Gas Generation Research Articles

Surface Reconstruction Reduces Internal Stress of Ni-Rich Cathode Particles.

High-voltage Ni-rich layered cathode materials are undoubtedly a powerful driving force for high-energy density lithium batteries. However, residual lithium impurities on the surface of Ni-rich materials can cause more severe side reactions under high-voltage, leading to rapid decay. There is still no reliable mechanistic explanation for this phenomenon. It has been detected that residual alkali on the cathode surface under high voltage can cause obvious side reactions. This side reaction will affect the capacity retention of the material and increase the internal stress of the particles. In addition, the surface reconstruction of Ni-rich cathodes is achieved through simple chemical reactions, turning waste into treasure. The newly generated Ti-based layer not only repairs the structure of the nickel-rich material but also optimizes the material from a dynamic perspective. Removing residual lithium components on the cathode surface effectively reduces the hydrolysis and self-catalytic side reactions of PF6 - at the electrolyte cathode interface and suppresses gas generation during cycling, promoting the application of the next generation of high-energy density Ni-rich layered cathode-based lithium batteries with high-voltage.

The Brazilian Research Scenario in Green Hydrogen: A Brief Contextualization

Hydrogen is crucial in various industrial sectors and can be obtained through different synthesis routes. However, a significant portion of its production still relies on chemical processes involving fossil fuels, resulting in hydrogen and the generation of greenhouse gases (GHGs) as the final byproduct. In alignment with the goals of the 2030 Agenda, where countries commit to implementing energy transition, hydrogen obtained through a green route has been increasingly explored by governmental and academic entities as an alternative energy source. Numerous studies and projects related to its production and use are being promoted. Within this context, this work aims to provide a concise overview of various topics and contextualizations associated with the use of hydrogen in the Brazilian scenario based on a brief literature review.

Effect of Nozzle Type on Combustion Characteristics of Ammonium Dinitramide-Based Energetic Propellant

The present study explores the influence of diverse nozzle geometries on the combustion characteristics of ADN-based energetic propellants. The pressure contour maps reveal a rapid initial increase in the average pressure of ADN-based propellants across the three different nozzles. Subsequently, the pressure tapers off gradually as time elapses. Notably, during the crucial initial period of 0–5 μs, the straight nozzle exhibited the most significant pressure surge at 30.2%, substantially outperforming the divergent (6.67%) and combined nozzles (15.5%). The combustion product variation curves indicate that the contents of reactants ADN and CH3OH underwent a steep decline, whereas the product N2O displayed a biphasic behavior, initially rising and subsequently declining. In contrast, the CO2 concentration remained on a steady ascent throughout the entire combustion process, which concluded within 10 μs. Our findings suggest that the straight nozzle facilitated the more expeditious generation of high-temperature and high-pressure combustion gases for ADN-based propellants, expediting reaction kinetics and enhancing combustion efficiency. This is attributed to the reduced intermittent interactions between the nozzle wall and shock waves, which are encountered in the divergent and combined nozzles. In conclusion, the superior combustion characteristics of ADN-based propellants in the straight nozzle, compared to the divergent and combined nozzles, underscore its potential in informing the design of advanced propulsion systems and guiding the development of innovative energetic propellants.

Numerical Simulation of the Coal Measure Gas Accumulation Process in Well Z-7 in Qinshui Basin

The process of coal measure gas accumulation is relatively complex, involving multiple physicochemical processes such as migration, adsorption, desorption, and seepage of multiphase fluids (e.g., methane and water) in coal measure strata. This process is constrained by multiple factors, including geological structure, reservoir physical properties, fluid pressure, and temperature. This study used Well Z-7 in the Qinshui Basin as the research object as well as numerical simulations to reveal the processes of methane generation, migration, accumulation, and dissipation in the geological history. The results indicate that the gas content of the reservoir was basically zero in the early stage (before 25 Ma), and the gas content peaks all appeared after the peak of hydrocarbon generation (after 208 Ma). During the peak gas generation stage, the gas content increased sharply in the early stages. In the later stage, because of the pressurization of the hydrocarbon generation, the caprock broke through and was lost, and the gas content decreased in a zigzag manner. The reservoirs in the middle and upper parts of the coal measure were easily charged, which was consistent with the upward trend of diffusion and dissipation and had a certain relationship with the cumulative breakout and seepage dissipation. The gas contents of coal, shale, and tight sandstone reservoirs were positively correlated with the mature hydrocarbon generation of organic matter in coal seams, with the differences between different reservoirs gradually narrowing over time.

The Gas Generation Process and Modeling of the Source Rock from the Yacheng Formation in the Yanan Depression, South China Sea

The research on deepwater oil and gas exploration areas is relatively limited, and sample collection is difficult. A drilled coal sample from Yanan Depression was used to investigate the hydrocarbon generation process, and the potential, by a gold tube thermal simulation experiment. The results show that the total gas yield was much higher than the oil yield. According to an analysis of the gas pyrolysis data, as represented by ln(C1/C2) and ln(C2/C3), the gas generation process consisted of two forms, namely, primary gas with ~1.33% Ro and secondary gas that occurred at levels greater than 1.33% Ro. The primary gas from kerogen was generated at ~1.33% Ro, which coincided with the %Ro value of the maximum oil yield. The activation energy distribution of the C1–C5 generation processes ranged from 54 to 72 kcal/mol, with a frequency factor of 6.686 × 1014 s−1 for the coal sample. We constructed the history of gas generation on the basis of the process and kinetic parameters, combined with data on the sedimentary burial and thermal history. The extrapolation of the gas history revealed that the gas has been generated from 5 Ma to the present, with a maximum yield of 178.5 mg/gTOC. This history suggests that the coal has good primary gas generation potential and provides favorable gas source conditions for the formation of gas fields. This study provides a favorable basis for expanding the effective source rock areas.

Exploring the influence of metal oxides on the pyrolytic behavior and decomposition mechanism of the green gas generating agent 5-Aminotetrazole

5-Aminotetrazole (5AT) is widely used as a green gas-generating agent in fire extinguishers, but it exhibits low combustion stability. To enhance its combustion rate and modify gas production performance, this study investigated the catalytic effects of adding different metal oxides (Bi2O3, PbO, TiO2, and CoO) on its pyrolysis process and decomposition mechanism. The pyrolysis behavior and pyrolysis products of 5AT were studied by simultaneous thermal analyzer (thermogravimetry - differential thermal analysis, TG-DTA) and TG-FTIR/MS (mass spectrometry and fourier transform infrared spectroscopy) hyphenated instrument. Isoconversional methods were used to calculated kinetic parameters, and reaction mechanism was also speculated by combining the experimental and calculational results. The experimental results indicated that Bi2O3, PbO, TiO2 and CoO have minimal impact on the ring opening reaction process of 5AT, but they catalyzed the polymer decomposition process of 5AT, especially CoO. Consequently, the addition of metal oxides as catalysts to 5AT holds significant potential for improving its thermal safety and enhancing its suitability as a solid propellant gas generator.

Temperature effect of biogas production from a greenhouse biogas digester

Globally, energy challenges are increasing with population growth. Many countries solely depend on fossil fuels (oil, coal, natural gas, etc.) for energy generation for different processes. Fossil fuels fall under non-renewable energy sources, are polluters of the environment, and get depleted faster, thus making it challenging to sustain a continuous energy supply. Therefore, there is a need for alternative sources of energy to mitigate the hazards associated with the utilization of fossil fuels. The present study aims to monitor the performance of a three-meter cubic (3 m3) greenhouse biogas digester, focusing on the temperature effect in biodegrading cow dung materials for gas generation. The study was conducted under mesophilic temperature conditions, pH, and hydraulic retention time for 30 days. Results revealed that slurry temperatures of about 33.5 ℃ and ambient temperatures of about 35 ℃ resulted in a remarkable peak biogas yield of 0.3 m3 on the 23rd day of the month. After the optimum yield of the biogas, the performance declined and was ascribed to the non-supply of the new feedstock, and the environment in the reactor became acidic, hence hindering the biodegradation process. Ultimately, the total biogas yield obtained from the study was 2.58 m3, equivalent to 15.48 kWh of energy. This amount of bio-generated energy was twofold the average daily electricity consumption of middle-income South African households. It was demonstrated that temperature was a major factor influencing the performance of the assembled biogas digesters and, thus, should be closely monitored for appreciable biogas production. This study is envisaged to pave the way for the future affordable and environmentally friendly biogas production process.

Genesis of an Inorganic CO2 Gas Reservoir in the Dehui–Wangfu Fault Depression, Songliao Basin, China

This study systematically examines the origins and formation mechanisms of inorganic CO2 gas reservoirs located within the Dehui–Wangfu Fault in the southeastern uplift region of the Songliao Basin. The research aims to clarify the primary sources of inorganic CO2, along with its migration and accumulation processes. The identification of the Wanjinta gas reservoir within the Dehui–Wangfu Fault Zone, abundant in inorganic CO2, has sparked significant interest in the pivotal roles of volcanism and tectonic activity in gas generation and concentration. To analyze the release characteristics of CO2, this study conducted degassing experiments on volcanic and volcaniclastic rock samples from various boreholes within the fault trap. It evaluated CO2 release behaviors and controlling factors across varying temperatures (150 °C to 600 °C) and particle sizes (20, 40, and 100 µm). The findings indicated a negative correlation between CO2 release and particle size, with a notable transition at 300 °C—marking this temperature as critical for the release of adsorbed and lattice gases. Moreover, volcaniclastic rocks exhibited higher CO2 release compared to volcanic rocks, attributable to their larger specific surface area and higher porosity. At 600 °C, the decomposition of the rock crystal structure results in substantial gas escape. These observations suggest that the inorganic CO2 in this area derives not only from mantle sources but is also influenced by crustal components. Elevated temperatures prompted by tectonic activity and magmatic intrusion facilitated the degassing of the surrounding rocks, allowing released CO2 to migrate upwards through the fracture system and accumulate in the shallow crust, ultimately forming a gas reservoir. This study enhances the understanding of volcanic rock’s roles in inorganic CO2 gas generation and migration, highlighting the fracture system’s critical controlling influence on gas transport and aggregation. The findings indicate that inorganic CO2 gas reservoirs in the Dehui–Wangfu Fault Zone primarily originate from mantle sources with a mixture of crustal gases. This discovery offers new theoretical insights and practical guidance for the exploration and development of gas reservoirs in the Songliao Basin and similar regions.

Research on thermal runaway and gas generation characteristics of NCM811 high energy density lithium-ion batteries under different triggering methods

Safety concerns, including thermal runaway and gas generation, present significant challenges for high-energy-density lithium-ion batteries. Thermal abuse, a common trigger for thermal runaway, can be induced by various methods, including heating rods, coils, plates, and lasers. This study compares the impacts of three heating techniques—heating rods, coils, and plates—on thermal runaway and gas generation in a commercially used NCM811 lithium-ion battery, which has a high energy density of 280.24 Wh/kg (the latest cylindrical 46950 model). The study found that the heating coil was the most effective, triggering thermal runaway more quickly and at a higher temperature than the heating plate and rod. Gas production analysis revealed that the heating coil method generated significantly more gas, particularly CO2, than the other methods. The concentrations of gases produced during thermal runaway (CO, CO2, H2, and CH4) varied by heating method, with the heating coil leading to a more complete battery reaction. The safety evaluation highlighted the hazardous nature of the heating rod method, which produced the widest flammable gas concentration range and the highest explosion risk among the tested heating methods. This study provides critical insights into heating techniques in lithium-ion battery thermal runaway scenarios and offers valuable data for improving safety measures in energy storage systems.

Performance response analysis and optimization for integrated renewable energy systems using biomass and heat pumps: a multi-objective approach

The focus of this study is to optimize the exploration of biomass-driven multi-energy systems, which include combined heat, power, and gas generation. The objective is to enhance the thermal, environmental, and economic performance indicators of the system. The optimization objectives encompass the quantities of internal combustion engines and air source heat pumps, as well as the dimensions of tanks utilized for anaerobic fermentation. A mathematical model was developed to optimize multiple objectives for combined heat, power, and gas generation systems by employing multi-objective intelligent optimization algorithms. The validation and analysis were conducted using rural residences in Lanzhou, Gansu Province, China, as a case study. The sensitivity analysis of biomass gasification combined heat and power systems was conducted from both technical and cost perspectives, examining the dynamic impact characteristics on the outcomes of multi-objective optimization. The findings indicate that the annual energy-saving rate of the optimized combined generation system decreased from 3.62% to -6.78%, while the growth in carbon emissions reduction rate increased from 76.05 to 81.38%, and the annual cost-saving rate grew from 0.97 to 14.96%. The power generation efficiency of the cogeneration station and hydraulic retention time were found to have a significant impact on the multi-objective optimization results of the combined generation system among the technical parameters. The unit cost of anaerobic fermentation tanks had a more significant impact on the multi-objective optimization results in terms of cost parameters, compared to the price of biogas residue.

Study on the effects of aging on the pyrolysis of plastic and the synergistic mechanisms of co-pyrolysis with lignite

Co-pyrolysis of waste plastic with low-rank coal explored how photoaging impacts the pyrolysis of plastics and delves into the synergistic mechanisms involved in co-pyrolysis. The results of elemental analysis, X-ray powder diffraction and Fourier transform infrared spectroscopy showed that photoaging primarily involves oxidizing and breaking the aliphatic chains in polyethylene (PE), as well as generating oxygen-containing functional groups like hydroxyl (-OH), carbonyl (-C=O), and ether (-C-O), thereby reducing the crystallinity of PE. The results of individual plastic pyrolysis showed that photoaging is beneficial to the generation of gas and tar. Pyrolysis tar of PE samples contains significant amounts of alcohols, and olefins and alkynes (O&As). The results of co-pyrolysis indicated that photoaging can enhance the yields of gas and oil from the co-pyrolysis between PE and Naomaohu (NMH) coal. Co-pyrolysis effectively reduced the relative content of O&As in the tar from the pyrolysis of PE samples alone by 8.0%-29.0%. The synergistic mechanism of co-pyrolysis between aged PE and NMH involved supplying a significant quantity of hydrogen and hydroxyl radicals by NMH, which react with alkyl radicals generated from PE pyrolysis, leading to the production of additional alkanes and alcohols. These findings offered new insights for a deeper understanding of the co-pyrolysis behaviors between waste plastic and lignite.

A multifunctional cascade gas-nanoreactor with MnO2 as a gatekeeper to enhance starvation therapy and provoke antitumor immune response

Glucose oxidase (GOx)-mediated starvation therapy is an effective tumor treatment that blocks energy and activates the immune response. However, the insufficient tumor immunogenicity and immunosuppressive tumor microenvironment (TME) limited its therapeutic efficacy. To address this, we have designed a multifunctional cascade gas-nanoreactor with a MnO2 coating, which serves as an out gatekeeper to encapsulate both GOx and a carbon monoxide (CO) donor (denoted as GCM). Due to the protective effect of MnO2 coating, GCM maintains better stability in normal physiological environments, enhancing the catalytic activity of GOx and minimizing toxic side effects. Upon accumulation in the tumor, the degradation of MnO2 coating exposes the GOx enzyme, thereby initiating a cascade catalysis reaction to generate hydrogen peroxide (H2O2) and release CO in the hypoxic conditions. Additionally, the released Mn2+ reacts with H2O2 to generate toxic hydroxyl radical (•OH) as chemodynamic therapy (CDT). The synergistic treatments of starvation therapy, CO gas therapy and CDT effectively kill cancer cells and amplify immunogenic cell death (ICD), maturing DC cells and activating anti-tumor immune response. Furthermore, the released CO increases M1 macrophages infiltration and reduces myeloid-derived suppressor cells (MDSCs) infiltration, thus reversing the immunosuppressive TME. This multifunctional gas-nanoreactor provides a strategy for CO gas generation to trigger a robust anti-tumor immune response and has the potential for clinical application in cancer immunotherapy. Statement of significanceA multifunctional cascade gas-nanoreactor with a MnO2 gatekeeper was developed to perform synergistic treatments involving starvation therapy, CO gas therapy and chemodynamic therapy (CDT) for tumor elimination. The MnO2 gatekeeper enhanced the catalytic activity of GOx within the nanoreactor by generating oxygen, thereby minimizing toxic side effects after intravenous injection. The gas-nanoreactor amplified ICD through synergistic treatments to mature DC cells and activate anti-tumor immune response. Furthermore, the released CO could reverse the immunosuppression of the TME to enhance cancer immunotherapy. The combination strategy utilizing the gas-nanoreactor demonstrates clinical potential for facilitating cancer immunotherapy.

Sources and exploration potential of Ordovician subsalt natural gas in Ordos Basin, China

With the continuous increase in exploration efforts in new zones and new strata, significant breakthroughs have been made in the natural gas exploration of the O1m56 to O1m4 formations in the Ordos Basin. Thus, the origin and exploration potential of subsalt natural gas have attracted much attention and urgently need to be addressed. On the basis of certain geochemical characteristics, genetic types, and sources of natural gas, a comprehensive study on the sedimentary environment, organic geochemical characteristics, and spatial distribution scale of source rocks are conducted in this paper by using geological and geochemical methods. The study shows that: (1) The Ordovician subsalt natural gas is mainly “pyrolysis dry gas,” among which the δ13C1 of Ordovician subsalt low sulfur (sulfur-free) natural gas is lighter, with an average value of −39.6‰; the δ13C2 ranges more largely from −35.6‰ to −25.8‰. In contrast, both δ13C1 and δ13C2 values are heavier in high-sulfur natural gas, revealing that different Thermochemical Sulfate Reduction (TSR) reaction stages have different degrees of influence on natural gas components and carbon isotope composition. (2) Subsalt natural gas is classified as “oil-type gas,” which is self-generated and self-accumulated, whose source rocks are mainly Ordovician subsalt marine deposits. (3) Three types of marine source rocks are developed in Ordovician subsalt, including black argillaceous rock, dark argillaceous dolomite (dolomitic mudstone), and dark micrite (bioclastic) limestone. In addition to micrite limestone, these rocks were mainly formed in a confined lagoon sedimentary environment with high salinity and anoxia. Sedimentary water was significantly stratified and the environment was highly reduced. The organic matter content of the source rocks is relatively high, with an average TOC value of 0.45%. The hydrocarbon-generating parent materials are mainly composed of bacteria and algae, and the organic matter evolution reaches high-over maturity stage. The total gas generation amount of the marine source rocks in Ordovician subsalt is approximately 43.8×1012 m3, which can provide hydrocarbons and accumulate for the subsalt favorable reservoir facies located far from Upper Paleozoic gas sources.

Influence of tectonic evolution processes on burial, thermal maturation and gas generation histories of the Wufeng-Longmaxi shale in the Sichuan Basin and adjacent areas

The Wufeng-Longmaxi (WL) shale is widely distributed in the Sichuan Basin and adjacent areas in southwest China. The basin experienced multiple-stage complex tectonic movements, whose influences on burial, thermal maturation and gas generation histories in different areas are poorly understood. Based on a detailed study of the denudation stages, strata thickness, and thermal history of the basin, burial and thermal maturation histories of seven wells in different areas were modelled using PetroMod software. Due to the high maturity of the WL shale, a low-maturity Silurian Polish Llandovery shale was used for gold tube closed-system pyrolysis experiments to obtain kinetic parameters for evaluating methane generation history. The Polish shale was selected due to its depositional age, sedimentary environment and organic type, which are similar to the WL shale. The burial history of the WL shale can be divided into five stages: I. Early to Middle Silurian rapid burial; II. Caledonian uplift and denudation; III. Permian to Triassic sustained burial and denudation; IV. sustained burial since the Late Triassic; and V. Late Cretaceous to present sustained uplift and denudation. The thermal maturity of the WL shale in all wells increased with burial depth during stage IV. In addition, high calculated reflectance increments in wells JY1 and N201 during stage III occurred due to the relatively high basal heat flow and deep burial depth, resulting in higher current thermal maturities than in the other wells. The late Permian–Early Triassic and the Middle Jurassic–Early (or Late) Cretaceous were the key methane generation periods for wells JY1 and N201. In contrast, the other five wells had a single methane generation stage, mainly determined by burial and thermal maturation processes. The time of uplift and the amount of denudation during stage V, the current burial depth, the development of faults and fractures, high proportion of retention and the seal capacity of the overlying caprock are key factors for shale gas preservation. Hence, this study will help guide future shale gas development in the Sichuan Basin.

Fast and Smart State Characterization of Large-Format Lithium-Ion Batteries via Phased-Array Ultrasonic Sensing Technology.

Lithium-ion batteries (LIBs) are widely used in electric vehicles and energy storage systems, making accurate state transition monitoring a key research topic. This paper presents a characterization method for large-format LIBs based on phased-array ultrasonic technology (PAUT). A finite element model of a large-format aluminum shell lithium-ion battery is developed on the basis of ultrasonic wave propagation in multilayer porous media. Simulations and comparative analyses of phased array ultrasonic imaging are conducted for various operating conditions and abnormal gas generation. A 40 Ah ternary lithium battery (NCMB) is tested at a 0.5C charge-discharge rate, with the state of charge (SOC) and ultrasonic data extracted. The relationship between ultrasonic signals and phased array images is established through simulation and experimental comparisons. To estimate the SOC, a fully connected neural network (FCNN) model is designed and trained, achieving an error of less than 4%. Additionally, phased array imaging, which is conducted every 5 s during overcharging and overdischarging, reveals that gas bubbles form at 0.9 V and increase significantly at 0.2 V. This research provides a new method for battery state characterization.

Honeycombed pomegranate-like sludge ceramsite particles: Preparation with fly ash floating beads as the pore-forming template and performance optimization

Ceramsite used in construction and building are typically limited by high water absorption rates, the contradiction between lightweight and high strength, and severe performance fluctuations. This can be attributed to the fact that ceramsites are currently prepared by high-temperature sintering expansion, wherein viscosity and surface tension of the liquid phases shall perfectly match with the gas generation rate. On the other hand, sand washing sludge and fly ash are common solid wastes in construction and building and their environmentally friendly disposal are of great significance. In this study, honeycombed pomegranate-like sludge ceramsites with low density (packing density = 733.2–968.3 kg/m3), high strength (cylinder compressive strength = 11.2–18.8 MPa), and low water absorption rate (one-hour water absorption rate = 1.2–2.8 %) were prepared with sand washing sludge and fly ash floating beads as the raw material and the pore-forming template, respectively. Also, the effects of particle size and content of fly ash floating beads on the structure and performance of the as-prepared ceramsite were investigated. The results indicated that the pore structure of the as-prepared ceramsite was directly dependent on size and content of the fly ash floating beads, suggesting that the performance of the as-prepared ceramsite can be customized by tuning size and content of the beads. Additionally, lightweight aggregate concrete prepared by using the as-prepared ceramsites exhibited improved 7-day and 28-day compressive strengths and reduced thermal conductivity compared with concrete prepared by using commercially available ceramsites. Overall, this study presents the preparation of ceramsite particles with both high strength and low density by using fly ash and sand washing sludge, both of which are abundant solid wastes in constructions, thus contributing to solid waste recycling in construction.

Insights into heat treatments of biodegradable Mg-Y-Nd-Zr alloys in clinical settings: Unveiling roles of β' and β1 nanophases and latent in vivo hydrogen evolution

Heat treatment serves as a viable strategy to effectively mitigate the intense corrosion of biodegradable WE43 alloys. However, limited comprehension of the passivation mechanisms underlying heat treatment and the dilemma to quantitatively examine the evolution of hydrogen gas in vivo introduce uncertainties in designing heat treatments for developing clinically applicable WE43. This work aims to advance this knowledge by applying cutting-edge atom probe tomography to provide atomic-scale insights into the passivation roles of rare earth (RE)-rich β1 (Mg3(Y, Nd)) and β' (Mg12NdY) nanophases induced by T6 heat treatment at 250 °C, and employing machine learning-based image analysis techniques to quantitatively unveil WE43’s in vivo gas evolution during a 12-week implantation. It was found that nanosized β1 and β' phases can effectively improve WE43′s corrosion resistance by inducing an accelerated passivation effect on the surface and confining the distribution of hydrogen ions in the matrix. Female rats presented slightly higher corrosion rates than male rats in weeks 1 and 4 but lower hydrogen gas volumes in vivo, while male rats possessed a superior ability to metabolise hydrogen gas in vivo. Notably, latent gas evolution against the corrosion rates was found which peaked at week 4 and subsided at week 12 despite the gradually decreased corrosion rates from week 1 to 12. This study offers insights for engineering heat treatments to develop clinically applicable WE43 with acceptable corrosion rates and in vivo gas generation at various implantation stages. Statement of SignificanceThe study aimed to reveal the role of β1 and β' nanophases on the good corrosion resistance of WE43. The influence of these nanophases on WE43′s corrosion performance has not been totally understood. Similarly, the understanding of hydrogen gas evolution as it relates to the magnesium implant's corrosion rate lacks clarity. Atom probe tomography (APT) indicates β1 and β' nanophases trap hydrogen, removing H2 from the lattice and disabling its catalytic role in Mg oxidation. Machine learning-aided analyses of computed tomography (CT) scan images indicate latent gas evolution, contradicting the monotonic in vivo H2 evolution that is widely accepted.

Explosion dynamics for thermal runaway gases of 314 Ah LiFePO4 lithium-ion batteries triggered by overheating and overcharging

Thermal runaway (TR) of LiFePO4 lithium-ion batteries (LFPs) can produce significant amounts of smoke, posing serious explosion hazards. This paper systematically investigated TR gas generation, explosion limits, explosion overpressure, and post-explosion gas compositions of 314 Ah LFPs under overcharging and overheating. Quantum chemical and explosion reaction kinetics calculations clarified the elementary reactions and compositional alterations occurring in gases and free radicals during the explosion process. The findings revealed that H2 constituted the primary component of TR gases, comprising 47.64 % and 53.12 % of the overcharging and overheating, respectively, followed by CO2 and CO. The ranges of explosion concentration for TR gases, when subjected to overheating and overcharging conditions, were 6.32–29.3 % and 6.83–26.91 %, respectively. At the point of maximum explosion overpressure (Pmax), the gas concentrations peaked at 15.86 % and 16.25 %. The elementary reaction R1 held a pivotal position in enhancing the explosion overpressure. As the TR gas concentration escalated, the Rate of Production (ROP) of R31 and R35 also surged, ultimately resulting in elevated concentrations of CO. The reactions R123, R250, and R279 facilitated the generation of H2 while simultaneously consuming hydrocarbon gases. This resulted in a risk of secondary explosion of the TR gas after the explosion. Post-explosion gas residual quantities followed the order: C2H6 < C2H4 < CH4 < H2 < CO. The results revealed crucial insights for developing explosion prevention and suppression in the process safety industry and Energy Storage Systems.

Influence of Atmospheric Gas Species on an Argyrodite-Type Sulfide Solid Electrolyte During Moisture Exposure.

Sulfide solid electrolytes have potential in practical all-solid-state batteries owing to their high formability and ionic conductivity. However, sulfide solid electrolytes are limited by the generation of toxic hydrogen sulfide and conductivity deterioration upon moisture exposure. Although numerous studies have investigated the hydrolysis degradation induced by "moisture," the influence of "atmospheric gases" during moisture exposure has not been extensively investigated despite the importance for practical fabrication. Therefore, in this study, we investigated the impact of atmospheric gases during moisture exposure on an argyrodite-type Li6PS5Cl via electrochemical impedance spectroscopy, X-ray diffraction, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. The electrolyte powder was exposed to various atmospheric gases, namely Ar, Ar + 500 ppm CO2, O2, and O2 + 500 ppm CO2, with moisture at a dew point of -20 °C, and H2S gas generation was monitored. As a result, the amount of H2S gas did not depend on the atmospheric gases. However, the atmospheric gases had a significant effect on the decrease in conductivity. Spectroscopic analyses revealed that CO2 facilitates the formation of carbonates and that O2 promotes the formation of phosphates and sulfonates. The formation of these compounds leads to surface degradation, which further decreases the conductivity.

Pressure‐Induced Capacity Recovery and Performance Enhancements in LTO/NMC‐LCO Batteries

AbstractLithium titanate oxide (LTO) batteries are a promising technology, particularly suitable for high‐power applications, owing to their inherent cyclic stability, fast charging capability, and superior safety. However, substantial gas generation and accelerated aging driven by the cathode remain substantial challenges. This study explores the mitigation of these aging mechanisms through the application of external mechanical compression. Continuous pressure of 0.3 MPa applied to pristine cells during cycling reduces capacity loss by 42% compared to unpressurized cells cycled under identical operating conditions. Applying short‐term pressure to aged cells leads to immediate capacity recovery, reclaiming up to 57% of the lost capacity. Subsequent cycling of these aged cells under continuous pressure demonstrates improved capacity retention. In contrast, intermittently applied transient pressure causes notable capacity fluctuations. This study reveals insights into aging and healing mechanisms influenced by external pressure, benefiting both first‐ and second‐life battery applications. Understanding these mechanisms is vital for enhancing performance and lifetime in battery packs, while the findings also highlight promising opportunities for capacity recovery in reused batteries.