能源化学最新文献

Owing to the distinctive structural characteristics, vanadium nitride (VN) is highly regarded as a catalyst for oxygen reduction reaction (ORR) in zinc-air batteries (ZABs). However, VN exhibits limited intrinsic ORR activity due to the weak adsorption ability to O-containing species. Here, the S-doped VN anchored on N, S-doped multi-dimensional carbon (S-VN/Co/NS-MC) was constructed using the solvothermal and in-situ doping methods. Incorporating sulfur atoms into VN species alters the electron spin state of vanadium in the S-VN/Co/NS-MC for regulating the adsorption energy of vanadium sites to oxygen molecules. The introduced sulfur atoms polarize the V 3d_z² electrons, shifting spin-down electrons closer to the Fermi level in the S-VN/Co/NS-MC. Consequently, the introduction of sulfur atoms into VN species enhances the adsorption energy of vanadium sites for oxygen molecules. The *OOH dissociation transitions from being unspontaneous on the VN surface to a spontaneous state on the S-doped VN surface. Then, the ORR barrier on the S-VN/Co/NS-MC surface is reduced. The S-VN/Co/NS-MC demonstrates a higher half-wave potential and limiting current density compared to the VN/Co/N-MC. The S-VN/Co/NS-MC-based liquid ZABs display a power density of 195.7 mW cm⁻², a specific capacity of 815.7 mA h g⁻¹, and a cycling stability exceeding 250 h. The S-VN/Co/NS-MC-based flexible ZABs are successfully employed to charge both a smart watch and a mobile phone. This approach holds promise for advancing the commercial utilization of VN-based catalysts in ZABs.

Developing efficient energy storage for sodium-ion batteries (SIBs) by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging. Besides, sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates. Herein, cross-linking nanoarchitectonics of WS₂/Ti₃C₂T_x heterojunction, featuring built-in electric field (BIEF), have been developed, employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity. Particularly, the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti₃C₂T_x to layered WS₂, spontaneously forming the BIEF and “ion reservoir” at the heterogeneous interface. Besides, the generation of cross-linking pathways further promotes the transportation of electrons/ions, which guarantees rapid diffusion kinetics and excellent structure coupling. Consequently, superior sodium storage performance is obtained for the WS₂/Ti₃C₂T_x heterojunction, with only 0.2% decay per cycle at 5.0 A g⁻¹ (25 °C) up to 1000 cycles and a high capacity of 293.5 mA h g⁻¹ (0.1 A g⁻¹ after 100 cycles) even at −20 °C. Importantly, the spontaneously formed BIEF, accompanied by “ion reservoir”, in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.

The development of a durable metallic coating on diverse substrates is both intriguing and challenging, particularly in the research of metal-conductive materials for applications such as batteries, soft electronics, and beyond. Herein, by learning from the pencil-writing process, a facile solid-ink rubbing technology (SIR-tech) is invented to address the above challenge. The solid-ink is exampled by rational combination of liquid metal and graphite particles. By harnessing the synergistic effects between rubbing and adhesion, controllable metallic skin is successfully formed onto metals, woods, ceramics, and plastics without limitation in size and shape. Moreover, outperforming pure liquid-metal coating, the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing. The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well. For applications, the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils. Meanwhile, advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from −196 to 120 °C. This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.

Lithium-sulfur (Li-S) batteries are one of the most promising modern-day energy supply systems because of their high theoretical energy density and low cost. However, the development of high-energy density Li-S batteries with high loading of flammable sulfur faces the challenges of electrochemical performance degradation owing to the shuttle effect and safety issues related to fire or explosion accidents. In this work, we report a three-dimensional (3D) conductive nitrogen-doped carbon foam supported electrostatic self-assembled MXene-ammonium polyphosphate (NCF-MXene-APP) layer as a heat-resistant, thermally-insulated, flame-retardant, and freestanding host for Li-S batteries with a facile and cost-effective synthesis method. Consequently, through the use of NCF-MXene-APP hosts that strongly anchor polysulfides, the Li-S batteries demonstrate outstanding electrochemical properties, including a high initial discharge capacity of 1191.6 mA h g⁻¹, excellent rate capacity of 755.0 mA h g⁻¹ at 1 C, and long-term cycling stability with an extremely low-capacity decay rate of 0.12% per cycle at 2 C. More importantly, these batteries can continue to operate reliably under high temperature or flame attack conditions. Thus, this study provides valuable insights into the design of safe high-performance Li-S batteries.

As a new generation electrode materials for energy storage, perovskites have attracted wide attention because of their unique crystal structure, reversible active sites, rich oxygen vacancies, and good stability. In this review, the design and engineering progress of perovskite materials for supercapacitors (SCs) in recent years is summarized. Specifically, the review will focus on four types of perovskites, perovskite oxides, halide perovskites, fluoride perovskites, and multi-perovskites, within the context of their intrinsic structure and corresponding electrochemical performance. A series of experimental variables, such as synthesis, crystal structure, and electrochemical reaction mechanism, will be carefully analyzed by combining various advanced characterization techniques and theoretical calculations. The applications of these materials as electrodes are then featured for various SCs. Finally, we look forward to the prospects and challenges of perovskite-type SCs electrodes, as well as the future research direction.

The safety valve is an important component to ensure the safe operation of lithium-ion batteries (LIBs). However, the effect of safety valve type on the thermal runaway (TR) and gas venting behavior of LIBs, as well as the TR hazard severity of LIBs, are not known. In this paper, the TR and gas venting behavior of three 100 A h lithium iron phosphate (LFP) batteries with different safety valves are investigated under overheating. Compared to previous studies, the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve types. Two significant results are obtained: (I) the safety valve type dominates over gas venting pressure of battery during safety venting, the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa, which is one order of magnitude higher than other batteries with oval or cavity safety valve; (II) the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy process. This study reveals the effect of safety valve type on TR and gas venting, providing a clear direction for the safety valve design.

Blade batteries are extensively used in electric vehicles, but unavoidable thermal runaway is an inherent threat to their safe use. This study experimentally investigated the mechanism underlying thermal runaway propagation within a blade battery by using a nail to trigger thermal runaway and thermocouples to track its propagation inside a cell. The results showed that the internal thermal runaway could propagate for up to 272 s, which is comparable to that of a traditional battery module. The velocity of the thermal runaway propagation fluctuated between 1 and 8 mm s⁻¹, depending on both the electrolyte content and high-temperature gas diffusion. In the early stages of thermal runaway, the electrolyte participated in the reaction, which intensified the thermal runaway and accelerated its propagation. As the battery temperature increased, the electrolyte evaporated, which attenuated the acceleration effect. Gas diffusion affected thermal runaway propagation through both heat transfer and mass transfer. The experimental results indicated that gas diffusion accelerated the velocity of thermal runaway propagation by 36.84%. We used a 1D mathematical model and confirmed that convective heat transfer induced by gas diffusion increased the velocity of thermal runaway propagation by 5.46%–17.06%. Finally, the temperature rate curve was analyzed, and a three-stage mechanism for internal thermal runaway propagation was proposed. In Stage I, convective heat transfer from electrolyte evaporation locally increased the temperature to 100 °C. In Stage II, solid heat transfer locally increases the temperature to trigger thermal runaway. In Stage III, thermal runaway sharply increases the local temperature. The proposed mechanism sheds light on the internal thermal runaway propagation of blade batteries and offers valuable insights into safety considerations for future design.

Although metal oxide compounds are considered as desirable anode materials for potassium-ion batteries (PIBs) due to their high theoretical capacity, the large volume variation remains a key issue in realizing metal oxide anodes with long cycle life and excellent rate property. In this study, polypyrrole-encapsulated Sb₂WO₆ (denoted Sb₂WO₆@PPy) microflowers are synthesized by a one-step hydrothermal method followed by in-situ polymerization and coating by pyrrole. Leveraging the nanosheet-stacked Sb₂WO₆ microflower structure, the improved electronic conductivity, and the architectural protection offered by the PPy coating, Sb₂WO₆@PPy exhibits boosted potassium storage properties, thereby demonstrating an outstanding rate property of 110.3 mA h g⁻¹ at 5 A g⁻¹ and delivering a long-period cycling stability with a reversible capacity of 197.2 mA h g⁻¹ after 500 cycles at 1 A g⁻¹. In addition, the conversion and alloying processes of Sb₂WO₆@PPy in PIBs with the generation of intermediates, K₂WO₄ and K₃Sb, is determined by X-ray photoelectron spectroscopy, transmission electron microscopy, and ex-situ X-ray diffraction during potassiation/depotassiation. Density functional theory calculations demonstrate that the robust coupling between PPy and Sb₂WO₆ endues it with a much stronger total density of states and a built-in electric field, thereby increasing the electronic conductivity, and thus effectively reduces the K⁺ diffusion barrier.

Fluorinated carbons CF_x hold the highest theoretical energy density (e.g., 2180 W h kg⁻¹ when x = 1) among all cathode materials of lithium primary batteries. However, the low conductivity and severe polarization limit it to achieve its theory. In this study, we design a new electrolyte, namely 1 M LiBF₄ DMSO:DOL (1:9 vol.), achieving a high energy density in Li/CF_x primary cells. The DMSO with a small molecular size and high donor number successfully solvates Li⁺ into a defined Li⁺-solvation structure. Such solvated Li⁺ can intercalate into the large-spacing carbon layers and achieve an improved capacity. Consequently, when discharged to 1.0 V, the CF_1.12 cathode demonstrates a specific capacity of 1944 mA h g⁻¹ with a specific energy density of 3793 W h kg⁻¹. This strategy demonstrates that designing the electrolyte is powerful in improving the electrochemical performance of CF_x cathode.