Application Of LIBS Research Articles

Feasibility of laser induced breakdown spectroscopy for quantification of zirconium in nuclear streams

AbstractLaser induced breakdown spectroscopy is explored for the estimation of Zr in metallic fuel and pyrochemical reprocessing stream using filter paper as a sample substrate. Zr(II) emission line at 339.20 nm has been identified and used for its quantitative determination. Calibration curves are obtained after normalizing the intensity of Zr to C/Y emission lines as an internal standard, to get better linearity. Analytical capability of LIBS for Zr estimation is tested by comparing the measured value with ICP-OES in simulated samples. Good agreement between the measured values confirms the ability of LIBS application in nuclear streams.

(Invited) Solvometallurgy as a Sustainable Approach for Lithium-Ion Batteries Recycling

Lithium-Ion Batteries, LIBs, are the core devices that made possible the diffusion of portable consumer electronics and, more recently, the booming of the electric vehicle market. [1] Their ubiquitous use and diffusion led to the well-known and urgent problem of spent LIBs management. Indeed, spent LIBs represent a complex and hazardous kind of waste for which specific regulation, disposal, and recycling routes are still missing. At the same time the continuous and growing production of LIBs involves the mandatory use of specific elements such as Li, Co, Ni, Cu, Al that are considered strategic or critical raw materials due to their limited availability, high costs, monopoly, and geological distribution. [2] The development of efficient and sustainable procedures for recycling of spent LIBs is the answer to these two main challenges as in enable to properly manage the LIBs waste and allow for the recovery of critical raw materials. While at industrial scale the high temperature pyrometallurgy and hydrometallurgy are the methods in use today, in the very last years, many approaches have been explored at research level, among them low temperature pyrometallurgy, soft hydrometallurgy, solvometallurgy, bioleaching. [3] Among them, the solvometallurgical approach exploiting Deep Eutectic Solvents (DESs) as leaching agents is particularly appealing thank to some specific features such as the low volatility, low flammability, low costs, ease of preparation combined with high leaching efficiencies.DESs are mixture of based on the presence of a hydrogen bond donors and acceptors forming a eutectic mixture at ambient temperature; although their first conceptualization is recent, several compositions have been already appeared in literature for this specific application. [4] At the same time, a rationalization of the role of the mixture components and a specific design of the composition, tailored for the application in LIBs recycling is still missing. We here present the results of our work on the development of new DESs compositions enabling the close-loop recycling of different spent cathodes. The DES compositions have been designed considering the overall recycling process, the effect of the DES compositions in terms of hydrogen bond donors and acceptors has been evaluated and rationalized through a preliminary chemical-physical characterization through thermal, NMR, FTIR, viscosity analysis. The leaching of the most common cathode has been optimized against the dominant parameters (temperature, treatment duration, cathode-to-DES ratio) opening the ways for two possibilities: the recovery of critical raw materials and the direct resynthesis of new cathodes. All the steps and products have been fully characterized with a multi-technique approach including structural and chemical investigation through the electrochemical testing of the re-synthetized materials. Finally, these two options have been assessed through LCA analysis, being able to provide an overview of the global sustainability of the proposed processes.[1] Ji et al., Chem Soc. Rev. (2023) doi 10.1039/d3cs00254c[2] Global Supply Chains of EV Batteries report, International Energy Agency[3] Yasa et al. J. En. Stor. 73 (2023) 109073[4] Padwal et al. Adv. En. Sus. Res. 3 (2022) 2100133

Accelerating Measurement Times by Correlating Electrode/Electrolyte Interface Properties with Cycle and Calendar Lifetimes

Electrochemical performance measurements on novel battery technologies are slow and require substantial resources. For example, a common metric for assessing the cycle lifetime of a cell is by charging and discharging at a rate of one cycle every six hours (C/3) for 1000 cycles and reporting the remaining capacity after the measurement. At this rate, a single measurement takes eight months to acquire useful data. Even worse, the benchmark for an acceptable shelf-life (calendar life) is to retain 80% of the initial cell capacity through 10 years. As of now, the only reliable method for acquiring this value is to hold the cell at open circuit for the duration of the time (10 years) while performing intermittent reference performance tests. The ability to quickly screen new chemistries for LIB applications offers tremendous value for accelerating discovery. Here, I will present an electrochemical impedance technique that measures a key parameter of the solid|electrolyte interface. This method uses the Helmholtz and Gouy-Chapman-Stern models of electrochemical interfaces to approximate the ‘health’ of the anode|electrolyte interface. These measurements strongly correlate to the average Coulombic efficiency of batteries with different cell chemistries which may offer predictive power for assessing the long-term cycle and calendar lifetimes.

Improved cycle capability of Mn-doped Fe2TiO5 anode for lithium-ion batteries

Good cycling stability and high theoretical capacity are provided by Fe2TiO5 (iron titanate) as an electrode material due to its distinct crystal structure and numerous redox couples. The conventional ceramic method successfully and effectively synthesises the material. This study discloses the successful doping and replacement of Ti4+ with Mn4+ in the unit cell of Fe2TiO5 pseudobrookite, resulting in decreased band gap energy and a regular increase in unit cell volume with increased Mn-concentration. Doping improves the overall electrical conductivity due to a higher ratio of Ti3+ to Ti4+ which ultimately boosts the electrochemical performance as an anode in LIBs application. The Fe2Ti1-xMnxO5 (x = 0.2) achieves a high specific surface area of 338.6 m2 g−1 with an average pore size distribution of ∼10 nm, which is beneficial to reduce the Li-ion diffusion path and provides large contact areas between electrolyte and electrode surface. The Fe2Ti1-xMnxO5 (x = 0.2) stays ahead in its electrochemical performance compared to all counter partners delivering 765.6 mAh g−1 of initial discharge capacity and having a capacity retention of 392.3 mAh g−1 after 100 continuous charge discharge cycles at a current density of 100 mA g−1. Additionally, an excellent rate performance of 327.9 mAh g−1 is observed even at 5000 mA g−1. No further capacity fading is noted for another 45 cycles, demonstrating the structural stability of electrode material at variable current densities. The superior electrochemical results of Mn4+ doped Fe2TiO5 manifestly show the possibility of serving as an electrode material for high-performance battery applications.

Boosting both electronic and ionic conductivities via incorporation of molybdenum for LiFe0.5Mn0.5PO4 cathode in lithium-ion batteries

As the EV and ESS markets expand, there is a growing interest in LiFexMn1-xPO4 (LFMP) cathode materials amidst the increasing demand for LIBs. The LFMP cathode material is cost-effective and structurally stable; however, it has the drawback of low conductivity. Therefore, the development of an LFMP cathode material with high ionic/electronic conductivity is essential for high-stability and high-C-rate LIB applications. We propose a carbon-coated LFMP cathode material with Mo placed at the Fe and Mn sites. The samples were synthesized using a solvothermal method. Mo contributes to enhanced Li-ion diffusion and charge transfer rates. The XRD Rietveld refinement results showed elongated Li–O bonds within the Mo-doped LFMP/C, which accelerated the Li+ ion diffusion. Through SEM, TEM–EDS mapping, and XPS analysis we have confirmed the properties and morphology of the material. The electrochemical evaluation of the material was conducted using galvanostatic charge-discharge, CV, and EIS methods. Based on these tests, Mo incorporation not only increased the capacity but also enhanced the rate performance, reduced the voltage polarization, and improved the lithium-ion diffusion coefficient. Based on the 3.7 V additional plateau, which is attributed to the sluggish kinetics of Mn3+, Mo6+ played a role in enhancing the kinetic behavior of Mn3+. Low-temperature performance tests demonstrated that the Mo-doped samples exhibited high energy density, cycle retention, and superior ionic conductivity. In summary, an appropriate amount of Mo doping is effective for improving the electrochemical performance of LFMP, making it a promising cathode material.

Controllable amorphization and morphology engineering on mixed-valence MOFs for ultra-fast and high-stability near-pseudocapacitance Li+ storage.

Coulombic efficiency (CE) and rate capability are crucial parameters for advanced secondary batteries. Herein, for the first time, we report controllable amorphization and morphology engineering on mixed-valence Fe(II,III)-MOFs from the crystalline to amorphous state and micro-clustered to hollow nano-spherical geometry through valence manipulation by a dissolved oxygen-mediated pathway. The disordered structure and the hollow nanostructure can endow the MOFs with the highest initial CE (>80%) to date for MOF electrodes, and ultrafast and super-stable near-pseudocapacitance lithium storage. These findings can provide new ideas for the engineering of MOF systems for application in LIBs.

Quantification of lithium using handheld instruments: application of LIBS and XRF spectroscopy to assay the lithium content of mineral processing products

Two lithium assay methods have been developed using handheld tools, offering fast and reliable results. These methods are crucial for inline optimization of processes, particularly in the extraction of lithium from hard rock deposits.

MgV3O8 incorporated carbon nanofibers as anode material for high-performance lithium-ion batteries

The rich redox chemistry of vanadate-based materials makes them a potential anode for the fabrication of advanced lithium-ion batteries (LiBs). However, poor electrical conductivity as well as volume variation of vanadate-based anode materials hinders practical applications. Herein, magnesium vanadate (MgV3O8) incorporated carbon nanofibers (CNFs) (MgVO@CNFs) composites were prepared via a simple and scalable electrospinning technique, followed by pyrolysis. The synergistic effect of MgVO and CNFs effectively offers a good conductive path and excellent integrity between the active particles with highly porous network. As an anode for LiBs, the MgVO@CNFs composite electrode exhibited good discharge capacity values of 457 mA h g−1 (over 300 cycles) and 245 mA h g−1 (over 500 cycles) at 0.1 and 0.5 A g−1, respectively and revealed excellent rate performance. The charge storage mechanism of MgVO@CNFs is contributed by both capacitive and diffusion-controlled behaviors. Consequently, this novel preparation process of the MgVO@CNFs may provide a new idea for the fabrication of different kinds of nanostructures for LiB applications.

Modification of VPO4 with carbon and 3DG for high performance lithium‐ion battery anode

AbstractLithium‐ion batteries (LiBs) are one of the most promising energy storage devices. However, the large‐scale application of LiBs is limited by their electrochemical properties. In this study, we built a three‐dimensional (3D) conductive network structure with carbon and 3DG coating VPO4 (VPO4@C@3DG) via a one‐pot hydrothermal method with subsequent high‐temperature annealing. The effects of the content of three‐dimensional porous graphene (3DG) on the crystal structure, morphology, and electrochemical properties of VPO4/C are investigated using characterization and electrochemical test techniques. The SEM images show that the size of sphere‐like particles of VPO4@C@3DG composite with 20 wt.% of 3DG (VPO4@C@3DG‐20) is the smallest in all samples. In addition, the electrochemical experimental results reveal that VPO4@C@3DG‐20 exhibits the best cycling and rate performance compared to other VPO4@C@3DG composites. Specifically, VPO4@C@3DG‐20 achieves an initial charge capacity of 601.2 mAh g−1 at 0.2 C (110 mA g−1) and keeps at 354 mAh g−1 at the 100th cycle. This is because the introduction of 20 wt.% 3DG graphene inhibits the growth and aggregation of the particles, thus shortening the diffusion path of Li+. In addition, the 3D conducting network structure boosts the conductivity of the materials and buffers the volume variation resulting from the charging/discharging process.

Dynamics of laser-induced plasma and cavitation bubble at high pressures and the impacts on underwater LIBS signals

Characteristics of laser-induced plasma depends strongly on its ambient pressure, and a deeper understanding of the high pressure impact on the underwater plasma emission is essential for the application of LIBS in the deep-sea. In this work, we investigated the temporal evolution of underwater plasma and cavitation bubble at the high pressures up to 50 MPa, by using fast imaging and shadowgraph techniques. It showed that as the ambient pressure increases, the plasma expansion is much suppressed with a stronger emission intensity and a slower emission decay, but it quenches much earlier and ends with a sharp drop at the higher pressures. From the shadowgraph imaging results, it showed that the increase in pressure has a great impact on the bubble evolution. Both the bubble maximum radius and the bubble lifetime decrease dramatically with the pressure as a consequence of faster dynamics. By comparing between the plasma and bubble results, we demonstrated the critical role of bubble dynamics on the characterization of plasma emission at high pressures. At relatively low pressures, the bubble expansion time is long enough to finish the plasma radiation. While at high pressures, strong bubble-plasma interaction occurs that will guide the plasma evolution behavior at the late stage. The plasma can gain energy from the confinement effect caused by the bubble shrinking process which leads to an increase in the emission intensity, but it will quench immediately after the bubble collapse. Such effects caused by bubble dynamics at high pressures explain well the evolution behaviors of underwater LIBS signals of OH, Ca II, Ca I, and CaOH, considering the different lifetimes of these emitting species in the plasma. This work reveals the complex impacts of high pressure on underwater plasma emissions and underwater LIBS signals.

Temperature-Dependent Gassing Analysis By on-Line Electrochemical Mass Spectrometry of Lithium-Ion Battery Cells with Commercial Electrolytes

Li-ion batteries (LiBs) are known to evolve gases during their first few formation cycles due to the formation of a solid electrolyte interphase (SEI) at the anode active material particle surface. Simultaneously, the electrolyte can react by other mechanisms leading to the formation of volatile species. 1,2 At a high state-of-charge, the cathode can also release reactive oxygen which causes the formation of CO and CO2 from the oxidative decomposition of the electrolyte.3,4 Consequently, by the analysis of evolved gas species one can study the effect of electrolyte additives, reveal substantial degradation processes within LiBs, and rationalize optimized formation strategies.4–6 The evolution of gaseous species is typically quantified in-situ by monitoring the cell pressure (e.g., via the so-called Archimedes principle) or by online mass spectrometry.5,7 Concerning the latter, an on-line electrochemical mass spectrometer (OEMS) was developed for the application in LiB research and proved to be particularly powerful, since it allows a quantitative analysis and the identification of the evolved and consumed gas during the operation of a battery.4,7 The quantification of OEMS data, however, is challenging when the vapor pressure of the electrolyte is high, which, e.g., is the case for linear carbonates, particularly at elevated temperatures. Mixtures of linear and cyclic carbonates are widely used in LiB applications due to their low viscosity, high salt solubility, and high conductivity. In contrast to the cyclic ethylene carbonate (EC) with a vapor pressure of 0.25 mbar, the vapor pressure for the typically used linear carbonates dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) can vary from 23 to 80 mbar at room temperature.8 Their vapor pressure further increases by a factor of ~3 when increasing the temperature from room temperature to 45 °C.9 Thus, a significant share of the gas in the head-space of the OEMS cell consists of electrolyte vapor. As they undergo fragmentation in the mass spectrometer, a background signal is superimposed on the relevant mass traces related to hydrogen, ethylene, carbon monoxide, oxygen, and carbon dioxide.1 Furthermore, the cell pressure inherently decreases due to the continuous leak through the capillary (with a leak rate of ~1 µL/min) that connects the OEMS cell (~10 mL volume) with the mass spectrometer. Because of the liquid reservoir of electrolyte in the OEMS cell and its constant vapor pressure, this results in an enrichment of the gas phase with electrolyte vapor. Analyzing the pressure-dependent flow of gaseous species into the mass spectrometer allowed us to introduce corrections for signal normalization, electrolyte background change, and signal quantification.In the present study, we applied these corrections in the investigation of the influence of LP57 (1 M LiPF6 in EC:EMC 3:7wt/wt) and LP47 (1 M LiPF6 in EC:DEC 3:7wt/wt) electrolyte on the gassing characteristics during the formation of full-cells with a graphite anode and a Ni-rich cathode from low (10 °C) to high (45 °C) temperatures. From that, we were able to conclude how the formation temperature influences the gas evolution related to SEI formation as well as the trans-esterification of the electrolyte and the lattice oxygen reactivity towards different electrolytes. A comparison to a model electrolyte (1.5 M LiPF6 in EC) with a low vapor pressure (< 0.25 mbar) allowed us to assess the detection limits of all the signals depending on the electrolyte’s vapor pressure and to evaluate the validity of our proposed signal corrections. Acknowledgment: The authors thank BMW AG for their financial support.

Interlayer expanded SnS/N-doped carbon/SnS ultra-thin composite driven from layered tin chalcogenides as advanced anode for lithium and sodium ion battery

The unique 2D-layered structure of tin (II) sulfide (SnS) compounds has led to the emergence of strong intensities, showcasing their significant potential in lithium (LIBs) and sodium (SIBs) ion batteries. However, the commercialization process of SnS compounds remain hindered due to the poor cycle stability caused by its substantial volume expansion during cycling in battery applications. In this study, a simple and scalable synthesis of ultra-thin composite with a well-connected structure SnS/N-doped carbon/SnS (SnS/NC/SnS) is reported. The structure is directly derived from layered tin chalcogenides (A2Sn3S7·xH2O, where A represents an organic cation). Within this configuration, SnS nanosheets are decorated on the N-doped carbon material. The composite exhibits an expanded layer of 9.7 Å, enabling rapid movement of Na+ ions (approximately 7 times the diffusion coefficient of bulk SnS). This expansion also aids in accommodating volume changes during the discharging and charging processes. Concurrently, theoretical calculations demonstrate that the structure maintains a relatively stable state at the interlayer spacing mentioned. The SnS/NC/SnS composite material exhibited significant potential for application in both SIBs and LIBs. In SIBs, it demonstrated excellent long-term cyclic stability, maintaining a capacity of 190 mA h g−1 even under high current density conditions of 2.5 A g−1 after 300 cycles. In LIBs, it exhibit a superior discharge capacity of 990 mA h g−1 and retains 94.1 % of its capacity after 150 cycles at 0.2 A g−1. Notably, this synthesis method is versatile, as the interlayer spacing can be adjusted by varying the type of organic cations used in the process.

N-doped graphitized carbon-coated Fe2O3 nanoparticles in highly graphitized carbon hollow fibers for advanced lithium-ion batteries anodes

Ferric oxide (Fe2O3) has become one of the most competitive candidates for the next-generation lithium-ion batteries anode materials due to its high theoretical reversible specific capacity (Cs, 1007 mAh g−1) and low price. However, the rapid capacity fading and poor rate performance deriving from drastic volume expansion (∼200 %), low Coulombic efficiency (CE), and poor electrical conductivity limit its application in LIBs. Herein, a novel encapsulation structure of Fe2O3 nanoparticles has been developed. Fe2O3 nanoparticles inlaid in the shells of hollow highly graphitized carbon fibers are coated by N-doped graphitized carbon (GF-FeO@NGC) by a catalytic graphitization, oxidation route of Fe-based catalyst. The GF-FeO@NGC electrode shows the first specific discharge/charge capacities of 1355/974 mAh g−1 with high initial Coulombic efficiency (ICE) of 72.0%, and excellent reversibility of lithiation/delithiation reaction. After 200 cycles at 0.1 A g−1, the GF-FeO@NGC electrode keeps a high reversible Cs of 918 mAh g−1 (retention of 94.3%) with a CE of 99.6%. It is noticeable that the GF-FeO@NGC electrode has good rate performance and robust cycling stability at high current density. After 300 cycles at 2 A g−1, the Cs retention is up to 97.1% with a CE of 99.7%. These are far superior to those of the GF-FeO (without NGC coating) and the most reported Fe2O3-based electrode materials. The mechanism behind these phenomena are studied.

Metallized Plastic Foils: A Promising Solution for High‐Energy Lithium‐Ion Battery Current Collectors

AbstractTo meet the growing demand for safe and high‐energy batteries, particularly for the commercialization of electric vehicles, a need for further advancement has arisen. An innovative and promising solution for current collectors in LIBs is a metallized plastic current collector (MPCC) with metal‐polymer‐metal multilayer composite structure. This approach offers several advantages. First, it effectively reduces the inert weight and thickness of LIBs, thereby enhancing their energy density. Second, a polymer with electrical insulation and high elongation properties in the MPCC significantly improves the safety performance of LIBs by preventing thermal runaway. Despite its potential for large‐scale application in LIBs, the MPCC still faces significant challenges, such as weak interfacial adhesion force and low electrical conductivity. Therefore, researchers in the field of energy storage are currently focusing on the design, modification, and development of practical MPCCs. Hence, in this review various polymers, preparation approaches, and MPCCs are comprehensively analyzed and summarized. Additionally, detailed discussions are provided on the advances, key issues, improvements and corresponding mechanisms associated with MPCCs. Finally, valuable guidance and future directions are provided for the design and improvement of advanced MPCCs in high‐energy LIBs, thus facilitating the commercialization process.

Nanotechnology Applications in Cathode and Anode Materials of Li-Ion Battery

Lithium-ion batteries (LiBs), with their high energy/specific density, extended cycle life, and minimal self-discharge rate, have gained considerable popularity in the manufacturing of portable devices and electric vehicles, where space and weight constraints are of utmost importance. Additionally, LiBs have played a pivotal role in the advancement of electric vehicles, promoting sustainable energy practices, and reducing greenhouse gas emissions. However, the limitations that stem from the inherent structures and properties of the conventional component materials of batteries might pose obstacles to the application and development of LiBs, despite their numerous advantages. Nevertheless, significant strides have been made towards improving the capacity, cycling performance, and rate performance of these batteries using nanotechnology. This approach leverages the outstanding properties of nanomaterials to enhance the electrochemical performance of battery components, such as cathode materials, which includes NMC, NCA, LMO, LFP, and anode materials such as Silicon and LTO. This paper provides a comprehensive discussion of the applications of nanotechnology in lithium-ion batteries, offering insights into the future of this promising field.

Micro-hole array sprayer combined with an organic membrane to assist LIBS (MASOM-LIBS): A novel highly sensitive detection method for dissolved trace heavy metals in water

The development of highly sensitive and rapid detection technology for heavy metal elements in water is of great significance to the monitoring of water environmental pollution, sewage discharge control and other application fields. As an alternative detection method with great potential in the above fields, LIBS technology still has some problems that need to be solved. To improve the sensitivity and efficiency of LIBS detection of trace metals in water, a new method Micro-hole Array Sprayer combined with an Organic Membrane to assist LIBS (MASOM-LIBS) was proposed in this study. In this method, water samples were transformed into a large number of micrometer droplets by a micro-hole array injection device and were sprayed onto a rotating polypropylene organic film. After natural drying, LIBS analysis was performed. The test results of the mixed solution show that plasma with lower electron density and higher electron temperature can be obtained after full drying, the signal intensity will be stronger, and the stability can be reduced to less than 1%. The experimental results of Cu, Cd, Mn, Pb, Cr and Sr as target elements show that the LODs of the MASOM-LIBS method for most elements is less than 0.1 mg/L when the detection time is less than 3 min, which has certain advantages over similar LIBS methods. If the detection time is increased appropriately, the LODs of this method is even expected to be reduced to less than 0.01 mg/L. These results indicate that MASOM-LIBS is a feasible method to improve the sensitivity and speed of the detection of trace heavy elements in liquid samples and can facilitate the wide application of LIBS in water quality monitoring. In view of the short detection time, high sensitivity and low LODs of MASOM-LIBS, this method is expected to be developed into a water trace heavy metal detection technology with fully automatic, real-time, highly sensitive and multi-element detection technology in the future.

Enhanced lithium storage capability of Ni-rich LiNi0.9CoxMn0.1−xO2(0 ≤ x ≤ 0.1) cathode by co-operation of Al-doping and V-coating

The Nickel-rich layer materials LiNixCoyMn1−x−yO2 (x ≥ 0.9) are usually accompanied by structural instability and inevitable capacity loss due to surface degradation during long cycles. The Al-V dual-modification is used in this research to enhance the stability of the structure and the electrochemical capacity of LiNi0.9Co0.05Mn0.05O2 (NCM). First, Al source was added during the co-precipitation synthesis of the precursors. Then, the Al-doped precursors were treated at 720 ℃ for 10 h with slight excess lithium to prevent volatilization of lithium during the sintering process. Finally, Al-doped LiNi0.9Co0.04Mn0.03Al0.03O2 (NCMA) materials were treated with V2O5 at 450 ℃ for 4 h. During calcination, Li3VO4-coated LiNi0.9Co0.04Mn0.03Al0.03O2 materials (NCMAV) were generated by employing residual lithium. Meantime, the Al-V dual-modification helps reduce the mingling degree of Ni2+/Li+ and promotes the diffusion of Li+. Hence, the Al-V dual-modified NCMAV displays a superior rate capability of 162.2 mAh g−1 at 5 C, remaining predominant capability retention of 90.5% after 100 cycles at 4.3 V. Compared with NCMAV, the discharge capability of pure NCM is 140.3 mAh g−1 and its capability retention is 81.6% at 5 C. This dual-modification strategy provides a facile and scalable method to achieve massive application of NCM LIBs with high density and excellent cycling stability.

Constructing bimetallic oxides with yolk structure enables high efficient anode for lithium ion batteries

Developing anode materials with high specific capacity, excellent rate performance and cycling performance is of great significance. Herein, transition metal oxides (TMOs) have been aroused much interest owing to their low cost, large theoretical capacity and chemical stability. In this work, the bimetallic oxides CoFe2O4/C composite is synthesized by solvothermal and subsequent annealing process. When used as the anode for lithium ion batteries, the CoFe2O4/C microspheres exhibit a reversible specific capacity of 1270 mAh g−1 at 100 mA g−1 after 100 cycles and about 500 mAh g−1 at a high current density of 1.0 A g−1 after 1000 cycles. These satisfactory electrochemical properties are mainly attributed to the unique yolk structure, the synergistic effect of two metal ions, carbon coating and small nanoparticles of CoFe2O4/C. This work provides an effective synthesis method for mixed TMOs with high-performance lithium storage for LIB applications.

Cross-Linked Gel Polymer Electrolyte Based on Multiple Epoxy Groups Enabling Conductivity and High Performance of Li-Ion Batteries

The low ionic conductivity and unstable interface of electrolytes/electrodes are the key issues hindering the application progress of lithium-ion batteries (LiBs). In this work, a cross-linked gel polymer electrolyte (C-GPE) based on epoxidized soybean oil (ESO) was synthesized by in situ thermal polymerization using lithium bis(fluorosulfonyl)imide (LiFSI) as an initiator. Ethylene carbonate/diethylene carbonate (EC/DEC) was beneficial for the distribution of the as-prepared C-GPE on the anode surface and the dissociation ability of LiFSI. The resulting C-GPE-2 exhibited a wide electrochemical window (of up to 5.19 V vs. Li+/Li), an ionic conductivity (σ) of 0.23 × 10-3 S/cm at 30 °C, a super-low glass transition temperature (Tg), and good interfacial stability between the electrodes and electrolyte. The battery performance of the as-prepared C-GPE-2 based on a graphite/LiFePO4 cell showed a high specific capacity of ca. 161.3 mAh/g (an initial Coulombic efficiency (CE) of ca. 98.4%) with a capacity retention rate of ca. 98.5% after 50 cycles at 0.1 C and an average CE of about ca. 98.04% at an operating voltage range of 2.0~4.2 V. This work provides a reference for designing cross-linking gel polymer electrolytes with high ionic conductivity, facilitating the practical application of high-performance LiBs.

A Novel Sugar-Assisted Solvothermal Method for FeF2 Nanomaterial and Its Application in LIBs

Due to its quite high theoretical specific-energy density, FeF2 nanomaterial is a good candidate for the cathode material of high-energy lithium-ion batteries. The preparation of FeF2 nanomaterial is very important for its application. At present, the preparation process mostly involves high temperature and an inert atmosphere, which need special or expensive devices. It is very important to seek a low-temperature and mild method, without the need for high temperature and inert atmosphere, for the preparation and following application of FeF2 nanomaterial. This article reports a novel sugar-assisted solvothermal method in which the FeF3∙3H2O precursor is reduced into FeF2 nanomaterial by carbon derived from the dehydration and condensation of sugar. The obtained FeF2 nanomaterials are irregular granules of about 30 nm, with inner pores inside each granule. Electrochemical tests show the FeF2 nanomaterial's potential as a lithium-ion battery cathode material.