Electrode Materials For Li-ion Batteries Research Articles

Strain Imaging of Electrode Materials in Li-Ion Batteries

Li-ion batteries operate through the migration of Li ions between the electrodes. Therefore, non-destructive observation of the migration with high spatial resolution is important.When charging and discharging, Li-ions are extracted or inserted into electrode materials, which generally causes changes in volume. An atomic force microscope (AFM) can detect and image these volume changes through current collectors with high spatial resolution, which enables us to investigate Li-ion migration without destruction. AFM detects surface displacements synchronizing the charging/discharging cycle, and provides strain images along with topography of the current collector.1) Here, we present our results of lithium titanate oxide (LTO: Li x Ti5O12). LTO is an anode material with high safety having a theoretical capacity of 160 mA h g−1 (from LiTi2O4 to Li2Ti2O4). But the phase change from spinel to rock-salt lead to very small volume changes. Therefore, it might be difficult to observe the Li migration by this method.However, Li4Ti5O12 with a spinel structure has high resistivity, whereas charged Li7Ti5O12 with a rock-salt structure is a conductor. The former is a transparent semiconductor and the latter is a dark metal. The state of charge of LTO can be observed by an optical microscope. The spatial resolution is not enough though the method is easy-to-use.2) High-resolution method has been proposed.3) Photoinduced strain imaging discriminates semi-conductors having bandgap from metallic materials with no bandgap. The method images bandgap variations based on the detection of electric strains caused by electron-hole pair generation. When electron-hole pairs are generated by photon injection, strains are induced, because the lattice constants are determined as the energy of the electron band structure becomes minimum, and the generation changes the energy configuration. The generation of electron-hole pairs is determined from the magnitude relationship between photon and bandgap energies. Bandgap energies can be measured quantitatively by scanning the injected photon energy. When the photon energies are larger than bandgap energies, strains are generated by electron-hole pairs generation. Therefore, mapping of the strains reveals changes in bandgap energies, that is, state-of-charge of LTO.The lithium metal anode has fruitful advantages that are the lowest electrode potential of Li+/Li and low density of Li, which are −3.04 V and 0.534 g/cm3, respectively. However, the lithium dendrite issue is a serious barrier standing in way of the development of high-energy-density batteries with a lithium metal anode.We have been successful in imaging electrochemical reactions in the interface between lithium metal and electrolyte using strain imaging. Precipitation and dissolution of lithium ions in the surface of lithium metal, and electrolyte flow induced by the gradient of lithium-ion concentration should cause the surface displacements of the current collector. We will be able to get a lot of knowledge and information from this observation.

Differences in the Ti4+/Ti3+ Redox Reactions between Li4Ti5O12 and LiTi2(PO4)3 Observed By Soft X-Ray Spectroscopy

Clarification of the redox reaction in electrode materials for Li-ion batteries is essential to obtain strategies to improve the performances such as charge-discharge capacity, voltage and cyclability. We focus on the difference in voltage, i.e., redox potential between Li4Ti5O12 (LTO) and LiTi2(PO4)3 (LTP). Spinel-type LTO with a redox potential around 1.5 V vs Li/Li+ is one of the anode materials [1], while the main redox potential of LTP (NASICON-type structure) is around 2.4 V vs Li/Li+ [2]. Although the difference in redox potential is as large as ~0.9 V, it has been thought to be that Ti4+/Ti3+ redox couple is identical for both LTO and LTP. Here, we demonstrate the electronic-structure analysis of LTO and LTP by using soft X-ray absorption spectroscopy (XAS) and soft X-ray photoemission spectroscopy (XPS). Operando Ti L 2,3-edge XAS by use of an all-solid-state cell [3,4] successfully revealed reversible Ti4+/Ti3+ redox reactions by discharge/charge for both materials, but the XAS line shapes were different. By analyzing the spectra using multiplet calculation [5], differences in the crystal-field splitting for the TiO6 octahedron and O 2p -> Ti 3d charge-transfer (CT) effect were found. The different CT effect was also confirmed by Ti 2p-3d resonant XPS measurements for the initial-state LTO and LTP samples. Moreover, the difference in redox potential is mostly explained by the energy levels of the pre-edge structures in the O K-edge XAS calibrated with the O 1s XPS spectra. In the presentation, the understandings of the spectroscopic results will be discussed in detail.

What Affects More the NMC811 Cathode Powders: Lithium Excess, Washing or Aging?

Lithium Nickel Manganese Cobalt Oxides with R-3m space group have gained significant attention in recent years due to their high energy density, high power capability, and long cycle life. There are several synthesis methods to obtain NMC active powders, like solid-state or sol-gel, but co-precipitation synthesis is a widely used method for preparing NMC cathode materials for lithium-ion batteries, offering advantages in terms of control over particle size, morphology, and homogeneity (Xie et al., 2016).The main difficulty of synthesizing Ni-rich materials is the minimization of the degree of Li/Ni cation mixing, which refers to the interchange of the nickel and lithium ions in the 3a/3b sites of the crystal lattice. Perfect NMC materials have a hexagonal layered structure of α-NaFeO2-type, where Li and transition metal atoms form alternating layers between oxygen layers. To minimize phenomenon of cation mixing an excess of lithium source prior to sintering is required (Arai et al., 1995).However, unreacted lithium remain on the surface of NMC after the synthesis in the form of Li2O and it turns into LiOH and Li2CO3 as impurities if stored in ambient conditions. Those residual lithium compounds (RLC) on NMC811 surface can have significant impacts on the cathode's morphology, crystal structure, surface chemistry and, thus, electrochemical performance. Despite it was previously shown that Ni-rich materials have poor charge-discharge capacity retention, related to the electrolyte oxidization at the positive electrode surface (Jung et al., 2017) and/or structural changes of the material, such as large c-axis shrinkage, at high potentials (Teichert et al., 2020), many efforts are made to synthesize Ni-rich NMC for battery applications.Our research explores the impact of lithium excess on the physicochemical properties of NMC811. We compared self-made fresh samples with commercially available NMC811 in terms of structural parameters, morphology and electrochemical performance at high C-rates before and after lithium surplus was washed. Lithium removing procedure was applied to mitigate issues with RLC during battery operation, such as electrolyte degradation and gassing (Hartmann et al., 2022). However, over-washing can change physical properties of NMC811, including surface reconstruction as a consequence of the leaching of active transition metal ions and lithium from the cathode. Therefore, it is important to carefully optimize the washing procedures to balance the removal of RLC with the preservation of the cathode's electrochemical performance and stability.Here we want to point the effectiveness of washing procedure on NMC811 morphology, structural stability and electrochemistry. Additionally, our studies addressed the effects of calendar aging of active powders, i.e. prolonged shelf-storage in an ambient conditions for washed and unwashed samples, especially an influence of LiOH and Li2CO3 on structural parameters, electrodes preparation and electrochemical behavior. We want to open the discussion about preferable strategy on storage of Ni-rich NMCThe work was supported by the University of Warsaw through Action I.3.4. “The circular economy – energy storage”: "New electrode materials for next generation Li-ion batteries" (project no. PSP 501-D112-20-0001340) within the “Excellence Initiative – Research University (2020-2026)” programme of the Ministry of Science and Higher Education, Poland.ReferencesArai, H., Okada, S., Ohtsuka, H., Ichimura, M., Yamaki, J., 1995. Solid State Ion 80, 261–269.Hartmann, L., Ching, C.H., Kipfer, T., Koch, M., Gasteiger, H.A., 2022. J Electrochem Soc 169, 070516.Jung, R., Metzger, M., Maglia, F., Stinner, C., Gasteiger, H.A., 2017. J Phys Chem Lett 8, 4820–4825.Teichert, P., Eshetu, G.G., Jahnke, H., Figgemeier, E., 2020. Batteries 6, 8.Xie, H., Hu, G., Du, K., Peng, Z., Cao, Y., 2016. J Alloys Compd 666, 84–87.

(Invited) Challanges with Novel Binders for LiNi0.5Mn1.5O4 li-Ion Battery Electrodes

In the search for high-energy density Li-ion battery electrode materials which are also comparatively sustainanble, LiNi0.5Mn1.5O4 (LNMO) is often targeted as a promising next-generation alternative. While the capacity of LNMO is limited, it has a high operating voltage around 4.7 V vs. Li+/Li, and the spinel structure of the materials renders useful power capacilities. Moreover, it is a cobalt-free cathode. However, fabricating functional electrodes have shown problematic due to inherent instabilities at both bulk and surfaces, where especially operation at elevated temperatures has shown to cause capacity degradation. Problems comprise structural changes, loss of oxygen, and Mn dissolution, often interconnected with each other. One strategy to improve stabilization would be through coatings of the LNMO particles, either inorganic or organic.The polymer binder used for battery processing is inherently an organic coating layer, since it wraps around the particles of the electrodes. Thereby, binders has been shown to being able to add functionalities to electrode materials, e.g. to improve electronic conductivity, add storage capacity or mitigate side-reactions. The binder is at interplay with the reactions causing interphase layer formation. Thereby, changing or taioring the binder can cause direct improvements in cell performance.Poly(vinylidene difluoride) (PVdF) and its many derviates is since long time the standard for Li-ion battery electrodes, despite not being particular sustainable and being dependent on toxic solvents such as N-methyl-2-pyrrolidone (NMP). LNMO is, in this context, no exception. Nevertheless, while PVdF is chemically intert, it provides little other capabilities to the battery electrodes, and other binder systems could improve in this context: either through electochemica performance or through being more sustainable.Here, two other binder systems for LNMO are discussed: polyacrylonitrile (PAN) and polyacrylic acid (PAA). Polynitriles are often promoted as being comparatively stable at higher potentials, while also being ionically conductive, and should therefore in principle add functionalities into the resulting electrodes. PAA, on the other hand, has shown good adhesion and adherence to oxide surfaces, and can thereby form more robust interfacial layers on the cathode. We show here, however, that challenges remain for these alternative binder systems, not least due to the high operating potential of LNMO electrodes which cause side-reactions of both types of alternative binders. These side-reactions are their products are analyzed through a range of methods, e.g. photoelectron spectroscopy, electron microscopy and electroanalytical techniques, thereby providing guidance to the development of novel binders for high-voltage electrodes.

Theoretical Investigation of 2D M3C2S2 (M = Cr, Zr) as Potential Electrode Materials for Li-Ion Batteries

Theoretical Investigation of 2D M3C2S2 (M = Cr, Zr) as Potential Electrode Materials for Li-Ion Batteries

Crystalline Tin Disulfide by Low-Temperature Plasma-Enhanced Atomic Layer Deposition as an Electrode Material for Li-Ion Batteries and CO2 Electroreduction

Crystalline Tin Disulfide by Low-Temperature Plasma-Enhanced Atomic Layer Deposition as an Electrode Material for Li-Ion Batteries and CO₂ Electroreduction

Structural, electrical, and electrochemical studies of the olivine LiMPO4 (M=Fe, Co, Cr, Mn, V) as cathode materials for lithium-ion rechargeable batteries based on the intercalation principle

Despite significant efforts to identify other substituents, carbon remains the only economically viable negative electrode (anode) material for Li-ion batteries (LIBs). The current state of knowledge on the understanding, characterization, and improvement of carbon anode materials is reviewed. A brief history of developments in carbon host lattices is provided. The methodologies used to characterize the lithium insertion and de-insertion processes and a wide spectrum of carbon materials, from amorphous to highly oriented graphitic materials, are described. The basic studies of the electrochemical process on natural graphite and highly oriented pyrolitic graphite materials are then thoroughly examined. Following that, the issues and opportunities of several hard carbon compounds that boost battery capacity are examined. Several innovative carbon materials and carbon-based composites are also introduced. The electrochemical interaction of anode material with lithium could produce an intercalation product, which serves as the foundation for a novel battery system. Structural retention causes this reaction to proceed quickly and with a high degree of reversibility at room temperature. Titanium disulfide is one of the latest solid cathode materials. In this context, the paper presents a comprehensive theoretical comparison of the electrochemical electrical and physical properties of iron (Fe)-, cobalt (Co)-, manganese (Mn)-, chromium (Cr)-, and vanadium (V)-based LiMPO4 materials for cathode design in lithium (Li)-ion battery applications using the intercalation principle. The work highlighted many material and performance aspects of the cathode design, such as the cohesive energy of the material, Li-intercalation energy in olivine structure, and physical, electrochemical, and electrical analyses of LiMPO4 for rechargeable Li-ion batteries. We also examine the evolution of LIB technology based on the olive cathode materials, which are also evaluated.

Feeling the strain: Enhancing the electrochemical performance of olivine LiMnPO[formula omitted] as cathode materials for Li-ion batteries through strain effects

Currently, the improvement of Li-ion batteries (LIBs) is more important than ever, especially due to the increasing spread and rapid progress of electric vehicles and high-tech applications. Materials used for positive electrodes are one of the main constituents of batteries, which typically determine their electrochemical efficiency. Phospho-olivine LiMnPO4 (LMP) material has been regarded as a potential positive electrode material for LIBs due to its outstanding properties. However, it suffers from low electronic and ionic conductivity. Therefore, this work aims to overcome these drawbacks by applying a biaxial strain to LMP. In this regard, we used density functional theory calculations to investigate the effect of biaxial strain on the dynamic and thermal stabilities, structural, electronic, ionic diffusion, electrochemical potential, and defect properties of LiMnPO4 (LMP) structure, as well as on the Average (Mn–O, Li–O and P–O) bond lengths, electrical conductivity, and charge transfer. Moreover, the influence of anti-site defects on the ionic conductivity of LMP compound was evaluated. Our findings suggest that the biaxial tensile strain has a remarkable effect on the rate performance of LMP cathode material. A biaxial tensile strain of +2% reduces the band gap of LMP from 3.51 to 3.41 eV, and ameliorates the diffusion coefficient by 100 times. Furthermore, the migration barrier was calculated to be 0.37 eV for strained (+2%) defective MP, lower than 1.12 eV for unstrained defective MP, indicating that biaxial tensile strain can mitigate the negative effect of anti-site defects on Li-ion migration. These results can prompt us to suggest biaxial tensile strain as a good strategy for improving the electrochemical performance of LMP as cathode material for LIBs. Furthermore, this study may supply insights to cathode material designers and engineers on the importance of an appropriate biaxial strain value to improve the rate performance of LiMnPO4 as cathode materials for LIB batteries.

Influence of graphene-based additives on behaviours of electrode materials of Li-ion batteries: A systematic evaluation

Two-dimensional (2D) materials offer interesting properties which cannot be found in bulk materials. Clearly, one of the most important 2D materials is graphene (G) and its derivatives (e.g. graphene oxide, GO, reduced graphene oxide, rGO, etc.). Requirement of the electron conductivity make the G-based materials as potentially promising additives to modify the electrode properties of Li-ion batteries. Consequently, a systematic analytical evaluation is required to understand the effect of these additives in the electrode behaviours and its origins. To this aim, charge-discharge data of the various cathode materials with G-based additives prepared in different situations and labs are taken from literature. The data are applied to three specific diagrams in order to assess the additives' effect on rate-capability, performance, particle activations, and goodness of the active particles. We evaluate the influence of G-based additives, its origins, and their functionalization on each electrode materials as well as entire considered materials. The results show that effectiveness of the additives highly depends on nature of the electrode material, synthesis route, and functionalization of the G-based components during the synthesis; and slightly depends on the preparation parameters and fraction of the additives.

Layered GeSe/thermally-reduced graphene oxide composites as efficient anodes for high-performance Li-ion batteries

Due to their layered structure and greater electrical conductivity compared to traditional metal oxides, layered metal selenides have been extensively explored as promising electrode materials for Li-ion batteries. The greatest obstacles to their continued growth, however, are the substantial volume change and particle agglomeration during cycling. In this work, layered GeSe/ thermally-reduced graphene oxide (TRG) composites were successfully synthesized by using a facile shear-force exfoliation approach. When a highly conductive TRG matrix was incorporated with GeSe particles, the resultant GeSe/TRG composite electrode achieved an impressive reversible capacity (>840.1 mAh g−1 at 0.1C), improved rate capability as well as excellent cycling stability. The remarkable improvement in electrochemical performance of the GeSe/TRG composite electrode corresponds to the TRG matrix, which potentially constructs an efficient conductive channel and serves as a flexible mechanical buffer for the restriction of volume expansion and particle aggregation.

Investigating the Structural and Lithium Storage Properties of High-Entropy Oxides in the Mg-Co-Ni-Cu-Zn-O System

Recently, a new class of materials known as high-entropy oxides (HEOs) has emerged as an alternative electrode material for the next-generation Li-ion batteries. However, the discovery of these materials brings forth a broad range of compositions remained unexplored. This study aimed to investigate the structural and electrochemical characteristics of the non-equiatomic HEOs. Accordingly, ten different samples were synthesized in the Mg-Co-Ni-Cu-Zn-O system at very high (35 mol. %) and very low (5 mol. %) constituent proportions. Our experimental and theoretical results indicated that the thermodynamic stability of the HEOs was affected significantly by the enthalpic contributions arising from the lattice strain. These findings may provide a more consistent design approach in selection of a suitable component for the synthesis of the single-phase HEOs. Furthermore, the specific capacity, cycling stability and lithiation voltage of the electrodes have also been shown to be influenced by each individual constituent of the electrode.

Fundamental methods of electrochemical characterization of Li insertion materials for battery researchers

Li-ion batteries have gained intensive attention as a key technology for realizing a sustainable society without dependence on fossil fuels. To further increase the versatility of Li-ion batteries, considerable research efforts have been devoted to developing a new class of Li insertion materials, which can reversibly store Li-ions in host structures and are used for positive/negative electrode materials of Li-ion batteries. Appropriate evaluations of electrochemical properties of Li insertion materials are essential for the research of electrode materials in laboratory. In this article, we describe fundamental methods of electrochemical characterization of Li insertion materials including electrode preparation, cell assembly, and electrochemical measurement in the laboratory-scale research. The importance of selection for battery components such as electrolyte solutions, polymer binders, separators, and current collectors on the electrochemical properties of Li insertion materials, is also discussed. This article offers basic knowledge and techniques for electrochemical characterizations of Li insertion materials to students and beginners for battery research.

Surface, Structural, and Electrochemical Analysis of High-Voltage Spinel Cathode LiNi0.5Mn1.5O4 Evolution Upon Ambient Storage Conditions

Spinel LiNi0.5Mn1.5O4 as one of the high-energy positive electrode materials for next generation Li-ion batteries has attracted significant interest due to its economic and environmental advantages. However, the sensitivity of this type of material upon short to long term ambient storage conditions and the impact on the electrochemical performances remains poorly explored. Nevertheless, this remains an important aspect for practical large-scale synthesis, storage and utilization. Herein, we study and compare the evolution of surface chemistry, bulk crystal structure and elemental content evolution and distribution of LiNi0.5Mn1.5O4 using a variety of characterization techniques including XPS and STEM-EDS-EELS, as well as electrochemical analysis. We show that Mn species dominate the outer surface (0–5 nm), while Ni and Li are preferentially located further away and in the bulk. The studied LiNi0.5Mn1.5O4 material is found to be stable, with minor changes in surface or bulk characteristics detected, even after 12 months of storage under ambient air conditions. The low surface reactivity to air also accounts for the minor changes to the electrochemical performance of the air-exposed LiNi0.5Mn1.5O4, compared to the pristine material. This study provides guidance for the appropriate storage, handling and processing of this high-performance cathode material.

Influence of Backbone on the Performance of Pendant Polymer Electrode Materials in Li-ion Batteries.

Pendant polymers are a promising class of electrode materials due to their synthetic simplicity, derivation from sustainable feedstocks, and potentially benign synthesis. These materials consist of a redox-active pendant tethered to a polymer backbone, which mitigates dissolution during electrode cycling. To date, an extensive number of pendant groups have been studied within the context of metal-ion batteries. However, the choice of the polymer backbone and its impact on the electrode performance have been relatively understudied. In this work, we use a postpolymerization modification approach to synthesize a series of viologen-bearing redox-active pendant polymers with similar molecular weights but three distinct chemical backbones, namely, polyacrylamide, polymethacrylamide, and polystyryl. By evaluating the polymers in lithium-ion batteries, we show that the polymer backbone has a significant influence on electrode performance and behavior. Specifically, the polymethacrylamide displays slower kinetics than the other two polymers, resulting in lower capacities, particularly at high cycling rates. Furthermore, the charge storage mechanism is dependent on the nature of the backbone: the polyacrylamide shows a significant capacitive contribution to charge storage, while the polystyryl does not. The difference in performance between the polymer electrode materials is ascribed to a difference in chain mobility and packing within the electrode films. Overall, this work shows that the fundamental properties of the polymer backbone are critical to the design of high-performance polymer electrodes.

(Invited) Advanced Organic Electrode Materials for High-Performance and Sustainable Na-Ion Batteries

Na-ion batteries (NIBs) are promising alternatives to Li-ion batteries (LIBs) due to the low cost, abundance, and high sustainability of sodium resources. However, the high performance of inorganic electrode materials in LIBs does not extend to NIBs because of larger ion size of Na+ than Li+ and more complicated electrochemistry. Therefore, it is vital to search for high-performance electrode materials for NIBs. To this end, organic electrode materials (OEMs) with the advantages of high structural tunability and abundant structural diversity show great promise in developing high-performance NIBs. To achieve advanced OEMs for NIBs, a fundamental understanding of the structure–performance correlation is desired for rational structure design and performance optimization. Tailoring molecular structures of OEMs can enhance their performance in Na-ion batteries, however, the substitution rules and the consequent effect on the specific capacity and working potential remain elusive. Herein, we explored the electrochemical performances and reaction mechanisms of various carboxylate-based anode materials, including halogenated sodium carboxylates, N-doped sodium carboxylates, etc. By examining sodium carboxylates with different functional groups, selective N substitution, and extended conjugation structure, we exploited the correlation between structure and performance to establish substitution rules for high-capacity OEMs. Our results show that substitution position and types of functional groups are essential to create active centers for uptake/removal of Na+ and thermodynamically stabilize organic structures. Furthermore, rational host design and electrolytes modulation were performed to extend the cycle life. In addition to sodium carboxylate-based anode materials, we also designed and synthesized novel organic cathode materials based on azo and carbonyl groups for NIBs. The electrochemical performance of the organic cathode materials with an extended conjugated structure such as a naphthalene backbone structure is better than that with benzene and biphenyl structures due to faster kinetics and lower solubility in the electrolyte. It unravels the rational design principle of extending π-conjugation aromatic structures in redox-active polymers to enhance the electrochemical performance. To further optimize the organic cathodes, nitrogen-doped or single layer graphene is employed to increase the conductivity and mitigate the dissolution of organic materials in the electrolytes. The resulting organic cathodes deliver high specific capacity, long cycle life, and fast-charging capability. Post-cycling characterizations were employed to study the chemical structure and morphology evolution upon cycling, demonstrating that the active centers (azo and carbonyl groups) in the organic cathode materials can undergo reversible redox reactions with Na+ for sustainable NIBs. Our work provides a valuable guideline for the design principle of high-capacity and stable OEMs for sustainable energy storage.

Structure and Lithium Insertion in Oxides of Molybdenum

Oxides MoOx of molybdenum have a rich structural chemistry arising from the accommodation of oxygen deficiency as MoO3 is reduced, and varied redox behavior arising from the ability of Mo to take on several different oxidation states. We have reviewed MoO3, MoO2, and all the reduced Mo oxides with intermediate compositions for their performance as Li-ion battery electrode materials. These reduced oxides are perhaps the most structurally diverse in the field of energy storage materials, taking on structures ranging from ones with crystallographic shear to bronze-like structures and distorted rutile. Crystal structure can have a significant impact on the performance of battery materials, which makes the reduced Mo oxides a promising domain of study. Electrochemical studies of these oxides from as early as 1971 to as recently as 2022 have been compiled, and characteristics of capacity, capacity retention, and rate performance have been compared. We found that certain oxides indeed display promising and highly reversible capacities for Li+ storage. Typical redox voltages for Mo oxides lie in a regime that hinders maximizing energy density when they are paired with higher-voltage cathodes or lower-voltage anodes. The possibility of decreasing the redox voltage in the future will expand the promise of these materials, while offering an alternative to more critical elements such as Nb. Figure 1

Recent Progress in Design Principles of Covalent Organic Frameworks for Rechargeable Metal-Ion Batteries.

Covalent organic frameworks (COFs) are acknowledged as a new generation of crystalline organic materials and have garnered tremendous attention owing to their unique advantages of structural tunability, frameworks diversity, functional versatility, and diverse applications in drug delivery, adsorption/separation, catalysis, optoelectronics, and sensing, etc. Recently, COFs is proven to be promising candidates for electrochemical energy storage materials. Their chemical compositions and structures can be precisely tuned and functionalized at the molecular level, allowing a comprehensive understanding of COFs that helps to make full use of their features and addresses the inherent drawback based on the components and functions of the devices. In this review, the working mechanisms and the distinguishing advantages of COFs as electrodes for rechargeable Li-ion batteries are discussed in detail. Especially, principles and strategies for the rational design of COFs as advanced electrode materials in Li-ion batteries are systematically summarized. Finally, this review is structured to cover recent explorations and applications of COF electrode materials in other rechargeable metal-ion batteries.

Decarboxylative - Dimerization of levulinic acid using spent Li-ion battery electrode material with lithium nickel cobalt manganese oxide as a catalyst

A low cost catalyst prepared by pyrolyzing electrode coating material from spent Li-ion battery cells was shown as an effective catalyst for the decarboxylative - dimerization of levulinic acid to a mixture of C6 and C9 fuel precursors. The highest levulinic acid conversion of 94% was observed with 10% (w/w) catalyst loading under 1.24 MPa H2 at 140 °C, 15 h. A reaction scheme was proposed to explain the novel transformation producing C9 lactone products and C6 unsaturated alcohol product through a decarboxylative pathway followed by the aldol dimerization of levulinic acid.

Conversion-type Ni2.5Co0.5(PO4)2 phosphate as negative electrode material for rechargeable Li-ion batteries

The production of clean energy requires efficient energy storage systems, such as Lithium-ion batteries, to store wind and solar energy. To meet this demand, suitable electrode materials must be chosen. Conversion-type negative electrode materials are considered promising candidates due to their high reversible capacity. In this study, pure Ni2.5Co0.5(PO4)2 (NCP) orthophosphate was synthesized using a solid-state reaction at 900 °C in air and its electrochemical behavior was studied for the first time as a negative electrode material. Carboxymethyl cellulose (CMC) and polyvinylidene fluoride (PVDF) binders were used and the obtained performances were compared. The electrochemical properties were explored over a voltage range of 0.5 – 3.0 V and 0.01 – 3.0 V. The results showed that NCP exhibits the best electrochemical properties, delivering a high reversible discharge capacity of 200 mAh g−1 after 30 cycles at a C/5 current rate over 0.01 – 3.0 V voltage range, using a water-based CMC binder. Additionally, NCP@C delivers a reversible discharge capacity of 211 mAh g−1 after 400 cycles at a 2 C rate with a coulombic efficiency of 100 %

Efficient optimization of the Li-ion conductivity of borovanadate glass materials for Li-ion batteries

The lithium-doped borovanadate glasses of high chemical purity are obtained via the traditional-melt quenching method. The obtained glasses are identified as having an amorphous character by XRD. DSC spectra reveal the glassy nature and good thermal stability of the prepared samples. FTIR spectroscopy reveals the structural groups of these glasses. The incorporation of Li+ ions into the glass modifies the boron coordination so that the boron coordination number changes from BO4 to BO3. The structural conversion of BO4 to BO3 boosts the number of NBOs. The increased number of NBOs indicates borate network depolymerization and a more open network structure, which leads to Li+ ions easily transferring in the glass network. This, in turn, optimizes the ionic conductivity of the present glassy system and can be of order 10−4 S.cm−1 at 300 K. This is the highest value of ionic conductivity reached by the borovanadate glasses at 300 K. Accordingly, borovanadate glasses containing lithium could pave the way for the use of glass materials as electrode material for Li-ion batteries.