Electrode Materials For Li-ion Batteries Research Articles

Insights into the electronic structure and vibrational dynamics of Li7MnN4 anode material for Li-ion battery: A combined experimental and computational study

The electronic structure of the promising Li-ion battery anode material Li7MnN4 synthesized by a solid-state reaction is studied using ab initio calculations completed by Raman spectroscopy experiments. The structural optimization reliably reproduces the experimental one, hence validating the accuracy of the chosen Density Functional Theory method. The theoretical analysis of the electronic structure reveals the nature of the valence band as composed from band filled by electrons with spin-up states only, which allows refuting literature data about the claimed electronic character of Li7MnN4. Actually, the calculated electronic band gap Eg = 0.95 eV is found to be in good agreement with available experimental data. A careful experimental approach provides the first experimental Raman spectra of hygroscopic Li7MnN4 at 293 K and 130 K. The analysis of the phonon states in the Γ-point of the Brillouin zone, completed by the computation of the Raman scattering intensities of the vibrational modes of the Li7MnN4 structure give a remarkable agreement between simulated and experimental Raman spectra. With such a good matching, a reliable assignment of all the observed Raman peaks to the vibrations of specific structural units in the Li7MnN4 lattices is proposed. In particular, the most intense band in the Raman spectrum is ascribed to a totally symmetric MnN4 breathing mode. We also show that, using different wavelengths of exciting radiation, the transition from off-resonance to resonance Raman scattering process can be observed. Furthermore, Raman spectroscopy is revealed as an efficient in situ diagnostic tool to control the degradation of the Li7MnN4 powder in open air through the observation of extra bands in the Raman spectra. Results of this study shed a light on the understanding of the fundamental properties of Li7MnN4 and pave a way for the upcoming operando Raman spectroscopy investigation of the atomic-scale induced structural changes of this negative electrode material for Li-ion battery.

2D Homogeneous Holey Carbon Nitride: An Efficient Anode Material for Li-ion Batteries With Ultrahigh Capacity.

In present day Li-ion batteries (LIBs) is the most successful and widely used rechargeable batteries. The continuous effort is going on in finding suitable electrode material for LIBs for improved performance in terms of life-time, storage capacity etc. Computational chemistry plays an important role in identifying suitable electrode materials through electronic structure calculation. By employing state of the art density functional theory we herein explored the electronic structure of homogeneous holey carbon nitride monolayers (Cx N3 , x=10,19) to understand its suitability as electrode material for rechargeable LIB. The monolayers have shown high negative adsorption energy for Li adsorption and more interestingly the band structure of monolayers reveal Dirac semimetallic character thus would exhibit high electronic conductivity. Meanwhile, monolithiation introduces metallicity in these monolayers. The calculated average open circuit voltages of the monolayers lie in the range of 0.45 to 0.09 V, which are typically observed in high performance anode materials. Moreover, these monolayers achieve ultrahigh theoretical specific capacity upto 2092.01 mAh/g and low diffusion barrier from 0.004 to 0.44 eV. Based on our computational study we suggest that, the Cx N3 monolayers could be a promising anode material in search of low-cost and high performance LIBs.

ZIF-8 derived CuFe2O4 nanoparticles: Evolution of composition and microstructures, and their electrochemical performances as anode for lithium-ion batteries

• MOF-derived CuFe 2 O 4 anode materials were prepared by facile hydrothermal route. • The coulomb efficiency of CuFe 2 O 4 /ZIF-8 and CuFe 2 O 4 was 70.8 and 91.3% respectively. • Outstanding electrochemical behavior of CuFe 2 O 4 /anode materials generated from MOFs could be used in high-performance LIBs. Improving electrical conductivity and exposing more active surface area in metal–organic frameworks remains a challenge. Metal-organic frameworks (MOF) are interesting precursor for developing new Li-ion battery electrode materials (LIBs). Herein, we report a convenient and straightforward one-pot hydrothermal strategy to prepare MOF-derived CuFe 2 O 4 . X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), and Brunauer-Emmett-Teller (BET) were used to evaluate the CuFe 2 O 4 and CuFe 2 O 4 /ZIF-8 composites. CuFe 2 O 4 /ZIF-8 nanocomposites showed a noticeable improvement electrochemical property in terms of increased the discharge/charge capacity of CuFe 2 O 4 /ZIF-8 was determined to be 1478/980 mAhg −1 as an anode for lithium ion batteries. Similarly the pure CuFe 2 O 4 electrode exhibits discharge/charge was 986/678 mAhg −1 . The coulomb efficiency of CuFe 2 O 4 /ZIF-8 and CuFe 2 O 4 was 70.8 and 91.3% respectively. In the end of 10th cycle, the discharge /charge capacity of CuFe 2 O 4 /ZIF-8 was found to be 790/695 mAhg −1 . Similarly the pure CuFe 2 O 4 electrode exhibits discharge/charge was 560/535 mAhg −1 . Whereas, the columbic efficiency of CuFe 2 O 4 /ZIF-8 and CuFe 2 O 4 was 79 and 69.5%, respectively (10th cycle). These outstanding electrochemical capabilities suggest that CuFe 2 O 4 anode materials generated from MOFs (ZIF-8) could be used in high-performance Li-ion batteries.

Sea urchin-like LiAlO2@NiCoO2 hybrid composites with core-shell structure as high-performance Li storage materials

Sea urchin-like LiAlO2@NiCoO2 hybrid composites with core-shell structure assembled with nanoneedles have been successfully fabricated through a facile hydrothermal route followed by a calcination procedure in N2 for the first time. The sea urchin-like architecture with large accessible surface can offer numerous active sites for redox reaction. The synergy of two advantages has dramatically improved the electrochemical behavior in terms of specific capacity, cycle performance and rate capability, especially at high current densities. The LiAlO2(5.0 wt%)@NiCoO2 displays charge capacities are 1309.0 and 933.6 mAh g−1 at 0.5 and 1A g−1, respectively, after 400 cycles. However, the charge capacities of bare NiCoO2 are only 562.9 and 476.7 mAh g−1 at corresponding rates. Especially, LiAlO2(5.0 wt%)@NiCoO2 preserves 358.1 mAh g−1 after 500 cycles at 2A g−1 with a capacity retention of 74%. The superior electrochemical property is related to the sea urchin-like nature and the ingenious composition design. In addition, the DFT calculation result shows that the formed stable, well-coordinated, and metallic interface between LiAlO2 and NiCoO2 are very helpful for reducing the interfacial impedance and beneficial for the improved rate capability of the materials. Therefore, such LiAlO2@NiCoO2 composites with unique morphology demonstrate a huge potential as electrode materials for Li-ion batteries.

A C 54 B 2 Polycyclic π-System with Bilayer Assembly and Multi-Redox Activity

A C ₅₄ B ₂ Polycyclic π-System with Bilayer Assembly and Multi-Redox Activity

Transition Metal Carbo-Chalcogenide "TMCC:" A New Family of 2D Materials.

Here, a new family of 2D transition metal carbo-chalcogenides (TMCCs) is reported, which can be considered a combination of two well-known families, TM carbides (MXenes) and TM dichalcogenides (TMDCs), at the atomic level. Single sheets are successfully obtained from multilayered Nb2 S2 C and Ta2 S2 C using electrochemical lithiation followed by sonication in water. The parent multilayered TMCCs are synthesized using a simple, scalable solid-state synthesis followed by a topochemical reaction. Superconductivity transition is observed at 7.55 K for Nb2 S2 C. The delaminated Nb2 S2 C outperforms both multilayered Nb2 S2 C and delaminated NbS2 as an electrode material for Li-ion batteries. Ab initio calculations predict the elastic constant of TMCC to be over 50% higher than that of TMDC.

A Pyrene-4,5,9,10-Tetraone-Based Covalent Organic Framework Delivers High Specific Capacity as a Li-Ion Positive Electrode.

Electrochemically active covalent organic frameworks (COFs) are promising electrode materials for Li-ion batteries. However, improving the specific capacities of COF-based electrodes requires materials with increased conductivity and a higher concentration of redox-active groups. Here, we designed a series of pyrene-4,5,9,10-tetraone COF (PT-COF) and carbon nanotube (CNT) composites (denoted as PT-COFX, where X = 10, 30, and 50 wt % of CNT) to address these challenges. Among the composites, PT-COF50 achieved a capacity of up to 280 mAh g–1 as normalized to the active COF material at a current density of 200 mA g–1, which is the highest capacity reported for a COF-based composite cathode electrode to date. Furthermore, PT-COF50 exhibited excellent rate performance, delivering a capacity of 229 mAh g–1 at 5000 mA g–1 (18.5C). Using operando Raman microscopy the reversible transformation of the redox-active carbonyl groups of PT-COF was determined, which rationalizes an overall 4 e–/4 Li+ redox process per pyrene-4,5,9,10-tetraone unit, accounting for its superior performance as a Li-ion battery electrode.

Sustainable Recycling of Electrode Materials in Spent Li-Ion Batteries through Direct Regeneration Processes

Sustainable Recycling of Electrode Materials in Spent Li-Ion Batteries through Direct Regeneration Processes

Could λ-Ti3O5 with lamellar and channel microstructure characteristics determine the excellent properties of LIBs? The first-principles study of λ-Ti3O5 lithiation mechanism

While people are searching for potential electrode materials for Li-ion batteries (LIBs), it is controversial whether the microstructure is a critical factor of electrochemistry property. λ-Ti3O5 is an example due to its lamellar and channel microstructure characteristics to discuss whether the microstructure characteristic is the critical factor of properties of LIBs. The intercalation/de-intercalation mechanisms and diffusion behavior of Li-ion in λ-Ti3O5 are studied by DFT. The binding energies with the different number of Li-ions are from − 3.1 to − 2.2 eV, and the volume changes are from 0.1% to 1.3%, indicating λ-Ti3O5 is stable during lithiation. The supercell and (001) slab of λ-Ti3O5 is constructed to investigate the diffusion behaviors of Li-ion in bulk and Li-ion escaping from the system, respectively. The former energy barriers are about 1.0 eV, and the latter energy barriers are above 2.0 eV, suggesting it is difficult for Li-ion to diffuse in or escape from the system. It presumably can be inferred that the microstructure is not the critical factor of diffusion property for electrode materials. More studies are needed to optimize the performance of λ-Ti3O5 as an electrode material, such as interionic distance and strength of bonding.

The effect of removing the native passivation film on the electrochemical performance of lithium metal electrodes

Lithium metal is accepted as the promising anode for next-generation Li batteries such as solid-state, Li–S, and Li-air batteries, etc. Besides, it is commonly employed as the reference electrodes for evaluating the electrode materials of Li-ion batteries (LIBs) in a half-cell. However, native passivation film (NPF), which is inevitable on the surface, can change the topography and surface composition distribution, and thus deteriorate the performance stability of lithium metal electrodes. Unfortunately, these effects are always neglected during the evaluation of anode or cathode materials of LIBs. Here, we conduct a comprehensive study on the effects of NPF on the electrochemical performance of lithium metal electrodes. After the removal of NPF by polishing, both the interfacial impedance and electrode overpotential are significantly decreased, with a more homogeneous lithium deposition during the charge/discharge process. When it is employed as the reference electrode for characterizing the commercial LiFePO4 or graphite materials in a coin cell, the consistency of the results is remarkably improved. This work not only provides an insight for the interfacial electrochemistry of lithium metal electrodes, but also helps characterize electrode materials in a reliable way.

Halogenated Ti3C2 MXene as High Capacity Electrode Material for Li-ion Batteries

Halogenated Ti₃C₂ MXene as High Capacity Electrode Material for Li-ion Batteries

Metal–organic frameworks and their derivatives as electrode materials for Li-ion batteries: a mini review

Research progress on metal–organic frameworks and their derivatives as functional materials for lithium-ion battery applications has been presented.

Atom probe analysis of electrode materials for Li-ion batteries: challenges and ways forward.

The worldwide development of electric vehicles as well as large-scale or grid-scale energy storage to compensate for the intermittent nature of renewable energy generation has led to a surge of interest in battery technology. Understanding the factors controlling battery capacity and, critically, their degradation mechanisms to ensure long-term, sustainable and safe operation requires detailed knowledge of their microstructure and chemistry, and their evolution under operating conditions, on the nanoscale. Atom probe tomography (APT) provides compositional mapping of materials in three dimensions with sub-nanometre resolution, and is poised to play a key role in battery research. However, APT is underpinned by an intense electric field that can drive lithium migration, and many battery materials are reactive oxides, requiring careful handling and sample transfer. Here, we report on the analysis of both anode and cathode materials and show that electric-field driven migration can be suppressed by using shielding by embedding powder particles in a metallic matrix or by using a thin conducting surface layer. We demonstrate that for a typical cathode material, cryogenic specimen preparation and transport under ultra-high vacuum leads to major delithiation of the specimen during the analysis. In contrast, the transport of specimens through air enables the analysis of the material. Finally, we discuss the possible physical underpinnings and discuss ways forward to enable shielding from the electric field, which helps address the challenges inherent to the APT analysis of battery materials.

Synthesis-structure relationships in Li- and Mn-rich layered oxides: phase evolution, superstructure ordering and stacking faults.

Li- and Mn-rich layered oxides are promising positive electrode materials for future Li-ion batteries. The presence of crystallographic features such as cation-mixing and stacking faults in these compounds make them highly susceptible to synthesis-induced structural changes. Consequently, significant variations exist in the reported structure of these compounds that complicate the understanding of how the crystallographic structure influences its properties. This work investigates the synthesis-structure relations for three widely investigated Li- and Mn-rich layered oxides: Li2MnO3, Li1.2Mn0.6Ni0.2O2 and Li1.2Mn0.54Ni0.13Co0.13O2. For each compound, the average structure is compared between two synthetic routes of differing degrees of precursor mixing and four annealing protocols. Furthermore, thermodynamic and synthesis-specific kinetic factors governing the equilibrium crystallography of each composition are considered. It was found that the structures of these compounds are thermodynamically metastable under the synthesis conditions employed. In addition to a driving force to reduce stacking faults in the structure, these compositions also exhibited a tendency to undergo structural transformations to more stable phases under more intense annealing conditions. Increasing the compositional complexity introduced a kinetic barrier to structural ordering, making Li1.2Mn0.6Ni0.2O2 and Li1.2Mn0.54Ni0.13Co0.13O2 generally more faulted relative to Li2MnO3. Additionally, domains with different degrees of faulting were found to co-exist in the compounds. This study offers insight into the highly synthesis-dependent subtle structural complexities present in these compounds and complements the substantial efforts that have been undertaken to understand and optimise its electrochemical properties.

Synthesis of Tostadas‐Shaped Metal‐Organic Frameworks for Remitting Capacity Fading of Li‐Ion Batteries

AbstractElectrode design strategies that aim to increase the electrochemical performance of Li‐ion batteries (LIBs) play a key role in tapping into the power of the energy transformations involved. Metal‐organic frameworks (MOFs) have attracted scientific interest as electrode materials for LIBs, while the utilization of pristine MOFs is hindered by limited conductivity and stability, partly due to their lack of hierarchically structured pores. Herein a hydrothermal‐mechanical synthesis is reported by combining the one‐pot chemical fabrication of Ni3(2,3,6,7,10,11‐hexaiminotriphenylene)2 sheets and particles, and the mechanical assembly of these building blocks to improve electrical conductivity is also described. The as‐prepared ensemble (denoted as NHM) exhibits a Tostadas‐shaped structure with enriched ultramicropores and micropores. The charge‐discharge profile of NHM gives a superior reversible capacity of 1280 mA h g−1 after 100 cycles at the rate of 0.1 A g−1, surpassing the state‐of‐art pristine MOFs‐based anodes. Moreover, NHM is capable of maintaining 392 mA h g−1 at 1 A g−1 after 1000 cycles, the completion of a stability test in coin cell‐powered light emitting diodes further visualizes the remitted capacity fading of NHM. This work breaks through the limitation of capacity for pristine MOFs, providing a new pathway for achieving better energy conversion and storage.

Comparative Study of the Thermal Stability of Electrode Materials for Li-Ion and Na-Ion Batteries

The thermal stability of the cathode and anode materials for Li-ion and Na-ion batteries─LiNi1/3Mn1/3Co1/3O2, LiFePO4, Li4Ti5O12, graphite, O3-NaNi1/3Fe1/3Mn1/3O2 (NFM), Na3V2(PO4)3 (NVP), β-NaVP2O7 (NVPO), Na3V2(PO4)2F3 (NVPF), and hard carbon─was studied by means of differential scanning calorimetry of the electrodes in the charged state and ex situ powder X-ray diffraction. The obtained results indicate that the thermal stability of the Na-ion cathode materials increases in the order NFM < NVPF < NVP < NVPO. The “heat on energy” term has been proposed and analyzed for all of the studied materials.

Nanosized and metastable molybdenum oxides as negative electrode materials for durable high-energy aqueous Li-ion batteries

Significance This study describes a high-energy and durable aqueous battery system with metastable and nanosized Mo-based oxides used as high-capacity negative electrodes. A wider electrochemical window is achieved with concentrated aqueous electrolytes through which highly reversible Li storage without the decomposition of water molecules is achieved for the Mo-based oxides. A full cell with an Mn-based oxide shows good capacity retention over 2,000 cycles. X-ray absorption spectroscopy reveals that the solid-state redox reaction of Mo ions reversibly proceeds in aqueous electrolytes for the metastable Mo oxide. This study opens a way to develop high-energy, durable, and safe batteries on the basis of metastable and nanosized oxides with aqueous electrolyte solutions.

Revisited Ti2Nb2O9 as an Anode Material for Advanced Li-Ion Batteries.

Ti2Nb2O9 with a tunnel-type structure is considered as a perspective negative electrode material for Li-ion batteries (LIBs) with theoretical capacity of 252 mAh g-1 corresponding to one-electron reduction/oxidation of Ti and Nb, but only ≈160 mAh g-1 has been observed practically. In this work, highly reversible capacity of 200 mAh g-1 with the average (de)lithiation potential of 1.5 V vs Li/Li+ is achieved for Ti2Nb2O9 with pseudo-2D layered morphology obtained via thermal decomposition of the NH4TiNbO5 intermediate prepared by K+→ H+→ NH4+ cation exchange from KTiNbO5. Using operando synchrotron powder X-ray diffraction (SXPD), single-phase (de)lithiation mechanism with 4.8% unit cell volume change is observed. Operando X-ray absorption near-edge structure (XANES) experiment revealed simultaneous Ti4+/Ti3+ and Nb5+/Nb4+ reduction/oxidation within the whole voltage range. Li+ migration barriers for Ti2Nb2O9 along [010] direction derived from density functional theory (DFT) calculations are within the 0.15-0.4 eV range depending on the Li content that is reflected in excellent C-rate capacity retention. Ti2Nb2O9 synthesized via the ion-exchange route appears as a strong contender to widely commercialized Ti-based negative electrode material Li4Ti5O12 in the next generation of high-performance LIBs.

Rivalry at the Interface: Ion Desolvation and Electrolyte Degradation in Model Ethylene Carbonate Complexes of Li+, Na+, and Mg2+ with PF6 - on the Li4Ti5O12 (111) Surface.

Spinel lithium titanate, Li4Ti5O12 (LTO), emerges as a “universal” electrode material for Li-ion batteries and hybrid Li/Na-, Li/Mg-, and Na/Mg-ion batteries functioning on the basis of intercalation. Given that LTO operates in a variety of electrolyte solutions, the main challenge is to understand the reactivity of the LTO surface toward single- and dual-cation electrolytes at the molecular level. This study first reports results on ion desolvation and electrolyte solvent/salt degradation on an LTO surface by means of periodic DFT calculations. The desolvation stages are modeled by the adsorption of mono- and binuclear complexes of Li+, Na+, and Mg2+ with a limited number of ethylene carbonate (EC) solvent molecules on the oxygen-terminated LTO (111) surface, taking into account the presence of a PF6– counterion. Alongside cation adsorption, several degradation reactions are discussed: surface-catalyzed dehydrogenation of EC molecules, simultaneous dehydrogenation and fluorination of EC, and Mg2+-induced decay of PF6– to PF5 and F–. Data analysis allows the rationalization of existing experimentally established phenomena such as gassing and fluoride deposition. Among the three investigated cations, Mg2+ is adsorbed most tightly and is predicted to form a thicker fluoride-containing film on the LTO surface. Gassing, characteristic for carbonate-based electrolytes with LTO electrodes, is foreseen to be suppressed in dual-cation batteries. The latter bears promise to outperform the single-ion ones in terms of durability and safety.

Utilizing nanoscale particulate matter from the combustion of diesel fuels as a carbonaceous anode electrode for Li-ion batteries

According to the Environmental Protection Agency's National Emissions Inventory Report, hundreds of thousands of tons of particulate matter (PM2.5) are released by diesel combustion per year (Enviromental Protection Agency 2020; Hammer et al., 2020). The toxic PM2.5 air pollution causes serious public health problems and is responsible for millions of worldwide deaths each year (Apte et al., 2015). In this study, we investigate the electrochemical energy storage capability of annealed soot PM originating from diesel exhaust. Soot composite electrodes were utilized as anode electrodes and cycled against Li counter electrodes. X-ray diffraction and Raman spectroscopy showed the graphitized carbon structure of the annealed soot particles. The cycle life and rate capability of the electrodes were investigated via galvanostatic cycling tests. The electrodes exhibited excellent rate performance with discharge capacities of 235, 195, 150, 120, and 80 mAh/g when cycled at rates of 1C, 2C, 5C, 10C, and 20C, respectively. The electrode demonstrated an initial discharge capacity of 154 mAh/g at a 4C rate with a capacity retention of almost 77% after 500 cycles. Raman analysis confirms the retention of structural ordering in the soot carbon after 500 cycles. Kinetic analysis, obtained through cyclic voltammetry at different scan rates, indicates pseudocapacitive charging behavior in the soot composite electrode. Our study provides a viable pathway towards a sustainable energy environment by converting an abundant toxic pollutant into a valuable electrode material for Li-ion batteries.