Materials For Li-ion Batteries Research Articles

Simple Solution Plasma Synthesis of Ni@NiO as High-Performance Anode Material for Lithium-Ion Batteries Application.

Pursuing of straightforward and cost-effective methods for synthesizing high-performance anode materials for lithium-ion batteries is a topic of significant interest. This study elucidates a one-step synthesis approach for a conversion composite using glow discharge in a nickel formate solution, yielding a composite precursor comprising metallic nickel, nickel hydroxide, and basic nickel salts. Subsequent annealing of the precursor facilitated the formation of the Ni@NiO composite, exhibiting exceptional electrochemical properties as anode material in Li-ion batteries: a capacity of approximately 1000 mAh g-1, cyclic stability exceeding 100 cycles, and favorable rate performance (200 mAh g-1 at 10 A g<M-.1). Comparative analysis across various methods for synthesizing NiO-based materials underscored the superiority of the Ni@NiO composite. Furthermore, an assessment of resource costs demonstrated the cost-effectiveness and scalability of the approach in terms of resource consumption per Ah. Lastly, the integration of a Ni@NiO anode with an NMC532 cathode in a full battery highlights Ni@NiO's potential for conversion anodes, achieving a practical gravimetric energy density of 92 Wh kg-1.

Coral-shaped AlSi anode materials for Li-ion batteries enabled by THF-based electrolyte

This research aims to implement a strategy of using a controlled acidic etching on AlSi alloy particles to partially remove Al and preserve a porous Si framework as anode materials. The etched AlSi materials with different Al/Si weight ratios have been investigated in lithium-ion batteries. Microstructural analysis shows the evolution of the AlSi material during selective wet etching, highlighting the preservation of coral-shaped Si nanostructures with an Al-rich core. Lower Al/Si ratios result in increased surface area and pore volume, which is favorable for improving lithium-ion diffusion and accommodating volume expansion during cycling. Evaluation of electrochemical performance in different electrolytes proves the importance of electrolyte selection for AlSi anodes. The tetrahydrofuran-based (THF-based) electrolyte stabilizes electrochemical reactions, resulting in superior specific capacity, cycle life, and Coulombic efficiency compared to the carbonate-based electrolyte with fluoroethylene carbonate additive. Rate performance analysis shows excellent high-rate capability with stable capacity retention at 3C, particularly in Al53Si47 and Al10Si90 materials. Electrochemical impedance spectroscopy measurements emphasize the critical role of porous structure and electrolytes in sustaining low resistance and enhancing cycle life performance. Selective aluminum etching and the THF-based electrolyte effectively mitigate the breakdown and subsequent reformation of the solid electrolyte interphase, resulting in superior efficiency and extended lifespan.

A novel morphology of high voltage LiMn1.5Ni0.5O4 cathode material with niobium-doping

Spinel LiMn1.5Ni0.5O4 (LMNO) is one of the promising cathode materials for the next generation Li-ion batteries due to its voltage platform. However, the dissolution of the transition metal at high voltage is the biggest obstacle that LMNO suffers from. In this study, we successfully suppressed transition metal dissolution in LMNO by the morphology control from regular octahedron to spherical. Niobium was integrated as a dopant, which restricted the growth of (111) crystal face, and increased the indices of crystal faces by homogenizing the surface energy. By changing to a smaller surface area with spherical morphology, the contact area with the electrolyte was reduced, thus suppressing the dissolution of the Mn ion. Consequently, the niobium-doped LMNOexhibited superior rate performance, capacity retention with 74.1% at 1C after 500 cycles in half-cell, and thermal stability compared to pristine LMNO.

Providing high stability to suppress metal dissolution in LiMn0.5Fe0.5PO4 cathode materials by Zn doping

LiMnxFe1-xPO4 (LMFP) is a promising cathode material for Li-ion batteries owing to its higher energy density than that of LiFePO4. However, the Jahn-Teller distortion caused by Mn3+ and oxidation of Fe2+ leading electrolyte decomposition lowers its cycling performance and structure stability. To address these problems, this study proposes an optimized Zn-doping content to enhance the electrochemical performance of LMFP. Results indicate that doping with 1.0 % Zn (LMFP-Zn 1.0 %) achieves the optimal cycling performance. Especially, LMFP-Zn 1.0 % exhibits 92.6 % capacity retention after 100 cycles at 2C. The HR-TEM and XPS analyses confirm that this level of doping suppresses metal dissolution and structure destruction effectively after cycling at high C-rates, resulted in improving the electrochemical performance and stability of LMFP cathode materials.

In situ anchoring in carbon matrix of Bi2O2CO3 as a high-performance anode material for Li-ion batteries

In situ anchoring in carbon matrix of Bi2O2CO3 as a high-performance anode material for Li-ion batteries

Enhanced electrochemical performance of MgFeO4 spinel as anode materials for Lithium-ion batteries through manganese doping

Existing graphite anode materials are reaching their limits, and iron-based AB2O4 spinel materials are considered as potential anodes for Li-ion batteries owing to their significant theoretical capacities. In this work, novel nanocrystalline MgFe2-xMnxO4 (x = 0, 0.1, 0.2, and 0.3) spinel ferrites were evaluated as anode materials for high-capacity Li-ion batteries. The Mn-doped MgFe2-xMnxO4 (x = 0, 0.1, 0.2, and 0.3) spinel ferrites were synthesized through a facile sol-gel synthesis method coupled with an annealing process. Their crystal structure, morphology, and purity were examined via X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The X-ray diffraction analyses with Rietveld refinement of the synthesized ferrites reveal pure cubic structure with a characteristic Fd3̅m space group for all prepared samples. This was confirmed by Raman spectroscopy by revealing five spinel Raman active modes. The SEM images showed interconnected nanosized particles for all compositions, which led to a porous morphology. Their electrochemical proprieties as anode materials for Li-ion batteries were examined by cyclic voltammetry and galvanostatic charge-discharge tests. For all compositions, the cyclic voltammetry plots demonstrate the conversion type for the Li-ion storage mechanism. At an applied current density of 150 mA g−1, the compositions x = 0, 0.1, 0.2, and 0.3 show initial discharge/charge capacities of 1235/712, 1187/680, 1542/938, and 1239/768 mAh g−1, respectively. After 100 operational cycles, their galvanostatic charge/discharge capacities remain 529/534, 612/606, 642/663, and 700/700 mAh g−1. However, the compositions x = 0.2 and 0.3 exhibit excellent cycling stability during 100 cycles, even at higher rates. As a result, the Mn doping led to enhanced specific capacity and cycling stability of the MgFe2O4 spinel. The optimized compositions with x = 0.2 and 0.3 are, thus, proposed as promising anodes materials compositions for Li-ion batteries.

Structural modeling of high-entropy oxides battery anodes using x-ray absorption spectroscopy

High-entropy oxides (HEOs) are single phase solid solutions where five or more metals share the same sublattice, giving rise to unexpected features in various fields of applications. Recently, HEOs have emerged as an alternative conversion electrode anode material for next-generation Li-ion batteries, where the combination of several different elements in a single solid solution can synergistically act to overcome some of its main drawbacks, improving performance. Due to their chemical complexity, x-ray absorption spectroscopy (XAS) emerges as an appropriate technique to study the electronic (x-ray absorption near edge structure, XANES) and local structure (extended x-ray absorption fine structure, EXAFS) of these compounds as a function of cycling. This work aims to highlight the capabilities of XAS as an element-specific probe to understand a material’s structure at the atomistic level through EXAFS modeling of (MgFeCoNiCuZn)O high-entropy system and how to extract valuable information about the bond distance, number of near neighbors, and local disorder, which are crucial to a full understanding of the electrochemical reaction mechanisms of such battery electrodes.

A DFT modeling of 4-cyclohexene-1,3-dione embedded in covalent triazine framework as a stable anode material for Li-ion batteries

Developing porous organic anode materials with outstanding electrical conductivity and high capacity is crucial to enhancing the performance of Li-ion batteries (LIBs). Herein, 4-cyclohexene-1,3-dione-functionalized covalent triazine framework (CYC-CTF0) monolayer as a new anode material in LIBs was explored through density functional theory calculations. The monolayer demonstrates good thermal, mechanical, and cycling stability and has a strong affinity for Li-ions to bind to the C=O and C=N redox-active sites. The adsorption of Li-ions transforms the CYC-CTF0 monolayer from being semiconducting to becoming metallic, reflecting its high electrical conductivity. Remarkably, the lattice undergoes a minimal expansion of 1.1 % throughout the charging and discharging process, suggesting an extended cycle life. The unit cell of the monolayer can be fully loaded with four Li-ions at different adsorption sites, exhibiting a specific theoretical capacity of 585.41 mAh g−1 and a low open-circuit voltage of 0.12 V. Moreover, the adsorbed Li-ions display a low diffusion energy barrier of 0.17 eV, enabling effective rates of charging and discharging. Our findings reveal the unique characteristics of the CYC-CTF0 monolayer as a promising anode material in LIBs.

Bridging scales with Machine Learning: From first principles statistical mechanics to continuum phase field computations to study order–disorder transitions in Li[formula omitted]CoO[formula omitted]

LixTMO2 (TM=Ni, Co, Mn) forms an important family of cathode materials for Li-ion batteries, whose performance is strongly governed by Li composition-dependent crystal structure and phase stability. Here, we use LixCoO2 (LCO) as a model system to benchmark a machine learning-enabled framework for bridging scales in materials physics. We focus on two scales: (a) assemblies of thousands of atoms described by density functional theory-informed statistical mechanics, and (b) continuum phase field models to study the dynamics of order–disorder transitions in LCO. Central to the scale bridging is the rigorous, quantitatively accurate, representation of the free energy density and chemical potentials of this material system by coarse-graining formation energies for specific atomic configurations. We develop active learning workflows to train recently developed integrable deep neural networks for such high-dimensional free energy density and chemical potential functions. The resulting, first principles-informed, machine learning-enabled, phase-field computations allow us to study LCO cathodes’ order–disorder transitions in terms of temperature, microstructure, and charge cycling. We highlight several insights gained to the dynamics of the phase transitions, and that have been made possible by the quantitatively rigorous scale bridging. To the best of our knowledge, such a scale bridging framework has not been previously demonstrated for LCO, or for materials systems of comparable technological interest. This approach can be expanded to other materials systems and can incorporate additional physics to that studied here.

Polyaniline layered N-doped carbon-coated iron oxide nanocapsules for extremely active Li-ion battery anode and oxygen evolution reaction

We report the effective synthesis of polyaniline (PANi)-layered nitrogen-doped carbon-coated Fe3O4 (FNC@PANi) nanocapsules (NCs) for electrocatalysis of oxygen evolution reaction (OER) as well as anode material for lithium (Li)-ion batteries (LIBs) via a simple hydrothermal method and oxidative polymerization technique. The prepared FNC@PANi NCs revealed a dual core-shell structure, in which an intermediate carbon layer allowed excellent electrical conduction between the Fe3O4 NCs and PANi. The dual core-shell structure also allowed the Fe3O4 NCs to expand freely during the Li-ion insertion/extraction and OER processes without breaking the outer layer, thus providing a high surface area (147.85 m2 g−1) and enhanced electrical conductivity. These properties facilitate the application of the dual core-shell FNC@PANi NCs as an advanced electrode material for LIBs, delivering a high reversible specific capacity of 1556.48 mAh g−1 at 0.1 A g−1, excellent rate performance (896.96 mAh g−1 at 1 A g−1), and durable cycling life (680.12 mAh g−1 at 5 A g−1 for 3000 cycles). The dual core-shell FNC@PANi NCs exhibited high electrocatalytic activity in the OER, with a small Tafel slope of 108.7 mV dec−1 owing to synergistic effects between the copious active sites of the Fe3O4 NCs and the carbon core-shell structure and a modest overpotential of 219 mV at 10 mA cm−2. The electrodes showed excellent stability over 10 h, as determined by chronopotentiometry at 10 mA cm−1. The resultant dual-core-shell FNC@PANi NCs are efficient iron-oxide-based electrode materials for LIBs and OER electrocatalysts.

Redox Mechanisms upon the Lithiation of Wadsley-Roth Phases.

The Wadsley-Roth family of transition metal oxide phases are a promising class of anode materials for Li-ion batteries due to their open crystal structures and their ability to intercalate Li at high rates. Unfortunately, most early transition metal oxides that adopt a Wadsley-Roth crystal structure intercalate Li at voltages that are too high for most battery applications. First-principles electronic structure calculations are performed to elucidate redox mechanisms in Wadsley-Roth phases with the aim of determining how they depend on crystal structure. A comparative study of two very distinct polymorphs of Nb2O5 reveal two redox mechanisms: (i) an atom-centered redox mechanism at early stages of Li intercalation and (ii) a redox mechanism at intermediate to high Li concentrations involving the bonding orbitals of metal-metal dimers formed by edge-sharing Nb cations. Our study motivates several design principles to guide the development of new Wadsley-Roth phases with superior electrochemical properties.

Is Aluminium Useful in NiMn Cathode Systems?: A Study of the Effectiveness of Al in Co-Free, Ni-Rich Positive Electrode Materials for Li-Ion Batteries

Aluminium has become a dopant of interest in many positive electrode materials, particularly the widely used LiNi1−x−yMnxCoyO2 (NMC). Despite the shift of the positive electrode active material space towards Co-free alternatives, the benefits of Al-doping in Co-free LiNixMn1−xO2 (NM) systems have yet to be extensively studied. In this work a series of polycrystalline NM and NMA pairs are compared head-to-head to better understand the effect of Al in Ni-rich, Co-free systems in terms of electrochemical, mechanical, surficial, and thermal stability. The materials tested vary in Ni-content, Al-doping amount as well as secondary particle size, as these parameters influence the effect of Al-presence on certain aspects of material performance. Although Al can bring certain advantages to NM materials, Al-substitution does not universally lead to improved performance in these systems.

Microwave assisted synthesis of α-Fe2O3 half-hexagon nanoplates as an anode material for Li ion batteries

In this study, hematite α-Fe2O3 half-hexagon nanoplates have been successfully prepared by ethanol–water mediated microwave assisted solvothermal method. The high crystalline nature and rhombohedral crystal structure of the synthesized α-Fe2O3 were confirmed from X-ray diffraction (XRD) results. No impurity phase other than hematite α-Fe2O3 was detected. Raman spectroscopy results further revealed the hematite structure of α-Fe2O3. X-ray photoelectron spectroscopy (XPS) study disclosed the chemical composition and valence states in the synthesized α-Fe2O3 material. Field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) studies confirmed the half-hexagon plate like architecture for α-Fe2O3 along with some irregular shape nanoplates. When treated as an anode material for Li ion battery (LIB), α-Fe2O3 half-hexagon nanoplates delivered a reversible discharge capacity of 520 mAh.g−1 after 100 cycles at a high current density of 500 mA.g−1. The α-Fe2O3 half-hexagon nanoplates also exhibited excellent cycling performance and coulombic efficiency. The excellent performance of the α-Fe2O3 electrode is mainly ascribed to the plate like morphology of the particles, which offers large effective contact area with the electrolyte and significantly enhances the electrochemical performance.

Hydrothermal synthesis of αILiVOPO4 as a cathode material for Li-ion batteries

This paper presents the synthesis of a novel cathode material, αI-LiVOPO4, featuring a porous multilayered lamellar structure, achieved through the hydrothermal method. Initially, αI-LiVOPO4·2 H2O was synthesized by maintaining a reaction kettle at 160 °C for 40 h. Subsequently, the parent compound underwent dehydration at various temperatures for 2 h to yield αI-LiVOPO4. The dehydration process was investigated through thermogravimetric analysis. Analysis via powder X-ray diffraction confirmed the crystallization of the product into the αI-LiVOPO4 phase. TEM and EDS analyses revealed an irregular porous structure with uniform distribution of elements. The electrochemical performance of αI-LiVOPO4 was evaluated through constant current charge-discharge tests within a voltage range of 3–4.5 V. Results demonstrated an initial capacity of 106.9 mAh·g–1 at 0.05 C, with a capacity retention of 100.9 mAh·g–1 after the 50th cycle. Additionally, cyclic voltammetry indicated favorable cycling performance and minimal polarization at elevated voltages.

Improved ACOM pattern matching in 4D-STEM through adaptive sub-pixel peak detection and image reconstruction

The technique known as 4D-STEM has recently emerged as a powerful tool for the local characterization of crystalline structures in materials, such as cathode materials for Li-ion batteries or perovskite materials for photovoltaics. However, the use of new detectors optimized for electron diffraction patterns and other advanced techniques requires constant adaptation of methodologies to address the challenges associated with crystalline materials. In this study, we present a novel image-processing method to improve pattern matching in the determination of crystalline orientations and phases. Our approach uses sub-pixel adaptive image processing to register and reconstruct electron diffraction signals in large 4D-STEM datasets. By using adaptive prominence and linear filters, we can improve the quality of the diffraction pattern registration. The resulting data compression rate of 103 is well-suited for the era of big data and provides a significant enhancement in the performance of the entire ACOM data processing method. Our approach is evaluated using dedicated metrics, which demonstrate a high improvement in phase recognition. Several features are extracted from the registered data to map properties such as the spot count, and various virtual dark fields, which are used to enhance the handling of the results maps. Our results demonstrate that this data preparation method not only enhances the quality of the resulting image but also boosts the confidence level in the analysis of the outcomes related to determining crystal orientation and phase. Additionally, it mitigates the impact of user bias that may occur during the application of the method through the manipulation of parameters.

Beam Effects in Synchrotron Radiation Operando Characterization of Battery Materials: X-Ray Diffraction and Absorption Study of LiNi0.33Mn0.33Co0.33O2 and LiFePO4 Electrodes.

Operando synchrotron radiation-based techniques are a precious tool in battery research, as they enable the detection of metastable intermediates and ensure characterization under realistic cycling conditions. However, they do not come exempt of risks. The interaction between synchrotron radiation and samples, particularly within an active electrochemical cell, can induce relevant effects at the irradiated spot, potentially jeopardizing the experiment's reliability and biasing data interpretation. With the aim of contributing to this ongoing debate, a systematic investigation into these phenomena was carried out by conducting a root cause analysis of beam-induced effects during the operando characterization of two of the most commonly employed positive electrode materials in commercial Li-ion batteries: LiNi0.33Mn0.33Co0.33O2 and LiFePO4. The study spans across diverse experimental conditions involving different cell types and absorption and scattering techniques and seeks to correlate beam effects with factors such as radiation energy, photon flux, exposure time, and other parameters associated with radiation dosage. Finally, it provides a comprehensive set of guidelines and recommendations for assessing and mitigating beam-induced effects that may affect the outcome of battery operando experiments.

Reducing Voltage Hysteresis in Li-Rich Sulfide Cathodes by Incorporation of Mn.

Conventional intercalation-based cathode materials in Li-ion batteries are based on charge compensation of the redox-active cation and can only intercalate one mole of electron per formula unit. Anion redox, which employs the anion sublattice to compensate charge, is a promising way to achieve multielectron cathode materials. Most anion redox materials still face the problems of slow kinetics and large voltage hysteresis. One potential solution to reduce voltage hysteresis is to increase the covalency of the metal-ligand bonds. By substituting Mn into the electrochemically inert Li1.33Ti0.67S2 (Li2TiS3), anion redox can be activated in the Li1.33-2y/3Ti0.67-y/3Mn y S2 (y = 0-0.5) series. Not only do we observe substantial anion redox, but the voltage hysteresis is significantly reduced, and the rate capability is dramatically enhanced. The y = 0.3 phase exhibits excellent rate and cycling performance, maintaining 90% of the C/10 capacity at 1C, which indicates fast kinetics for anion redox. X-ray absorption spectroscopy (XAS) shows that both the cation and anion redox processes contribute to the charge compensation. We attribute the drop in hysteresis and increase in rate performance to the increased covalency between the metal and the anion. Electrochemical signatures suggest the anion redox mechanism resembles holes on the anion, but the S K-edge XAS data confirm persulfide formation. The mechanism of anion redox shows that forming persulfides can be a low hysteresis, high rate capability mechanism enabled by the appropriate metal-ligand covalency. This work provides insights into how to design cathode materials with anion redox to achieve fast kinetics and low voltage hysteresis.

Investigation of N C and B C bilayers as anode materials for Li-ion batteries by first-principles calculations.

The best choice today for a realistic method of increasing the energy density of a metal-ion battery is to find novel, effective electrode materials. In this paper, we present a theoretical investigation of the properties of hitherto unreported two-dimensional B C and N C bilayer systems as potential anode materials for lithium-ion batteries. The simulation results show that N C bilayer is not suitable for anode material due to its thermal instability. On the other hand B C is stable, has good electrical conductivity, and is intrinsically metallic before and after lithium intercalation. The low diffusion barrier (0.27 eV) of Li atoms shows a good charge and discharge rate for B C bilayer. Moreover, the high theoretical specific capacity (579.57 mAh/g) connected with moderate volume expansion effect during charge/discharge processes indicates that B C is a promising anode material for Li-ion batteries.

Sulphonated coal tar pitch as a carbon source to develop the storage capacity of Fe2O3@C materials

Utilizing metal oxides as substitutes for carbon anodes is imperative in advancing LIBs. Recently, the researchers regarding to the Fe2O3 have become very popular owing to its advantages such as a high theoretical capacity (1007 mAh g−1), cost-effectiveness and sustainability. In our present studies, the Fe2O3@SCTPC (Fe2O3 nanosphere coated by carbons which are obtained by the carbonizations using the sulphonated coal tar pitches) materials are firstly and successfully fabricated by a one-step hydrothermal method using the Fe(NO3)3·9 H2O and sulphonated coal tar pitches (SCTPs). An intriguing observation is that the nanosphere Fe2O3 is encapsulated by carbons with a core-shell structure. This specific core-shell structure effectively mitigates the volume expansion of Fe2O3, and exhibits a notable enhancement in conductivity. Thanks to this unique structure, the Fe2O3@SCTPC electrode has a maximum capacity of 1106.74 mAh g−1 after 100 cycles at a current density of 0.1 A g−1 and a high reversible specific capacity of 373.5 mAh g−1 after 500 cycles at a current density of 2 A g−1, when it is used as an anode material for Li-ion battery. These results suggest that adjusting the structures of carbons is crucial to develop the potential storage capacity of the covered Fe2O3.

Revisit of Polyaniline as a High-Capacity Organic Cathode Material for Li-Ion Batteries.

Polyaniline (PANI) has long been explored as a promising organic cathode for Li-ion batteries. However, its poor electrochemical utilization and cycling instability cast doubt on its potential for practical applications. In this work, we revisit the electrochemical performance of PANI in nonaqueous electrolytes, and reveal an unprecedented reversible capacity of 197.2 mAh g-1 (244.8 F g-1) when cycled in a wide potential range of 1.5 to 4.4 V vs. Li+/Li. This ultra-high capacity derives from 70% -NH- transformed to =NH+- during deep charging/discharging process. This material also demonstrates a high average coulombic efficiency of 98%, an excellent rate performance with 73.5 mAh g-1 at 1800 mA g-1, and retains 76% of initial value after 100 cycles, which are among the best reported values for PANI electrodes in battery applications.