Rechargeable Lithium Batteries Research Articles

Solvent-mediated oxide hydrogenation in layered cathodes.

Self-discharge and chemically induced mechanical effects degrade calendar and cycle life in intercalation-based electrochromic and electrochemical energy storage devices. In rechargeable lithium-ion batteries, self-discharge in cathodes causes voltage and capacity loss over time. The prevailing self-discharge model centers on the diffusion of lithium ions from the electrolyte into the cathode. We demonstrate an alternative pathway, where hydrogenation of layered transition metal oxide cathodes induces self-discharge through hydrogen transfer from carbonate solvents to delithiated oxides. In self-discharged cathodes, we further observe opposing proton and lithium ion concentration gradients, which contribute to chemical and structural heterogeneities within delithiated cathodes, accelerating degradation. Hydrogenation occurring in delithiated cathodes may affect the chemo-mechanical coupling of layered cathodes as well as the calendar life of lithium-ion batteries.

Development of Solid-State Lithium-Ion Batteries (LIBs) to Increase Ionic Conductivity through Interactions between Solid Electrolytes and Anode and Cathode Electrodes

Although in general ions are not able to migrate in the solid-state position due to rigid skeletal structure, in some solid electrolytes with a low energy barrier and high ionic conductivities, these ion transition can occur. In this work, we considered several solid electrolytes including lithium phosphorus oxy-nitride (LIPON), a lithium super-ionic conductor (SILICON), and thio-LISICON. For the fabrication and characterization of the solid electrolyte’s fabrication, we used a single-step ball milling (SSBM) procedure. Through this research on all-solid-state rechargeable lithium-ion batteries, our target is to discuss solving several problems in solid LIBs that have recently escalated due to raised concerns relating to safety hazards such as solvent leakage and the flammability of the liquid electrolytes used for commercial LIBs. Through this research, we tested the conductivity amounts of various substrates containing amorphous glass, SSBM, and glass-ceramic samples. Obviously, the SSBM glass-ceramics increased the conductivity, and we also found that the values for conductivity attained by SSBM were higher than those values for glass-ceramics. Using an SSBM technique, silicon nanoparticles were used as an anode material and it was found that the charge and discharge curves in the battery cell cycled between 0.009 and 1.45 V versus Li+/Li at a current density of 210 mA g−1 at room temperature. Since high resistance causes degradation between the cathode material (LiCoO2) and the solid electrolyte, we added GeS2 and SiS2 to the Li2S-P2S5 system to obtain higher conductivities and better stability of the electrode–electrolyte interface.

A Flexible Multifunctional Cyanoethyl-Modified Bacterial Cellulose Nanofiber Framework for High-Energy and High-Power Density Aqueous Li-Ion Batteries.

Aqueous rechargeable lithium-ion batteries (ARLIBs) are extensively researched due to their inherent safety, typical affordability, and potential high energy density. However, fabricating ARLIBs with both high energy density and power performance remains challenging. Herein, based on cyanoethyl-modified bacterial cellulose nanofibers (CBCNs), a multifunctional fast ion transport framework is developed to construct the flexible free-standing ARLIBs with high areal loading and excellent rate performance. Benefiting from the unique merits of CBCNs, such as ultra-high aspect ratio, excellent toughness, superior adhesion, good lithiophilicity and ideal stability, the flexible free-standing and highly robust electrodes are fabricated and exhibit a long-term stable cycling of 1200 cycles with a high specific capacity of 117 mAh∙g-1 at 15 C. Remarkably, the corresponding full cell with the free-standing high mass loading (45.5 mg∙cm-2) electrodes under the condition of ultra-low addition of battery binder demonstrates a cycle lifespan of over 1000 cycles with a specific capacity of 120 mAh∙g-1 and a capacity decay as low as 0.03% per cycle, which is far superior to those of almost all previous reports. This work provides a strategy for constructing ARLIBs with high energy density and power performance by introducing a unique fast ion transport nanofiber framework.

First-principles study of solvent polarity effects in the Menshutkin reaction

Quaternary ammonium salts (QASs) have been used as antimicrobial agents, surfactants, and ionic liquids in electrical double-layer capacitors, rechargeable lithium-ion batteries, and dye-sensitized solar cells. It is well known that solvents and reactants strongly affect the Menshutkin reaction. However, QASs are potentially harmful to humans and the environment. To address these issues, we report the effects of solvent polarity on the thermochemistry of two selected Menshutkin reactions, (1) trimethylamine and 1-iodopropane yielded propyltrimethylammonium, and (2) methylacetamide and 1-iodopropane yielded acetylpropylmethylammonium. We systematically constructed possible QAS unique conformers within the first-principles framework in solvents that have three various polarities: toluene, acetonitrile, and water. The polar solvent shifted both reactions toward exergonic and decreased the Gibbs free activation energy. In addition, the polar solvent changed the favorable reaction for the acetylpropylmethylammonium formation only due to an intramolecular hydrogen bond. Therefore, we suggest that selecting high solvent polarity should be considered to address the potential health and environmental effect.

Metal-Organic Frameworks as Electrode Materials for Lithium-Ion Battery

Over recent decades, Metal-Organic Frameworks (MOFs) have distinguished themselves as a unique class of porous materials due to their adaptable surface and structural properties. This versatility has made MOFs highly relevant across various fields, including drug delivery, gas separation, catalysis, and sensor technology. Additionally, their conductive properties have made them promising candidates for use in energy storage systems like high-energy-density batteries and supercapacitors. MOFs are particularly noted for their role in the development of rechargeable lithium-ion batteries (LIBs) and supercapacitors, where they serve as both anode and cathode materials. The ability to fine-tune MOFs at a molecular level allows for precise control over their structure and chemistry, enhancing their functionality in energy storage applications. This control facilitates superior electronic and ionic transport within MOFs, which is critical during the charging and discharging cycles of LIBs. This review delves into the various synthetic methods used to develop specific MOF structures, focusing on their implementation within LIBs to improve cyclic stability and discharge capacity. Recent advancements in MOF technology as anode and cathode materials are explored, providing insights into how these developments can optimize reaction conditions and design choices within the battery development community and broader electrochemical energy storage sectors. The aim is to highlight how MOFs’ inherent characteristics can be leveraged to enhance the performance and efficiency of energy storage devices.

Impact of diverse material precursors on microstructure and ionic conductivity Li0.33La0.56TiO3 solid-state electrolyte properties

The development of rechargeable lithium-ion batteries (LIBs) with solid-state electrolyte (SSE) is gaining attention in recent years. Among various SSE materials, lithium lanthanum titanate (LLTO) has emerged as a promising candidate due to its high ionic conductivity and excellent chemical stability. This study aims to synthesis and investigate the potential of Indonesian locally source lanthanum oxide compared to commercial lanthanum oxide for use as an SSE material. LLTO powders were synthesized via the solid-state reaction method. The local LLTO pellet achieved an impressive relative density of 99 %, slightly higher than the commercial LLTO at 97 %. This high relative density enhances ionic conductivity. The local LLTO sample achieved the highest ionic conductivity of 2.68×10−5 S/cm at 100°C and 1.15×10−5 S/cm at room temperature, nearly double that of commercial LLTO measuring approximately 8.40×10−6 S/cm at 100°C and around 4.57×10−6 S/cm at room temperature. The research findings indicate that lanthanum oxalate sourced from waste generated during monazite sand mining operations in the Bangka Belitung region of Indonesia, exhibits potential as a material for lithium-ion-conducting electrolytes in all-solid-state batteries.

Glassy Oxides as Positive Electrode Materials for Sustainable and High Energy Density Li-Ion and Na-Ion Batteries: First Attempts to Establish Relationships between Glass Compositions, Physicochemical Characterizations and Electrochemical Properties with Machine Learning and Design of Experiments Approaches

Today, rechargeable lithium-ion batteries (LIBs) represent one of the best alternatives to reduce our dependency on fossil fuels. LIBs are using cathode materials based on polycrystalline oxides or polyanionic compounds [1]. However, their performances can be limited by their crystalline structure when other compounds suffer from metallic dissolution and irreversible phase changes during cycling [2]. To overcome these key shortcomings, implementing glasses or glass-ceramics as cathode materials is an interesting approach [3]. Glasses have a structure composed of more free volume, and, in the literature that is mainly concerning glasses containing Vanadium transition metal, the glasses can so accept a large amount of lithium [4] and easily accommodate structural changes upon lithium ions extraction/insertion [5]. Furthermore, glass production is a scalable process and can be commercially easier to implement than most of synthesis processes of conventional cathode materials.The main objective targeted is to develop high capacity positive electrodes (up to 300mAh/g) for Li-ion batteries based on glassy oxides without critical transition metals such as Cobalt and Vanadium. The ambitious target is to exceed 1000Wh/kg at the active material level and so enable energy densities of 300-350 Wh/kg at the Li-Ion cell level. Additionally, the electrochemical behavior of some alkali-free glass compositions will be evaluated in sodium-ion configuration. The major scientific objective is to correlate the most relevant physicochemical properties of glass with the corresponding electrochemical performances using machine learning approaches or design of experiment methodology. For a better understanding of involved processes, three oxides glass families are studied as promising cathode materials for sustainable and high energy density lithium batteries. These oxides are composed of: i) a glass network-forming element (Si, B, P) leading to the 3 different families, ii) a transition metal (Mn, Fe, ...) and optionally iii) an alkali (Li, Na).The influence of the nature of the transition metal and the polyanionic group corresponding to the network-forming element (PO4, BO3, SiO4) on the electrical properties of the as-prepared glasses measured at different temperatures will be presented mainly for the lithiated compounds. For microstructural characterization, several techniques were coupled such as X-Ray Diffraction (XRD), SEM-EDX, DTA/TGA, Raman, IR and UV-Vis spectroscopies, Electrochemical Impedance Spectroscopy (EIS) and chronoamperometry.Finally, the electrochemical properties in terms of specific capacity, redox potentials, first cycle capacity loss, coulombic and energetic efficiencies of these materials were investigated in coin-cells vs lithium (or sodium) metal electrode. To understand the electrochemical processes involved in these materials at room temperature, SEM-EDX, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Mossbauër Spectroscopy for iron based compounds were coupled and performed on the as-prepared glasses and on ex-situ (after cycling) materials at different electrochemical states of charge.All the generated data and measurements were analyzed by machine learning approach and tools and in some cases compared with a more classical Design of Experiments (DOE) approach. For instance, figure 1 illustrates the contour diagram of first discharge capacities in the mixture diagram of phosphate glasses based on 3 different transition metal oxides. The final goal is to establish more precisely the relationships between the different glassy oxides structures and their electrochemical performances. First results of this important work of elaboration, characterization and data analysis will be presented here. This new study will bring significant elements to optimize both the glass composition and its elaboration conditions to obtain high performance cathode materials without critical materials.[1] Nitta, N. et al., Li-ion battery materials: present and future. Materials Today 18, 252–264 (2015).[2] Tesfamhret, Y. et al., On the Manganese Dissolution Process from LiMn2O4 Cathode Materials. ChemElectroChem 8, 1516–1523 (2021).[3] K. Kercher et al., « Mixed polyanion glass cathodes: Glass-state conversion reactions », J. Electrochem. Soc., vol. 163, no 2, p. A131-A137, 2016, doi: 10.1149/2.0381602jes [4] Afyon, S. et al., New High Capacity Cathode Materials for Rechargeable Li-ion Batteries. Scientific Reports 4, 7113 (2015).[5] Kindle, M. et al., Alternatives to Cobalt. ACS Sustainable Chemistry Engineering 9, 629–638 (2021). Figure 1

Operando Stress Evolution in Hard Carbon Anodes – Insight into the Mechanical Degradation Induced Failure Mode in Rechargeable Sodium Ion Batteries

Microstructural instabilities in electrodes arising from cycling induced stress is a primary failure mode in rechargeable batteries. Therefore, a quantitative knowledge of the cycling induced stress evolution in rechargeable battery electrodes is important for understanding the electrode microstructural instabilities during cycling that can potentially inform the electrode design to prolong battery cycle life. The cycling induced stress in electrodes typically arises from the volume changes associated with insertion/extraction of the electroactive species in the electrode matrix. For example, operando measurement of lithiation-delithiation induced stress in graphite electrodes that typically show 10% volume change has previously resulted in useful information that correlates well with the lithiation-delithiation mechanism in graphite anodes1. The size of the shuttling-electroactive species can be taken as an indicator of the cycling induced stress magnitude that drives the electrode microstructural instabilities. In this regard, quantification of the cycling induced stress in rechargeable Na-ion battery electrodes is warranted for understanding mechanical degradation induced failure modes owing to the larger size of the electroactive species, i.e., Na ions (vs. Li-ion).Hard carbons as potential anodes in rechargeable sodium ion batteries has gained considerable attention in the recent past due to their superior Na-ion storage capability (vs. graphite that is a canonical anode in rechargeable lithium-ion batteries). However, hard carbon anodes typically show significant capacity fade that can potentially arise from cycling induced mechanical degradation of the anodes. Operando stress measurements coupled with comprehensive electrode microstructural characterization will provide valuable insights in this context. Here we report on the operando stress evolution in hard carbon anodes in rechargeable sodium ion batteries as probed by Multiple Optical-beam Sensing (MOS) technique that basically involves monitoring the spacings among a group of laser spot (Fig. 1). Preliminary measurements have shown that the stress correlates with the potential with a maximum around 12 MPa in compression during sodiation and tensile stress of ~ 2MPa during desodiation. Operando stress measurements are performed in hard carbon anodes in two different electrode configurations – typical composite anodes (with binder and conductive agents) and hard carbon thin film anodes (without binder and conductive agents). The thin film configuration is considered to evaluate intrinsic stress response in hard carbon anodes in absence of any secondary phase. A comparison of operando stress response in these two types of hard carbon anodes along with comprehensive electrode microstructural characterization will be presented. Additionally, attempts will be made to shed light on the current debate in the mechanism of sodium storage in hard carbon anodes by comparing operando stress response of hard carbons from multiple sources along with their structural characterization (Raman, XPS, surface area etc.). V. A. Sethuraman, N. Van Winkle, D. P. Abraham, A. F. Bower, and P. R. Guduru, Journal of Power Sources, 206, 334–342 (2012). Figure 1

(Invited) The Role of Carbon in Enabling Stable Solid State Batteries

Carbonaceous materials are widely used as the anode materials in rechargeable lithium-ion batteries. In that context, they serve as the host for lithium ions. Their structural stability and limited volume changes underpin the long-term stability of the batteries. In solid-state batteries, however, their roles have evolved. With the focus on raising cell energy density and the promise of stable operation of lithium metal due to the absence of organic solvent, carbon has not been widely studied as an anode material. Unfortunately, the promise of lithium metal has encountered significant challenges: it chemical reacts with virtually all known solid state electrolytes; lithium also grows dendrites which can eventually lead to shorting; the stripping of lithium is also often inhomogeneous which had led to void formation at the interface. To address these challenges, carbonaceous materials have been reintroduced.In this talk, we overview several applications of carbonaceous materials in solid state batteries. We have shown that graphite can be engineered as a 3D host for lithium deposition. Lithiated graphite becomes lithiophilic with low nucleation barrier for lithium metal deposition. The voids between the graphite particles can accomodate lithium metal. As a result, the critical current density and cycling stability of both full cells and symmetric cells have greatly improved. We note that in this context, the anode is essentially a graphite electrode that experiences intentional overlithiation.In a second application, we show that carbon can serve as an effective interlayer between lithium and the solid electrolyte. This interlayer reduces the side reaction between lithium and the electrolyte, thus greatly improving the cycle life and coulombic efficiency. It is rather surprising that upon lithiation, the interlayer enables lithium transport and preferential lithium deposition at the carbon/lithium interface, rather than the carbon/electrolyte interface. This desirable outcome is observed despite the fact that the interlayer itself is electrically conducting. We studied a wide variety of carbon materials in terms of surface area, crystal structure, and defect density. With the optimized carbon material, critical current densities of over 30 mA/cm2 have been observed. The mechanism of lithium transport will be discussed along with the design criteria for using carbon as an effective mixed electron and ion conductor.

Exploring the Impact of Oxygen Doping in Li2FeS2 Cathode Materials for Li-Ion Batteries

Over the past few decades, rechargeable lithium-ion batteries have become popular for a variety of applications, such as electric vehicles, smart grids, and portable energy devices. However, due to their limited capacity, stability, and lifespan, they are not suitable for advanced transportation applications. To overcome these challenges, researchers have investigated the use of low-cost, high-energy-density, and safe positive electrode materials for secondary lithium batteries, including lithium iron sulfide. In this particular study, our focus is to investigate the effect of highly electronegative anion doping on the properties of lithium iron sulfide cathode through the solid-state method. Our approach involves using both in-situ and ex-situ observations to establish a correlation between the Redox behavior and structural properties of the prepared cathode materials. We have designed and characterized the material using various techniques, such as X-ray absorption spectroscopy (XAS) and synchrotron-based X-ray diffraction (XRD). Scanning electron microscope (SEM) measurement was conducted to study the morphology of the cathode material. Transmission electron microscopy (TEM) was employed to further study the microstructure of the cathode material at an atomic level. We analyzed the electron density distribution of the modified cathode material using XANES measurement and studied the structural properties through synchrotron-based XRD. Our study has revealed that oxygen-doping helps to improve material stability. As a result, the modified cathode (with optimal oxygen doping) exhibited a 50% capacity enhancement compared to pristine after 100 cycles. We also observed a shift to a higher voltage oxidation plateau of the oxygen-doped cathode material which is due to the influence of anion substitution on the electrochemistry and charge storage mechanisms. In summary, our detailed characterization and experimental results demonstrate the potential of oxygen-doped Li2FeS2 as a promising cathode material for advanced lithium-ion battery applications. The study's detailed characterization and experimental results will be presented, along with future perspectives.

Seeding and Growing Plain Li-Metal Surfaces - New Approaches to Increase the Coulombic Efficiency of Anodeless Lithium-Metal Batteries

In the pursuit of higher energy densities, lithium-ion batteries with lithium metal anode appear as one particular promising technology. Especially the option to plate non-dendritic, superficially even Li-layers [1] directly onto the current collector of the negative electrode without the use of an anode active material (“anode-less battery design”) should enable gravimetric energy densities of up to 400 Wh/kg [2] and 1200 Wh/l [3] in future cell systems [4].In the presented work, Swagelok-cells in “anode-less” configuration, comprising a NMC 811-cathode and an ether-based electrolyte containing 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) and 1,2-dimethoxyethane (DME) in 1.2:3 molar ratio, 1.5 M LiFSI [2] were cycled under the application of pressure (up to 400 kPa) onto the cell stack.As the proper formation of Li-nuclei (number, morphology, etc.) and the even growth of lithium-layers onto the Cu-based anode (Figure 1) seems from great importance to plate and stripe Li-metal at high coulombic efficiencies, several charging programs with presumably Li-nucleation promoting effects were tested in a cycling experiment along 50 full cycles (Figure 2). As a promising result and as clear improvement compared to standard charging processes (e.g. 0.1 C), average coulombic efficiencies as high as 99.2 % together with low capacity fading were observed.Due to the design-related limitation of Swagelok-based cells and a noticeable diffusion of air fractions (N2, O2, H2O) across the PFA-seals into the cell, in a second experimental part the influence of ambient air on the cycling performance was tested under three conditions (Figure 2, left, middle and right diagram): a) Cells cycling in common (humid), laboratory air, b) under dry air (P2O5) in sealed steel-containers and c) inside an argon filled glovebox (< 0.1 ppm H2O, < 0.1 ppm O2). As a result, a strong sensitivity of operating Li-metal cells not solely versus traces of ambient, humid air, but also versus P2O5-dried nitrogen and oxygen was obvious. Reference s [1] Fang, C.; Lu, B.; Pawar, G.; Zhang, M.; Cheng, D.; Chen, S.; Ceja, M.; Doux, J.-M.; Musrock, H.; Cai, M.; Liaw, B.; Meng, Y. S., Pressure-tailored lithium deposition and dissolution in lithium metal batteries. Nature Energy 2021, 6, (10), 987-994.[2] Niu, C.; Liu, D.; Lochala, J. A.; Anderson, C. S.; Cao, X.; Gross, M. E.; Xu, W.; Zhang, J.-G.; Whittingham, M. S.; Xiao, J.; Liu, J., Balancing interfacial reactions to achieve long cycle life in high-energy lithium metal batteries. Nature Energy 2021, 6, (7), 723-732.[3] Louli, A. J.; Eldesoky, A.; Weber, R.; Genovese, M.; Coon, M.; deGooyer, J.; Deng, Z.; White, R. T.; Lee, J.; Rodgers, T.; Petibon, R.; Hy, S.; Cheng, S. J. H.; Dahn, J. R., Diagnosing and correcting anode-free cell failure via electrolyte and morphological analysis. Nature Energy 2020, 5, (9), 693-702.[4] Li, Q.; Yang, Y.; Yu, X.; Li, H., A 700 W⋅h⋅kg−1 Rechargeable Pouch Type Lithium Battery. Chinese Physics Letters 2023, 40, (4), 048201. Figure 1

Morphology Controled LiFePO4 Electrodes Via Polyol Refluxing for Enhanced Lithium-Ion Battery Performance

In the synthesis of LiFePO4 cathodes with secondary nanorod structures and nano-plate morphologies, researchers utilized a polyol refluxing process. Notably, we achieved this without the use of characteristic structure directing agents. Through varying the reaction time, they were able to modulate the morphological characteristics of the synthesized samples.X-ray diffraction studies conducted on the prepared samples indicated a highly crystalline nature. This suggests that the synthesized cathodes possessed a robust and ordered atomic structure, which is crucial for their electrochemical performance.Electron microscopy investigations provided insights into the morphology of the samples obtained at different reaction times. Samples produced after 1 to 16 hours of polyol reaction exhibited secondary nanorod bundles. However, the sample recovered after 32 hours of polyol reaction displayed a distinct nano-plate morphology. These observations highlight the influence of reaction time on the final morphology of the synthesized cathodes.The dimensions of the obtained samples ranged from a few tens to a few hundred nanometers. This nano-scale size is advantageous for enhancing the electrode's surface area, which can facilitate rapid ion diffusion and electron transport during battery cycling.When employed in lithium test cells, the LiFePO4 cathodes synthesized for different durations delivered varying discharge capacities. Specifically, cathodes prepared under 1, 4, 8, 16, and 32 hours of reaction time exhibited discharge capacities of 161, 162, 171, 143, and 155 mAhg−1, respectively. Notably, all samples displayed a well-defined discharge plateau at 3.4 V, indicating stable electrochemical behavior during cycling.Remarkably, among the prepared electrodes, the LiFePO4 nanorod bundle cathode synthesized under 1 hour reaction time demonstrated the highest average reversible capacities. It maintained capacities of 123 and 103 mAhg−1 at C-rates as high as 3.2 and 6.4 C, respectively. This highlights the importance of reaction time in controlling the electrochemical performance of the synthesized cathodes.The crystal growth mechanism during the polyol refluxing method can be elucidated through several stages. These include precursor dissolution and nucleation, oriented crystal growth and alignment through self-assembly, aggregation, partial dissolution, and finally, complete re-crystallization. Understanding these mechanisms is essential for optimizing the synthesis process and tailoring the properties of LiFePO4 cathodes for various applications. Tarascon JM, Armand M. Issues and challenges facing rechargeable lithium batteries. Nature 2001;414:359–67Amatucci GG, Tarascon JM, Klein LC. CoO2, the end member of the LixCoO2 solid solution. J Electrochem Soc 1996;143:1114–23Ravet N, Chouinard Y, Magnan JF, Besner S, Gauthier M, Armand M. Electroactivity of natural and synthetic triphylite. J Power Sources 2001;97–98:503–7 Figure 1

Design of Localized High-Concentration Electrolytes from the Perspective of Physicochemical Properties.

The physicochemical properties of electrolytes profoundly impact the energy density, rate performance, and manufacturability of rechargeable lithium batteries. Localized high-concentration electrolytes (LHCEs), a novel electrolyte class, have attracted considerable interest, yet the impact of diluents on their physicochemical properties remains unclear, as most reports involve only a few samples. Here we prepared 345 electrolyte samples using 21 diluents and systematically investigated the effect of diluent type and content on the miscibility, density, viscosity, and ion conductivity of LHCEs. We found that the physicochemical properties of LHCEs are mainly affected by the diluents' density and viscosity, regardless of type. Notably, the ionic conductivity exhibits two typical variance trends, "volcano" and "descending," both correlating strongly with diluents' viscosity rather than dielectric constant, a parameter commonly employed in electrolyte design. This anomaly can be explained by the "plum pudding" solvation model, providing essential insights for developing lightweight, highly fluid, and conductive LHCEs.

Review—Advances in Rechargeable Lithium-Ion Batteries Utilizing Polyoxometalate-Functionalized Nanocarbon Materials

Abstract Polyoxometalates (POMs) are inorganic nanoclusters that consist of oxygen and transition metals. These nanoclusters serve as excellent precursors for creating electrode materials that contain transition metals. Additionally, the interaction between POMs and carbon substrates produces positive synergistic effects. There has been considerable attention on employing POMs and carbon nanostructures (for example carbon nanotubes, graphene, and mesoporous carbon) in composite materials for diverse purposes including catalysis, transformation, storage of energy, molecular detection, and electrical detection. By combining the reactive nature of POMs with the exceptional electrical properties of carbon nanostructures, highly desirable composite features can be achieved. This review delves into the extensive use of POM/nanocarbon materials for constructing rechargeable lithium-ion batteries, providing an in-depth analysis of the characteristics of POMs and the techniques employed for binding carbon.

Conjugated Nitroxide Radical Polymer with Low Temperature Tolerance Potential for High-Performance Organic Polymer Cathode.

Low-temperature operation poses a significant challenge for current commercial rechargeable lithium-ion batteries (LIBs). Organic polymer electrode materials, exhibiting a nonintercalation redox mechanism, offer a viable solution to mitigate the decline in electrochemical performance at low temperatures in LIBs. Herein, a radical polymer P(DATPAPO-TPA) with a conjugated nitrogen-rich triphenylamine derivative as the backbone and high-density nitroxide pendants has been synthesized. Due to the large interstitial spaces between adjacent structural units and polymer chains, resulting from the significant torsion angle between the benzene rings in the P(DATPAPO-TPA) skeleton, ions could effectively transport. This structural feature demonstrated a notable discharge capacity of 143.3 mA h·g-1 and a high charge-discharge plateau at ∼3.75 V vs Li+/Li, outperforming most reported radical polymer cathode materials. In addition, its capacity retention could reach 83.1% after 2000 cycles at an ultrahigh current density of 50 C, showing excellent rate capability and promising cyclability. Also notable was P(DATPAPO-TPA)'s favorable low-temperature performance that maintains a high discharge capacity of 139.2 mA h·g-1 at 0 °C. The synthesized P(DATPAPO-TPA) is a tangible illustration of a viable design strategy for low-temperature electrode materials, thereby contributing to broadening applications for radical polymer electrode materials.

Low-pressure dendrite-free sulfide solid-state battery with 3D LiSi@Li-Phen-Ether anode

Lithium-metal batteries with solid electrolytes (SEs) have emerged as promising electrochemical energy storage devices due to high energy density and safety. However, inherent challenges of deleterious lithium dendrite growth and poor interfacial stability hinder their practical application. Herein, a new type of room-temperature liquidous Li metal arene complex—Li-Phenanthrene (Phen)-Ether is explored to enable a 3D LiSi@Li-Phen-Ether (3D LSLL) anode with low cost, high safety and high ion/electron-conductivity. Symmetric cells with sulfide SE and 3D LSLL anode deliver an ultra-high critical current density (> 13 mA cm−2) and long cycle life (> 1000 h, 0.25 mA cm−2). Moreover, full battery (LFP/sulfide SE/3D LSLL) can operate at low-external pressure (0.5 MPa) and ambient temperature by introducing a flexible cathode/sulfide interlayer with high ion conductivity (2 mS cm−1). This unprecedented battery configuration demonstrates high-rate (2C) performance and long cycle life (over 300 cycles), which exceeds preciously-reported sulfide SE/lithium batteries at low stack pressures, and may open up a promising route for high-energy-density, cost-effective and safe rechargeable lithium batteries.

MOFite: A High-Density Lithiophilic and Scalable Metal-Organic Framework Anode for Rechargeable Lithium-Ion Battery.

Developing an anode material that has better performance efficiency than commercial graphite while keeping the features of economic scalability and environmental safety is highly desirable yet challenging. MOFs are a promising addition to the ongoing efforts, however, the relatively poor performance, chemical instability, and large-scale economic production of efficiency-proven pristine MOFs restrict their utility in real-life energy storage applications. Furthermore, hierarchical porosity for lucid mass diffusion, high-density lithiophilic sites are some of the structural parameters for improving the electrode performance. Herein, we have demonstrated the potential of economically scalable salicylaldehydate 3D-conjugated-MOF (Fe-Tp) as a high-performance anode in Li-ion batteries: the anode-specific capacity achieved up to 1447 mA h g-1 at 0.1 A g-1 and 89% of cyclic stability after 500 cycles at 1.0 A g-1.for pristine MOF. More importantly, incorporating 10% Fe-Tp doping in commercial graphite (MOFite) significantly enhanced lithium storage, doubling capacitance after 400 cycles. It signifies the potential practical utility of Fe-Tp as a performance booster for commercial anode material.

Comprehensive recovery of valuable metals from spent LiCoO2 cathode material by a method of NH4HSO4 roasting- (NH₄)₂S leaching

With the retirement of rechargeable lithium-ion batteries (LIBs) entering peak period, the recycling of LiCoO2 has become a hot topic. The spent LiCoO2 batteries are rich in carcinogenic metal Co and high-value metal Li, so they are needed to be recovered in time before causing serious environmental pollution and resource waste. Thus, a clean and efficient process is proposed for the comprehensive recovery of Li, Co, and Mn from the spent LiCoO2 cathode material. It is an integrated pyro-hydrometallurgical process, mainly consisting of sulfation roasting with NH4HSO4 and selective sulfurizing leaching with (NH4)2S solution. Using low melting point ammonium salt as roasting auxiliary, 99.7 %, 99.1 %, and 99.8 % of Li, Co, and Mn in the spent LiCoO2 powder can be converted into sulfate when roasting under 400 ℃ for 75 min. Then 99.5 % of Li in the sulfation roasting product can be selectively leached with an aqueous (NH4)2S solution, which is also a precipitator for Co, Mn, and impurity Al. In addition, 96.4 % of Co and 96.0 % of Mn in the sulfurized precipitate can be separated with impurity elements Al and C via oxidation roasting–water leaching process. Compared to traditional recycling, this method can achieve a higher Li leaching rate at a low roasting temperature, and the recovery of Co and Mn can be realized without adding any acid/base reagents or impurity cations. More importantly, the circulation of NH3/NH4+ and S element in the recycling system has been taken into account, making it an environmental-friendly and economical process. In this study, the sulfation reduction roasting and selective sulfurizing leaching mechanisms were both revealed in details, and the behavior of the valuable elements was also elucidated.

Al–Ta dual-substituted Li7La3Zr2O12 ceramic electrolytes with two-step sintering for Stable All-solid-state Lithium Batteries

Cubic phase Li7La3Zr2O12 (LLZO) is a promising electrolyte material for all-solid-state rechargeable lithium-ion batteries. The homogeneous densification of the garnet solid electrolyte ceramic material is crucial for enhancing its ionic conductivity performance. Herein, an Al/Ta co-doped strategy is employed to stabilize the cubic phase structure of LLZO and is combined with a two-step sintering method to enhance densification, in order to investigate its effect on microstructure, ionic conductivity, and electrochemical properties. During the formation process, amorphous Li2O reacts with doped Al2O3 to create a Li–Al–O liquid phase at the grain boundaries. Combined with two-step sintering to ensure that the desired material transformation is achieved, resulting in a dense microstructure and better mechanical properties. The solid electrolyte Li6.4Al0.1La3Zr1.7Ta0.3O12 under two-step sintering (LLZATO-2) is successfully synthesized, delivering an ionic conductivity up to 7.33 × 10−4 S cm−1 at room temperature and an activation energy of 0.22 eV. This work also highlights the critical role of co-doping combined with two-step sintering in preparing well-performing solid-state electrolytes and all-solid-state lithium-ion batteries.

A gel polymer electrolyte obtained from cellulose acetate/polyvinylidene fluoride composite electrospun membrane for safe lithium metal batteries with high-rate capability

Li metal battery is a promising next-generation power storage devices, but faces the serious safety issues caused by the uncontrolled Li dendrite growth and leakage of the flammable organic electrolyte. Herein, a low-cost CA/PVDF (cellulose acetate/polyvinylidene fluoride) composite membrane is prepared via electrospinning technology for safe lithium metal batteries. This membrane (45 μm) exhibits the high porosity (76.9 %) and excellent thermally stability (>180 °C) preventing the short circuit during abuse. The CA/PVDF-based gel polymer electrolyte (GPE), fabricated with CA/PVDF electrospun membrane swelled by carbonate-based organic liquid electrolyte, delivers the ionic conductivity of 1.82 mS cm−1 and Li + transfer number of 0.506, which achieve uniform Li+ ion electrodeposition and inhibit the formation of lithium dendrites. As the results, the symmetrical cell Li/CA/PVDF-based GPE/Li exhibits the impressive reversible Li stripping/plating behavior over 300 h at 1 mA cm−2 with the capacity of 1 mA h cm−2. Furthermore, the assembled LiFePO4/GPE/Li battery exhibits the capacity of 101.2 mA h g−1 at 5C with the capacity retention of 94.6 % after 400 cycles, which exceeds that of traditional liquid electrolytes. This research provides a low-cost gel polymer electrolyte via the electrospinning technique for rechargeable lithium batteries with good electrochemical performance and high security.