Latest ArticlesThe complexity of lithium iron phosphate waste sources dictates the intricate composition of the solution after acid leaching. Particularly during the pretreatment process, lithium iron phosphate waste can become mixed with anode materials and may contain trace amounts of nickel, cobalt, and manganese. Therefore, in addition to the characteristic impurities of lithium iron phosphate, such as iron, aluminum, and phosphate, the acid leach solution obtained from lithium iron phosphate waste through high-pressure oxidation leaching is typically accompanied by small amounts of copper, nickel, cobalt, manganese, fluorine, and other impurity elements. On one hand, regarding product purity, if these impurity elements are not adequately removed, they may lead to the deterioration of lithium carbonate quality, adversely affecting subsequent processing. On the other hand, considering recycling value, metals like copper, nickel, and cobalt have significant market value, necessitating their recovery to improve the economic viability of the entire process.
Remove Cu, Fe, Al, P, Ni, Co, Mn and other impurities by chemical method. Removal of calcium impurities by HP4040 resin. The adsorption process of Ca2+ was correlated using kinetic equations, confirming that the adsorption process of HP4040 resin for calcium removal aligns more closely with a pseudo-second-order kinetic model. This indicates that the adsorption reaction between calcium ions and the resin is predominantly governed by chemical adsorption. Thermodynamic analysis revealed that the adsorption process of calcium ions on the resin conforms to the Langmuir isotherm model. Removal of fluorine impurities by modification of MgO-modified β-spodumene, both pseudo-first-order and pseudo-second-order kinetic equations were employed to describe the adsorption of fluoride ions onto the adsorbent. The fitting results suggest that the fluoride adsorption process largely adheres to the pseudo-second-order kinetic model. Thermodynamic analysis further indicated that the adsorption of fluoride by the defluorination agent aligns better with the Langmuir model, suggesting a preference for monolayer adsorption.
The main conclusions of this study are summarized as follows. This research systematically investigates the purification and decontamination processes of waste LiFePO4 lithium-containing leach solutions, focusing on the reduction and removal of copper, neutralization of iron, aluminum, and phosphorus, alkalization for nickel, cobalt, and manganese removal, resin-based calcium removal, and adsorption for fluoride removal. The distribution of impurity ions in the acid leach solution, including Fe, Al, Cu, Ni, Co, Mn, Ca, and F, has been analyzed throughout the decontamination process, and the entire flow of acid leach solution decontamination has been experimentally validated. The findings are as follows: To effectively reduce and remove copper, the optimal addition of iron powder is 1.1 times the theoretical amount, achieving a recovery rate of 99.95% and a copper sponge purity of 95.02%. For neutralization to remove iron, aluminum, and phosphorus, the optimal reaction conditions are a temperature of 30 ℃, an endpoint pH value of 4, and a reaction time of 30 min. Under these conditions, the impurity elements Fe, Al, and P are predominantly removed, while the loss of valuable metals like Ni, Co, and Mn is minimal. In the alkalization process for removing Ni, Co, and Mn, precipitation occurs at pH 12, with precipitation rates exceeding 99.5% for all target metals. The resin-based calcium removal process studies and compares the advantages of three commercially available calcium removal resins, ultimately selecting HP4040 resin, which demonstrates a maximum adsorption capacity of 35.28 mg/g for calcium, achieving over 91.6% single-stage calcium adsorption. Meanwhile, the synthesized MgO-modified β- spodumene adsorbent material achieves a single-stage adsorption rate of over 85.8% for fluoride, providing a pathway for developing low-cost deep fluoride removal materials.
This study systematically investigates the purification and decontamination process for waste LiFePO4 lithium leach solutions. After the reduction to remove copper, neutralization to eliminate iron, aluminum, and phosphorus, alkalization for nickel, cobalt, manganese removal, resin-based calcium removal, and adsorption for fluoride removal, the purification of the liquid obtained allows for lithium carbonate recovery.
To enhance the lithium leaching rate, carbon thermal reduction can be employed to convert lithium into lithium carbonate, thereby enabling selective recovery through water leaching. However, due to the relatively low solubility of lithium carbonate, it is challenging to significantly improve the efficiency of water leaching. Furthermore, the extent of carbon thermal reduction is highly dependent on factors such as the amount of added carbon source, reaction temperature, and reaction time. Consequently, there is an urgent need for advanced technologies that are characterized by low energy consumption, a simplified process, and high efficiency for the recovery of active cathode materials from spent lithium-ion batteries. While traditional metallurgical recovery processes can effectively extract most valuable metals from cathode waste, the current lithium extraction process typically requires multi-stage extraction or stepwise precipitation to produce lithium carbonate. This results in a lengthy back-end lithium extraction process, with intermediate steps prone to lithium metal loss, leading to a recovery rate of only 60% to 80%. In the context of comprehensive utilization recycling technologies, efficient lithium extraction and selective leaching of target elements remain bottleneck issues. To address the challenge of efficient lithium extraction, this study proposes the use of waste ternary positive and negative electrode mixed materials as raw materials, employing a process flow of "reduction roasting for priority lithium extraction" followed by water leaching and acid leaching to comprehensively recover valuable metals from the waste.
Weigh accurately an appropriate amount of experimental raw materials and transfer them into a mortar for thorough grinding. Subsequently, transfer the ground materials into a corundum crucible. Place the crucible containing the raw materials into a tube furnace for roasting. Prior to initiating the program, introduce argon gas at a flow rate of 200 mL/min for 30 min to ensure an inert atmosphere. Heat the materials at a controlled heating rate of 5 ℃/min until reaching the set temperature. Once the temperature naturally decreases to room temperature, carefully weigh the mass of the roasted product and record the mass difference before and after roasting. Transfer the roasted product into a beaker, add pure water at a liquid-to-solid ratio of 80 mL/g, and stir using a mechanical stirrer at a constant speed of 500 r/min. Systematically investigate the effects of roasting temperature (500-700 ℃), roasting time (30-150 min), and stirring time (water leaching time of 2-10 h) on the leaching rate of lithium. Calculate the mass differences of various elements based on the recorded mass differences of the roasted products before and after treatment, combined with the leaching efficiency.
Using the positive and negative electrode mixtures from waste lithium-ion batteries as raw materials, lithium was selectively extracted via an in-situ reduction roasting-water leaching process without requiring additional reagents. Single-factor experiments were conducted to determine the optimal process conditions, which were identified as a roasting temperature of 600 ℃, a roasting time of 30 min, and a stirring time of 4 h. Under these conditions, the leaching rate of Li reached 72.23%, while Ni, Co, and Mn exhibited negligible leaching. The elemental contents before and after carbon-thermal reduction were quantitatively analyzed using SEM-EDS. In conjunction with ICP-OES detection results, it was determined that the raw materials contained impurities such as Al, F, and P. Carbon-thermal reduction reactions of commercial ternary cathode materials free of impurities were performed under identical conditions. The leaching rate of Li from the pure ternary material reached 96.6%, significantly higher than that achieved with impure materials (72.23%). Roasting products under various conditions were characterized by X-ray diffraction. It was observed that as the roasting temperature increased from 500 ℃ to 600 ℃, the characteristic peaks of NCM disappeared, indicating the complete destruction of the NCM (LiNixCoyMn1-x-yO2) crystal structure. The resulting roasting products primarily consisted of Li2CO3, Co, Ni, CoO, NiO, and unreacted graphite.
The optimal process were identified to be roasting temperature of 600 ℃, roasting duration of 30 min, and stirring time of 4 h, through single-factor experiments. The lithium leaching efficiency of 72.23% was achieved, while nickel, cobalt, and manganese exhibited negligible dissolution. Notably, under identical conditions, commercially sourced pure ternary cathode materials demonstrated significantly enhanced lithium recovery at 96.6%, maintaining minimal co-leaching of transition metals (<0.5%). To optimize the comprehensive lithium recovery efficiency in spent lithium-ion battery recycling, strategic introduction of additives capable of exerting synergistic reduction effects during the carbon thermal reduction stage is proposed. Subsequent research should focus on systematic evaluation of additive economics coupled with rigorous quantification of their lithium extraction enhancement potential.
The advancement of solid oxide cells (SOCs) technology has led to a reduction in the operating temperature to 700-800 ℃, substantially enhancing the long-term stability of cells. However, as the temperature declines, the sluggish oxygen reduction/oxygen evolution reaction (ORR/OER) at the oxygen electrode emerges as a critical constraint on SOCs power output efficiency. (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF), renowned for its excellent ORR/OER catalytic and electrical conductivities, is widely adopted in SOCs oxygen electrodes. However, its inherent drawback lies in the incompatibility of its thermal expansion coefficient (TEC) with traditional electrolytes like GDC and YSZ, often inducing fuel cell or stack failure during cycling due to thermal stress. To address this interface compatibility issue, combining LSCF with an electrolyte material, specifically Sm0.2Ce0.8O2-δ (SDC), to form a composite electrode proves to be viable. This not only mitigates the average TEC but also optimizes the reaction kinetics. In this study, LSCF and SDC materials were synthesized via the sol-gel method, and the impacts of varying SDC content in the composite electrode on phase structure, conductivity, thermal expansion, and ORR/OER performance were meticulously examined. Results indicate that SDC incorporation effectively curtails the material TEC, enhances ionic conductivity, and boosts ORR/OER activity. Ultimately, the LSCF/40SDC composite electrode manifests remarkable electrochemical performance and long-term stability in fuel cell and water electrolysis mode.
A series of LSCF/xSDC composite electrodes were synthesized using the sol-gel method. Detailed structural analyses of the materials were conducted by X-ray diffraction (XRD). Electrical conductivity and thermal expansion coefficient of electrode strips were measured from room temperature to 800 ℃. Electrochemical impedance spectroscopy of symmetrical cells was performed, while the electrochemical performance and long-term stability of single cells were evaluated by electrochemical workstation.
XRD results confirm pure phase LSCF and SDC were prepared via sol-gel method. LSCF exhibits a hexagonal perovskite structure, and SDC oxide adopts a cubic fluorite configuration. The composite powders exhibit only the characteristic diffraction peaks of LSCF and SDC, confirming their excellent chemical compatibility. The conductivity of LSCF/xSDC materials ascends steadily within 200-600 ℃. Above 600 ℃, the conductivity declines with the increasing temperature. Thermal expansion tests clearly demonstrate that combining strategy with SDC electrolyte markedly diminishes the TEC of LSCF electrode, achieving better alignment with the TECs of YSZ and SDC (10.5×10-6 K-1 and 11.4×10-6 K-1 respectively).
Impedance analysis of symmetrical cells shows that increasing SDC content leads to a continuous reduction in polarization impedance. This stems from SDC-induced enhancements in material ionic conductivity and expansion of the electrode reaction three-phase interface, thereby improving oxygen catalytic capacity. The Distribution of Relaxation Times (DRT) outcomes for LSCF/40SDC at 650-850 ℃ signify that elevated temperatures notably propel each electrode reaction step, particularly influencing the oxygen surface and interface charge transfer processes.
Electrochemical performance analysis of single cells indicates that a higher SDC proportion correlates with stronger oxygen electrode catalytic ability and improved cell performance, with the LSCF/40SDC cell exhibiting best performance. Moreover, composite SDC significantly boosts hydrogen production efficiency during water electrolysis, attributable to enhanced oxygen electrode OER activity and reduced electrode reaction polarization resistance. After 400 h of stable operation, the cell voltage diminishes marginally from 0.70 V to 0.68 V, yielding an degradation rate of 7.15%/1000 h The cell microscopic morphology remains intact, with tight cohesion among the oxygen electrode, isolation layer, and electrolyte without devoid of detachment or separation. La, Sr, Co, and Fe are uniformly distributed, with no interdiffusion or chemical reaction occurrences after the long-term test.
(La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ perovskite and Sm0.2Ce0.8O2-δ powders were synthesized by sol-gel method, The effect of SDC content on material crystal structure, conductivity, thermal expansion coefficient, and electrochemical performance were investigated. The LSCF/40SDC material offers a superior TEC match with the electrolyte. In symmetrical cell tests, LSCF/40SDC presents the lowest polarization resistance and reduced activation energy. In full cell tests at 750 ℃, the peak power density surges to 1132 mW/cm2, 1.87 times that of the base LSCF electrode. During water electrolysis at 1.3 V, the full cell with the LSCF/40SDC electrode attains a current density of -875 mA/cm2. Notably, the LSCF/40SDC cell sustains stable operation for 400 h under 750 ℃ and 1000 mA/cm2 discharge conditions, with an ultra-low attenuation rate of 7.15%/1000 h epitomizing outstanding long-term stability.
Cement concrete materials are one of the most widely used building materials in modern infrastructure, but their production process is associated with high energy consumption and significant carbon emissions, imposing substantial environmental and resource pressures. While traditional mineral admixtures (such as fly ash and slag) can improve concrete workability, enhance mechanical properties, reduce hydration heat, and improve durability by partially replacing cement, they suffer from low early-stage activity. The application of advanced grinding or sorting technologies to refine mineral admixtures into ultrafine particles has proven effective. This process increases the specific surface area of the admixtures, thereby enhancing particle surface energy and reactivity, which compensates for the deficient early-stage activity of conventional mineral admixtures. Ultrafine mineral admixtures demonstrate remarkable potential in improving concrete workability, early-stage mechanical performance, and durability. In recent years, this approach has garnered widespread attention in academic and industrial research.
This paper first elucidates the characteristics of fly ash microsphere, ultrafine fly ash, and ultrafine slag powder. Subsequently, it systematically investigates the impacts of these three typical ultrafine mineral admixtures on various properties of cement and concrete, accompanied by comparative analyses of their performance differences compared with conventional mineral admixtures. Furthermore, the intrinsic properties, compatibility design principles, and comprehensive effects of ultrafine composite mineral admixtures on cement concrete performance are expounded. Finally, the current application status of ultrafine mineral admixtures in cement concrete is summarized. Ultrafine mineral admixtures exert multiple beneficial effects in cementitious systems, including filling effect, morphological effect, nucleation effect, pozzolanic effect, density effect, dispersion effect, specific surface area effect, and interfacial effect. Their dosage and fineness significantly influence critical parameters such as water demand for standard cement consistency, setting time, rheological properties, and hydration heat release. Appropriately formulated fly ash microsphere, ultrafine fly ash, or ultrafine slag powder with optimized fineness can enhance concrete workability, improve durability, inhibit shrinkage, and suppress alkali-aggregate reactions, though potentially compromising carbonation resistance. These materials also demonstrate pore structure refinement, microstructural optimization, and mechanical performance enhancement. The primary distinction between ultrafine and conventional mineral admixtures (e.g., fly ash and slag) lies in particle fineness, which yields differential performance outcomes despite sharing identical chemical reaction mechanisms. Conventional admixtures typically enhance concrete workability, long-term strength, and durability at the expense of early-age strength reduction. In contrast, ultrafine variants leverage superior pozzolanic reactivity and filling capability, where the increased specific surface area amplifies nucleation effects, leading to significant improvements in early-age strength development and workability. Their micro-aggregate effect and enhanced pozzolanic activity further contribute to more pronounced durability enhancement. Compared with single-type ultrafine admixtures, ultrafine composite mineral admixtures employ "gradient hydration" and "functional complementarity" mechanisms to synergistically accelerate hydration processes. This strategy effectively increases amorphous C-S-H gel formation, optimizes pore structure of hardened paste, and enhances matrix compactness through multi-scale interactions. In the concrete mix design, the dosage of ultrafine mineral admixtures is recommended to be controlled between 20% and 35%, which can significantly improve the workability and mechanical properties of concrete. However, excessive dosage may trigger a significant dilution effect, which is detrimental to the overall performance of concrete. Ultrafine mineral admixtures have shown great application potential in enhancing the workability of cement-based repair materials, manufacturing cement-based refractory materials, producing high-performance insulation materials, enabling steam-free curing of prefabricated components, and improving the comprehensive performance of ultra-high-performance concrete (UHPC). Currently, the application of ultrafine mineral admixtures mainly faces two major challenges: First, the relevant standard and specification system is still incomplete. Second, it is challenging to produce ultrafine powders that meet the standard requirements using diverse and complex raw materials. Due to the complex sources of mineral admixtures, the performance of ultrafine mineral admixtures can vary significantly, and improper dosage control may adversely affect the performance of concrete. Therefore, it is urgent to improve the standard specifications, enhance the preparation processes and equipment, reduce energy consumption and pollution, and further investigate their effects on the hydration mechanisms of cementitious materials to promote their wider application.
Compared with traditional mineral admixtures such as fly ash and slag, ultrafine mineral admixtures, characterized by higher specific surface area and pozzolanic reactivity, have shown significant advantages in improving the workability, mechanical properties, and durability of cementitious materials. Against the backdrop of green and low-carbon transformation in the cement and concrete industry, significant progress has been made in the application research of ultrafine mineral admixtures. By reducing the clinker factor and decreasing the cement content per unit of concrete, they provide an effective pathway for achieving sustainable development in building materials. Future research should focus on the following key areas: First, improving existing grinding equipment and processes to achieve rational composite grinding of mineral admixtures, thereby enhancing quality and reducing costs. Second, leveraging artificial intelligence technology to accurately predict the performance of ultrafine mineral admixtures, significantly improving design efficiency. Third, conducting in-depth studies on the hydration synergistic effects and microstructural evolution mechanisms of different ultrafine mineral admixtures. Fourth, refining technical standards and specifications to promote product quality improvement and the expansion of application fields. With technological advancements and increasing environmental demands, ultrafine mineral admixtures will play a more important role in enhancing the performance of cement concrete, reducing costs, and driving the development of green buildings.
The precise characterization of microstructure in cement-slag blended pastes is pivotal for understanding reaction mechanisms and optimizing material performance. Traditional methods relying on single-model analysis face limitations in distinguishing phases with similar grey value ranges and integrating multi element mappings. This study proposes an intelligent Backscattered electron and Energy-Dispersive X-ray Spectroscopy (BSE-EDS) image analysis methodology, integrating standardized pre-processing procedures, Potential of Heat-diffusion for Affinity-based Trajectory Embedding and Gaussian Mixture Model (PHATE-GMM) based phase identification model, and Glue-based Multiview visualization, to achieve multimodal characterization of cement-slag pastes. The framework bridges the gap between the BSE image and EDS element mappings with multimodal features in cementitious systems, enabling comprehensive phase identification, element migration analysis, chemical composition analysis, phase evolution tracking, and microstructure quantitative characterization.
Cement-slag paste (30% slag replacement ratio, water-to-binder ratio 0.4) were prepared, cured (0, 7 d and 14 d), and examined by Scanning electron microscope (SEM) after epoxy impregnating and polishing. The BSE image, qualitative element mappings, and quantified element mappings were acquired with accelerating voltage of 15 kV, working distance of 11 mm. A BSE-EDS data preprocessing pipeline was developed: (1) Guided filtering enhanced EDS element mapping resolution using BSE image as guided image; (2) Generating phase masks excluding pore and epoxy interference; (3) Super-pixel segmentation on phase region (10 000 units) to integrates grey value information from BSE images and element information from quantified element mappings. The PHATE-GMM model combined PHATE dimensionality reduction algorithm for 2D visualization with GMM for clustering PHATE-derived attributes, achieving automated and interpretable phase identification. Glue platform enabled synchronized multi-view interactive analysis (element scatterplots, phase maps, PHATE plots, element histograms, density plots) to validate phase identification results and explore phase relationships.
PHATE-GMM model achieved great consistency with visual inspection-labeled phases. In raw materials, distinct clusters corresponded to cement clinker, slag and gypsum. The C3A/C4AF phases are frequently embedded within the C2S/C3S phases, which results in partial super-pixel regions containing both phases during super-pixel segmentation. Consequently, interconnected clusters can be observed in PHATE plot. For hydrated pastes, rim phases (e.g., C2S/C3S-rim, slag-rim, CH-rim) emerged as transitional zones between critical phases and C-S-H. The spatial distribution and element composition analyses of both slag-rim and slag demonstrate that the slag-rim exhibits a lightly higher Mg/Ca ratio compared to slag, indicating a distinct enrichment of Mg ions in the rim region. Local analysis mode via Glue facilitates element exploration in un-clustered cementitious systems, particularly for complex or novel binders. Global analysis mode via Glue, suitable for well-characterized cementitious systems. PHATE-derived element density maps further enable visualization of ion migration pathways. The phase network topology diagram achieves tri-dimensional synergistic representation through spatial positioning, radial scale, and connection line thickness parameters, while preserving the original relational information between phases shown in PHATE plots and simultaneously incorporating phase content features. The BSE-EDS image intelligent analysis methodology established in this study enables efficient and accurate determination of pore and phase in cement-slag binders, thereby enabling multiple downstream applications including elemental composition analysis of phases, investigation of evolutionary patterns, and quantitative characterization of microstructure.
1) The proposed pipeline for generating BSE-EDS datasets demonstrates strong generalizability and practicality, effectively mitigating the impact of pore interference and excessive interaction volume on phase identification, providing a viable data management solution for multimodal feature extraction and downstream analysis in cementitious systems.
2) The developed PHATE-GMM phase identification model exhibits high interpretability and intelligence, enabling comprehensible automated phase identification. The visualization structure of PHATE plot offers novel analytical insights for scientifically describing reaction mechanisms and microstructure evolution in cementitious systems.
3) The Glue-based multimodal feature analysis technique facilitates synchronous and interactive exploration of chemical and spatial modalities, allowing for expert-guided optimization of automated phase clustering results.
4) The intelligent BSE-EDS image analysis methodology enables comprehensive downstream applications, which fully exploits the analytical potential of BSE-EDS for microstructural characterization, realizing the technical vision of "single independent micro-characterization - multimodal feature fusion analysis".
The pursuit of carbon neutrality has become one of global priorities, requiring the widespread adoption of electrification technologies across various sectors, including transportation, industrial processes, and residential applications. A critical factor in this transition is the integration of distributed energy systems that harness renewable energy sources, such as solar, wind, and hydroelectric power. These intermittent energy sources necessitate advanced energy storage systems to ensure a continuous and efficient energy supply. Among the various energy storage technologies under investigation, lithium-ion batteries (LIBs) have emerged as the most widely applied due to their high energy density, long cycle life, and scalability. However, the rapid growth in LIB ownership and demand has led to concerns about resource scarcity and the environmental pollution caused by spent batteries. Traditional recycling methods, such as pyrometallurgy and hydrometallurgy, although mature and widely used, suffer from several disadvantages, including high energy consumption, substantial pollution, lengthy processing times, and high costs. These limitations make them unsuitable for meeting the modern industry's demands for efficiency, economic viability, and environmental sustainability. Therefore, there is an urgent need to develop rapid, efficient, and environmentally friendly direct repair methods for battery materials.
This review begins by examining the failure mechanisms of electrode materials and extends to the current advancements in electrode material repair methods. The failure mechanisms can be broadly categorized into active material degradation and interface reaction failures. Cathode materials, due to their higher recovery value, have attracted significant attention and research. The main recovery methods for cathode materials include solid-state sintering regeneration (SSR), hydrothermal regeneration (HTR), electrochemical regeneration (ECR), eutectic salt regeneration (ESR), and chemical lithiation regeneration (CLR). Among these, solid-state sintering and hydrothermal regeneration are the most technologically mature, with the highest industrial potential. However, both methods still require prolonged high-energy input, raising concerns regarding their economic and environmental sustainability. On the other hand, anode material recycling, driven more by the need to extract valuable metals than by economic incentives, primarily focuses on upgrading waste materials.
Compared to traditional synthesis techniques, which suffer from high energy consumption and inefficiency, ultra-fast synthesis technology can instantaneously release large amounts of energy to quickly initiate chemical reactions. After the reaction is completed, energy input can be rapidly withdrawn to facilitate efficient cooling. This technology has attracted increasing attention in the materials synthesis field due to its efficiency and low energy consumption. The review then summarizes representative methods, including Joule heating, laser-assisted techniques, and microwave-assisted techniques, discussing their advantages, disadvantages, and applicability. It also analyzes the thermodynamic and kinetic differences between ultra-fast and traditional synthesis methods, emphasizing how ultra-fast synthesis breaks through conventional limitations by combining ultra-high temperatures with instantaneous reaction times. This approach provides new pathways for the novel synthesis of advanced functional materials, such as energy materials, high-performance catalysts and high-strength metal materials.
Ultra-fast synthesis, with its low energy consumption and high efficiency, is rapidly becoming a critical breakthrough in the field of electrode material repair and regeneration. This review comprehensively outlines recent advancements in ultra-fast synthesis for both cathode and anode materials. Ultra-fast synthesis has successfully facilitated the regeneration of electrode materials such as LiCoO2 (LCO), LiFePO4 (LFP), LiNixCoyMn1-x-yO2 (NCM), graphite anodes, and silicon-based anodes. Despite the promising progress, challenges remain in scaling up ultra-fast synthesis for industrial applications. Precise control over energy input and product quality uniformity is crucial for industrial implementation. Moreover, the adaptation of ultra-fast synthesis to various material systems and a deeper understanding of the reaction mechanisms are ongoing research topics. The rapid development of artificial intelligence (AI) offers new opportunities for integrating AI into ultra-fast synthesis, enabling better process optimization and outcome prediction. In conclusion, ultra-fast synthesis represents a revolutionary approach in battery material repair and regeneration, offering a promising alternative to traditional recycling methods and supporting the transition towards a more sustainable energy future.
This review comprehensively summarizes the development background, application progress, and challenges faced in the recycling and repair of battery materials, with a focus on ultra-fast synthesis technology. Compared to traditional methods, ultra-fast synthesis has made significant advancements in the field of battery materials due to its speed, efficiency, and environmental sustainability. It has increasingly become the focal point of research. Meanwhile, the rapid development of artificial intelligence technology has provided strong support for deepening the understanding of the mechanisms behind ultra-fast synthesis, guiding its research direction, and improving its adaptability for industrial applications. Looking ahead, with the continued advancement of green low-carbon technologies and the growing demand for efficient recycling techniques, ultra-fast synthesis is expected to play a crucial role in promoting the recycling and utilization of battery materials, driving industrial upgrades, and providing key momentum for the sustainable development of the new energy industry through continuous innovation and optimization.
Female scientific talents constitute a critical force in the field of inorganic non-metallic materials, having made remarkable contributions to disciplinary development. This paper examines the status and challenges faced by female researchers in project applications, research funding, and career advancement by analyzing supporting policies implemented by the inorganic non-metallic materials discipline (hereinafter referred as "the discipline") under the national natural science foundation of China (NSFC) in recent years. Here the paper evaluates the effectiveness of these policy measures in promoting the growth of female scientific talents, thereby providing empirical support for the discipline policy making and the sustainable development of outstanding female researchers. Looking ahead, the discipline will intensify efforts to cultivate female reserve talents, continuously advance the reform of the science funding system, and enhance the innovative contributions of female researchers to China's scientific self-reliance and technological independence in the inorganic non-metallic materials domain.
With the rapid development of portable electronic devices and electric vehicles, the production and demand of lithium-ion batteries (LIBs) have increased exponentially. Due to the limited life of LIBs, a huge amount of spent LIBs will inevitably be produced in the next 10~20 years. Efficient and clean recovery of spent LIBs is significant for resource recycling and environmental protection. In the recovery process, the cathode active material containing valuable metals must be separated efficiently from the Al foil collector. This procedure is a crucial link to reduce the difficulty of subsequent metal extraction and to achieve resource recovery. However, the organic binder polyvinylidene fluoride (PVDF), due to its strong adhesion and stability, has become a critical factor hindering the separation of cathode active materials. Currently, the methods for separating cathode active materials from Al foils can be classified into physical, thermal treatment, solvent dissolution, and electrochemical methods. The physical methods include mechanical crushing and grinding. The active materials separate when the cathode is exposed to mechanical forces in a shredder or impact/shear crusher. However, using mechanical crushing or conventional grinding methods are difficult to remove the organic binders on the active material surface only by mechanical force.
Depending on the difference in thermal stability of the PVDF, Al foil and the active material, melting or degrading the PVDF binder on the surface of the cathode material can be used to separate the cathode active material. Direct calcination of PVDF is prone to pollutant emissions, and the pyrolysis process using a fully enclosed environment allows for better control and treatment of pollutant gases. Meanwhile, alkaline calcium oxide can accelerate the catalytic degradation of PVDF and enable the in-situ capture of inorganic fluoride. Apart from direct calcination/pyrolysis, new technology, such as molten salt-mediated treatment, can achieve the melting or degradation of PVDF in solid thermal media, detaching the cathode material from the Al foil and preventing the release of fluoride.
Traditional strong polar organic solvents such as NMP, DMF, etc. can dissolve the binder by using the principle of similar solubility. However, the volatility and toxicity of these solvents are important obstacles to large-scale applications. The exploitation of organic solvents such as ethylene glycol and triethyl phosphate is expected to enable the replacement of highly volatile organic solvents. In addition, ionic liquids and deep eutectic solvents, as the new generation of green solvents, have shown potential for application in the separation of cathode materials. In addition to organic solvents, alkaline dissolution, oxidation by Fenton's reagent and electrochemical methods as representative of aqueous systems provide diverse options for the separation of cathode materials.
In summary, the current separation of spent LIBs cathode materials from the collector has made remarkable progress. In terms of overall effect, the current separation methods have successfully separated the cathode material from the collector Al foil, and the basic principles and process methods have been well investigated. However, analysis from a partial point of view, there are still some problems that need to be solved for different separation methods in terms of environment, economy and scale of use. Although the physical method has been widely used in industrial practice, problems such as low separation accuracy remain. The separation effect can be improved by the combined use of heat treatment method and physical method, i.e., the binder is removed by pyrolysis followed by crushing and sorting. This method achieves the separation of active materials from metal foils and substantially reduces the content of metal impurities in the active materials. However, this method is still difficult to achieve high-precision separation, and the development of more efficient physical separation methods and processes is still an important direction for future research. Compared with the physical method, the chemical method separates with higher precision. However, traditional chemical separation of active materials mostly uses toxic or volatile substances, with a high risk of secondary pollution. Fenton oxidation and supercritical fluid are green and environmentally friendly, but the high cost makes it difficult to industrialize and promote the application. The development of green, safe and low-cost solvents to achieve economic and efficient separation of active materials is another important direction that needs attention in the future.
Alkaline environment-induced (Basalt fiber reinforced polymer) BFRP bars degradation is the prominent issues to BFRP-reinforced seawater sea sand concrete (SSSC) durability. A new type of basalt-carbon hybrid FRP (HFRP) bars was developed to improve the mechanical properties and durability of BFRP bars in marine environments. Herein, the effect of simulated SSSC pore solution alkalinity on the durability of HFRP bars was studied. Macro- and micro-properties of HFRP samples were tested, i.e., tensile properties, interlayer shear properties, microstructure, chemical composition, and chemical stability. Meanwhile, the degradation mechanism of HFRP bars in simulated SSSC pore solutions with different alkalinity has also been summarized. The results show that compared with BFRP bars, the initial tensile strength of HFRP bars has been significantly improved, and its interfacial strength has not weakened. After 90 d of corrosion, the increase in alkalinity leads to a maximum decrease in tensile strength and interlayer shear strength degradation of 19.67% and 23.43%, respectively. The degradation of HFRP bars includes fiber etching, resin hydrolysis, degradation of interfaces on fiber/resin and BFRP/CFRP. The smaller diameter and excellent corrosion resistance of carbon fiber, and BFRP/CFRP interface barrier function delay the penetration and corrosion of moisture and existing ions, i.e., Cl- and OH-, improving the durability of HFRP bars in high alkaline SSSC environments.
Tensile properties, interlayer shear properties, microstructure, chemical composition, and chemical stability of HFRP bars in simulated SSSC pore solution with different alkalinity were systematically measured. The research mainly adopts a combination of macroscopic performance testing and microscopic testing analysis.
Both epoxy resin based BFRP and HFRP bars with a nominal diameter d of 10 mm were prepared by pultrusion process. HFRP bars consists of inner and outer cores made of CFRP and BFRP materials, respectively. The volume fraction of carbon fiber replacing basalt fiber was 25%.
Three alkaline salt solutions with different pH values were designed to study the effects of simulated SSSC pore solution alkalinity on HFRP bars. The ordinary SSSC pore solution (Ca(OH)2 2 g/L, KOH 19.9 g/L, NaOH 2.4 g/L) was prepared from seawater with a pH value of 13.2. Two lower alkalinity SSSC pore solutions with pH value of 12.3 and 10.1 were diluted with artificial seawater, respectively. All corrosion exposure experiments were conducted in a constant temperature water tank at 55 ℃.
The tensile performance was evaluated according to ACI 40.3R-12. The total length of the sample was 1000 mm, and the testing section was 10 d. The interlayer shear performance was determined based on ASTM D4475. The length and span of the sample were 7d and 6d, respectively. All experiments were conducted using MTS testing. The testing rates for tension and interlayer shear are 2 mm/min and 1.3 mm/min, respectively.
Digital microscopy (DM) and SEM-EDS were used to analyze the corrosion morphology and composition of BFRP and HFRP bars after corrosion. AFM was used to analyze the microstructure of the transition zone at the BFRP/CFRP interface.
The macroscopic morphology analysis results indicate that the carbon fiber hybrid did not change the tensile line elastic failure mode and interlayer interface failure modes of HFRP bars. Compared to BFRP bars, the ultimate load of HFRP bars was increased, and the explosive fibers during failure were significantly reduced with the extension of corrosion time and the increase in simulated SSSC pore solution alkalinity; Both BFRP and HFRP bars interlayer interface failures involve a main crack that runs through and deviates from the BFRP/CFRP interface.
The carbon fiber hybrid improves the tensile properties and interlayer interface properties of HFRP bars, and enhances its corrosion resistance in alkaline simulated SSSC pore solution. Taking tensile strength as an example, compared with BFRP bars, the tensile strength of BFRP bars in simulated SSSC pore solutions with pH values of 10.1, 12.4, and 13.2 was 78.48%, 71.20%, and 26.20% of its original value, while the corresponding values of HFRP bars were 87.86%, 85.22%, and 55.26%, respectively. After 90 d of corrosion, the maximum decrease in tensile strength and interlayer shear strength due to the increase in alkalinity was 19.67% and 23.43%, respectively.
The degradation of HFRP bars in alkaline SSSC pore solution includes fiber etching, resin hydrolysis, and degradation of fiber/resin interfacial and BFRP/CFRP interfacial properties. The smaller diameter of carbon fiber, excellent corrosion resistance, and BFRP/CFRP interface barrier function delay the penetration and corrosion of moisture and existing ions, improving the durability of HFRP bars in high alkaline SSSC environments.
The global transition toward renewable energy and electric vehicles has triggered exponential growth in lithium-ion batteries (LIBs), resulting in a surge of retired batteries. As the predominant anode material in LIBs, graphite accounts for a significant mass proportion of batteries. However, improper disposal of spent graphite (S-Gr) through incineration or landfilling poses severe environmental risks, including particulate emissions and toxic residue release. Recycling S-Gr is critical to alleviating resource shortages, reducing production costs of high-purity graphite (which requires energy-intensive graphitization processes at 2500-3000 ℃), and achieving sustainable development goals. This review focuses on the failure mechanisms, recycling strategies, and reuse pathways of S-Gr, providing key insights for advancing closed-loop battery ecosystems.
The degradation of graphite anodes during LIB cycling originates from multiscale failure mechanisms. Deterioration of the solid electrolyte interphase (SEI) caused by chemical decomposition, mechanical stress, and thermal instability leads to irreversible lithium loss and capacity fade. Concurrently, lithium dendrite growth on graphite surfaces increases internal short-circuit risks, while repeated Li+ intercalation/deintercalation induces microcracks and structural collapse of graphite layers. These coupled mechanisms initiate a vicious cycle of performance degradation, highlighting the necessity for tailored recycling approaches.
Current recycling technologies focus on efficient separation and purification of S-Gr. Physical methods (e.g., flotation and sieving) achieve preliminary separation but suffer from impurity retention (purity <73.56%). Innovative techniques such as Fenton reagent-assisted flotation and pyrolysis-ultrasonic synergy enhance recovery efficiency, but face scalability challenges. Hydrometallurgical processes utilizing HCl, H2SO4, or organic acids (e.g., citric acid) effectively leach impurities like Li, Al, and Fe but generate corrosive waste. Pyrometallurgical approaches (e.g., inert atmosphere calcination and catalytic graphitization) restore graphite crystallinity but demand high energy consumption (>2600 ℃) and emit hazardous gases. Hybrid strategies combining hydrometallurgical treatment with high-temperature annealing emerge as promising solutions.
Regenerated S-Gr demonstrates versatility in energy storage and functional applications. For secondary batteries, carbon-modified S-Gr via rapid thermal shock or phenolic resin coating exhibits superior performance in LIBs. In sodium/potassium-ion batteries, defect-engineered S-Gr shows enhanced kinetics and stability. Beyond energy storage, S-Gr can be transformed into high-value materials. Advanced applications include graphene production through lithium-intercalation exfoliation and catalytic composites for environmental remediation.
Despite progress, critical challenges persist. The heterogeneity of S-Gr sources (natural, synthetic, or composite graphite) complicates standardized recycling. High costs, toxic emissions (e.g., fluorine), and intensive energy-consuming steps hinder process scalability. Future directions should prioritize intelligent sorting systems, AI-driven process optimization, and green alternatives like bioleaching. Integrating ultrasound, microwave, or electrochemical technologies could streamline processes and reduce energy consumption. Expanding S-Gr applications (e.g., flexible electronics, CO2 capture, and defect-engineered catalysts) requires interdisciplinary innovation. Addressing these issues will accelerate commercialization of S-Gr recycling technologies, promote sustainable battery ecosystems, and advance global carbon neutrality goals.
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