能源化学最新文献

The scarcity, high cost and susceptibility to CO of Platinum severely restrict its application in alkaline hydrogen oxidation reaction (HOR). Hybridizing Pt with other transition metals provides an effective strategy to modulate its catalytic HOR performance, but at the cost of mass activity due to the coverage of modifiers on Pt surface. Herein, we constructed dual junctions’ Pt/nitrogen-doped carbon (Pt/NC) and δ-MoC/NC to modify electronic structure of Pt via interfacial electron transfer to acquire Pt-MoC@NC catalyst with electron-deficient Pt nanoparticles, simultaneously endowing it with high mass activity and durability of alkaline HOR. Moreover, the unique structure of Pt-MoC@NC endows Pt with a high CO-tolerance at 1,000 ppm CO/H₂, a quality that commercial Pt-C catalyst lacks. The theoretical calculations not only confirm the diffusion of electrons from Pt/NC to MoC/NC could occur, but also demonstrate the negative shift of Pt d-band center for the optimized binding energies of *H, *OH and CO.

With the large-scale service of lithium-ion batteries (LIBs), their failures have attracted significant attentions. While the decay of active materials is the primary cause for LIB failures, the degradation of auxiliary materials, such as current collector corrosion, should not be disregarded. Therefore, it is necessary to conduct a comprehensive review in this field. In this review, from the perspectives of electrochemistry and materials, we systematically summarize the corrosion behavior of aluminum cathode current collector and propose corresponding countermeasures. Firstly, the corrosion type is clarified based on the properties of passivation layers in different organic electrolyte components. Furthermore, a thoroughgoing analysis is presented to examine the impact of various factors on aluminum corrosion, including lithium salts, organic solvents, water impurities, and operating conditions. Subsequently, strategies for electrolyte and protection layer employed to suppress corrosion are discussed in detail. Lastly and most importantly, we provide insights and recommendations to prevent corrosion of current collectors, facilitate the development of advanced current collectors and the implementation of next-generation high-voltage stable LIBs.

The slow water dissociation is the rate-determining step that slows down the reaction rate in alkaline hydrogen evolution reaction (HER). Optimizing the surface electronic structure of the catalyst to lower the energy barrier of water dissociation and regulating the binding strength of adsorption intermediates are crucial strategy for boosting the catalytic performance of HER. In this study, RuO₂/BaRuO₃ (RBRO) heterostructures with abundant oxygen vacancies and lattice distortion were in-situ constructed under a low temperature via the thermal decomposition of gel-precursor. The RBRO heterostructures obtained at 550 °C exhibited the highest HER activity in 1 M KOH, showing an ultra-low overpotential of 16 mV at 10 mA cm⁻² and a Tafel slope of 33.37 mV dec⁻¹. Additionally, the material demonstrated remarkable durability, with only 25 mV of degradation in overpotential after 200 h of stability testing at 10 mA cm⁻². Density functional theory calculations revealed that the redistribution of charges at the heterojunction interface can optimize the binding energies of H* and OH* and effectively lower the energy barrier of water dissociation. This research offers novel perspectives on surpassing the water dissociation threshold of alkaline HER catalysts by means of a systematic design of heterogeneous interfaces.

Transition metal carbides and nitrides (MXenes) nanosheets are attractive two-dimensional (2D) materials, but they suffer from oxidation/degradation issues during storage and/or applications due to their sensitivity to water and oxygen. Despite the great research progress, the exact oxidation kinetics of Ti₃C₂T_x (MXene) and their final products after oxidation are not fully understood. Herein, we systematically tracked the oxidation process of few-layer Ti₃C₂T_x nanosheets in an aqueous solution at room temperature over several weeks. We also studied the oxidation effects on the electrocatalytic properties of Ti₃C₂T_x for hydrogen evolution reaction and found that the overpotential to achieve a current density of 10 mA cm⁻² increases from 0.435 to 0.877 V after three weeks of degradation, followed by improvement to stabilized values of around 0.40 V after eight weeks. These results suggest that severely oxidized MXene could be a promising candidate for designing efficient catalysts. According to our detailed experimental characterization and theoretical calculations, unlike previous studies, black titanium oxide is formed as the final product in addition to white Ti (IV) oxide and disordered carbons after the complete oxidation of Ti₃C₂T_x. This work presents significant advancements in better understanding of 2D Ti₃C₂T_x (MXene) oxidation and enhances the prospects of this material for various applications.

Developing technologies that can be applied simultaneously in battery thermal management (BTM) and thermal runaway (TR) mitigation is significant to improving the safety of lithium-ion battery systems. Inorganic phase change material (PCM) with nonflammability has the potential to achieve this dual function. This study proposed an encapsulated inorganic phase change material (EPCM) with a heat transfer enhancement for battery systems, where Na₂HPO₄∙12H₂O was used as the core PCM encapsulated by silica and the additive of carbon nanotube (CNT) was applied to enhance the thermal conductivity. The microstructure and thermal properties of the EPCM/CNT were analyzed by a series of characterization tests. Two different incorporating methods of CNT were compared and the proper CNT adding amount was also studied. After preparation, the battery thermal management performance and TR propagation mitigation effects of EPCM/CNT were further investigated on the battery modules. The experimental results of thermal management tests showed that EPCM/CNT not only slowed down the temperature rising of the module but also improved the temperature uniformity during normal operation. The peak battery temperature decreased from 76 °C to 61.2 °C at 2 C discharge rate and the temperature difference was controlled below 3 °C. Moreover, the results of TR propagation tests demonstrated that nonflammable EPCM/CNT with good heat absorption could work as a TR barrier, which exhibited effective mitigation on TR and TR propagation. The trigger time of three cells was successfully delayed by 129, 474 and 551 s, respectively and the propagation intervals were greatly extended as well.

Nickel (Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity. However, the poor thermodynamic stability (including cyclic performance and safety performance or thermal stability) will restrain their wide commercial application. Herein, a single-crystal Ni-rich LiNi_0.83Co_0.12Mn_0.05O₂ cathode material is synthesized and modified by a dual-substitution strategy in which the high-valence doping element improves the structural stability by forming strong metal–oxygen binding forces, while the low-valence doping element eliminates high Li⁺/Ni²⁺ mixing. As a result, this synergistic dual substitution can effectively suppress H2-H3 phase transition and generation of microcracks, thereby ultimately improving the thermodynamic stability of Ni-rich cathode material. Notably, the dual-doped Ni-rich cathode delivers an extremely high capacity retention of 81% after 250 cycles (vs. Li/Li⁺) in coin-type half cells and 87% after 1000 cycles (vs. graphite/Li⁺) in pouch-type full cells at a high temperature of 55 °C. More impressively, the dual-doped sample exhibits excellent thermal stability, which demonstrates a higher thermal runaway temperature and a lower calorific value. The synergetic effects of this dual-substitution strategy pave a new pathway for addressing the critical challenges of Ni-rich cathode at high temperatures, which will significantly advance the high-energy-density and high-safety cathodes to the subsequent commercialization.

Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion batteries. However, this theoretical characteristic has not yet been converted into a real device with high cyclability. Problems with air contamination, metallic lithium reactivity, and complex discharge and charge reactions are the main issues for this technology. A fast and reversible oxygen reduction reaction (ORR) is crucial for good performance of secondary batteries’, but the partial knowledge of its mechanisms, especially when devices are concerned, hinders further development. From this perspective, the present work uses operando Raman experiments and electrochemical impedance spectroscopy (EIS) to assess the first stages of the discharge processes in porous carbon electrodes, following their changes cycle by cycle at initial operation. A growth kinetic formation of the discharge product signal (Li₂O₂) was observed with operando Raman, indicating a first-order reaction and enabling an analysis by a microkinetic model. The solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time constants. While the time constant for the anode interface reveals to remain relatively constant after the first discharge, its surface seemed to be more non-uniform. The model indicated that the reaction occurs at the Li₂O₂ surface, decreasing the associated resistance during the initial discharge phase. Furthermore, the growth of Li₂O₂ forms a hetero-phase between Li₂O₂/electrolyte, while creating a more compact and homogeneous on the Li₂O₂/cathode surface. The methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis.

Photoelectrochemical (PEC) energy conversion has emerged as a promising and efficient approach to sustainable energy harvesting and storage. By utilizing semiconductor photoelectrodes, PEC devices can harness solar energy and drive electrochemical reactions such as water splitting or carbon dioxide (CO₂) reduction to generate clean fuels and value-added chemicals. However, PEC energy conversion faces several challenges such as high overpotential, sluggish reaction kinetics, charge carrier recombination, and stability issues, which limit its practical implementation. Recently, significant research has been conducted to improve the overall conversion efficiency of PEC devices. One particularly promising approach is the use of cocatalysts, which involves introducing specific cocatalysts onto the photoelectrode surface to promote charge separation, improve reaction kinetics, and reduce the overpotential, thereby enhancing the overall performance of PEC energy conversion. This review provides a comprehensive overview of the recent developments in the earth-abundant cocatalysts for PEC water splitting and CO₂ reduction. The main earth-abundant catalysts for the PEC water splitting include transition-metal dichalcogenide (TMD)-based materials, metal phosphides/carbides, and metal oxides/hydroxides. Meanwhile, PEC-CO₂RR was divided into C₁ and C₂₊ based on the final product since various products could be produced, focusing on diverse earth-abundant materials-based cocatalysts. In addition, we provide and highlight key advancements achieved in the very recent reports on novel PEC system design engineering with cocatalysts. Finally, the current problems associated with PEC systems are discussed along with a suggested direction to overcome these obstacles.

Lithium-sulfur (Li-S) batteries are considered highly promising as next-generation energy storage systems due to high theoretical capacity (2600 W h kg⁻¹) and energy density (1675 mA h g⁻¹) as well as the abundant natural reserves, low cost of elemental sulfur, and environmentally friendly properties. However, several challenges impede its commercialization including low conductivity of sulfur itself, the severe “shuttle effect” caused by lithium polysulfides (LiPSs) during charge–discharge processes, volume expansion effects and sluggish reaction kinetics. As a solution, polar metal particles and their compounds have been introduced as the main hosts for sulfur cathode due to their robust catalytic activity and adsorption capability, effectively suppressing the “shuttle effect” of LiPSs. Bimetallic alloys and their compounds with multi-functional properties exhibit remarkable electrochemical performance more readily when compared to single-metal materials. Well-designed bimetallic materials demonstrate larger specific surface areas and richer active sites, enabling simultaneous high adsorption capability and strong catalytic properties. The synergistic effect of the “adsorption-catalysis” sites accelerates the adsorption-diffusion-conversion process of LiPSs, ultimately achieving a long-lasting Li-S battery. Herein, the latest progress and performance of bimetallic materials in cathodes, separators, and interlayers of Li-S batteries are systematically reviewed. Firstly, the principles and challenges of Li-S batteries are briefly analyzed. Then, various mechanisms for suppressing “shuttle effects” of LiPSs are emphasized at the microscale. Subsequently, the performance parameters of various bimetallic materials are comprehensively summarized, and some improvement strategies are proposed based on these findings. Finally, the future prospects of bimetallic materials are discussed, with the hope of providing profound insights for the rational design and manufacturing of high-performance bimetallic materials for LSBs.

Sluggish storage kinetics is considered as the main bottleneck of cathode materials for fast-charging aqueous zinc-ion batteries (AZIBs). In this report, we propose a novel in-situ self-etching strategy to unlock the Palm tree-like vanadium oxide/carbon nanofiber membrane (P-VO/C) as a robust free-standing electrode. Comprehensive investigations including the finite element simulation, in-situ X-ray diffraction, and in-situ electrochemical impedance spectroscopy disclosed it an electrochemically induced phase transformation mechanism from VO to layered Zn_xV₂O₅⋅nH₂O, as well as superior storage kinetics with ultrahigh pseudocapacitive contribution. As demonstrated, such electrode can remain a specific capacity of 285 mA h g⁻¹ after 100 cycles at 1 A g⁻¹, 144.4 mA h g⁻¹ after 1500 cycles at 30 A g⁻¹, and even 97 mA h g⁻¹ after 3000 cycles at 60 A g⁻¹, respectively. Unexpectedly, an impressive power density of 78.9 kW kg⁻¹ at the super-high current density of 100 A g⁻¹ also can be achieved. Such design concept of in-situ self-etching free-standing electrode can provide a brand-new insight into extending the pseudocapacitive storage limit, so as to promote the development of high-power energy storage devices including but not limited to AZIBs.