 0.58d (where d represents the outlet diameter). At 40%, 20%, and 15% rated loads, the RZ became annular, with diameters of 0.30d, 0.40d, and 0.39d, respectively, with a length of 1.0d. At 20% and 15% rated loads, the recirculation peak and the range of particle volume flux were comparable to those at 40% rated load. The prototype burner demonstrated that, without oil support, the gas temperature within 0 to 1.8 m from the primary air outlet remained below 609 °C, insufficient to ignite faulty coal. As the load rate increased from 20% to 30%, the prototype’s central region temperature remained low, with a maximum of 750 °C between 0 and 2.0 m. In contrast, the DPRB’s central region temperature reached 750 °C at around 0.65–0.70 m. At a 3%·min⁻¹ load-up rate, when the load increased from 20% to 30%, the prototype burner extinguished after 30 s. However, the DPRB maintained stable combustion throughout the process.

Enzymatic biofuel cells (EBFCs), which generate electricity through electrochemical reactions between metabolites and O₂/air, are considered a promising alternative power source for wearable and implantable bioelectronics. However, the main challenges facing EBFCs are the poor stability of enzymes and the low electron transfer efficiency between enzymes and electrodes. To enhance the efficiency of EBFCs, researchers have been focusing on the development of novel functional nanomaterials. This mini-review first introduces the working principles and types of EBFCs, highlighting the key roles of nanomaterials, such as enzyme immobilization and stabilization, promotion of electron transfer and catalytic activity. It then summarizes the recent advancements in their application in wearable and implantable devices. Finally, it explores future research direction and the potential of high-performance EBFCs for practical applications.