LiFePO4 Research Articles

Mechanically Reinforced Pseudosolid Polyelectrolyte Membranes via Layer‐by‐Layer Assembly for High‐Performing Lithium‐Metal Batteries

AbstractIonogels are emerging as high‐potential pseudosolid electrolytes for lithium‐metal batteries (LMBs), leveraging their intrinsic high ionic conductivity from entrapped ionic liquid (IL) electrolytes. However, their practical application is hindered by poor mechanical strength stemming from the confinement of ILs within a polymer matrix. To address this challenge, the formation of conformal polyion coatings with functional groups is reported to be relevant to LMBs’ application on ionogels, utilizing a layer‐by‐layer (LbL) assembly strategy. This approach significantly enhances the mechanical strength (Young's modulus and tensile strength) and electrochemical performance of ionogels, owing to the tailored interface modifications introduced by functional groups’ specific conformal polyion coatings. The core of this methodology leverages the inherent ionic structure of ionogels to enable facile interface modification through Coulombic interactions between polyanions and polycations. These conformally coated interface functionalized membranes show improved electrochemical performance when integrated with cathode materials such as LiFePO4 (LFP) and LiNi0.8Mn0.1Co0.1O2 (NMC811) in an LMB configuration, underscoring their potential for robust, high‐conductivity, pseudosolid membranes for LMB applications. These innovative pseudosolid membranes offer improved mechanical and electrochemical properties, leading to higher battery efficiency and safety, making them promising candidates for next‐generation LMB technology.

A Method of Efficiently Regenerating Waste LiFePO4 Cathode Material after Air Firing Treatment.

Waste LiFePO4 (LFP) batteries can be harmful to the environment and lead to waste of resources if not properly disposed of. In this study, an efficient and environmentally friendly method for solid-phase recycling waste LFP cathode material (W-LFP) is proposed. Most of the impurities in the W-LFP are removed by air firing. The regenerated LFP is then obtained by adding lithium carbonate and triethanolamine for repair during heat treatment. The addition of triethanolamine converts Fe3+ to Fe2+ and also allows the formation of an N-doped modified carbon layer on the surface of the LFP particles, which improves the electrochemical properties of the regenerated material. Physical characterization and electrochemical tests are used to investigate the attenuation and regeneration mechanism of LFP. The regenerated LFP possesses a high specific discharge capacity (152.87 mAh g-1 at 0.2 C), which is about 95.32% of the commercial LFP, and the capacity retention rate is 88.52% after 600 cycles at 1 C. It is worth noting that we do not use solvents such as acids and alkalis in the regeneration process, thus avoiding the generation of large quantities of acid and alkaline waste liquids, which is friendly to the environment. This solid-phase regeneration process offers a promising method for the future recycling of used LFP batteries because of its simplicity, environmental friendliness, and high efficiency.

Formicarium-Like Micron Porous Si Synergistically Adjusted by Surface Hard-Soft Nanoencapsulation as Long-Life Lithium-Ion Battery Anode.

Micron porous silicon (MPSi) is a promising lithium-ion battery (LIB) anode that can provide enough space to effectively alleviate the volume expansion and large number of transmission channels to rapidly transport the Li-ions. However, a long-term stable MPSi anode at high current density is still a great challenge. Herein, a double-regulated formicarium like-MPSi composite using the surface hard-soft titanium dioxide-few layered MXene nanotemplate (FMPSi@TiO2@FMXene) was designed and synthesized via an in situ assembly strategy as long-life LIB anode. Such hard-soft TiO2-FMXene nanoencapsulation can collaboratively tune the internal/external stress, inhibit the volume expansion, reduce the interfacial reactions, and improve the electrical conductivity of MPSi, resulting in the great enhancement of structural stability and electrochemical performance in cycling even at high current density. Especially, this FMPSi@TiO2@FMXene anode exhibits a high reversible capacity of 1254.9 and 970.4 mAh/g after 500 cycles at 0.5 and 1 A/g, respectively. Moreover, a full cell is assembled with the FMPSi@TiO2@FMXene anode and commercial LiFePO4 (LFP) cathode, exhibiting a high capacity retention rate of 91.6% in 100 cycles. This work provides an effective surface nanoengineering tactic to obtain the structurally stable MPSi anodes by hard-soft nanotemplate for large-scale and long-term LIB application.

Recycling Li-Ion Batteries via the Re-Synthesis Route: Improving the Process Sustainability by Using Lithium Iron Phosphate (LFP) Scraps as Reducing Agents in the Leaching Operation

The development of hydrometallurgical recycling processes for lithium-ion batteries is challenged by the heterogeneity of the electrode powders recovered from end-of-life batteries via physical methods. These electrode materials, known as black mass, vary in composition, containing differing amounts of nickel, manganese, and cobalt (NMC), as well as other chemicals, such as lithium iron phosphate (LFP). This study presents the results of the hydrometallurgical treatment of mixed NMC and LFP black masses aimed at creating flexible recycling processes. This approach leverages the reducing power of LFP to optimize the leach liquor composition for re-synthesizing NMC precursors. In particular, the leaching conditions were optimized based on the LFP content in the solid feed to maximize the extraction of key metals (Ni, Mn, Co, and Li). The leaching solid residue, graphite, was treated and characterized as a secondary raw material for new anode preparation. Iron phosphate was recovered by increasing the pH of the leach liquor, and the NMC precursors were obtained via coprecipitation. This process achieved a recycling rate of 51%, based on the black mass input and the mass of recovered elements in the output products. Additionally, substituting LFP scraps as the reducing agent in place of H2O2 reduced the recycling process’s environmental impact by avoiding 1.7 tons of CO2-equivalent emissions per ton of NMC black mass.

Difluorobenzene as an Antisolvent for Fluorinated Electrolyte to Achieve Unparalleled Cycle Life of Lithium Metal Battery.

Electrolytes play a crucial role in enhancing the cycling stability and overall lifespan of lithium metal batteries (LMBs). However, conventional electrolytes achieve ununiform and low ionic conductivity solid electrolyte interphase (SEI), leading to uncontrolled lithium dendrite growth and dead lithium formation, rendering them inadequate for meeting the performance of high energy density LMBs. Herein, a 1,2-difluorobenzene (1,2-dFBn) is introduced as antisolvent in fluorinated electrolyte which is composed of fluoroethylene carbonate (FEC) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The low energy level of the lowest unoccupied molecular orbital (LUMO) and the high fluorine-donating ability of 1,2-dFBn jointly modify the solvation structure and electrode/electrolyte interphase chemistry. As a result, this simple electrolyte formulation enables the Li||Li symmetric cells exhibit remarkable stability, enduring 700 h of continuous cycling under 2 mA cm-2 and Li||Cu cell achieve an impressive average Coulombic efficiency (CE) of 99.76%. Moreover, the full cell assembled with electrochemically deposited lithium capacity of 5 mAh cm-2 and LiFePO4 (LFP) as cathode achieves exceptional performance, maintaining a discharge specific capacity of 134.9 mAh g-1 while retaining 95.1% capacity at 2C after 1000 cycles. This study offers a plausible ratio design for fluorinated electrolyte, which achieving high CE and long-life LMBs.

Revealing role of oxidation in recycling spent lithium iron phosphate through acid leaching

Revealing role of oxidation in recycling spent lithium iron phosphate through acid leaching

Development of Low Temperature Lithium Ion Batteries

This article briefly introduces the history of the birth of lithium-ion batteries and discusses the necessity of studying how to make lithium-ion batteries work properly under low-temperature conditions. It also introduces the development of ternary materials, a common material for lithium-ion batteries, in the past two years, as well as the working conditions and performance advantages and disadvantages of ternary materials and another commonly used positive electrode material, lithium iron phosphate, in different environments. Finally, a comprehensive overview of the development path of lithium-ion positive electrode materials under low-temperature conditions is given.

Research Progress of Lithium Iron Phosphate in the Cathode of Lithium-Ion Battery

Lithium-ion batteries (LIBs) have been a new candidate for various industries. Unlike other types of lead-acid batteries, LIBs have a very high energy density, power density, and nominal voltage, making them a beneficial choice of battery for many electronic devices like electric vehicles. The role of cathode material in the battery is to start the electrochemical reaction, and the rate capacity is highly dependent on the ion-diffusion rate at the cathode. This makes the cathode the most critical component in the battery. Therefore, it is essential to have excellent cathode material to perform its function. Lithium iron phosphate has always been a desirable cathode material due to its stable structure, high safety, and low cost. By choosing the appropriate material, high capacity and performance can be achieved. By modifying the material through different strategies, LFP has the potential to exceed its theoretical capacity and be applied in the broader field of the electronics industry. First, this article focuses on a comparison of different cathode materials and explains why LFP is superior. Then, it will introduce the synthesis methods, including solid-state, hydrothermal, and sol-gel methods. Finally, it will discuss ways to modify LFP, including nanostructured LFP, carbon coating, and doping. This paper aims to serve as a guide and reference for research in the battery industry.

Advances in Lithium Iron Phosphate Cathode Materials for Lithium-Ion Batteries

LiFePO4 has become very prospective cathode materials for lithium-ion batteries because of its stable charge/discharge performance, high specific capacity and high safety. At present, the main challenges facing lithium iron phosphate cathode materials is the poor conductivity and low energy density, which urgently need to be optimized. This paper summarizes the mainstream modification strategies for lithium iron phosphate cathode materials by exploring the relevant literature in recent years. In detail, the crystal structure and the reaction mechanism of LiFePO4 cathode materials during the charging and discharging process were investigated and reviewed. Based on the disadvantages of LiFePO4 cathode, the three targeted modification methods including carbon coating, metal ion doping and nanosizing are also analyzed. By strengthening the research on the above improvement strategies, the ideal LiFePO4 with excellent performance is expected.

Redox Mediator as Highly Efficient Charge Storage Electrode Additive for All‐Solid‐State Lithium Metal Batteries

AbstractAll‐solid‐state lithium metal batteries (ASSLBs) have the potential to provide a significant increase in energy density and safety. However, most ASSLBs are still suffering from low cathode loading, poor rate capability, and low attainable energy/power densities, which seriously limit their practical application. Besides developing solid electrolytes with high conductivity, constructing a highly loaded cathode with rapid reaction kinetics is also essential for achieving high‐performance ASSLBs. Herein, the methylamine hydroiodide (CH6NI) is investigated as a functional electrode additive to enable rapid Li+ transport and charge transfer in LiFePO4 (LFP) cathode, whereby the CH6NI serves as a charge storage carrier that facilitates the reaction kinetics during the delithiation and lithiation process of LFP. As a result, the ASSLB assembled with LFP@CH6NI cathode shows excellent cycling stability over 700 cycles at 2 C with a high capacity retention of 87.6%, while the cell with bare LFP cathode shows no capacity at high current rates (≥0.5 C). Moreover, the ASSLB pared with a high active loading cathode (5.6 mg cm−2) still exhibits a high specific capacity of 144.9 mAh g−1 at 0.5 C. This work provides a facile strategy that opens new possibilities for designing high‐loading electrodes for high‐performance ASSLBs.

Unveiling the potential of lithium fluoride phosphate (Li2MPO4F, M = Fe, V, Mn) for the next generation of lithium-ion batteries: A comparative study based on first principles and molecular dynamic simulations

LiFePO4 (LFP) cathode with olivine crystal structure has been a key player in safe and affordable energy storage, owing to its low-cost iron and high electrochemical stability within a voltage range of commercial electrolytes (2.8–3.4 V). To maintain these benefits while enhancing its energy density, Li2MPO4F was developed by introducing fluorine (F) and replacing iron with other transition metals (M). However, previous studies on these materials primarily measured performance within a limited voltage window (e.g., 2.5–4.5 V), making it challenging to analyze their performance under advanced electrolytes with a broader voltage range. In this study, we took a novel approach by utilizing first principles and molecular dynamic calculations to investigate the electrochemical performance of Li2MPO4F with three types of transition metals (M = V, Fe, Mn). This unique methodology, which includes calculations on theoretical voltages, atomic structures, and diffusion coefficient after structural optimization, allowed us to predict the impact of transition metals on cathode performance. By closely comparing the expected results, this study discusses the pros and cons of each cation substitution and suggests suitable cathode materials for batteries with high energy density and superior rate capability.

Polymeric Lithium Battery using Membrane Electrode Assembly

Alternative configuration lithium cell exploits electrode and polymer electrolyte cast all‐in‐one to form a membrane electrode assembly (MEA), in analogy to fuel cell technology. The electrolyte is based on polyethylene oxide (PEO), lithium bis‐trifluoro sulfonyl imide (LiTFSI) conducting salt, LiNO3 sacrificial film‐forming agent to stabilize the lithium metal, and fumed silica (SiO2) to increase the polymer amorphous degree. The membrane has conductivity ranging from ~5×10−4 S cm‐1 at 90 °C to 1×10−4 S cm‐1 at 50 °C, lithium transference number of ~0.4, and relevant interphase stability. The MEA including LiFePO4 (LFP) cathode is cycled in polymer lithium cells operating at 3.4 V and 70 °C, with specific capacity of ~155 mAh g‐1 (1C = 170 mA gLFP‐1) for over 100 cycles, without signs of decay or dendrite formation. The cell exploiting the MEA shows enhanced electrochemical performance as compared with the one using simple polymeric membrane stacked between cathode and anode. Furthermore, the MEA reveals the key advantage of possible scalability and applicability in roll‐to‐roll systems for achieving high‐energy lithium metal battery, as demonstrated by pouch‐cell application. These data may trigger new interest on this challenging battery exploiting the polymer configuration for achieving environmentally/economically sustainable, and safe energy storage.

The Recycling of Lithium from LiFePO4 Batteries into Li2CO3 and Its Use as a CO2 Absorber in Hydrogen Purification

The growing adoption of lithium iron phosphate (LiFePO4) batteries in electric vehicles (EVs) and renewable energy systems has intensified the need for sustainable management at the end of their life cycle. This study introduces an innovative method for recycling lithium from spent LiFePO4 batteries and repurposing the recovered lithium carbonate (Li2CO3) as a carbon dioxide (CO2) absorber. The recycling process involves dismantling battery packs, separating active materials, and chemically treating the cathode to extract lithium ions, which produces Li2CO3. The efficiency of lithium recovery is influenced by factors such as leaching temperature, acid concentration, and reaction time. Once recovered, Li2CO3 can be utilized for CO2 capture in hydrogen purification processes, reacting with CO2 to form lithium bicarbonate (LiHCO3). This reaction, which is highly effective in aqueous solutions, can be applied in industrial settings to mitigate greenhouse gas emissions. The LiHCO3 can then be thermally decomposed to regenerate Li2CO3, creating a cyclic and sustainable use of the material. This dual-purpose process not only addresses the environmental impact of LiFePO4 battery disposal but also contributes to CO2 reduction, aligning with global climate goals. Utilizing recycled Li2CO3 decreases the demand for virgin lithium extraction, supporting a circular economy. Furthermore, integrating Li2CO3-based CO2 capture systems into existing industrial infrastructure provides a scalable and cost-effective solution for lowering carbon footprints while securing a continuous supply of lithium for future battery production. Future research should focus on optimizing lithium recovery methods, improving the efficiency of CO2 capture, and exploring synergies with other waste management and carbon capture technologies. This comprehensive strategy underscores the potential of lithium recycling to address both resource conservation and environmental protection challenges.

Synthesis of spherical LiFePO₄ microparticles with encapsulated carbon nanotubes for high-power lithium-ion batteries

Lithium ferrophosphate – LiFePO₄(LFP) – is one of the widely studied and used materials for lithium-ion batteries. However, one of the main drawbacks of LFP is its poor electrical conductivity. To address this issue, we propose an effective approach based on encapsulating carbon nanotubes within the volume of LFP particles in the volume of spherical LFP particles. Electrodes based on the obtained materials exhibit more aTₜᵣactive electrochemical characteristics than LFP obtained by the standard method: increased specific capacity (62 and 92 mAh g–1 at a current density of 20C for LFP and LFP/SWCNT, respectively), stability of cyclic characteristics (preservation of 98% capacity after 100 charge/discharge cycles for LFP/SWCNT and 96.5% for LFP), as well as reduced charge transfer resistance. Encapsulation of SWCNT into the structure of iron phosphate during deposition is an easy-to-implement approach to formation modified LFP-based cathodes with improved characteristics, which expands the possibilities of their practical application in high-power lithium-ion batteries.

Room-temperature ionic liquid electrolytes for carbon fiber anodes in structural batteries

Structural batteries require thermally stable electrolytes paired with carbon fibers (CFs), which offer advantages of lightweight, high mechanical strength, and good electrical conductivity. This work evaluated various room-temperature ionic-liquids (RTILs) as compatible electrolytes for CF anodes and LiFePO4 (LFP) cathodes on CFs. This LFP/CF full-cell design eliminates Cu and Al current-collectors, potentially enhancing gravimetric energy and reducing costs. Among various RTILs, LiTFSI in N-propyl-N-methylpyrrolidinium (PYR13) – bis(fluorosulfonyl)imide (FSI) offered promising LFP/CF full-cell performances, attributed to the formation of solid electrolyte interphase (SEI) layer on the CF anode with components such as Li2Sx, Li2S–SO3, LiF, LixFy and F–SO2, identified through X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analyses further confirmed the electrochemical stability of the SEI layer on CF anodes. The LFP/CF cell delivered an initial capacity of 119 mAh/g and relatively high Coulombic efficiency when using the 1 M LiTFSI in PYR13-FSI. CF cycled in different electrolytes exhibit varying mechanical properties with up to 10.08 % loss in tensile strength, which may be related to CF surface degradation during cycling. The 1 M LiTFSI in PYR13-FSI is non-flammable, offering a significant thermal safety. This work successfully demonstrated the significant potential of 1 M LiTFSI in PYR13-FSI RTILs, which enables the use of CF as both an anode active material and cathode current collector for structural battery applications.

Experimental Investigation of Thermal Runaway Behaviour and Inhibition Strategies in Large-Capacity Lithium Iron Phosphate (LiFePO4) Batteries for Electric Vehicles

Large-scale lithium-ion batteries play an important role in the electric vehicle market and the thermal runaway (TR) behaviour of batteries is one of the significant threats to the passengers. In this study, we conducted a series of thermal abuse tests concerning single battery and battery box to investigate the TR behaviour of a large-capacity (310 Ah) lithium iron phosphate (LiFePO4) battery and the TR inhibition effects of different extinguishing agents. The study shows that before the decomposition of the solid electrolyte interphase (SEI) film, temperature consistency within the battery were maintained and it was advisable to use temperature detectors. With the destruction of the internal structure of the battery and the uneven temperature distribution at the subsequent battery reaction stage, a large amount of combustible gas was released when the safety valve was opened. The combustible gas fire detector is used to improve alarm reliability and provided a stable early warning response time. Based on this TR behaviour, a LiFePO4 battery box with a standard size of 1060 × 660 × 250mm was constructed. The TR inhibition effect of two different extinguishing agents (heptafluoropropane and perfluorohexanone) were investigated using a metal tube spraying method with a spraying dose of 1.8kg (spraying rate of 0.06kg/s) and a spraying pressure of 2.5MPa. The results showed that using either of these, satisfy the requirements for TR inhibition in large-capacity LiFePO4 batteries and the flames could be completely extinguished without any reignition, and the chain reaction of the surrounding batteries was effectively prevented. Moreover, heptafluoropropane was proven to have a shorter fire-extinguishing time, whereas perfluorohexanone had the advantage of inhibiting temperature rise. This study provides valuable experimental results for early warning and inhibition of TR in large-capacity LiFePO4 batteries for electric vehicles.

Surface iron concentration gradient: A strategy to suppress Mn3+ Jahn-Teller effect in lithium manganese iron phosphate

To address the low energy density of LiFePO4 (LFP) for electric vehicles and high-voltage energy storage, LiMn0.5Fe0.5PO4 (LMFP) provides a potential solution but faces performance degradation due to Mn3+-induced Jahn-Teller distortion and Mn ion dissolution during cycling. This study proposes a surface engineering strategy to enhance LMFP’s electrochemical performance by increasing surface iron concentration and reducing manganese content, based on the electronic differences between Mn3+ and Fe3+ in MO6 octahedra. Density Functional Theory (DFT) calculations confirmed the viability of this approach by analyzing volume changes and binding energies with HF during charging. Guided by DFT, an LMFP@LFP/C material was synthesized with a high-iron-concentration surface layer (∼2 nm), as observed through AC-STEM. Post-cycling TEM analysis and corrosion simulations demonstrated that LMFP@LFP/C suppresses Mn ion dissolution and stabilizes the crystal lattice compared to unmodified LMFP/C. Electrochemical tests showed that LMFP@LFP/C has superior electronic conductivity and faster lithium-ion diffusion. It delivered an initial discharge capacity of 150.82 mAh g−1 at 0.1C, surpassing LMFP/C (147.65 mAh g−1). At 1C, LMFP@LFP/C retained 95.85 % of its capacity after 500 cycles, significantly outperforming LMFP/C (74.18 %). This surface modification strategy advances phosphate-based cathode materials for electric vehicles and renewable energy applications.

Robust polymer electrolytes with fast ion-transport nanochannels constructed by carbon dots for long lifespan Li metal batteries

As an anode material in energy storage systems, Li metal has exceptional merits, including high specific capacity, low density, and low redox potential. However, challenges such as lithium dendrites and unstable solid electrolyte interphase (SEI) hinder the practical application of lithium metal batteries (LMBs). Solid polymer electrolytes (SPEs), notably PVDF-HFP, are expected to overcome the above problems because of their mechanical merits and safe features, but their limited ion transportation behaviors result in insufficient ionic conductivity at room temperature. Herein, we invent an approach to prepare high performance electrolytes composed by porous PVDF-HFP and functionalized carbon dots (CDs). Such porous PVDF-HFP polymer membranes are created by a subtle phase inversion process, possessing a sponge-like structure, vertical lithium-ion transport channels and CDs decorated surfaces, thus able to uptake the liquid electrolyte (LE) to form gel polymer electrolytes (GPEs). The CDs fillers are produced in large scale with adjustable surface states, which can enhance Li salts disassociation to release free Li ions. As a result, the optimal conductivity of the as-prepared GPEs at room temperature is up to 8.7 mS cm−1 and the lithium transference number reaches 0.64. Our GPEs endow Li symmetric batteries with very stable SEI and long cycling life over 2200 h, and help realize high capacities and retention rates of the LMBs using LiFePO4(LFP) or LiCoO2(LCO) cathodes.

Experimental study on the internal pressure evolution of large-format LiFePO4 battery during thermal runaway

The safety problems of lithium-ion batteries, such as fire and explosion, have become the main issues constraining the rapid development of electrochemical energy storage. This paper proposes a new method to obtain the internal pressure and gas components of battery under adiabatic condition. Subsequently, the internal pressure evolution of a fully charged 300 Ah LiFePO4 (LFP) cell during thermal runaway (TR) are analyzed. At the temperature of safety venting (SV), the internal peak pressure recorded is 412 kPa and the gas release of H2 and CO are 35.2 % and 23.7 %, respectively. Basing on the analysis, the gas release temperature calculated by internal pressure is about 5 K lower than self-generated heat temperature. Before SV, the electrolyte volatilization and gas releasing are decoupled, and the gas release is about 0.009 mol. The internal pressure evolution of battery can be divided into three stages. At stage C, the gas release which cause SV account for 43.97 % of the gas volume and the reactions releasing H2 and CO gas are the prime chemical reason for SV. These results are of great significance to the setting of early warning system and the emergency response to TR.

Lithium Anode Stability Enhanced by Micro-Potentials from Spontaneous Polarization in BaTiO3 Films

Lithium metal is widely recognized as an ideal anode material due to its high specific capacity and low redox potential. However, challenges such as severe lithium dendrite growth have significantly impeded its practical applications. Herein, we introduce a BaTiO3 (BTO) ferroelectric thin film into the lithium anode. During the charge/discharge cycles, the BTO film generates a micro-potential in the direction opposite to the applied electric field, owing to its spontaneous polarization. The micro-potential effectively reduces the electric field gradient, thereby suppressing inhomogeneous nucleation and the growth of lithium dendrites. Consequently, the incorporation of the BTO ferroelectric thin film significantly enhances the cycling performance of the batteries. The half cells demonstrate stable operation after more than 100 cycles at high capacity of 4 mAh·cm−2. Furthermore, the LiFePO4 (LFP) full cell delivers a specific capacity of 146.6 mAh·g−1 after 300 cycles. This work demonstrates a promising strategy for the development of lithium batteries with improved longevity and enhanced capacity.