Lithium-ion Battery Cathode Research Articles

Enhanced elevated-temperature performance of LiMn2O4 cathodes in lithium-ion batteries via a multifunctional electrolyte additive

LiMn2O4 is a promising cathode material for lithium-ion batteries (LIBs) due to its low cost, environmental friendliness, and high voltage operation. However, its electrochemical performance deteriorates at elevated temperatures, primarily by reason of the structural degradation during cycling and proliferation of adverse reactions at the electrode/electrolyte interface. One of the main reasons is that the hydrolysis and decomposition of the LiPF6 at high temperatures produces HF, which leads to corrosion at the electrode/electrolyte interface and accelerates manganese dissolution. In this work, we report a multifunctional silane-based electrolyte additive, trimethoxyphenylsilane (TMPS), to solve these problems. Theoretical calculations and experimental results both demonstrate that TMPS can eliminate HF, stabilize PF5, and inhibit LiPF6 hydrolysis, thereby mitigating transition metal leaching. Additionally, TMPS improves the stability between cathode and electrolyte by constructing a highly stable and homogeneous cathode-electrolyte interfacial. The LiMn2O4//Li cell using the electrolyte containing 1 wt% TMPS retains 95.5 % and 83.7 % of its capacity after 500 cycles at 25 °C and 60 °C, respectively. Moreover, 18650-type cylindrical cells with this electrolyte also exhibit enhanced electrochemical performance at elevated temperatures. It demonstrates that TMPS is a promising multifunctional additive for manganese-based cathodes in LIBs.

Fluorine-doped carbon coating of LiFe0.5Mn0.5PO4 enabling high-rate and long-lifespan cathode for lithium-ion batteries

The limited electron and ionic conductivity, along with the sluggish kinetics caused by the Jahn-Teller effect of Mn3+, impose constraints on the electrochemical performance of LiFexMn1-xPO4. Herein, the surface of LiFe0.5Mn0.5PO4 (LFMP) is modified with a F-doped carbon using the solvothermal and calcination methods. The incorporation of F-doped carbon coating, along with the formation of interfacial F-Li, F-Fe and F-Mn bonds between the carbon layer and LFMP nanoparticles, significantly mitigates charge transfer resistance, facilitates rapid electron transfer, as well as enhances Li+ diffusion kinetics. The LFMP@C-F2 cathode prepared in this study exhibits an unexceptionable capacity retention of 90.5 % after 300 cycles at a low rate of 0.2C and a capacity retention of 78.8 % over 1000 cycles at a high rate of 1C. When incorporated into the solid battery configuration (Li/PEO-LATP CSE/LFMP@C-F2), it exhibits an initial discharge specific capacity of 148 mAh g−1 and maintains a capacity retention of 85.8 % after 60 cycles at 0.1C, thereby offering an innovative approach to enhance the performance of LFMP in terms of cycling stability and rate capacity in lithium-ion batteries, as well as to apply LFMP into solid-state lithium batteries.

Selective Leaching for the Recycling of Lithium, Iron, and Phosphorous from Lithium-Ion Battery Cathodes’ Production Scraps

The market for lithium iron phosphate (LFP) batteries is projected to grow in the near future. However, recycling methods targeting LFP batteries, especially production scraps, are still underdeveloped. This study investigated the extraction of iron phosphate and lithium from LFP production scraps using selective leaching, considering technical and economic aspects. Two leaching agents, sulfuric acid (0.25–0.5 M, 25 °C, 1 h, 50 g/L) and citric acid (0.25–0.5 M, 25 °C, 1 h, 70 g/L) were compared; hydrogen peroxide (3–6%vv.) was added to prevent iron and phosphorous solubilization. Sulfuric acid leached up to 98% of Li and recovered up to 98% of Fe and P in the solid residues. Citric acid leached 18–26% of Li and recovered 98% of Fe and P. Totally, 28% of Li was precipitated for sulfuric acid process, while recovery with citric acid did not produce enough precipitate for a characterization. Sulfur is the main impurity present in the precipitates. The total operative costs associated with reagents and energy consumption of the sulfuric acid route were below 3.00 €/kg. In conclusion, selective leaching provided a viable and economic method to recycle LFP production scraps, and it is worth further research to optimize Lithium recovery.

Ambient-pressure relithiation of spent LiFePO4 using alkaline solutions enables direct regeneration of lithium-ion battery cathodes

Lithium iron phosphate (LiFePO4) is widely recognized for its cost-effectiveness in manufacturing and high safety during usage, making it a favored choice for electric vehicles and energy storage stations. Nevertheless, the development of efficient and low-cost recycling methods has emerged as an urgent priority due to the economic and environmental benefits associated with it. Here, the present study successfully demonstrates the ambient-pressure relithiation of lithium-deficient LiFePO4 particles in alkaline solutions. Specifically, the incorporation of reductive sodium nitrite with lower redox potential in the alkaline environment spontaneously repairs the compositional and structural defects, facilitating effective lithium-ion insertion back into the original site. Consequently, the short-term annealing step promotes the formation of more thermodynamically stable particles, resulting in enhanced cycling stability and rate capability comparable to that of the pristine materials. The regenerated LiFePO4 cathode exhibits improved electrochemical performance in terms of long-term cyclability, high-rate properties and reduced polarization (a high retention of 93 % after 1000 cycles at 5C). The findings of this study suggest the significant potential for utilizing various reductants in an alkaline environment to achieve ambient-pressure relithiation, thereby facilitating the recycling and remanufacturing of spent lithium-ion cathode materials.

Synergetic pyrolysis of lithium-ion battery cathodes with polyethylene terephthalate for efficient metal recovery and battery regeneration

Spent LiNixCoyMnzO2 (x + y + z = 1) and polyethylene terephthalate are major solid wastes due to the growing Li-ion battery market and widespread plastic usage. Here we propose a synergistic pyrolysis strategy to recover valuable metals by thermally treating LiNi1/3Co1/3Mn1/3O2 and polyethylene terephthalate. With polyethylene terephthalate assistance, LiNi1/3Co1/3Mn1/3O2 decomposes at 400 °C, and fully converts to Li2CO3, MnO, and Ni-Co alloy at 550 °C within 30 min, using a 1.0:0.3 mass ratio of LiNi1/3Co1/3Mn1/3O2 to polyethylene terephthalate. Furthermore, density functional theory calculations confirm the preference for O-Li bonding. Surface adsorption and free radical/gaseous reduction reactions explain the role of polyethylene terephthalate in promoting lattice destruction. The complete decomposition facilitates efficient post-treatment, achieving over 99% recovery of Li, Ni, Co, and Mn via water washing. Regenerated LiNi1/3Co1/3Mn1/3O2 was synthesized by using recovered Li- and transition metal-containing products as feedstocks. This study provided a chemical-free, energy-saving, and scalable recovery strategy while addressing polyethylene terephthalate waste minimization.

Embedment of Molybdenum Disulfide in Electrospun Fibers as an Integrated Cathode for Lithium-Ion Batteries

As an important component of LIBs, the electrode material plays a crucial role in determining the lithium (Li) storage performance in LIBs. In this study, MoS2 nano-flowers were synthesized using a one-pot hydrothermal method. The resulting MoS2 nano-flower, along with PAN, were used as raw materials for electrospinning. After annealing treatment, MoS2/(carbon nanofibers) CNFs nano-composites coated with carbon fibers were formed. The CNFs coating exhibited electrical conductivity and enhanced structural stability of the MoS2 due to the stabilizing effect of the carbon fibers. Additionally, electrochemical tests, including CV and GCD, indicated that the optimal capacity and cycling stability were achieved when the MoS2 content was 10%. The results indicated that the charge/discharge capacity of MoS2/CNFs-10% at a current density of 100 mA/g was ~650 mAh/g. After the cycling current returned to 100 mA/g, the current recovery was ~600 mAh/g, thereby indicating outstanding cycling stability. Accordingly, our fabrication technique and new insight could both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal sulfides in next-generation high-performance lithium-ion batteries.

Effect of La3+ Doping on the Electrical Properties of LiCoO2 Cathodes for Lithium-Ion Batteries

Effect of La3+ Doping on the Electrical Properties of LiCoO2 Cathodes for Lithium-Ion Batteries

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.

Progress in the Application of LiMnPO4 Nanomaterials in Lithium-ion Battery Cathode

Lithium-ion batteries (LIBs) have become vital in today's energy storage systems, especially for electric cars and portable gadgets. High energy density, extended cycle life, and quick charging times are features of lithium batteries. Compared to conventional batteries, they are lightweight, ecologically benign, and have a low self-discharge rate. LiMnPO4 nanomaterials have garnered significant interest among various cathode materials due to their superior thermal stability, safety, and high operating voltage. The main topics of this paper are the structural characteristics, production techniques, and performance improvements of LiMnPO4 nanoparticles as LIBs cathodes. The basic operating principles of LIBs were covered in this article, with particular attention paid to the redox reactions occurring at the electrodes, the unique olivine structure of LiMnPO4, and how these factors affect electrochemical performance. The efficiency of many synthesis methods, such as spray pyrolysis, sol-gel, solid-state, hydrothermal, and solvothermal processes, in yielding superior LiMnPO4 nanoparticles is assessed. Additionally, surface modifications through ion doping and carbon coating are reviewed to highlight their roles in enhancing conductivity and stability. This article aims to provide ideas for developing high-performance LiMnPO4 cathode materials to affect LIBs' development positively. This article aims to provide ideas for developing high-performance LiMnPO4 cathode materials to influence LIBs' development positively.

Oxygen vacancies-enriched spent lithium-ion battery cathode materials loaded catalytic membrane for effective peracetic acid activation and organic pollutants degradation

Advanced oxidation processes combined with membrane filtration technique offer a promising approach for pollution mitigation and catalyst recovery. Herein, a waste ternary lithium-ion battery cathode material of LiNixCoyMnzO2 (LNCM) loaded polytetrafluoroethylene (PTFE) membrane was synthesized for peracetic acid (PAA) activation (LNCM-PTFE/PAA) and 2,4,6-trichlorophenol (TCP) degradation. Such a novel membrane, with a catalyst loading of 10 mg (0.796 mg/cm2) of LNCM achieved 96.4 % removal of TCP (2 mg/L) within 20 min in neutral pH. The redox cycles of surface metals (such as Co3+/Co2+, Ni3+/Ni2+, and Mn4+/Mn3+/Mn2+) in spent LNCM efficiently enhance charge transfer and mediated PAA activation. And intrinsic oxygen vacancies in LNCM facilitated PAA adsorption and its cleavage. The resulting carbon-centered radicals (R-C•, CH3C(O)OO•) and 1O2 are identified as the primary reactive species that collaboratively participate in TCP degradation. Quantitative structure-activity relationship analysis demonstrated a substantial reduction in product toxicity. The successful practical application of the LNCM-PTFE/PAA membrane was exemplified by treating chlorophenol industrial wastewater. This study presents a new LNCM-PTFE/PAA catalytic membrane for high-efficiency water treatment and a novel perspective for green utilization of waste LNCM.

Enhancing chemomechanical stability and high-rate performance of nickel-rich cathodes for lithium-ion batteries through three-in-one modification

Ni-rich cathode, recognized for high specific capacities and cost-effectiveness, are deemed promising candidates for high-energy Li-ion batteries. However, these cathodes display notable structural instability and experience severe strain propagation during rapid charging and extended cycling under high voltage, hindering their widespread commercialization. To tackle this chemo-mechanical instability without compromising energy and power density, we propose an efficient modification strategy involving hexavalent metal cation-induced three-in-one modification to reconstruct the nanoscale surface phase. This strategy includes uniform W-doping, integration of cation-mixed phases, and Li2WO4 nanolayers on the surface of Ni-rich cathode microspheres. W-doping strengthen the bond to oxygen, thereby enhancing structural stability and suppressing oxygen loss linked to a layered-to-rock salt phase transition during deep delithiation process. Additionally, establishing a cation-mixing domain with an optimal thickness on the cathode surface enhances Li⁺ diffusivity and alleviates particle structural degradation. Moreover, Li2WO4 nanolayers reduce electrolyte side reactions and act as a damping medium against cycling stresses. Importantly, detailed investigations into structural changes before and after modification at varying current rates were conducted to better comprehend the rate-dependent degradation mechanism. These findings yield valuable mechanistic insights into the high-rate utilization of a viable Ni-rich cathode, ensuring prolonged service life in electric vehicles.

Thermal characteristics of LiMnxFe1-xPO4 (x = 0, 0.6) cathode materials for safe lithium-ion batteries

Lithium-ion batteries have recently gained attention as energy storage devices due to their high energy densities and various applications. Layered Ni-Mn-Co-based cathode materials are widely used for their high energy density; however, their high cost necessitates the exploration of alternatives. Consequently, olivine-type LiMnxFe1-xPO4 materials are gaining popularity and are being increasingly adopted. While the synthesis methods and electrochemical properties of these materials have been extensively studied, thermal analyses remain limited. In this study, we investigated the thermal properties of olivine-type LiMnxFe1-xPO4 by combining thermal analysis, structural analysis, and computational calculations to evaluate the safety of lithium-ion batteries. Our results show that the formation energy of LiMn0.6Fe0.4PO4 is more stable than that of LiFePO4. As temperature increases, LiFePO4 decomposes at 350 °C, whereas LiMn0.6Fe0.4PO4 begins to decompose at 450 °C. The P-O bond plays a crucial role in the thermal stability of these materials; as the temperature rises, the thermal stability of the PO4 group diminishes, leading to structural decomposition. To enhance thermal stability, it is recommended to experiment with doping small amounts of various elements at the P site. This paper provides valuable insights for the design and development of thermally stable olivine-structured cathodes for lithium-ion batteries.

Green low-melting mixture solvents/ionic liquids-based carbon materials and lithium-ion batteries recycling leachate unexpectedly cause water pollution from dissolved organic matter

Low-melting mixture solvents (LoMMSs) and ionic liquids (ILs) are regarded as green solvents for the recovery of lithium-ion batteries (LIBs) cathode with high sustainability. Unexpectedly, we find for the first time that the release of LoMMSs- or ILs-based carbon materials and LIBs recycling leachate into water can lead to significant pollution from dissolved organic matter (DOM). Moreover, COD, NH4–N and total P concentration in river from Jingjinji Region is relatively high due to the high concentration of DOM. This work would provide us a hint that the application of so-called green LoMMSs and ILs in materials preparation and LIBs recovery should be treated with high caution in order to minimize DOM pollution for the rivers in Jingjinji Region.

High-entropy doping for high-voltage LiCoO2 with enhanced electrochemical performances

Lithium cobalt oxide (LiCoO2), as a pioneering layered oxide cathode material for lithium-ion batteries (LIBs), possesses exceptional theoretical specific capacity and cycling stability, positioning it as a leading candidate for commercial LIB applications. Boosting the upper-limit of charge voltage of LiCoO2 is a promising strategy to increase the capacity of batteries, vital for advancing energy storage solutions from portable electronics to electric vehicles. Nevertheless, hybrid redox reactions at high voltages speed up oxygen evolution, electrolyte decomposition, and irreversible phase transitions, ultimately causing rapid capacity fading.To address these challenges, we present a novel approach to enhance the structural stability and electrochemical performances of LiCoO2 cathode via La-Al-Mg-Y high-entropy doping. This strategy significantly improves the high-voltage cycling stability of the cathode material by retaining 72.5 % of its initial capacity after 500 cycles at 5 C under 4.6 V. Furthermore, the structural change caused by the phase transition between the O3 and H1-3 phases is remarkably suppressed. This advancement in LIB cathode technology paves the way for the development of high performance batteries and it is crucial for meeting the growing demand for sustainable energy storage.

Alternatives assessment of polyvinylidene fluoride-compatible solvents for N-methyl pyrrolidone substitution in lithium-ion battery cathodes

Lithium-ion batteries (LIBs) are central to electrification yet, to increase the efficiency and scalability of electric systems, energy storage technologies must integrate sustainability concepts into their design. Notably, the incumbent LIB technology uses the reprotoxic solvent N-methyl pyrrolidone (NMP) to dissolve polyvinylidene fluoride (PVdF) as a binder. This solvent, of concern to human and ecological health, must be replaced with less toxic alternatives. Accordingly, the objective of this study was to determine which potential solvents, compatible with PVdF binder within the cathode processing of LIBs, could replace NMP. This study followed the U.S. National Research Council’s Framework to Guide Selection of Chemical Alternatives, and thus assembled and compared data concerning ecological and human hazards, performance, and cost. Five solvents were assessed as alternatives to NMP, derived from an analysis of 948 cells of data (708 cells of hazard data, 54 cells of performance data, and 186 cells of cost data). Triethyl phosphate (TEP) and N-N’-dimethylpropyleneurea (DMPU) are found to exhibit reprotoxic properties, and dimethylsulfoxide (DMSO) raised concerns in all three data categories studied. The most promising alternatives to NMP were dihydrolevoglucosenone (Cyrene) and γ-valerolactone (GVL). With demand for sustainable energy storage growing, the results of this study aim to guide research and innovation of LIB technologies while avoiding regrettable substitutions in developing NMP-free LIBs.

Recommended Practices for the Electrochemical Recovery of Cobalt from Lithium Cobalt Oxide: A Case Study of the Choline Chloride:Ethylene Glycol Deep Eutectic Solvent.

We recommend best practices for the recovery of cobalt from LiCoO2 (LCO) lithium-ion battery (LIB) cathodes by (i) leaching using green deep eutectic solvents (DES) and (ii) subsequent electrodeposition, through a case study of the choline chloride (ChCl):ethylene glycol (EG) DES. DES physical properties (conductivity, viscosity, and surface tension) were tailored by varying the composition between mole ratios of 1 : 2 and 1 : 5 (ChCl:EG). Examined along with leaching process parameters (temperature, duration), increasing the fraction of hydrogen bond donors (HBDs) decreased DES surface tension and enhanced leaching. Complete Co recovery was achieved using 1 : 5 ChCl:EG DES at 160 °C and 48 h. Leaching temperatures >160 °C are discouraged due to DES thermal degradation. The electrodeposition process was optimized for selective Co recovery with high faradaic efficiency. The leaching ability of the DES was antithetical to the stability of electrodeposition cell components and required operational parameter adjustment to minimize degradation. The optimized system (copper cathode and stainless-steel anode) employing 1 : 5 DES leachate exhibited a faradaic efficiency of ~80 %, specific Co recovery of ~0.8 mg hr<M-1 cm-1 at 50 °C and evidence of uniform deposition. DES surface tension is a key descriptor of metal recovery, and guidelines are presented to maximize selective Co recovery.

Systematic electrochemical analysis of high-capacity NMC-88 and NMC-83 cathodes for lithium-ion batteries

Systematic electrochemical analysis of high-capacity NMC-88 and NMC-83 cathodes for lithium-ion batteries

Mechanisms of Thermal Decomposition in Spent NCM Lithium-Ion Battery Cathode Materials with Carbon Defects and Oxygen Vacancies.

Resource recovery from retired electric vehicle lithium-ion batteries (LIBs) is a key to sustainable supply of technology-critical metals. However, the mainstream pyrometallurgical recycling approach requires high temperature and high energy consumption. Our study proposes a novel mechanochemical processing combined with hydrogen (H2) reduction strategy to accelerate the breakdown of ternary nickel cobalt manganese oxide (NCM) cathode materials at a significantly lower temperature (450 °C). Particle refinement, material amorphization, and internal energy storage are considered critical success factors for the accelerated decomposition of NCM cathode materials. In our proposed approach, NCM cathode materials can develop active sites with carbon defects (Cv) and oxygen vacancies (Ov), which improve the reduction and breakdown of H2. The adsorbed H2 on the surface of NCM decomposes into H* and combines with oxygen to form OH species, which can be facilitated by Ov via the enhanced charge transfer. The introduced Cv can enhance H2 cracking and generate *C-H species to promote the thermal decomposition of NCM. The presence of defects proves to foster the preferential reduction of Mn(IV) by H2, leading to a lower activation energy for the NCM decomposition (from 139 to 110 kJ/mol) with less H2 consumption. Life cycle assessment suggests a reduction of 4.42 kg CO2 eq for the recycling of every 1.0 kg of retired batteries. This study can promote material circularity and minimize the environmental burden of mining technology-critical metals for a low-carbon transition.

Selective separation of Co(II) from leachate of lithium-ion battery cathode material using novel molecular sieve-based MOFs composite NaA-MOFs(Al)

Selective separation of Co(II) from leachate of lithium-ion battery cathode material using novel molecular sieve-based MOFs composite NaA-MOFs(Al)

A Hybrid Modelling Approach Coupling Physics-based Simulation and Deep Learning for Battery Electrode Manufacturing Simulations

Lithium-ion battery (LIB) performance is significantly influenced by its manufacturing process. Manufacturing of an optimized electrode can incur high production costs such as high energy consumption, high scrap rates and emissions. This is due to the process that consists of a series of manufacturing steps presenting a complex interrelationship, thus limiting the understanding of performance as a function of manufacturing parameters. While several empirical and computational methods are employed for optimization, they are demanding in terms of resources such as materials or computational effort. By leveraging Deep Learning (DL), we can enhance our understanding of the complex manufacturing processes and accelerate its optimization. We propose a data-driven supervised DL methodology to complement physics-based LIB cathode manufacturing simulations. The trained DL-based predictive model integrates well into the manufacturing simulation framework to forecast cathode slurry microstructures. The DL model demonstrates robust predictive performance for LIB NMC-111 and LiFePO4–based slurries and slurries for a solid-state battery NMC-622/argyrodite composite electrode preparation. While the current work is focused on the cathode slurry process, the proposed methodology has potential for application to drying and calendering steps. This approach will be helpful in streamlining lab-scale electrode manufacturing, and reducing errors, waste and resource consumption.