Commercial LiFePO4 Research Articles

Core-shell structured LiFePO4/C nanocomposite battery material for lithium production from brines

The development of affordable and environmentally friendly methods to produce lithium is urgently required to cope with the accelerating growth of the lithium battery market. Battery materials such as LiFePO4 can be used to selectively sequestrate lithium from brine natural resources, thus producing a high-purity lithium salt for battery manufacture, but the long-term stability of the material is currently not sufficient for practical applications. Here, we report, for the first time, the development of a nanosized core-shell structured LiFePO4/C material for applications in lithium production from brines. This LiFePO4/C with a LiFePO4-core (∼123 nm size) covered by a pinhole-free carbon shell (∼5 nm thickness) was prepared via solvothermal synthesis, and the carbon content was optimised to 5 wt%. The optimal core-shell structured LiFePO4/C material exhibits a lithium extraction capacity of ca. 160 mA h g-1 at C/10 and ca. 130 mA h g-1 at 1C, and >87 % capacity retention after 50 cycles of lithium sequestration and release at C/10 in synthetic brines. This excellent electrochemical performance is attributed to the homogenous nanosizing of the LiFePO4 particles as well as the full coverage of the carbon coating, which provides effective protection by preventing the direct contact of LiFePO4 with the brines, thus stopping the surface degradation reactions that compromise the long-term stability. A direct comparison with three commercial LiFePO4 materials demonstrates that, while similar performance is obtained in non-aqueous lithium-ion batteries, for lithium production applications, core-shell nanostructuring is crucial to achieve high capacity and preserve the material's longevity.

Sustainable upcycling of mixed spent cathodes to a high-voltage polyanionic cathode material

Sustainable battery recycling is essential for achieving resource conservation and alleviating environmental issues. Many open/closed-loop strategies for critical metal recycling or direct recovery aim at a single component, and the reuse of mixed cathode materials is a significant challenge. To address this barrier, here we propose an upcycling strategy for spent LiFePO4 and Mn-rich cathodes by structural design and transition metal replacement, for which uses a green deep eutectic solvent to regenerate a high-voltage polyanionic cathode material. This process ensures the complete recycling of all the elements in mixed cathodes and the deep eutectic solvent can be reused. The regenerated LiFe0.5Mn0.5PO4 has an increased mean voltage (3.68 V versus Li/Li+) and energy density (559 Wh kg–1) compared with a commercial LiFePO4 (3.38 V and 524 Wh kg–1). The proposed upcycling strategy can expand at a gram-grade scale and was also applicable for LiFe0.5Mn0.5PO4 recovery, thus achieving a closed-loop recycling between the mixed spent cathodes and the next generation cathode materials. Techno-economic analysis shows that this strategy has potentially high environmental and economic benefits, while providing a sustainable approach for the value-added utilization of waste battery materials.

Composite Graphene‐Modified Aluminum Foil Cathode Current Collectors for Lithium‐ion Battery with Enhanced Mechanical and Electrochemical Performances

AbstractAluminum foil is a typical cathode collector in lithium‐ion batteries, yet it encounters various issues, including restricted contact with the active substance, poor adhesion, and regional corrosion associated with the electrolyte. Although conventional carbon‐coated aluminum foils partially alleviate such problems, they suffer from excess weight and thickness of their carbon layers. Here a simple casting method to prepare Ketjen Black/aqueous graphene dispersion slurry modified aluminum foil (KB‐AGD‐Al‐CCs) and graphene micro‐sheets/aqueous graphene dispersion slurry modified aluminum foil (GM‐AGD‐Al‐CCs). Our results indicate that batteries utilizing graphene‐modified aluminum foils exhibited superior electrochemical performance compared with that of carbon‐coated aluminum foils. The lithium‐ion battery employing GM‐AGD‐Al‐CCs as cathode current collectors exhibits reversible specific capacities of 155, 118, and 92.5 mAh/g at current densities of 0.1, 5, and 10 C. After cycling for 1800 cycles at 5 and 10 C, its specific capacities remain at 91 and 77.5 mAh/g. Combing contact angle measurement, electrical conductivity test with electrochemical impedance spectroscopy indicates that the graphene coating decreases the contact angle between the commercial LiFePO4 and current collector, increases the electrical conductivity of the electrode and adhesion. Moreover, the inclusion of GM and KB as conductive additives compensates for graphene‘s low interlayer conductivity by forming a conductive network.

Aging Mechanisms and Evolution Patterns of Commercial LiFePO4 Lithium-Ion Batteries

Aging Mechanisms and Evolution Patterns of Commercial LiFePO4 Lithium-Ion Batteries

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.

Electrochemically Driven Transformation of Olivine LiFePO4 to Olivine NaFePO4 in Cells with Sodium Anode and Carbonate Electrolyte

AbstractThe direct electrochemical transformation of commercial LiFePO4 to NaxFePO4 olivine in a Na||LiFePO4 electrochemical cell with sodium electrolyte has been studied. Electrolytes containing 1 M of NaClO4 in ethylene carbonate (EC), dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC) have been probed, and in the solvents with the ratio of EC:DMC:FEC=0.4:0.5:0.1 by volume, maximal values of the specific capacity (113 mAh g−1) with good cycling stability and maximal discharge currents are achieved upon sodiation. To determine the composition of the cathode material and utilization factor of LiFePO4, the dependence of open circuit voltage on specific capacity has been investigated. The general formula of the sodiation product can be written as Na0.88FePO4. Its theoretic specific capacity may be estimated as 135 mAh g−1. The composition of the products obtained is supported by XRD analysis, which suggests that in discharged cathodes, Coulombic influence of LiFePO4 crystallites on neighboring NaxFePO4 crystallites may enlarge the unit cell of the former and reduce its size of the latter. Probably, shrinkage in the presence of LiFePO4 stabilizes the olivine structure of NaxFePO4 and prevents its transformation from electrochemically active olivine to inactive maricite.

Two-step strategy to optimize interfacial compatibility of polyether sulfone-Li6.75La3Zr1.75Ta0.25O12 composite polymer electrolytes with Li anode for solid lithium battery with a wide working temperature range

Although composite polymer electrolytes (CPEs) are currently regarded as one of the most promising solid electrolyte systems closing to commercial application, some basic problems, including low conductivity at low temperature, serious interfacial compatibility with Li metal anode, inhibit the development of CPEs for solid state lithium batteries (SSLBs). Herein, a “polymer-in-ceramic” CPEs consisting of polyether sulfone (PESF), Li6·75La3Zr1·75Ta0·25O12 (LLZTO) and bis(trifluoromethane) sulfonimide lithium salt (LiTFSI) is reported, and a two-step strategy is proposed to optimize its conductivity and interfacial compatibility with Li metal anode. Benefitting from both the continuous porous structure to provide additional Li+ conducting pathways on internal porous interfaces and the typical heterogeneous bilayer structure to enhance compatibility with Li metal anode, the optimized CPEs delivers promising Li+ conductivities in a wide operating temperature range (>2.0 × 10−4 S cm−1 at −10 °C, >1.4 × 10−3 S cm−1 at 60 °C), improved tolerance against Li dendrites and/or pulverization. Moreover, commercial LiFePO4 cathode based SSLBs show acceptable discharge specific capacities of >160 mA h g−1 and excellent cycling stabilities of over 200 cycles at both room temperature and 60 °C at 0.2C.

Organic Acid‐Based Hydrothermal Leaching of LiFePO4 Cathode Materials

AbstractThis study conducts hydrothermal leaching of commercial LiFePO4 (LFPO) cathode materials with oxalic acid, citric acid, or glycine without any other oxidants or reductants. Of these acids, glycine exhibits the weakest leaching behavior, with the leaching efficiency of lithium (Li), iron (Fe), or phosphorus (P) less than 15% even at 200 °C and an acid concentration of 0.8 mol L−1 for 10 min. For oxalic acid, at 200 °C for 10 min, with a pulp density of 30 g L−1 and an acid concentration of 0.8 mol L−1, the leaching efficiencies for Li and P are 100% and 97%, respectively, and 98.5% of Fe precipitates as iron oxalate (FeC2O4) that can be used as a precursor for preparing LFPO cathode materials. Citric acid shows the highest leaching efficiency for Li, Fe, and P, reaching 96%, 100%, and 88%, respectively, at 90 °C for 10 min with a pulp density of 10 g L−1 and an acid concentration of 0.8 mol L−1. The continuous hydrothermal leaching of LFPO cathode materials with citric acid is first achieved. These results clarify the superiority of citric acid over oxalic acid and glycine with respect to the leaching efficiency for Li, Fe, and P from LFPO batteries under hydrothermal conditions.

Lithium zinc/lithium iodide composite modified layer toward highly stable lithium metal anodes

Lithium metal batteries (LMBs) are considered by most researchers as among the most prospective next-generation high energy density storage devices because of high theoretical capacity (3860 mAh g − 1) and low reduction potential (–3.040 V compared to standard hydrogen electrode) of Li metal anode. Nevertheless, the uncontrollable dendrite growth of the Li metal anode during cycling hinders the commercial application of LMBs. Herein, we put forward a hybrid protective layer containing LiZn alloy and LiI at the surface of the Li metal anode. Thanks to the "lithiophilic" feature of LiZn alloy and LiI having a low surface Li+ diffusion energy barrier, the constructed homogeneous hybrid protective layer can reduce the nucleation barrier and facilitate Li+ rapid diffusion. As a consequence, Li metal anode exhibits a smooth plating/stripping morphology and can suppress the dendrite formation. Notably, the constructed ZI@Li || ZI@Li symmetrical cell realizes stable cycling for 470 h at 2 mA cm−2 and 2 mAh cm−2, and LMBs matched with commercial LiFePO4 cathode deliver greatly enhanced electrochemical properties. This hybrid protective layer provides a feasible strategy to realize even plating/stripping of Li metal, which would promote the high energy density LMBs for practical applications.

Study on the influence of electrode materials on energy storage power station in lithium battery

Lithium batteries are promising techniques for renewable energy storage attributing to their excellent cycle performance, relatively low cost, and guaranteed safety performance. The performance of the LiFePO4 (LFP) battery directly determines the stability and safety of energy storage power station operation, and the properties of the internal electrode materials are the core and key to determine the quality of the battery. In this work, two kinds of commercial LFP batteries were studied by analyzing the electrical properties and material properties of the electrodes. After performing the rate and cycle performance tests of the battery cell, differential scanning calorimetry, scanning electron microscope, x-ray diffraction, and inductively coupled plasma were used to explore the performance of electrode materials to establish the correlation between the battery performance and the electrochemical reaction law of the internal materials and further to judge the influence of the key material properties on the battery performance. This work opens up an avenue for technical supervision of energy storage power stations.

Surface regulation of Si composite anode via synergistic coupling and Ti[sbnd]C bond for stable cycling lithium-ion battery

Silicon holds bright promise as the anode material for next-generation lithium-ion batteries (LIBs). Unfortunately, it is limited by enormous volume expansion and fast capacity fading in long-cycling or large current density. Here, we propose an in-situ assembling path to form a stable Si nanocomposite by introducing bicontinuous TiO2-C layer and graphene nano-sheets, and further enhance the stability for long-term LIBs. The enhanced synergistic coupling of graphene and bicontinuous TiO2-C layer and introduced TiC bond effectively improve long-cycling structural stability of Si nanocomposite for promising LIBs anode material. This anode material exhibits high capacity, long-term cycling and high-rate performance. Especially, it showed the high reversible capacities of 2147.6 mA h g−1 at 0.5 A g−1 after 800 cycles and 1328.2 mA h g−1 at 2 A g−1 after 500 cycles, which is much better than that of TiO2-C@Si and nano Si anodes. Moreover, the full cell including this composite anode and commercial LiFePO4 cathode exhibits a high capacity retention after 100 cycles. Our work demonstrates that this surface functionalization strategy can enhance synergistic coupling and introduce TiC bond to regulate the stability of Si nanocomposite as long-cycling LIBs anode.

Towards dendrite-free Zn metal batteries via formation of fluorinated interfacial layer with functional additive

Rechargeable aqueous zinc metal batteries are considered as an alternative in grid-scale energy storage since they offer several intrinsic merits that make them a promising choice including absolute safety, abundant reservoir, cost-effectiveness and sustainability, whereas the Zn anode sustained poor reversibility induced by active water-related parasitic reaction and uncontrollable Zn dendrite growth. In this work, we employed fluorophosphate ester (FEP) as functional additive for ZnSO4 aqueous electrolyte, which not only participated in the formation of protective fluorinated layer on surface of Zn electrode to facilitate the Zn2+ diffusion, but also preferentially adsorb on the Zn surface to manipulate the Zn deposition orientation. Consequently, dendrite-free Zn anode was achieved with extended cycling span of over 1800 h at 10 mA cm−2, 10 mAh cm−2 in Zn symmetric cell and appealing Coulombic efficiency up to 98.9% after 500 times of zinc plating/stripping in Zn||Cu asymmetric cell. Additionally, the FEP contained electrolyte supports full cells work when paired with MnO2 and commercial LiFePO4 cathode. This feasible strategy with electrolyte functional additive provides insightful direction in the design of interfacial layers to harvest stable Zn anodes in aqueous metal-based battery technology.

Study on the thermal runaway characteristics and debris of lithium-ion batteries under overheating, overcharge, and extrusion

As the use of lithium-ion batteries (LIBs) becomes more widespread in various fields, incidents of combustion caused by thermal runaway (TR) of LIBs are increasing. However, identifying the causes of TR is challenging. To address this, we employ a method that combines TR characteristics and debris analysis to identify the causes of TR in this study. We investigate a commercial LiFePO4 (LFP) battery and trigger TR under overheating, overcharge, and extrusion conditions. Following TR, we observe that under the overheating and overcharge condition, numerous floccule attach to the anode debris; under the extrusion condition, the anode debris is covered by numerous small particles; and under the overcharge condition, a large number of flocculant and smooth balls attach to the anode debris, and the composition of these substances contains numerous metal oxides. Moreover, under the overheating condition, the heat release, and gas release rate of the debris are the minimum, while they are the maximum under the extrusion condition. Due to the different reaction processes and degrees of TR under different conditions, the properties of the LIB debris also differ. By analyzing the debris and data, we can distinguish the debris under different conditions. This enables us to quickly identify the trigger factors of battery TR after it occurs.

Irreversible Mechanical Deformations Associated with the Formation of Cathode-Electrolyte Interface on Lithium Iron Phosphate Cathodes

The demand for rechargeable batteries for energy storage in electrical automobiles is rising presently due to their key role in reducing carbon emissions. However, the increasing demands require improvement in batteries lifetime. interfacial instabilities associated with the formation of cathode-electrolyte interface and intercalation-induced volumetric expansions are the primary reasons behind the capacity fade. Although there have been great efforts to understand structural stress/strains in cathodes, there is a lack of knowledge about the formation mechanism of cathode-electrolyte interface (CEI) layers. To fill the gap, we investigate the role of electrolyte chemistry on the interfacial deformation of lithium iron phosphate (LFP) cathodes by employing digital image correlation (DIC), spectroscopy, and electrochemical techniques. DIC was utilized to study the dynamic physical behavior of the electrode materials and irreversible strains associated with the electrolyte decomposition on the electrode surface [1]. Therefore, the overall objective of this study is to elucidate the mechanical deformations in the LFP cathodes of battery electrodes by investigating the physical response of the electrode and dynamic changes on the electrode – electrolyte interface.To be able to understand the different effects of the electrolyte solution, electrolytes were made of either LiPF6, LiClO4, or LiTFSI salts dissolved in 1 M EC:DMC. When cycled in the LiClO4 and LiTFSI salts containing electrolytes, the volumetric contraction is observed in the electrode because of the extraction of lithium and associated phase transformations during the first delithiation. However, positive strain generation was observed only during the first cycle in LiPF6 containing electrolyte, although delithiation results in reducing the lattice parameters. Control experiments were conducted where the electrode was cycled in LiClO4-containing electrolyte for one cycle and electrolyte was changed to the LiPF6-containing electrolyte for the subsequent cycles. A similar irreversible mechanical behavior was also observed in the control experiments where positive strain generation is recorded during the subsequent first delithiation cycle in LiPF6-containing electrolyte. To further analysis, electrochemical impedance spectroscopy measurements were performed on each system to identify surface resistance of the electrodes in a voltage range between 3 - 4.4 V. Increasing in the surface resistance of the electrodes were associated with CEI layer formations [2, 3]. Chemical composition of the CEI layers were characterized by using x-ray photoelectron spectroscopy. Our study provides a pathway to investigate the formation of the cathode-electrolyte interface on the cathode electrodes by monitoring irreversible physical behavior of the electrode – electrolyte interface during cycling.This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences (Award numberDE-SC0021251). References Çapraz, Ö. Ö., Rajput, S., Bassett, K. L., Gewirth, A. A., White, S. R., & Sottos, N. R. (2019). Controlling expansion in lithium manganese oxide composite electrodes via surface modification. Journal of The Electrochemical Society, 166(12), A2357.Liu, Y., & Xie, J. (2015). Failure study of commercial LiFePO4 cells in overcharge conditions using electrochemical impedance spectroscopy. Journal of The Electrochemical Society, 162(10), A2208.Bassett, K. L., Çapraz, Ö. Ö., Özdogru, B., Gewirth, A. A., & Sottos, N. R. (2019). Cathode/electrolyte interface-dependent changes in stress and strain in lithium iron phosphate composite cathodes. Journal of the Electrochemical Society, 166(12), A2707.

Thermal oxidation of MoS2 into defective crystalline MoO3 with enhanced Li-ion storage kinetics

Thermal oxidation in air of molybdenum disulfide (MoS2) into layer structured molybdenum trioxide (α-MoO3) is investigated using a combination of thermal analysis, electron microscopy, Raman, X-ray diffraction and photoelectron spectroscopy. The phase evolutions occurred during the thermal process is characterized by the surface oxidation of MoS2, followed by the bulk oxidation to form α-MoO3 and the formation of Mo17O47 at higher temperatures. The single-phase MoO3 formed at optimum temperature condition is found to possess crystalline defects and considerably greater values of Li-ion storage cycling and rate performances in comparison with samples prepared at alternative temperatures and also the initial MoS2. This sample (P-MoO3-820) exhibits a charge capacity of 628 mA h g−1 after 250 cycles (100 mA g−1) with a Li+ diffusion coefficient of 2.3 × 10-13 cm2 s−1, substantially greater than that of initial MoS2 (8.1 ×10−16 cm2 s−1). The electrochemical performance of P-MoO3-820 in full-cell configuration against a commercial LiFePO4 cathode is evaluated and a specific capacity of 100 mAh g−1 after 500 cycles is recorded. This article, for the first time, discusses the thermal oxidation in air of MoS2 as a simple and relatively clean approach to fabricate defective crystalline MoO3 with enhanced Li-ion storage kinetics.

In Situ Synthesis of Porous Plate‐Like Li4Ti5O12 Lithium‐Ion Battery Anode with Advanced Li+ Storage Mechanism and Enhanced Electrochemical Kinetics

AbstractSpinel Li4Ti5O12 as the anode material for lithium‐ion batteries possessed “zero strain” characteristics, high safety, good stability, rapid Li+ diffusion rate, and fast charging and discharging performance, and has been used commercially. In this work, a porous plate‐like structure for Li4Ti5O12 is constructed via an economic in situ topological reaction with H1.07Ti1.73O4·H2O as the precursor. In terms of Li+ storage, not only the typical intercalation reaction of Li4Ti5O12 can be fully carried out, but also the Li+ storage in the form of pseudocapacitance can be introduced due to its porous structure, thus the enhanced Li+ storage mechanism can be realized and the reversible capacity in the work (197 mAh g−1 at 0.1 A g−1) break the bottleneck of 175 mAh g−1 for Li4Ti5O12. In terms of electrochemical reaction kinetics, its plate‐like shape effectively avoids agglomeration of particles reducing the charge transfer resistance, and the micropores increase the diffusion rate of Li+ (3.3 times faster than the commercial Li4Ti5O12 nanoparticles). During the practical test, it can maintain the reversible capacity of 134 mAh g−1 after 1000 cycles at the huge current density of 1.0 A g−1 and show good compatibility with commercial LiFePO4 cathode, which proves its great practical potential for LIBs.

An advanced CoNb2O6 anode material with in-situ interstitial doping for high-rate lithium-ion batteries

Niobium-based bimetallic oxide, as a potential anode material for fast-charging lithium-ion batteries, has attracted much attention owing to its unique lithium intercalation channel. However, the poor conductivity and structural instability of such material severely limit its further application. In this paper, CoNb2O6 was prepared by a molten-salt method and was in-situ doped with high-valence V5+ ion in different proportions. Different from conventional substitutional doping, a small amount of interstitial doping is more conducive to the entry of V5+ into the gap, which leads to lattice expansion. With the increase of doping amount, elemental Nb5+ was gradually replaced by V5+, which then hinders the Li+ intercalation/de-intercalation to a certain extent. Based on the DFT and electrochemical tests, the interstitial-doped CNO-V0.005 nanoparticles has not only faster Li+ diffusion kinetics and lower energy barrier, but also delivers high discharge capacity with long cycling stability at high current density of 2000 mA g−1 (≈ 8C). After assembling the full cell with CNO-V0.005 and commercial LiFePO4 cathode material, the reversible capacity of 150.6 mAh g−1 could be achieved after 200 cycles at the current density of 1000 mA g−1, demonstrating its application potential in fast- charging lithium-ion batteries.

Comprehensive analysis of gas production for commercial LiFePO4 batteries during overcharge-thermal runaway

The failure and fires have increasingly become puzzles that may not be ignored for Li-ion batteries (LIBs). Overcharging is notoriously difficult to detect in the early stage. To address this problem, eight types of commercial LiFePO4 batteries are used to evaluate overcharge-thermal runaway (TR) properties in a sealed chamber, including surface temperature, voltage, pressure, and vent gas. And a gas-based fault diagnosis method is proposed based on the gas results. The results show that the Tmax and Pmax of the cells are between 121–150 °C and 132–144 kPa except for the battery type 3. The primary gases measured by the gas chromatograph are CO, H2, CO2, and alkanes, and the total amount of gases ranges from 12 to 45 mmol. Moreover, the proportions of H2 and CO2 both exceeded 30 %. Furthermore, the overcharge-warning experiment showed that H2 was outperformed by CO and CH4, and the capture time was 271 s and 579 s earlier than smoke and TR. Once the gases are detected, TR may be completely suppressed, and the battery neither smokes nor fires. The gas-based TR method is significantly superior to the traditional method in terms of reliability and rapidity. This study can provide a reference for the fault diagnosis of LIBs.

Toward High-Performance Metal-Organic-Framework-Based Quasi-Solid-State Electrolytes: Tunable Structures and Electrochemical Properties.

Metal-organic frameworks (MOFs) have been reported as promising materials for electrochemical applications owing to their tunable porous structures and ion-sieving capability. However, it remains challenging to rationally design MOF-based electrolytes for high-energy lithium batteries. In this work, by combining advanced characterization and modeling tools, a series of nanocrystalline MOFs is designed, and the effects of pore apertures and open metal sites on ion-transport properties and electrochemical stability of MOF quasi-solid-state electrolytes are systematically studied. It isdemonstrated that MOFs with non-redox-active metal centers canlead to a much wider electrochemical stability window than those with redox-active centers. Furthermore, the pore aperture of MOFs is found to be a dominating factor that determines the uptake of lithium salt and thus ionic conductivity. The ab initio molecular dynamics simulations further demonstrate that open metal sites of MOFs can facilitate the dissociation of lithium salt and immobilize anions via Lewis acid-base interaction, leading to good lithium-ion mobility and high transference number. The MOF quasi-solid-state electrolyte demonstrates great battery performance with commercial LiFePO4 and LiCoO2 cathodes at 30°C. This work provides new insights into structure-property relationships between tunable structure and electrochemical properties of MOFs that can lead to the development of advanced quasi-solid-state electrolytes for high-energy lithium batteries.

Recovery of iron from titanium white waste for the preparation of LiFePO4 battery

The recovery of iron from by-product ferrous sulfate in titanium white industry to prepare battery-grade FePO4 represents a promising approach to address the solid waste disposal issue while simultaneously providing a precursor for new energy battery. However, a critical challenge lies in the elimination of impurities during the purification and synthesis process to prevent decrease in electrochemical performance of the product. In this work, we propose a simple, clean and cost-effective route based on Al/Ti precipitation purification, followed by selective synthesis of FePO4·2H2O with coexisting divalent metal ions. The results demonstrate precipitation efficiencies of 98.3% and 99.9% for Al and Ti, respectively, and only 1.3% loss of iron under the optimal conditions during the purification separation process. The contents of impurity in the synthesized FePO4 from waste ferrous sulfate met the battery-grade standard. Furthermore, the synthesized LiFePO4 materials exhibited comparable electrochemical performance with that of commercial LiFePO4. In addition, the growth mechanism of FePO4·2H2O particles under high temperature and high acid environment was clarified, which was dominated by surface nucleation. This work provides a guidance for the utilization of iron resource from waste ferrous sulfate to prepare battery-grade LiFePO4, and may promote the recycling industries and clean production strategies in titanium field.