LFP Battery Research Articles

Joint Model Parameter Identification and EKF Algorithm for the SOC Estimation of LFP Battery

Abstract Accurately estimating the state of charge (SOC) of batteries is crucial for achieving the safety and efficient driving of electric vehicles. To address the negative impact of voltage platform flatness and accumulated errors in current sampling, the SOC estimation method jointing model parameter identification and extended Kalman filter (EKF) algorithm is proposed and verified through simulation in this paper. Firstly, the parameter identification method is obtained based on the second-order dual polarization model, and effective identification of the parameters under different SOC is achieved using experimental conditions of hybrid pulse power characteristic and constant current discharge. On this basis, a function model with SOC as the independent variable and model parameters as the dependent variable is established by jointing model parameter identification and EKF algorithm, and the iterative estimation of SOC is achieved through the 1stopt and cftool methods. Finally, the SOC estimation accuracy of the proposed method is validated under three operating conditions that adopt the latest standards and are closer to the actual driving environment. The simulation results show that the SOC estimation method jointing model parameter identification and EKF algorithm has higher accuracy and smaller fluctuations than the traditional AH integration method, and the mean squared error (MSE) of estimation for the four test conditions are less than 0.29%, 0.72% and 0.25%, respectively.

Recycling of Spent Lithium Iron Phosphate Cathodes: Challenges and Progress.

The number of spent lithium iron phosphate (LiFePO4, LFP) batteries will increase sharply in the next few years, owing to their large market share and development potential. Therefore, recycling of spent LFP batteries is necessary and urgent from both resource utilization and environmental protection standpoints. In this review, the significance of pretreatment for LFP recycling is first underscored, and its technical challenges and recent advancements are presented. Following that, the current recycling methods for spent LFP cathodes are outlined in terms of the respective treating processes, advantages, and disadvantages. Additionally, the preparation methods of LFP cathode material are reviewed to guide the resynthesis of LFP that uses salts obtained from spent LFP, which are beneficial for closed-loop recycling of LFP batteries. Lastly, we explore the future development direction of spent LFP battery recycling, highlighting the importance of technological innovation to advance the sustainable growth of the LFP battery industry.

Approach towards the Purification Process of FePO4 Recovered from Waste Lithium-Ion Batteries

The rapid development of new energy vehicles and Lithium-Ion Batteries (LIBs) has significantly mitigated urban air pollution. However, the disposal of spent LIBs presents a considerable threat to the environment. Recycling these waste LIBs not only addresses the environmental issues but also compensates for resource shortages and generates substantial economic benefits. Current recycling processes primarily focus on the extraction of valuable metals, often overlooking the treatment of residual waste post-extraction. This project targets the iron phosphate (FePO4) derived from waste lithium iron phosphate (LFP) battery materials, proposing a direct acid leaching purification process to obtain high-purity iron phosphate. This purified iron phosphate can then be used for the preparation of new LFP battery materials, aiming to establish a complete regeneration cycle that recovers lithium carbonate and iron phosphate from waste LFP materials for the production of LFP. The study investigates process parameters such as acid types and concentrations, leaching time, and the number of leaching cycles. The results demonstrate that, after purification, the levels of impurity metals decrease while the iron content increases correspondingly. Under optimized experimental conditions, the dilute sulfuric acid leaching rates of Al, Cu, Ca, and Ni reached 36.0%, 51.4%, 89.5%, and 90.9%, respectively. Furthermore, hydrothermal treatment in dilute phosphoric acid achieved leaching rates of 87.9%, 85.8%, 98.4%, and 99.1% for Al, Ca, Cu, and Ni, respectively. The microstructure characterization revealed significant changes in phase and grain morphology during the leaching process in dilute phosphoric acid, which are likely associated with the liberation of impurity atoms from the lattice. These findings indicate that acid leaching is highly effective in removing impurities from the iron phosphate recycled from waste LIBs.

Fast track to a million: A simulative case study on the influence of charging management on the lifetime of battery electric trucks

Battery electric trucks are a well-suited solution for decarbonizing freight transport to achieve the emission reduction targets set by the European Union. Intelligent charging management is crucial to minimize time loss and to synchronize charging times with rest periods. In this paper, we investigate the impact of holistic charging management on the lifespan of the truck's battery. Based on battery aging models for the LFP and NMC chemistry, we present a framework for the end-of-life simulation and extend the existing time-optimal charging management to include overnight and weekend charging. Our results show that time-optimal on-route charging management positively impacts the lifetime, and with aging-focused overnight charging functions, a lifespan of over 1,100,000 km is achievable for trucks with a 500 kWh LFP battery. Furthermore, our study reveals that the shares of total aging up to the end-of-life are distributed almost evenly between the various operation events driving, on-route, overnight, and weekend charging for the long-haul application.

Energy Consumption and Saved Emissions of a Hydrogen Power System for Ultralight Aviation: A Case Study

The growing concern about climate change and the contemporary increase in mobility requirements call for faster, cheaper, safer, and cleaner means of transportation. The retrofitting of fossil-fueled piston engine ultralight aerial vehicles to hydrogen power systems is an option recently proposed in this direction. The goal of this investigation is a comparative analysis of the environmental impact of conventional and hydrogen-based propulsive systems. As a case study, a hybrid electric configuration consisting of a fuel cell with a nominal power of about 30 kW, a 6 kWh LFP battery, and a pressurized hydrogen vessel is proposed to replace a piston prop configuration for an ultralight aerial vehicle. Both power systems are modeled with a backward approach that allows the efficiency of the main components to be evaluated based on the load and altitude at every moment of the flight with a time step of 1 s. A typical 90 min flight mission is considered for the comparative analysis, which is performed in terms of direct and indirect emissions of carbon dioxide, water, and pollutant substances. For the hydrogen-based configuration, two possible strategies are adopted for the use of the battery: charge sustaining and charge depleting. Moreover, the effect of the altitude on the parasitic power of the fuel cell compressor and, consequently, on the net efficiency of the fuel cell system is taken into account. The results showed that even if the use of hydrogen confines the direct environmental impact to the emission of water (in a similar quantity to the fossil fuel case), the indirect emissions associated with the production, transportation, and delivery of hydrogen and electricity compromise the desired achievement of pollutant-free propulsion in terms of equivalent emissions of CO2 and VOCs if hydrogen is obtained from natural gas reforming. However, in the case of green hydrogen from electrolysis with wind energy, the total (direct and indirect) emissions of CO2 can be reduced up to 1/5 of the fossil fuel case. The proposed configuration has the additional advantage of eliminating the problem of lead, which is used as an additive in the AVGAS 100LL.

Study of Conversion of Waste LFP Battery into Soluble Lithium through Heat Treatment and Mechanochemical Treatment

Study of Conversion of Waste LFP Battery into Soluble Lithium through Heat Treatment and Mechanochemical Treatment

Study on Discharge Characteristic Performance of New Energy Electric Vehicle Batteries in Teaching Experiments of Safety Simulation under Different Operating Conditions

High-voltage heat release from batteries can cause safety issues for electric vehicles. Relevant scientific research work is carried out in the laboratory. The battery safety of laboratory experiments should not be underestimated. In order to evaluate the safety performance of batteries in the laboratory testing of driving conditions of electric vehicles, this paper simulated and compared the discharge characteristics of two common batteries (lithium iron phosphate (LFP) battery and nickel–cobalt–manganese (NCM) ternary lithium battery) in three different operating conditions. The operating conditions are the NEDC (New European Driving Cycle), WLTP (World Light Vehicle Test Procedure) and CLTC-P (China light vehicle test cycle) for normal driving of electric vehicles. LFP batteries have a higher maximum voltage and lower minimum voltage under the same initial voltage conditions, with a maximum voltage difference variation of 11 V. The maximum current of WLTP is significantly higher than NEDC and CLTC-P operating conditions (>20 A). Low current discharge conditions should be emulated in teaching simulation and experiments for safety reasons. The simulation data showed that the LFP battery had good performance in maintaining the voltage plateau and discharge voltage stability, while the NCM battery had excellent energy density and long-term endurance.

Influence of different causes on thermal runaway characteristic of LiFePO4 battery

To solve the current battery safety issues and accident investigation problems. Thermal runaway experiments triggered by nail penetration, hot box, flame heating and heating plate were carried out on a commercial 8 Ah pouch LiFePO4 battery. Recorded real-time phenomena, voltage and temperature. Then we discussed the TR process in the light of the latest mechanism study. The local TR is triggered by nail penetration within 3 s. The hot area above 700 °C and the spreading of internal TR was detected. LiFePO4 battery thermal runaway will generally emit white smoke, no fire. And it requires more attention to explosion risk. If the combustible gas is ignited, jet fire will appear, but the injection pressure is not extreme. Thermal runaway triggered by local heating is inconsistent with a voltage drop. A mapping method of thermal runaway parameters radar map is designed, which can indicate the danger degree of TR with shapes. Through comparison, some characteristics are obtained for the judgment of battery accident causes. This research can provide a basis for LFP battery safety evaluate and accident investigation.

Building Flame-Retardant Polymer Electrolytes via Microcapsule Technology for Stable Lithium Batteries.

Flame retardants could improve the safety properties of lithium batteries (LBs) with the sacrifice of electrochemical performance due to parasitic reactions. To concur with this, we designed thermal-response clothes for hexachlorophosphazene (HCP) additives by the microcapsule technique with urea-formaldehyde (UF) resin as the shell. HCP@UF combines with polyacrylonitrile (PAN) by hydrogen bonds successfully to form PAN-HCP@UF as the flame-retardant solid polymer electrolyte. The hydrogen bonds ensure excellent mechanical properties of the polymer electrolyte. The multiscale free radical-annihilating agent HCP effectively eliminates hydrogen free radicals of electrolytes under high temperature, showing excellent flame retardation. During the operation of the battery, functional groups on the UF resin act as active sites to promote the migration of lithium ions, while the internal HCP is protected from electrochemical reaction. With 25% HCP@UF addition, the limiting oxygen index of the PAN-HCP@UF increases to 28% and the Li+ transfer number up to 0.80. By UF protection, the initial capacity retention rate of the Li||LFP battery that assembles with PAN-HCP@UF is 88.8% after 500 cycles at 0.5 C. Thus, the microcapsule-encapsulated approach is deemed to provide an innovative strategy to prepare high-safety solid-state LB with a stable long cycle life.

Dendrite‐Free Lithium‐Metal Batteries Enabled by 2D Lithophilic Conjugated Polymer on Separator

AbstractTacking issues of uncontrolled lithium dendrites formation with polymer‐based separator has a significant impact on the applications of lithium‐metal batteries. Here, porous poly(acrylonitrile) nanosheets (PPNS) enriched with conjugated C═C/C═N groups is designed on PP separator by spray‐coating. The conjugated molecular structure of PPNS affords high mechanical strength and thermal conductivity. Density functional theory (DFT) calculations confirm that polar N‐containing groups in PPNS derived from the cyclization of C≡N exhibit lithiophilic properties and effectively accelerate Li+ transport kinetics. Finite element simulation indicates PPNS with porous 2D nanosheet structure ensures a sufficient and uniform concentration of Li+ on the anode surface. Besides, a rich inorganic phase solid‐electrolyte interphase forms at the lithium metal interface under the induction of N‐containing groups, which further facilitates uniform lithium deposition. As a result, Li||LFP battery using PPNS@PP separator can stably cycle for 300 cycles at a high rate of 3C, with a capacity retention rate of 94.0%. Moreover, the Li||LFP pouch battery with PPNS@PP separator achieves steady cycling for 100 cycles at 0.2C, with a capacity retention rate of 95.7%.

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.

Flexible bidirectional pulse charging regulation achieving long-life lithium-ion batteries

Typical application scenarios, such as vehicle to grid (V2G) and frequency regulation, have imposed significant long-life demands on lithium-ion batteries. Herein, we propose an advanced battery life-extension method employing bidirectional pulse charging (BPC) strategy. Unlike traditional constant current charging methods, BPC strategy not only achieves comparable charging speeds but also facilitates V2G frequency regulation simultaneously. It significantly enhances battery cycle ampere-hour throughput and demonstrates remarkable life extension capabilities. For this interesting conclusion, adopting model identification and postmortem characterization to reveal the life regulation mechanism of BPC: it mitigates battery capacity loss attributed to loss of lithium-ion inventory (LLI) in graphite anodes by intermittently regulating the overall battery voltage and anode potential using a negative charging current. Then, from the perspective of internal side reaction, the life extension mechanism is further revealed as inhibition of solid electrolyte interphase (SEI) and lithium dendrite growth by regulating voltage with a bidirectional pulse current, and a semi-empirical life degradation model combining SEI and lithium dendrite growth is developed for BPC scenarios health management, the model parameters are identified by genetic algorithm with the life simulation exhibiting an accuracy exceeding 99%. This finding indicates that under typical rate conditions, adaptable BPC strategies can extend the service life of LFP battery by approximately 123%. Consequently, the developed advanced BPC strategy offers innovative perspectives and insights for the development of long-life battery applications in the future.

Inhibition effect and extinguishment mechanisms of YS1000 microemulsion for lithium iron phosphate battery fires

The inhibition of Lithium ion battery (LIB) fires has attracted more and more attention from the public. However, an effective fire-extinguishing agent used for LIB fires has not been reported. The use of water mist containing additives for LIB fires is a promising method. In this work, the YS1000 microemulsion was prepared. A fine water mist fire extinguishing system was established to study the extinguishment efficiency of the fire-extinguishing agents for LIB fires. The fire suppression efficiency of pure water, F-500 fire extinguishing agent, and YS1000 microemulsion for the 32135-type lithium iron phosphate battery (LFP) were compared in this paper. The fire extinguishment mechanism of YS1000 microemulsion was revealed by thermo gravimetry, differential scanning calorimetry, mass spectrometry (TG-DSC-MS) combined technology. The results showed that it took more than 30 s for pure water to extinguish the LFP fire. In the case of pure water, three batteries went into thermal runaway (TR). It only took less than 1 s for YS1000 microemulsion to extinguish the fire. In the process of extinguishing the fire, only one battery experienced TR. Compared with pure water, the total heat dissipation of YS1000 microemulsions to the batteries increased by 79 %. The YS1000 microemulsion extinguished the LFP battery fire mainly depending on phosphoric acid decomposing product of YS1000 microemulsion at high temperature. The phosphoric acid could eliminate H∙ and OH∙ free radicals in the flame. Research results are expected to provide a significant reference for the design of fire-extinguishing agents used for LIB fires.

Excellent Stable Cycle Performance of Polyethylene Oxide‐Based 3D Solid Dual‐Salt Composite Electrolyte with Porous Polyimide Thin Films Host

AbstractPolyethylene oxide composite electrolytes are widely used in lithium‐ion batteries because of their excellent moldability, good flexibility, and favorable chemical compatibility. However, they still suffer from low ionic conductivity and weak mechanical strength. Herein, a 3D nanofiber‐reinforced dual‐salt composite solid electrolyte (PI@PCB) is synthesized. Benefiting from the support of the porous polyimide films and the addition of lithium bis(oxalate)borate, the obtained PI@PCB electrolyte exhibits high mechanical strength, good thermal stability, excellent electrochemical stability, and a high lithium ion transference number (0.70). In addition, the assembled Li/PI@PCB/Li cell shows the lowest overpotential of 200 mV at the initial cycling stage and increases to 246 mV slightly after 1500 h. The capacity retention rate of Li/PI@PCB/LFP battery is about 88.3% after 500 cycles at 60 °C.

Electrochemical benefits of conductive polymers as a cathode material in LFP battery technology

Electrochemical benefits of conductive polymers as a cathode material in LFP battery technology

Effects of capacity on the thermal runaway and gas venting behaviors of large-format lithium iron phosphate batteries induced by overcharge

Large-capacity lithium iron phosphate (LFP) batteries are widely used in electric bicycles. However, while crucial, thermal runaway (TR) behaviors under overcharge conditions have rarely been studied, leading to frequent fire accidents. This paper investigates the overcharge behavior and TR characteristics of four LFP batteries with the same components and materials but varying capacities (86, 100, 120, and 140 Ah). Overcharge tests were conducted in a customized apparatus, and the surface temperature, mass loss, and gas venting phenomenon were recorded. The results revealed that under the same overcharge conditions, the TR early warning temperature can differ considerably with respect to battery capacity, highlighting the importance of selecting the appropriate early warning temperature in real-time temperature monitoring based on the capacity of the LFP battery. Three characteristic times were used to describe the thermal behavior of the batteries, namely, the time to reach the voltage plateau (tPV), the time when the safety valve opens (tSV), and the start time of TR (tTR). Analysis of critical heat accumulation indicated that the 86 Ah LFP battery has the lowest tolerance to overcharge and, thus, the highest TR risk. However, after TR, the 86 Ah LFP battery exhibited the smallest maximum temperature (Tmax), maximum temperature increase rate (Rmax), maximum total mass loss, and maximum mass loss rate (Mmax) among all the batteries, suggesting the least TR hazard. Consequently, a safety evaluation and scoring system using these six parameters was established considering the overcharge behavior and TR characteristics of LFP batteries. The results indicated that the TR risk ranking of LFP batteries with different capacities was 86 Ah LFP > 100 Ah LFP > 140 Ah LFP > 120 Ah LFP, while the TR hazard ranking was 140 Ah LFP > 120 Ah LFP > 100 Ah LFP > 86 Ah LFP. This comparative study of LFP batteries with varying capacities enhances our understanding of their overcharge behavior and TR characteristics, and a safety evaluation and scoring system can also be used for risk and hazard assessments of other types of batteries.

Are solid-state batteries absolutely more environmentally friendly compared to traditional batteries-analyzing from the footprint family viewpoint

In recent years, with the change of global climate, carbon neutralization has become a global consensus. Solid state batteries have become the important way to develop batteries in the future due to their advantages such as high safety, high energy density, wider operating temperature range, and the battery production stage is the main contributor to the environmental impact of the battery life cycle.This article selects three traditional batteries, LFP battery, NMC battery, LTO battery, and two new solid-state batteries, Li-FeS2 battery and LLZO battery, to conduct a study on the carbon footprint and other footprint family impacts during the production stage. The inventory data is collected from highly cited literature published in recent years, and the footprint family impact values generated by different types of battery packs are compared and analyzed. When using 1 kg as the functional unit, the footprint values of LLZO and Li-FeS2 solid-state batteries are higher than those of NMC and LFP traditional batteries in most footprint indicators such as ionizing radiation and ozone layer depletion in carbon footprint, material footprint, ecological footprint, and health footprint, resulting in greater environmental pollution. Considering the energy density of the battery, with a functional unit of 1kWh, the high energy density of solid-state batteries significantly reduces their environmental impact, while traditional battery LTO increases its environmental impact due to the lower battery energy density. But in the material footprint, both functional units of solid-state batteries have a significant impact. The high energy density of solid-state batteries still holds great development prospects, and cleaner technology and energy, as well as higher energy density, remain the direction of battery development.

Comprehensive Technology for Recycling and Regenerating Materials from Spent Lithium Iron Phosphate Battery.

The lithium iron phosphate (LFP) battery has been widely used in electric vehicles and energy storage for its good cyclicity, high level of safety, and low cost. The massive application of LFP battery generates a large number of spent batteries. Recycling and regenerating materials from spent LFP batteries has been of great concern because it can significantly recover valuable metals and protect the environment. This paper aims to critically assess the latest technical information available on the echelon utilization and recycling of spent LFP batteries. First, it focuses on the progress of disassembly, evaluation and detection, regrouping, and application in echelon utilization. Then, the recycling technologies, including pretreatment, direct repair, and material regeneration, of spent LFPs are summarized. Finally, the paper proposes some challenges in the echelon utilization and recycling of spent LFP batteries, and concludes with recommendations for an intelligent, refined, and clean LFP battery circulation system that are required to ensure the sustainable development of spent LFP battery recycling.

Multi-fault detection and diagnosis method for battery packs based on statistical analysis

Rapid and accurate battery fault diagnosis and distinction is of great importance in electrical vehicles and electrochemical energy storage system. However, misdiagnosis and missed diagnosis happened occasionally. In this paper, a statistical analysis-based multi-fault diagnosis method is proposed to detect and localize short circuit faults, electrical connection faults and voltage sensor faults in LFP battery packs. This method uses non-redundant interleaved voltage measurement topology to detect battery voltages, where every voltage sensor measures the sum of two neighboring batteries and one connection resistor between them. The statistical analysis method sets detection thresholds based on the battery operating data, and captures fault characteristics by analyzing abnormal changes in battery voltage unrelated to current. Theoretical analysis and tests verified that this method can diagnose these three kinds of faults. Sensor faults of excessive error and data sticking can also be distinguished.

Preparation of lithium iron phosphate battery by 3D printing

Three-dimensional (3D) printed batteries are considered a special class of energy storage devices that allow flexible control of the electrode structure on a microscopic scale, which is crucial to improving the energy density of miniaturized devices. In this study, lithium iron phosphate (LFP) porous electrodes were prepared by 3D printing technology. The results showed that with the increase of LFP content from 20 wt% to 60 wt%, the apparent viscosity of printing slurry at the same shear rate gradually increased, and the yield stress rose from 203 Pa to 1187 Pa. The rheological property and printability of the slurry show that the printing slurry of 40 wt% LFP has excellent conformal property and self-supporting property. Due to the porous skeleton shortening the transfer distance of ions and electrons and enhancing the efficiency of the electrode reaction, the rate performances and cycle stability of LFP batteries were improved. The 3D-printed battery containing an active material loading of 15.9 mg cm−2 achieved a specific capacity of 121.7 mA h g−1 at 0.5C after 200 cycles and coulombic efficiency higher than 99.7 %, and the LFP battery had an energy density of 350 W h kg−1. These results suggest that 3D printing is an effective strategy for developing batteries with high active material loadings and energy densities at micro sizes.