The imbalance between the rapid growing market of lithium-ion batteries (LIBs) and the limited lithium reserves in the earth's crust hastens the urgent need to recycle spent LIBs. As the dominant in current power and energy storage batteries, the development of recycling technology for LiFePO4 batteries has naturally attracted tremendous attention. However, traditional LiFePO4 recycling strategies often involve stringent reaction conditions, complex processes, and lower economic benefits. In response, we have developed a "two birds with one stone" recycling and regeneration process for spent lithium iron phosphate (LiFePO4, LFP). This method achieves efficient separation and extraction of key elements by ion exchange resins (Total Li extraction rate of 99.5%, total Fe recovery rate of 96.2%, P recovery rate of 99.7%), which is comparable to most reported methods. Notably, the recovered FePO4, Fe2O3, and waste liquids are employed to synthesize Na4Fe3(PO4)2P2O7 cathode material suitable for sodium-ion batteries (SIBs), while also yielding high-value-added Li2CO3 as a by-product. Environmental and economic assessments confirm that the process offers advantages over conventional routes in terms of lower cost and reduced environmental pollution. This strategy simultaneously achieves high lithium recovery rates and the high-value transformation of low-value-added recycling products, demonstrates the significant advantages of this spent LFP recycling route in terms of its green closed-loop nature, high feasibility, and considerable economic benefits.

Lithium-ion batteries subjected to extreme operating conditions-such as high temperature, high C-rates, and deep overdischarge- exhibit rapid and coupled aging behaviors that are challenging to disentangle using conventional diagnostics. While purely data-driven models often lack interpretability ("black-box"), physics-based methods typically require measurements unavailable in practical applications. To bridge this gap, we propose the SIX-ICA framework, an interpretable machine learning approach that integrates Incremental Capacity Analysis (ICA) features with an XGBoost regressor and SHAP analysis. By extracting mechanism-informed ICA peak features from routine cycling data, the framework achieves robust State-of-Health (SOH) estimation. Crucially, SHAP analysis provides transparent feature attribution, linking statistical inputs directly to degradation pathways. Validated on LiFePO4/graphite pouch cells cycled at 65 degrees C and 3 C (comparing 2.5 V vs. 1.0 V cutoffs), the framework identifies Loss of Lithium Inventory (LLI) as the primary driver of capacity fade, noting its significant intensification under deep over-discharge, while Loss of Active Material (LAM) plays a secondary role. These findings are corroborated by OCV fitting and post-mortem characterization. This workflow advances interpretable SOH diagnostics under extreme conditions and offers a scalable route for other battery chemistries.

High-Voltage Fragmentation is a novel comminution technology that utilizes shock waves generated in water by nanosecond pulsed voltages with fast rise times (<500 ns) to fracture materials, offering significant advantages in energy efficiency and environmental friendliness. This study established an underwater pulsed discharge experimental platform to meet the fast-rise-time pulse parameter requirements. It analyzed the influence patterns of the needle-mesh electrode gap distance, the needle electrode tip radius of curvature, and water conductivity on shock wave pressure intensity and time-domain characteristics. The research found that the energy conversion efficiency of underwater pulsed discharge is significantly affected by the pre-breakdown process. The peak pressure, impulse, velocity, and rise slope of the shock wave exhibit a trend of initially increasing and then decreasing with increasing needle-mesh electrode gap distance and needle electrode tip radius of curvature. The maximum pressure intensity, maximum equivalent wave velocity, maximum rise slope, and shortest wavefront time occurred at a 20 mm gap distance and a needle electrode tip curvature radius of 0.45 mm. Both pressure intensity and propagation velocity initially increased and then decreased with increasing water conductivity, reaching their maxima at a water conductivity of 340 μS/cm. Water conductivity showed no significant effect on rise slope and wavefront time.

The lithium-ion batteries are always under a certain mechanical pressure when they are being used. This pressure has a tremendous influence on the extent to which the electrodes expand and shrink, as well as affecting the interface stabilities of electrodes. Nevertheless, we do not have a complete realization of the effect of mechanical pressure on battery performance and failure. The chemical and mechanical nature of the solid electrolyte interphase (SEI) under applied pressure is still not thoroughly understood. This further affects the performances of positive and negative electrodes. In this study, we investigated the pivotal role of mechanical pressure on LiFePO4/graphite full battery by testing LiFePO4/graphite full battery with and without external pressure. We discovered that the battery exhibits superior high-rate performance with an appropriate level of pressure. It was demonstrated that pressure assists in developing a robust and LiF-enriched SEI onto the graphite anode. This superior SEI film not only effectively preserves the graphite crystal structure but also prevents the movement of damaging substances of the cathode in the battery. Furthermore, on the cathode side, the corrosion of aluminium current collector is minimized, and the reversible phase transition of LiFePO4 is accelerated by pressure. This work systematically elucidates the effect of mechanical pressure in slowing down the degradation of the batteries, which is associated with the coupling of chemical and mechanical effects at the interface and the interaction between the anode and cathode. These results provide novel theoretical and practical insights for designing of superior and prolonged lithium-ion batteries based on mechanical control.

The growing demand for portable power has triggered a sharp increase in end-of-life lithium-nickel-cobalt-manganese oxide (NCM) batteries. Efficient recovery of NCM cathode materials is crucial for resource security. This study investigates an ascorbic acid-tartaric acid leaching system for extracting cobalt and manganese from spent NCM batteries. Temperature influences the leaching efficiencies of cobalt and manganese. Leaching efficiencies increase from 50 to 80 degrees C, consistent with the Arrhenius law. However, beyond 80 degrees C, side reactions inhibit cobalt leaching. Leaching efficiency increases with time over the range of 40 to 120 min, and then stabilizes at equilibrium. Ascorbic acid concentration plays a critical role. Within 0-1.5 mol/L, ascorbic acid promotes dissolution through reduction and coordination. At higher concentrations, excess H+ ions hinder complex formation. Similarly, tartaric acid concentration has an optimum range of 0.2-0.5 mol/L, where both H+ and ligands are supplied effectively. Outside this range, ligand availability is reduced. The solid-liquid ratio also affects performance. The optimal range of 5-15 g/L promotes mass transfer. Outside this range, efficiency declines due to solid accumulation or reduced diffusion. The results show that under optimal conditions, leaching recovery reaches 94.8% for Co and 99.3% for Mn. The optimal leaching conditions were determined as follows: tartaric acid, 0.5 M; ascorbic acid, 1.5 M; liquid-to-solid ratio, 15 g/L; stirring speed, 300 rpm; temperature, 80 degrees C; and leaching time, 120 min. This system represents a promising laboratory-scale approach for recovering cobalt and manganese from spent NCM batteries, pending further validation in larger-scale studies.

Understanding rate-induced degradation mechanisms is essential for ensuring the reliable operation of lithium-ion batteries under fast-discharging conditions. This study systematically examines LiFePO4/graphite cells cycled across a broad spectrum of discharge rates (1C-10C) to elucidate rate-dependent aging behaviors and failure mechanisms. A multiscale characterization framework-spanning from the electrode to the nanoscale and integrating electrochemical, thermal, morphological, and interfacial analyses-was developed to uncover the progressive degradation processes. Electrochemical analyses indicate that capacity fade is governed primarily by lithium inventory loss (LLI) rather than active material degradation (LAM), with lithium plating occurring above 3C and dendritic growth dominating at 5C. Morphological observations demonstrate that while the cathode structure remains largely intact, high-rate cycling induces particle cracking, interfacial instability, and CEI thickening. In contrast, the anode exhibited pronounced surface degradation, SEI growth, and increased severity of lithium plating, as confirmed by surface-sensitive chemical analyses and fluorescence imaging. Finite element simulations further revealed increasing spatial inhomogeneity in the potential distribution and electrode utilization with increasing discharge rates, aligning with the observed electrochemical and structural gradients. The study provides a quantitative and mechanistic understanding of how high-rate operation accelerates anode failure and interfacial degradation, offering critical insights for lifetime modeling and the optimization of fast-discharging protocols in commercial lithium-ion batteries. (c) 2025 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Amid the transformative progress in green energy innovations, lithium-ion batteries, serving as the core component of energy storage systems, have garnered significant research interest due to their susceptibility to performance degradation and limited lifespan. This study presents a comprehensive review of dominant aging mechanisms and prognostic models for lithium-ion batteries in energy storage systems, underpinned by a multidimensional analytical framework encompassing fundamental electrochemical mechanisms to practical model implementability. Firstly, the aging paths of lithium inventory loss, active material loss, electrolyte loss, and internal resistance increase are systematically summarized to reveal their essential effects on battery capacity degradation. Subsequently, from the perspective of modeling, the advantages and disadvantages of prediction models, including the Arrhenius model, electrochemical model, empirical model, data-driven model and hybrid model, are systematically compared. Finally, it is highlighted that current models still face challenges in adapting to multifactorial operating conditions and long-term prediction robustness. To address these, the integration of electrochemical experiments and multiscale modeling techniques should be warranted in the future, which will promote the engineering implementation of highly robust life-prediction systems for energy storage batteries.

Lithium iron phosphate (LiFePO4) serves as a commonly used cathode material in lithium-ion batteries and is an essential power source for consumer electronics and electric vehicles. Nevertheless, significant degradation in its electrochemical performance occurs at low temperatures, leading to energy and power losses, challenges in charging, a reduced lifespan, and heightened safety concerns—critical factors for LiFePO4 applications. This review outlines recent progress aimed at enhancing the low-temperature performance of LiFePO4 batteries, concentrating on the mechanisms involved in various modification strategies. The primary factors contributing to the reduced performance of LiFePO4 at subzero temperatures are first examined. A variety of strategies designed to improve the interfacial and internal electrochemical reaction kinetics of LiFePO4 cathodes under cold conditions are emphasized, and feasible approaches to improve low-temperature kinetics are also presented. These include optimizing cell design to enhance inherent reactivity and employing heating techniques to raise external reaction temperatures. In conclusion, this review discusses the challenges and limitations associated with LiFePO4 batteries in lowtemperature settings and examines advancements in low-temperature lithium-ion batteries from the cell to the system level. The insights provided are intended to motivate further developments in lithium-ion batteries and other technologies tailored for subzero applications.

Multi-scale analysis reveals that SOC-dependent calendar aging preconditions interfacial degradation and lithium loss in LiFePO 4 /graphite cells, governing subsequent cycle aging and highlighting the need for integrated aging models.

Comprehensive utilization of iron residues presents challenges for resource recovery and waste management. This work focuses on the direct preparation of battery-grade phosphate dihydrate (FePO4 center dot 2H2O) making use of iron residues. The effects of temperature, pressure, and phosphoric acid concentration on the crystallinity, particle size, and iron-to-phosphorus (Fe/P) ratio of FePO4 center dot 2H2O were systematically investigated. The results indicate that high-purity phosphate dihydrate with good crystallinity, iron-to-phosphorus ratio of 1.01, and median particle diameter (D50) of 6.86 mu m is obtained by hydrothermal process under the optimized conditions: 1.05 times the theoretical amount of phosphoric acid, temperature of 180 degrees C, and pressure of 4.5 MPa. The synthesized FePO4 center dot 2H2O was used to produce lithium iron phosphate (LiFePO4) via solid-state reaction. The produced LiFePO4 shows a specific capacity of 130 mAh/g at 0.1 C and a retention of 96.16 % (120.2 mAh/g) after 100 cycles at 1 C. The X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FTIR) analyses demonstrate that the chemical states of Fe, P and O, and the phosphate groups structural integrity of the produced LiFePO4 are consistent with those of commercial LiFePO4. This indicates that FePO4 center dot 2H2O synthesized from iron residues meets the quality requirement for lithium battery production.

LiFePO4 is extensively used as a cathode material in lithium-ion batteries because of its high safety profile, affordability, and extended cycle life. Nevertheless, its inherently low lithium-ion transport kinetics and restricted electronic conductivity considerably limit its rate performance. Furthermore, the failure mechanisms specific to various cycling rates are not well examined. This study presents a functional interface layer designed to regulate the rate-dependent failure behavior of LiFePO4. At elevated charge/discharge rates, this layer facilitates lithium-ion mobility, decreases internal polarization, alleviates mechanical stress, and reduces structural degradation. At lower cycling rates, it contributes to the formation of a stable cathode-electrolyte interphase (CEI), effectively suppressing side reactions and minimizing active lithium loss. Consequently, the modified LiFePO4 demonstrates enhanced cycling stability and capacity retention, with capacity retention after 400 cycles at 2C rate increasing from 76.5% to 98.6% and at 5C increasing from 40.2% to 90.0%. Through combinations of experimental data and theoretical analysis, this study elucidates key mechanisms underlying rate-specific failure regulation, providing valuable insights into the relationship between ion transport dynamics and structural stability. This approach represents an effective strategy for supporting its potential use in advanced energy storage systems that require both rapid charging and prolonged cycling stability.

Lithium-ion batteries (LIBs) are the most popular energy storage devices due to their high energy density, high operating voltage, and long cycle life. However, green and effective recycling methods are needed because LIBs contain heavy metals such as Co, Ni, and Mn and organic compounds inside, which seriously threaten human health and the environment. In this work, we review the current status of spent LIB recycling, discuss the traditional pyrometallurgical and hydrometallurgical recovery processes, and summarize the existing short-process recovery technologies such as salt-assisted roasting, flotation processes, and direct recycling. Finally, we analyze the problems and potential research prospects of the current recycling process, and point out that the multidisciplinary integration of recycling will become the mainstream technology for the development of spent LIBs.

To address China’s small coal power units facing shutdown and retirement, which urgently need life cycle extension and renovation, a complete solar thermal storage simulation power generation system based on the original site of a decommissioned thermal power unit is developed using Ebsilon software in this study. The operational characteristics of the simulated system are studied in depth to build a system with integrity and stability that can carry out economic and stable power production. The results of simulation tests on the solar collector system and the thermal storage subsystem show that the energy storage rate of the energy storage subsystem is affected by light intensity and significantly increases at approximately 8:00 a.m. The annual power generation capacity of the system is influenced by the energy storage hours set by the energy storage subsystem, and the annual power generation capacity increases more significantly when the energy storage hours are controlled within the range of 5–8 h. The operating efficiency of the corresponding subsystem can be improved by selecting a suitable location for the light intensity required and controlling the effective reflectivity of the mirror field and the energy storage hours, which can ensure the system’s stable operation. The research results provide theoretical guidance for reusing and transforming retired thermal power units.

Insulation oil is a crucial medium in oil-immersed power transformers, providing essential insulation to protect materials. However, prolonged operation triggers processes like cracking, carbonization, and oxidation in insulation oil. Thus, the development of high-performance electrospun filter membranes is paramount to advance oil purification and improve power grid operational safety. This study utilizes electrospinning technology to prepare a dual-layer structured composite PP/PVDF micro-nano hybrid membrane, with polypropylene microfiber membrane as the substrat. The research investigates the variations in surface morphology, hydrophobicity, and charge stability under different mass fractions of polyvinylidene fluoride. Additionally, it evaluates and analyzes the oil-water separation performance during oil filtration and the insulation oil purification and regeneration capabilities of the membrane. The composite micro nanofiber membrane, prepared on a PP fiber membrane substrate, demonstrates outstanding performance in the separation of oil and water as well as the filtration of minute impurities. It significantly reduces the dielectric constant and dielectric loss of aged insulation oil, restoring its insulation performance to a great extent. This provides a more practical method for the recovery of insulation oil.

Second-life batteries face huge challenges in cascade utilization due to poor consistency and weak safety.The dynamic reconfigurable battery network(DRBN)can effectively improve the consistency and safety of the second-life battery cascade utilization energy storage systems.Recently,DRBN energy storage systems have reached the stage of engineering applications.However,existing research lacks operational performance evaluation of large-scale DRBN energy storage systems.Therefore,we take a real-world large-scale second-life battery cascade utilization energy storage system as an example and choose the operation data of 80 DRBNs during one month for analysis.The effectiveness of the DRBN in improving the consistency of battery modules has been verified from three aspects:operating conditions,module balancing,and weak links.Data analysis shows that 90%of DRBNs have good consistency,and other DRBNs with poor consistency can be accurately evaluated.

The sorting of a group of battery cells with great consistency is critial for the safe and durable operation of battery pack. The conventional methods of battery sorting is based on the linear potential sweep methods, which are complicated and coarse. In this manuscript, the electrochemical impedance spectroscopy was used to determine the kinetic process and electrochemical reactions on the electrodes. There are 41 lithium iron phosphate battery cells(15 Ah) were investigated, and an equivalent circuit was developed to fitted the measure EIS spectrum. The dispersion of the fitting parameters and their variations with SOC were discussed, in which solution resistance RH, constant phase elements (CPEWarburg-Y0 and CPEct-N) at 100% SOC to identify and selected a group of cells with great consistency. The results showed that the sorted battery bells exhibit great consistency as compared the whole sample group. This manuscript demonstrated a non-destructive and effective method for battery sorting, which are instructive for the field of power battery and energy storage battery.

Under the background of"dual carbon",new energy has begun to be connected to the grid on a large scale.Still,the randomness and volatility of new energy generation have a specific impact on the power grid,and it is urgent to build a new power system.The need for flexibility is further deepened in the process of building new power systems.In this process,as the cornerstone of the power system,the traditional thermal power will transform to the basic security and system regulatory power supply that provides reliable capacity,peak regulation and frequency modulation and other auxiliary services,and the flexible transformation of thermal power units has become an inevitable choice.The phased objectives,difficulties and challenges of building a new power system were analyzed,and the problems encountered in the flexible transformation of thermal power units at the present stage were discussed.Combined with thermal power operation data,the technical ways of configuring energy storage equipment for thermal power units were analyzed.The research shows that there are some problems in the process of building a new power system,such as the power system stability,difficulties in the transformation of traditional thermal power,energy consumption,environmental protection and so on.The flexibility transformation of thermal power units is faced with some problems,such as the insufficient peak regulation capacity,high operation cost,load response,operation energy consumption and safety,etc.The operation mode of thermal power plus energy storage will bring better economic and environmental benefits.

Due to the influence of various factors on power, such as voltage fluctuations and load changes, these factors may lead to unstable power during the charging process, thereby increasing energy loss and reducing charging efficiency. Therefore, constant power cycle life testing has special significance and value for high-capacity energy storage batteries. This study, compared with traditional intermittent or low-power charge-discharge modes, more accurately reflects the real performance of energy storage batteries in working scenarios, providing important data for the long-term stability and reliability of the batteries.

The dissolution of iron from the cathode significantly contributes to the accelerated degradation of LiFePO4/Graphite batteries, particularly at elevated temperatures. However, a systematic understanding of the spatial distribution and impact of Fe ions on the dynamic solid electrolyte interphase (SEI) layer is lacking. In this study, a comprehensive and quantitative investigation is conducted into the effects of transition metals (TM) and thoroughly examined the interaction between dissolved Fe2+ and SEI in long-life LiFePO4/Graphite pouch cells. The dissolved Fe in the electrolyte is more prone to deposition at the negative electrode at elevated temperatures, leading to an accelerated loss of active lithium. Additionally, Fe deposition on the SEI catalyzes the decomposition of EC and contributes to an increase in organic components, particularly lithium alkyl carbonates within the SEI, as evidenced by mass spectrometry titration (MST) analysis. Neutron imaging (NI) provides more insights into the impacts of dissolved Fe2+ on active lithium loss, SEI components, and electrolyte decomposition, resulting in greater macroscopic heterogeneity in the electrode regions of the cells. This research sheds light on the mechanisms underlying the degradation of LiFePO4/Graphite batteries and provides valuable insights for the development of strategies to mitigate capacity fade and enhance battery performance and longevity.