Life Research Articles

Thermal Behavior of a Cylindrical 18650 LiFePO₄ Battery during Charge and Discharge Cycles

Thermal Behavior of a Cylindrical 18650 LiFePO₄ Battery during Charge and Discharge Cycles

Reuse of Lithium Iron Phosphate (LiFePO4) Batteries from a Life Cycle Assessment Perspective: The Second-Life Case Study

As of 2035, the European Union has ratified the obligation to register only zero-emission cars, including ultra-low-emission vehicles (ULEVs). In this context, electric mobility fits in, which, however, presents the critical issue of the over-exploitation of critical raw materials (CRMs). An interesting solution to reduce this burden could be the so-called second life, in which batteries that are no longer able to guarantee high performance in vehicles are used for other applications that do not require high performance, such as so-called stationary systems, effectively avoiding new over-exploitation of resources. In this study, therefore, the environmental impacts of second-life lithium iron phosphate (LiFePO4) batteries are verified using a life cycle perspective, taking a second life project as a case study. The results show how, through the second life, GWP could be reduced by ‒5.06 × 101 kg CO2 eq/kWh, TEC by ‒3.79 × 100 kg 1.4 DCB eq/kWh, HNCT by ‒3.46 × 100 kg 1.4 DCB eq/kWh, ‒3.88 × 100 m2a crop eq/kWh, and ‒1.12 × 101 kg oil eq/kWh. It is further shown how second life is potentially preferable to other forms of recycling, such as hydrometallurgical and pyrometallurgical recycling, as it shows lower environmental impacts in all impact categories, with environmental benefits of, for example, ‒1.19 × 101 kg CO2 eq/kWh (compared to hydrometallurgical recycling) and ‒1.50 × 101 kg CO2 eq/kWh (pyrometallurgical recycling), ‒3.33 × 102 kg 1.4 DCB eq/kWh (hydrometallurgical), and ‒3.26 × 102 kg 1.4 DCB eq/kWh (pyrometallurgical), or ‒3.71 × 100 kg oil eq/kWh (hydrometallurgical) and ‒4.56 × 100 kg oil eq/kWh (pyrometallurgical). By extending the service life of spent batteries, it may therefore be possible to extract additional value while minimizing emissions and the over-exploitation of resources.

Towards robust state estimation for LFP batteries: Model-in-the-loop analysis with hysteresis modelling and perspectives for other chemistries

The accurate estimation of a battery’s state of charge (SOC) is critical in battery management systems for various applications. Lithium Iron Phosphate (LFP) batteries, preferred for their long cycle life, cost efficiency, and enhanced safety, have emerged as favourable choices for stationary storage. Yet, they still face challenges in precise SOC estimation due to the flatness and hysteresis of their open circuit voltage. Addressing this, our study integrates a hysteresis model into a third-order battery model for BMS controlling a stationary storage system in frequency containment reserve (FCR) application. We analysed three advanced SOC estimation techniques — extended Kalman filter (EKF), dual unscented Kalman filter (DUKF), and particle filter (PF) — with the hysteresis model using a model-in-the-loop (MiL) toolchain. Performance testing under a 48-hour FCR load profile showed EKF with a 4% error, DUKF achieving the best result with a 1.1% error, and PF’s performance varying between 2.9% and 4% depending on particle count. Robustness tests against initialization and current sensor errors under an 8hr profile revealed DUKF maintained a 2% error boundary irrespective of the error introduced, highlighting the hysteresis model’s effectiveness. Broadening the scope, the study also explores extending the method to other lithium-ion chemistries.

Coconstruction of Supramolecular Lithium-Conducting Cross-Linked Networks Based on PVDF and Triblock Polymer Nanomicrosphere Solid-State Polymer Electrolytes for Lithium-Metal Batteries.

Uneven lithium plating and low ionic conductivity currently impede the realization of high-capacity rechargeable lithium metal batteries. And the conventional poly(ethylene oxide) (PEO) solid-state electrolytes are unsuitable for high-energy-density Li anode applications due to their low lithium-ion transference number and high reactivity with Li metal, leading to detrimental dendrite formation and potentially hazardous exothermic reactions with the electrolyte. In this study, we employ a supramolecular approach to develop a novel polymer solid-state electrolyte based on poly(vinylidene fluoride) (PVDF) and a novel triblock polymer nanomicrosphere, (poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone), (PCL-PEG-PCL). The abundance of carbonyl and ether-oxygen functional groups in PCL-PEG-PCL enhances the lithium coordination environment within the polymer solid-state electrolyte. Additionally, the original C-F moieties of PVDF form hydrogen bonds with C-H and terminal hydroxyl groups in PCL-PEG-PCL, collectively creating a multichannel fast Li+-conducting supramolecular cross-linked network. The resulting electrolyte demonstrates a high ionic conductivity of 1.4 × 10-3 S cm-1 and an extended electrochemical window of 5.2 V. Moreover, the electrolyte exhibits a high lithium-ion transference number (tLi+ = 0.63) at room temperature and exhibits excellent interfacial compatibility with the lithium metal anode. For the resulting electrolyte utilized in LiFePO4 batteries, the capacity retention of the cells assembled with this electrolyte exceeds 91.3% after 1000 cycles at 25 °C and 2 C (0.281 mA cm-2).

Toward Sustainable Lithium Iron Phosphate in Lithium‐Ion Batteries: Regeneration Strategies and Their Challenges

AbstractIn recent years, the penetration rate of lithium iron phosphate batteries in the energy storage field has surged, underscoring the pressing need to recycle retired LiFePO4 (LFP) batteries within the framework of low carbon and sustainable development. This review first introduces the economic benefits of regenerating LFP power batteries and the development history of LFP, to establish the necessity of LFP recycling. Then, the entire life cycle process and failure mechanism of LFP are outlined. The focus is on highlighting the advantages of direct recycling technology for LFP materials. Directly regenerating LFP materials is a very promising solution. Directly regenerating spent LFP (S‐LFP) materials can not only protect the environment and save resources, but also directly add lithium atoms to the vacancies of missing lithium atoms to repair S‐LFP materials. At the same time, simply supplementing lithium to repair S‐LFP simplifies the recovery process and improves economic benefits. The status of various direct recycling methods is then reviewed in terms of the regeneration process, principles, advantages, and challenges. Additionally, it is noted that direct recycling is currently in its early stages, and there are challenges and alternative directions for its development.

A comparative study on multidimensional signal evolution during thermal runaway of lithium-ion batteries with various cathode materials

Cathode materials significantly affect the failure behavior of lithium-ion batteries, but there is a lack of comparative research on the multidimensional signal evolution for batteries with various cathode materials when subjected to thermal runaway (TR). This study investigates the effect of cathode materials on battery safety properties by conducting overheating and overcharging abuse experiments on LiNixCoyMn(1-x-y)O2 (NCM 523, 622, and 811) as well as LiFePO4 (LFP) batteries. The multidimensional signals, including expansion force, gas concentrations, temperature, and voltage, are comprehensively and quantitatively analyzed. The results demonstrate that expansion force shows the earliest anomalies regardless of the cathode material in both abuse conditions. Gas can be detected after venting, followed by significant anomalies in voltage and temperature. Additionally, under overheating conditions, LFP cells exhibit the longest TR warning time of 677 s. However, the force anomaly-based warning method is more suitable for low-nickel NCM cells under overcharging scenarios. Specifically, NCM 523 cells achieve an overcharging warning time of 992 s at temperatures as low as 42.9 °C, and hold the highest venting force of 9859 N and venting temperature at 114.1 °C. On this basis, a hierarchical warning strategy based on multidimensional signal fusion is proposed. This study provides valuable insights into TR early warning and safety management in LIBs with different cathode materials.

High-power ultrasound facilitation of the generality for LiFePO4 regeneration

Renowned for its remarkable electrochemical performance, temperature stability, safety attributes, and long-lasting durability, the LiFePO4 battery has gained prominence in diverse applications, particularly within the electric vehicle sector. Despite not holding the top market position, approximately 69 % of global batteries comprise LiFePO4, raising concerns about a potential increase in discarded batteries. Present research predominantly concentrates on extracting valuable materials such as Co, Li, Ni, and Mn, frequently sidelining spent LiFePO4 batteries due to their perceived limited recoverable content compared to NMC and LCO batteries. However, LiFePO4 batteries removed from electric vehicles retain approximately 80 % of their initial capacity, with the cathode material sustaining a robust crystal structure. Here, direct recycling techniques employing a green reducing agent like ascorbic acid have shown promise in rectifying lithium vacancies and anti-sites in spent LiFePO4 through high power ultrasonic reactions. This work delves into exploring the influence of different lithium sources and Li + concentrations on the structure and electrochemical performance of regenerated LiFePO4. The direct regeneration of LiFePO4 showcases a favorable crystal structure that maintains stable phase transitions during charge and discharge processes. RLFP-0.2 M exhibits discharge specific capacity of 154.71 mAh∙g−1. It indicates RLFP-0.2 M maintains a discharge specific capacity of 132.89 mAh∙g−1 after 200 cycles at 1C current, retaining a remarkable capacity retention rate of 93.56 %. This study demonstrates that high-power ultrasonication is a universally applicable, low-energy, highly efficient, operationally simple, and environmentally friendly method for direct recycling of spent LiFePO4 batteries. Our research not only investigates the influence of various lithium sources and Li + concentration but also optimizes the recycling process for spent LiFePO4 batteries. Additionally, it provides an experimental foundation and reference for the recycling of other power batteries, contributing to achieving green direct recycling of various power batteries.

Regeneration of Black Powders of Waste Lithium Iron Phosphate Battery Produced by Large‐Scale Industrialization

Because the waste battery materials in the industry usually come from a rough shredding process, the most available waste battery materials consist of both cathode and anode materials. However, the separate recycling of waste cathode and anode materials requires a significant investment of time and manpower. Investigation on the rational disposal of mixed cathode/anode materials is in great need for the large‐scale recycling of spent lithium‐ion batteries. Taking the mixed materials of waste LiFePO4 cathode and graphite anode as the research object, this article puts forward a simple solid‐state method to effectively solve the problems in waste LiFePO4 materials such as structural defects, lithium site loss, and poor conductivity. By optimizing the concentration of the reducing agent and lithium supplement agent, the optimal regeneration condition for material is obtained. Ultimately, the obtained LiFePO4 material achieves efficient electrochemical performances. The first‐round capacity reaches 132 mAh g−1, accounting 84.6% of the new material (0.05 C). After 100 cycles in 1 C, the capacity remains at 99%, exhibiting good cycling stability. The total cost of the regenerated LiFePO4 material has been calculated to be only 41.2% of the new material cost. This work provides new ideas for the regeneration of waste LiFePO4 material by large‐scale industrialization.

Conformation inversion of succinonitrile towards long-life solid-state lithium metal batteries

Solid-state lithium metal batteries are considered as the next-generation energy storage devices, but their application is significantly hindered by poor interfacial compatibility between Li anodes and solid-state electrolytes, especially for succinonitrile (SN) based electrolyte. Herein, this issue is addressed by a conformation inversion strategy via introducing a PE separator grafted with poly-(lithium 2-acrylamido-2-methylpropanesulfonic acid) (PAMPSLi) brushes into a SN-based electrolyte. The PAMPSLi brushes inverse the conformation of SN molecules through the multiple interactions between −SO3Li and cyanide groups, alleviating the corrosion reactions of SN on Li anodes. Significantly, the PAMPSLi brushes regulate Li+ transport pathway with the inversed SN molecules at the anode/electrolyte interface to achieve uniform Li deposition. Notably, the PAMPSLi brushes contribute to a solid electrolyte interphase (SEI) film rich in LiF and Li3N. Consequently, the solid-state Li||LiFePO4 batteries with the resulting electrolyte exhibit a specific discharge capacity of 115.0 mAh/g and a considerably long cycle life of 1500 cycles at 3 C. A pouch cell with a high-loading LiFePO4 cathode (18 mg cm−2) also exhibits a high areal capacity and superior safety. This study provides a novel strategy for achieving a stable electrolyte/anode interface in SN-based electrolytes, which facilitates the practical application of solid-state batteries with long life and high energy density.

Study on the fire extinguishing effect of compressed nitrogen foam on 280 Ah lithium iron phosphate battery

This study conducted experimental analyses on a 280 Ah single lithium iron phosphate battery using an independently constructed experimental platform to assess the efficacy of compressed nitrogen foam in extinguishing lithium-ion battery fires. Based on theoretical analysis, the fire-extinguishing effects of compressed nitrogen foam at different outlet pressures from foam mixture tanks were analyzed, examining factors such as battery surface temperature, flame temperature, and thermal weight loss. The results indicate that the compressed nitrogen foam can extinguish the open flame of the battery in 14 s at 0.7 MPa, with the battery’s surface temperature dropping by approximately 11 % before and after the application of the extinguishing agent. Compared with other commonly used extinguishing agents, the compressed nitrogen foam demonstrates superior extinguishing efficiency, but its cooling efficiency is somewhat lower. At pressures ranging from 0.4 to 0.6 MPa, the foam displays prolonged drainage time and sustained cooling effects, rendering it more suitable for lithium-ion battery fire scenarios. To address the issue of reduced cooling performance during later stages of fire suppression by compressed nitrogen foam, an intermittent injection approach has been proposed to effectively preserve its cooling efficacy.

Experimental study on flame morphology, ceiling temperature and carbon monoxide generation characteristic of prismatic lithium iron phosphate battery fires with different states of charge in a tunnel

Lithium-ion battery (LIB) safety, in a long and narrow restricted space, can generate a high-temperature environment and massive toxic and harmful smoke in a short period. Hence, this work innovatively carried out a series of thermal runaway (TR) experiments on large prismatic lithium cells in a model tunnel. Results showed that the flame height of LIBs with above 50% SOC was above 40 cm for much time of the stage (Ⅰ) and (Ⅱ). The average flame height is further proposed to quantify the flame profile at different phases. The greater the SOC was, the higher the ceiling temperature and peak CO concentration were also relatively. For example, while decreasing the distance to the fire source from 0 m to -0.7 m, the peak ceiling temperature of 25 Ah batteries with 100% SOC decreases from 309°C to 118°C, with a decay rate of 62%. The CO concentration showed a comparable variation pattern to the tunnel ceiling temperature. Finally, a dimensionless relationship was employed to describe the ceiling temperature decay. Meanwhile, the ceiling maximum temperature rise for different capacity battery fires was integrated into a relational equation. The study results are expected to further understand the battery fire hazards in tunnel.

Heavily vanadium-doped LiFePO4 olivine as electrode material for Li-ion aqueous rechargeable batteries

Since LiFePO4 batteries play a major role in the transition to safe, more affordable and sustainable energy production, numerous strategies have been applied to modify LFP cathode, with the aim of improving its electrochemistry. In this contribution, a highly vanadium-doped LiFe0.9V0.1PO4/C composite (LFP/C-10V) is synthesized using the glycine combustion method and characterized by x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetry Differential Thermal Analysis (TGDTA) and Cyclic Voltammetry (CV). It is shown that 10wt.% of vanadium can substitute Fe positions, thus decreasing unit cell volume, which is followed by generation of Li3V2PO4 traces, as detected by CV. High vanadium doping does not change the carbon content in the composite (≈13 wt%) but improves its electronic conductivity and electrochemical performance in both aqueous and organic electrolytes. The reversibility and current response are increasing following the trend: LFP/C, LFP/C -3mol%V, LFP/C - 5 mol % and LFP/C-10 mol %. The best specific capacity is obtained for the most highly doped olivine, which exhibits a reversible process at 1 mV s−1 in an aqueous electrolyte, thus showing a peak-to-peak distance of 56 mV. The high capacity of LFPC-10V is measured in both LiNO3 and NaNO3 electrolytes amounting to around 100 mAh g−1 at 20 mV s−1. Still, the material is only stable in LiNO3 electrolyte, making it more suitable for Li than Na-ion aqueous rechargeable batteries.

A finite‐state machine‐based control design for thermal and state‐of‐charge balancing of lithium iron phosphate battery using flyback converters

AbstractBattery cell balancing plays a vital role in maximizing the performance of the battery system by enhancing battery system capacity and prolonging the battery system life expectancy. Active cell balancing using power converters is a promising approach to maintaining uniform state of charges (SoCs) and temperatures across battery cells. The SoC balancing function in the battery management system (BMS) increases the battery pack capacity, and the temperature balancing function mitigates variations in the aging of battery cells due to unbalanced temperatures. In this work, a finite‐state machine‐based control design is proposed for lithium iron phosphate (LFP) battery cells in series to balance SoCs and temperatures using flyback converters. The primary objective of this design is to ensure balanced SoCs by the end of the charging session while mitigating the temperature imbalance during the charging process. To achieve the SoC and temperature balancing functions using the same balancing circuits, a finite‐state machine control design decides on the operating mode, and a balancing strategy balances either temperature or SoC depending on the operating mode. The proposed control design has the advantages of low computational burden, simple implementation compared to the optimization‐based controller found in the literature, and the proposed balancing strategy offers faster balancing speed compared to conventional methods. The effectiveness of the proposed strategy is validated on battery cell RC models in series with unbalanced SoCs and temperatures.

Endogenous advanced oxidation process with peracetic acid for recycling spent LiFePO4 batteries

LiFePO4 batteries are becoming more widely used due to their low cost and high stability advantages, which means that many spent batteries are generated. Designing green and efficient recycling methods for used batteries is strategically significant for the sustainable development of the new energy industry. This study innovatively proposes a self-activated advanced oxidation process with peroxyacetic acid for recycling spent LiFePO4, selectively releasing Li+ while converting LiFePO4 to FePO4. Quenching tests show that the de-embedding of Li+ is mainly caused by the rapid attack from HO• and R-O• radicals. Furthermore, the recycled products Li2CO3 and FePO4 are employed to regenerate LiFePO4 cathode materials, forming a closed-loop recycling process. Compared with traditional hydrometallurgy and hydrogen peroxide oxidation methods, this technology has obvious advantages in terms of process complexity, energy consumption, reagent consumption, recovery profit, and environmental friendliness. This work opens up a new way for the recycling of spent lithium-ion batteries.

Investigating advanced strategies for enhancing energy density in lithium-ion batteries

Lithium-ion batteries have become a versatile energy storage solution for various applications, such as portable electronics and electric vehicles, due to their numerous advantages. The increasing demand for higher energy density has prompted researchers to explore innovative strategies to improve the performance of these batteries. This study systematically investigates cutting-edge techniques aimed at enhancing the energy density of lithium-ion batteries. By conducting a detailed analysis of different battery components, this study evaluates the feasibility, efficiency, and potential impact of these approaches on future battery technologies. By giving some concrete examples, such as NMA(LiNi1-x-yMnxAlyO2), LFP(LiFePO4) batteries in cathode, popular silicon-based materials in anode, novel dual conductive binder and solid electrolyte (solid electrolyte interface), some of the working principles are described and the electrochemical properties of the batteries are comparatively analysed. This research aims to provide readers with a comprehensive understanding and research direction for advancing the energy density capabilities of lithium-ion batteries.

Estimation of SOC in Lithium-Iron-Phosphate Batteries Using an Adaptive Sliding Mode Observer with Simplified Hysteresis Model during Electric Vehicle Duty Cycles

This paper develops a model for lithium-ion batteries under dynamic stress testing (DST) and federal urban driving schedule (FUDS) conditions that incorporates associated hysteresis characteristics of 18650-format lithium iron-phosphate batteries. Additionally, it introduces the adaptive sliding mode observer algorithm (ASMO) to achieve robust and swiftly accurate estimation of the state of charge (SOC) of lithium-iron-phosphate batteries during electric vehicle duty cycles. The established simplified hysteresis model in this paper significantly enhances the fitting accuracy during charging and discharging processes, compensating for voltage deviations induced by hysteresis characteristics. The SOC estimation, even in the face of model parameter changes under complex working conditions during electric vehicle duty cycles, maintains high robustness by capitalizing on the easy convergence and parameter insensitivity of ASMO. Lastly, experiments conducted under different temperatures and FUDS and DST conditions validate that the SOC estimation of lithium-iron-phosphate batteries, based on the adaptive sliding-mode observer and the simplified hysteresis model, exhibits enhanced robustness and faster convergence under complex working conditions and temperature variations during electric vehicle duty cycles.

Characteristics of graphite obtained by recycling lithium - iron phosphate batteries

Based on both the economic and environmental points of view, processing used lithium-ion batteries (LIBs) is of great importance. The valuable components contained in LIB (cathode, anode and current collectors) generate high interest in solving the problem of resource deficiency and reducing environmental destruction due to overexploitation. The starting anode material extracted from a used lithium iron phosphate battery is a mixture of graphite, acetylene carbon black, and polymer binder. Reusing this material in lithium batteries without additional cleaning is impractical owing to poor electrochemical characteristics and the presence of impurities. To achieve effective regeneration, the recycled anode material is first treated in a nitric acid solution to remove copper foil and lithium ions with electrolyte interaction products formed during battery operation. The next step is heat treatment of the material, which allows the removal of acetylene soot and polymer glue binder. The tests showed sufficiently high values of the specific capacity of recycled graphite (~330 mA h g-1 at 0.1 C), which are comparable to commercial materials and meet the requirements of reuse.

Optimizing Energy Arbitrage: Benchmark Models for LFP Battery Dynamic Activation Costs in Reactive Balancing Market

This study introduces a novel benchmark model for lithium iron phosphate (LFP) batteries in reactive energy imbalance markets, filling a notable gap by incorporating comprehensive operational parameters and market dynamics that are overlooked by conventional models. Addressing the absence of a holistic benchmark for energy-storage systems in electricity markets, this research focuses on the integration of LFP batteries, considering their unique characteristics and market responsiveness. Regression and regularization techniques, coupled with temporal cross-validation, were employed to ensure model robustness and accuracy in predicting energy trading outcomes. This methodological approach allows for a nuanced analysis of battery degradation, power capacity, energy content, and real-time market prices. The model, validated using Belgium’s system imbalance market data from the 2020–2023 period, incorporates both capital and operational expenditures to assess the economic and operational viability of LFP battery energy-storage systems (BESSs). The findings reveal that considering a broader range of operational parameters in energy arbitrage, beyond just the usual energy prices and round-trip efficiency, significantly influences the cost-effectiveness and performance benchmarking of energy storage solutions. This paper advocates for the strategic use of LFP batteries in energy markets, highlighting their potential to enhance grid stability and energy trading profitability. The proposed benchmark model serves as a critical tool for energy traders, providing a detailed framework for informed decision making in the evolving landscape of energy storage technologies.

Preoxidation and Prilling Combined with Doping Strategy to Build High-Performance Recycling Spent LiFePO4 Materials.

Direct regeneration has gained much attention in LiFePO4 battery recycling due to its simplicity, ecofriendliness, and cost savings. However, the excess carbon residues from binder decomposition, conductive carbon, and coated carbon in spent LiFePO4 impair electrochemical performance of direct regenerated LiFePO4. Herein, we report a preoxidation and prilling collaborative doping strategy to restore spent LiFePO4 by direct regeneration. The excess carbon is effectively removed by preoxidation. At the same time, prilling not only reduces the size of the primary particles and shortens the diffusion distance of Li+ but also improves the tap density of the regenerated materials. Besides, the Li+ transmission of the regenerated LiFePO4 is further improved by Ti4+ doping. Compared with commercial LiFePO4, it has excellent low-temperature performance. The collaborative strategy provides a new insight into regenerating high-performance spent LiFePO4.

Enhanced prelithiation performance of Li5FeO4 cathode additive and optimized solid electrolyte interface enabled by Mn substitution

In the pursuit of enhancing the energy density of lithium-ion batteries, cathode prelithiation emerges as a pivotal approach, introducing additional irreversible active lithium ions to augment performance. Li5FeO4 (LFO) stands out as an excellent option, boasting an impressive theoretical specific capacity and the additional advantages of cost-effectiveness in raw materials and low preparation cost. However, the impact of extra lithium incorporations on compositional changes at the electrode-electrolyte interface as well as on cell stability has impeded further researches. Herein, a Mn doping strategy is proposed and predicted by first-principles calculations to synthesize partially Mn-substituted Li5.125Fe0.875Mn0.125O4 (LFMO). And the prelithiation with LFMO improved the interfacial composition of LiFePO4 (LFP) batteries compared to LFO, achieving a charging capacity of 213 mAh∙g−1 in the first cycle at 0.05 C. The subsequent treatment demonstrated superior cycling stability, maintaining a discharge specific capacity as high as 155.3 mAh∙g−1 after 100 cycles at 0.2 C, and exhibiting a higher capacity retention in the full cell. These discoveries could contribute to enhancing the regulation of battery interface during the utilization of LFO, potentially promoting the development of cathode lithium additives.