Cathode Materials For Lithium-ion Batteries Research Articles

Novel synthesis of FeF3·0.33H2O@hollow acetylene black nanosphere and its long-life electrochemical properties as a cathode for lithium-ion batteries

Iron (III) fluoride (FeF3), characterized by high voltage and high specific capacity and emerges as a promising candidate for the forthcoming generation of cathode materials in lithium-ion batteries. This study employs a novel methodology by introducing Fe3+ sources into hollow acetylene black particles through a vacuum impregnation method. This innovative approach results in the synthesis of a composite material comprising FeF3∙0.33H2O encapsulated within hollow acetylene black nanospheres, denoted as the FeF3∙0.33H2O @hollow acetylene black nanosphere composite material (FF@HCN). The composite exhibits a shell composed of highly graphitized carbon and a core containing FeF3∙0.33H2O particles in the range of 10–20 nm. The proportion of active materials is 75.56 %. The acetylene black has chain-like structure and high specific surface area, significantly enhances the material's conductivity, contributing 74.4 % to the pseudocapacitance at a scan rate of 1 mV s−1. The cavity graphite shell plays a crucial role in restricting the expansion and pulverization decay of FeF3∙0.33H2O nanoparticles, thereby markedly improving the cycle stability. The initial capacity of the FF@HCN composite is 224.4 mAh g−1, and after 1000 cycles at 0.1 C, it maintains a capacity of 162.3 mAh g−1, resulting in a capacity retention rate of 72.3 % and decay per cycle of 0.027 %.

Regulation of surface structure to suppress voltage decay for high-stable Li-rich oxide cathodes

Layered lithium-rich manganese oxides (LMO) are promising cathode materials for high-energy density lithium-ion batteries due to their high specific capacity and working potential. However, serious voltage decay and undesirable cycle stability are big obstacles that hinder their industrialization and application. Herein, an innovative and industrially valuable strategy of constructing composite coatings and oxygen vacancies on the LMO surface is put forward to suppress voltage decay and enhance the cycling stability of LMO by precisely modulating NaBH4 treatment. The synergistic effect of surface spinel coating, NaBO2coating, and oxygen vacancies effectively inhibits the release of oxygen, impedes the occurrence of side reactions at the interface, inhibits the migration and dissolution of transition metals, suppresses the irreversible structure transformation and improves the reversibility of redox reaction. The capacity retention of the NaBH4-treated LMO material maintains 100 % after 200 cycles at 0.5C, as well as stable cycling at 2C with a discharge capacity of 180 mAh g−1 harvested. Moreover, the voltage decay is significantly suppressed by NaBH4 modification, especially the NaBH4-0.5 % sample exhibits a mere voltage decay of 1.73 mV per cycle in the 200 cycles. This study provides significant insights into the development of LMO cathodes with long-cycle performance.

Regulating the Electron Distribution of Metal-Oxygen for Enhanced Oxygen Stability in Li-rich Layered Cathodes.

Li-rich Mn-based layered oxides (LLO) hold great promise as cathode materials for lithium-ion batteries (LIBs) due to their unique oxygen redox (OR)chemistry, which enables additional capacity. However, the LLOs face challenges related to the instability of their ORprocess due to the weak transition metal (TM)-oxygen bond, leading to oxygen loss and irreversible phase transition that results in severe capacity and voltage decay. Herein, a synergistic electronic regulation strategy of surface and interior structures to enhance oxygen stability is proposed. In the interior of the materials, the local electrons around TM and O atoms may be delocalized by surrounding Mo atoms, facilitating the formation of stronger TM─O bonds at high voltages. Besides, on the surface, the highly reactive O atoms with lone pairs of electrons are passivated by additional TM atoms, which provides a more stable TM─O framework. Hence, this strategy stabilizes the oxygen and hinders TM migration, which enhances the reversibility in structural evolution, leading to increased capacity and voltage retention. This work presents an efficient approach to enhance the performance of LLOs through surface-to-interior electronic structure modulation, while also contributing to a deeper understanding of their redox reaction.

Lattice engineering of high-entropy olivine-type lithium metal phosphate as high-voltage cathodes

Engineering of high-entropy cathode materials for lithium-ion batteries has been actively pursued owing to the outstanding conductivity of high-entropy materials benefited from the maximum entropy and unique antisite disordering structure. Olivine lithium metal phosphates such as LiMnPO4 and LiNiPO4 feature high working voltages but low capacities due to their insulation nature. In this work, the synthesis of the high-entropy lithium metal phosphate materials (HELMPs) is realized by combining mechanochemistry with a calcination method. By regulating lattice of HELMPs, the high-entropy Li(Mn0.35Fe0.35Co0.1Mg0.1Ca0.1)PO4 reveals three typical high-voltage plateaus in charge–discharge curves corresponding to the redox of Fe, Mn, and Co in the voltage range of 2.0–4.9 V vs Li+/Li, and a much higher initial capacity than LiMnPO4 (104 vs 15 mAh g−1).

Recent Progress of High Voltage Spinel LiMn1.5Ni0.5O4 Cathode Material for Lithium-Ion Battery: Surface Modification, Doping, Electrolyte, and Oxygen Deficiency.

High voltage spinel LiMn1.5Ni0.5O4 (LMNO) is a promising energy storage material for the next generation lithium batteries with high energy densities. However, due to the major controversies in synthesis, structure, and interfacial properties of LMNO, its unsatisfactory performance is still a challenge hindering the technology's practical applications. Herein, this paper provides general characteristics of LiMn1.5Ni0.5O4 such as spinel structure, electrochemical properties, and phase transition. In addition, factors such as electrolyte decomposition and morphology of LMNO that influence the electrochemical performances of LMNO are introduced. The strategies that enhance the electrochemical performances including coating, doping, electrolytes, and oxygen deficiency are comprehensively discussed. Through the discussion of the present research status and presentation of our perspectives on future development, we provide the rational design of LMNO in realizing lithium-ion batteries with improved electrochemical performances.

Al-doped flower-like VO2(B) microspheres as high-performance cathode materials for lithium-ion batteries

VO2(B), as a potential cathode material for lithium-ion batteries (LIBs), is attracting extensive attention from researchers because of its great superiority in terms of theoretical specific capacity, energy density, and cost. Nevertheless, VO2(B), leads to irreversible decay of specific capacity during cycling for reasons including structural stability and inferior electrical conductivity. In this work, the electrochemical performance of VO2(B) electrode materials are further enhanced via Al ion doping. The results reveal that the prepared Al-doped 3D flower-like VO2(B) microspheres exhibit a high initial discharge specific capacity (as high as 314.8 mAh/g at 0.1 A/g current density) at an Al doping amount of n(Al3+)/n(V5+) = 6.0 %. Moreover, it displays a first discharge specific capacity of up to 229.2 mAh/g at a current density of 1 A/g with the capacity retention rate of 90.0 % after 120 cycles. As a result, Al-doped 3D flower-like VO2(B) microspheres provide enormous commercialization potential as cathode materials for LIBs.

Enhancing the Electrochemical Performances of Disordered Li1.23Ni0.3Nb0.3Fe0.16O0.85F0.15 Cathode Material for Lithium-Ion Batteries by LiNbOx Coating.

For the next generation of lithium-ion batteries (LIBs), it is primary to seek high capacity and long-lifetime electrode materials. Li-excess disordered rock-salt structure (DRS) cathodes have gained much attention due to their high specific capacity. However, Li-excess can lead to a decrease in the structural stability of an electrode material. A new Li-rich DRS oxyfluorides, Li1.23Ni0.3Nb0.3Fe0.16O0.85F0.15 (F0.15) with a series amounts of LiNbOx (LN) coating (0, 5, 10, and 15 wt % denoted as F0.15-LN0, F0.15-LN5, F0.15-LN10, and F0.15-LN15, respectively), are successfully synthesized and evaluated as cathode materials in LIBs. Among them, F0.15-LN10 exhibits the highest initial discharge specific capacity of 296.1 mAh g-1 (at a current density of 20 mA g-1) with the capacity retention rate of 14% higher than that of the uncoated F0.15 after 80 cycles. Even at 300 mA g-1, F0.15-LN10 still delivers the highest discharge specific capacity of 130 mAh g-1. After 20 cycles, the charge-transfer impedance of F0.15-LN10 remained the smallest. The characterizations indicate that LN coating reduces the surface polarization of the cathode materials, slows the interfacial side reactions between the electrolyte and the electrode, and speeds up the Li+ diffusion. These results demonstrate that LN coating is an effective strategy to improve the electrochemical performance.

High-capacity dilithium hydroquinone cathode material for lithium-ion batteries.

Lithiated organic cathode materials show great promise for practical applications in lithium-ion batteries owing to their Li-reservoir characteristics. However, the reported lithiated organic cathode materials still suffer from strict synthesis conditions and low capacity. Here we report a thermal intermolecular rearrangement method without organic solvents to prepare dilithium hydroquinone (Li2Q), which delivers a high capacity of 323 mAh g-1 with an average discharge voltage of 2.8V. The reversible conversion between orthorhombic Li2Q and monoclinic benzoquinone during charge/discharge processes is revealed by in situ X-ray diffraction. Theoretical calculations show that the unique Li-O channels in Li2Q are beneficial for Li+ ion diffusion. In situ ultraviolet-visible spectra demonstrate that the dissolution issue of Li2Q electrodes during charge/discharge processes can be handled by separator modification, resulting in enhanced cycling stability. This work sheds light on the synthesis and battery application of high-capacity lithiated organic cathode materials.

Bifunctional low molecular weight polyacrylic acid as aqueous binder and coating agent enables high performance LiMn2O4 cathode for lithium-ion batteries

LiMn2O4 is considered to be a promising cathode material for lithium-ion batteries due to its decent energy density, low price and environmental benignity. However, the problems of Mn dissolution, migration and deposition during the cycle, seriously affect its lifespan, especially at high temperature. In this study, we developed a strategy by which we killed two birds with one stone. A low molecular weight polyacrylic acid (PAA) mixed with sodium carboxymethyl cellulose (CMC) is applied as binder and coating agent for cathode particles at the same time. The conventional and environmental unfriendly polyvinylidene difluoride (PVDF)-N-methylpyrrolidone (NMP) system is replaced by the cheap and green aqueous binder with improved adhesive effect. Furthermore, the binder-based surface coating layer not only alleviates the side reaction between the electrolyte and the cathode particles, but also chelates the dissolved Mn2+ by the large amount of carboxyl groups in PAA molecules and so prevents the following migration and deposition of Mn2+. In the button half-cell with low molecular weight PAA based binder, the capacity retention reaches 94.1 % after 1000 cycles at room temperature and 92.0 % after 200 cycles at 60 degrees centigrade. Meanwhile, 18650-type cylindrical cells were prepared with this binder, which shows a great high temperature storage performance. After the cell was held at 60 degrees centigrade for 25 days at full charged state, the internal resistance increased by only 1.25mΩ, the voltage decreased by only 0.1 V, the residual capacity retention and recovery capacity retention reaches 85.6 % and 92.2 %. This work shows the great potential of the aqueous binder in dealing with the problem of Mn dissolution during the cycling of manganese-based cathode materials for lithium-ion batteries.

A modification engineering to form two kinds of truncated octahedrons by in situ LaBO3 coating for high-performance LiMn2O4 cathode material

Rapid capacity fade of spinel LiMn2O4 cathode material limits the application of lithium-ion batteries. Herein, the introduction of La/B elements achieves the dual-modification of surface coating and single-crystal truncated morphology, ensuring the compatibility of rate capability and cycling stability. The La and B introduction enables the in situ formation of LaBO3 coating layer. Both the LaBO3 coating and truncated morphology prevent the direct exposure of the cathode to the electrolyte, decreasing the Mn dissolution and providing the additional Li+ diffusion channels. The increase of La and B modification partially restrains the development of {110} crystal planes. The refinement manifests that the La3+/B3+ doping partially replaces Mn3+ of the LiMn2O4, inhibiting the Jahn-Teller effect and stabilizing the [MnO6] skeleton. Consequently, the optimized LiMn2O4@0.04LaBO3 with the favorable LaBO3 coating thickness and two truncated octahedrons exhibits the excellent electrochemical properties at high current rate. The first discharge capacities of 109.1, 104.2 and 96.9 mAh⋅g−1 are obtained, whilst the capacity retentions of 64.8 % (after 2000 cycles), 65.8 % (after 2000 cycles) and 80.5 % (after 1000 cycles) can be maintained at 5 C, 10 C and 20 C, respectively. Even at 5 C and 55 °C, the high initial discharge capacity of 113.6 mAh⋅g−1 and good cycling lifespans can be achieved. This modification strategy provides valuable insight for preparing the advanced LiMn2O4 cathode materials for lithium-ion batteries.

Synthesis and Properties of the LiMn2O4 Cathode Material for Lithium-ion Batteries

Spinel LiMn2O4 was synthesized by high-temperature solid-state method with lithium salt and manganese salt as raw materials, which were mixing with anhydrous ethanol as solvent under stirring, and calcining at high temperature in in the oxygen atmosphere. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that the size of lithium manganese particles with spinel structure was 80 to 200 nm, and the particle size distribution was uniform. The results showed that the prepared LiMn2O4 sample sintered at 700°C exhibited superior electrochemical performance when used as a cathode material for lithium-ion batteries with a voltage window of 2.5–4.8 V. The first charge-discharge specific capacity and first discharge capacity can reach 158.0 mAh‧g-1 and 138.4 mAh‧g-1, respectively, at 0.1 A‧g-1 current density, and the first Coulomb retention efficiency is 87.6%. The discharge specific capacity of the LiMn2O4 material can be maintained at 114 mAh‧g-1 when the test current density was returned to 0.1 A‧g-1 after 60 cycles.

Concerted Effect of Ion- and Electron-Conductive Additives on the Electrochemical and Thermal Performances of the LiNi0.8Co0.1Mn0.1O2 Cathode Material Synthesized by a Taylor-Flow Reactor for Lithium-Ion Batteries.

To address the issue that a single coating agent cannot simultaneously enhance Li+-ion transport and electronic conductivity of Ni-rich cathode materials with surface modification, in the present study, we first successfully synthesized a LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material by a Taylor-flow reactor followed by surface coating with Li-BTJ and dispersion of vapor-grown carbon fibers treated with polydopamine (PDA-VGCF) filler in the composite slurry. The Li-BTJ hybrid oligomer coating can suppress side reactions and enhance ionic conductivity, and the PDA-VGCFs filler can increase electronic conductivity. As a result of the synergistic effect of the dual conducting agents, the cells based on the modified NCM811 electrodes deliver superior cycling stability and rate capability, as compared to the bare NCM811 electrode. The CR2032 coin-type cells with the NCM811@Li-BTJ + PDA-VGCF electrode retain a discharge specific capacity of ∼92.2% at 1C after 200 cycles between 2.8 and 4.3 V (vs Li/Li+), while bare NCM811 retains only 84.0%. Moreover, the NCM811@Li-BTJ + PDA-VGCF electrode-based cells reduced the total heat (Qt) by ca. 7.0% at 35 °C over the bare electrode. Remarkably, the Li-BTJ hybrid oligomer coating on the surface of the NCM811 active particles acts as an artificial cathode electrolyte interphase (ACEI) layer, mitigating irreversible surface phase transformation of the layered NCM811 cathode and facilitating Li+ ion transport. Meanwhile, the fiber-shaped PDA-VGCF filler significantly reduced microcrack propagation during cycling and promoted the electronic conductance of the NCM811-based electrode. Generally, enlightened with the current experimental findings, the concerted ion and electron conductive agents significantly enhanced the Ni-rich cathode-based cell performance, which is a promising strategy to apply to other Ni-rich cathode materials for lithium-ion batteries.

Stable surface lattice for prolonged cycle life of single-crystal lithium-rich layered oxide cathodes

Lithium-rich layered oxides (LLOs) have garnered significant attention due to their outstanding capacity. However, the severe capacity fading resulting from lattice deterioration initiated at the surface constrains the further advancement of LLOs. Here, we present a method to stabilize the surface lattice to enhance the capacity stability of LLOs. Specifically, we have engineered a nanometer-thin Gd-doped NiO rock-salt epitaxial layer on the surface of single-crystal LLOs, along with an atomic-level thickness LiGdO2coating layer. The dual-nanolayer protection strategy has successfully stabilized the surface structure of LLOs and suppressed electrode–electrolyte interface side reactions. As a result, the modified sample achieves a capacity retention rate of 93.4% after 500 cycles at 1C and 94.2% after 200 cycles at 0.2C. Our study underscores the importance of surface structure in achieving high cyclic stability in LLOs and provides an important approach for designing stable lithium-ion battery cathode materials.

Analysis of Thermal Reduction of Mixture of Organic Components on Cathode Materials of Spent Ternary Lithium-Ion Battery

Analysis of Thermal Reduction of Mixture of Organic Components on Cathode Materials of Spent Ternary Lithium-Ion Battery

Fabricated and improved electrochemical properties of layered lithium-rich Co-free manganese-based Li1.2Mn0.6Ni0.2O2 cathode material for lithium-ion batteries

Fabricated and improved electrochemical properties of layered lithium-rich Co-free manganese-based Li1.2Mn0.6Ni0.2O2 cathode material for lithium-ion batteries

Status and Development of Cathode Materials for Lithium-Ion Batteries

Driven by the energy transition and the wave of electrification, efficient battery technology is a core requirement in today's society. Lithium-ion batteries, with their high energy density and long lifespan, occupy an important place in sustainable energy storage solutions. However, the overall performance and economics of the batteries greatly depend on the cathode materials used in them, and innovations in this area are critical to the advancement of battery technology. This study focuses on the latest research findings on cathode materials for lithium-ion batteries, providing an in-depth analysis of key materials such as lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, and ternary materials. The article details the chemical properties and performance optimisation of these materials. Through a comparative analysis, this paper aims to reveal the comprehensive performance of different cathode materials and explore their potential for improving battery energy density, reducing cost, and enhancing safety. The importance of this research lies in the fact that it provides an in-depth understanding of cathode materials for lithium-ion batteries, offering a key guide to the innovation and development of future battery technologies. This is not only of practical significance for the advancement of efficient, economical, and environmentally friendly battery technologies but also provides a valuable reference for related industries and academia.

Atomic-Scale Characterization of Microscale Battery Particles Enabled by a High-Throughput Focused Ion Beam Milling Technique.

The cathode materials in lithium-ion batteries (LIBs) require improvements to address issues such as surface degradation, short-circuiting, and the formation of dendrites. One such method for addressing these issues is using surface coatings. Coatings can be sought to improve the durability of cathode materials, but the characterization of the uniformity and stability of the coating is important to assess the performance and lifetime of these materials. For microscale particles, there are, however, challenges associated with characterizing their surface modifications by transmission electron microscopy (TEM) techniques due to the size of these particles. Often, techniques such as focused ion beam (FIB)-assisted lift-out can be used to prepare thin cross sections to enable TEM analysis, but these techniques are very time-consuming and have a relatively low throughput. The work outlined herein demonstrates a FIB technique with direct support of microscale cathode materials on a TEM grid that increases sample throughput and reduces the processing time by 60-80% (i.e., from >5 to ∼1.5 h). The demonstrated workflow incorporates an air-liquid particle assembly followed by direct particle transfer to a TEM grid, FIB milling, and subsequent TEM analysis, which was illustrated with lithium nickel cobalt aluminum oxide particles and lithium manganese nickel oxide particles. These TEM analyses included mapping the elemental composition of cross sections of the microscale particles using energy-dispersive X-ray spectroscopy. The methods developed in this study can be extended to high-throughput characterization of additional LIB cathode materials (e.g., new compositions, coating, end-of-life studies), as well as to other microparticles and their coatings as prepared for a variety of applications.

Electrochemical performance of Fe-doped modified high-voltage LiNiPO4 cathode material of lithium-ion batteries

Electrochemical performance of Fe-doped modified high-voltage LiNiPO4 cathode material of lithium-ion batteries

Mechanical properties modeling of cathode materials for lithium-ion batteries based on bond valence model

To clarify electrochemical-mechanical relation of cathode materials for lithium-ion batteries, a series of empirical mechanical property models based on the bond valence model are applied to estimate the hardness, bulk, shear, and Young’s moduli, Poisson’s ratio and fracture toughness of typical cathode materials, such as LiCoO2, LiNi1-x-yCoxMnyO2, LiNi0.80Co0.15Al0.05O2, LiMn2O4, and LiFePO4. The calculated results are in agreement with experimental values. The mechanical properties have been predicted for low Ni compounds LiNixCo1–2xMnxO2 (0 ≤ x ≤ 0.5), high Ni compounds LiNi0.8Mn0.2-xCoxO2 (x = 0, 0.1, 0.2), and free Co compounds LiNixMn1-xCo0O2 (x = 0.5, 0.6, 0.8). For LiCoO2 during lithiation and delithiation processes, the hardness and bulk modulus of LixCoO2 decrease nearly linearly with the decrease of Li concentration. The effects of Al doping on the mechanical properties of LiAlxCo1-xO2 are also revealed from the insights into the chemical bonds. The models are powerful for extensively predicting and tuning electrochemical-mechanical properties of cathode materials.

Resource Recovery of Spent Lithium-Ion Battery Cathode Materials by a Supercritical Carbon Dioxide System.

The increasing global market size of high-energy storage devices due to the boom in electric vehicles and portable electronics has caused the battery industry to produce a lot of waste lithium-ion batteries. The liberation and de-agglomeration of cathode material are the necessary procedures to improve the recycling derived from spent lithium-ion batteries, as well as enabling the direct recycling pathway. In this study, the supercritical (SC) CO2 was innovatively adapted to enable the recycling of spent lithium-ion batteries (LIBs) based on facilitating the interaction with a binder and dimethyl sulfoxide (DMSO) co-solvent. The results show that the optimum experimental conditions to liberate the cathode particles are processing at a temperature of 70 °C and 80 bar pressure for a duration of 20 min. During the treatment, polyvinylidene fluoride (PVDF) was dissolved in the SC fluid system and collected in the dimethyl sulfoxide (DMSO), as detected by the Fourier Transform Infrared Spectrometer (FTIR). The liberation yield of the cathode from the current collector reaches 96.7% under optimal conditions and thus, the cathode particles are dispersed into smaller fragments. Afterwards, PVDF can be precipitated and reused. In addition, there is no hydrogen fluoride (HF) gas emission due to binder decomposition in the suggested process. The proposed SC-CO2 and co-solvent system effectively separate the PVDF from Li-ion battery electrodes. Thus, this approach is promising as an alternative pre-treatment method due to its efficiency, relatively low energy consumption, and environmental benign features.