Electrodes For Lithium-ion Batteries Research Articles

Insights Into the Role of Porosity in Lithium-Ion Battery Electrode Performance Using the TESCAN Unitom HR Micro-CT

Abstract Use of lithium-ion batteries is extensive with many applications. One of the most common analyses performed in quality control for battery production is the characterization of porosity after calendaring. In this study we report the use of micro-CT to evaluate porosity at the micron scale to enable geometrical quantification of the copper anode current collector. Micro-CT resolution permitted analysis of particle disintegration and delamination from the current collector, which provided a starting point for porosity characterization. Segmentation analysis revealed an average porosity below 30% with a wide range of pore sizes from 1.2 µm to 9.6 µm. This information is critical for the optimization of electrical resistance and may improve the economy of production by reducing the time for battery cell soaking with electrolyte.

Anisotropic, free-standing anodic films with aligned anatase-bronze TiO2-integrated graphene for high-capacity lithium-ion batteries

The composition modification and structure manipulation of carbon-based battery electrodes is becoming an increasingly urgent need for safer, more reliable, and effective electric vehicles. Herein, we fabricate a free-standing hybrid anatase-bronze TiO2-grafted reduced graphene oxide (TiO2-rGO) through a one-pot solvothermal procedure. The TiO2-rGO composite was transformed into a film with an anisotropic alignment and assembled as an anode into lithium-ion batteries (LIBs) to enhance its performance. Our previously developed “Pulse Freezing” process, with modifications including: (1) dimensional and structural optimization for larger and faster film production and (2) optimal microfluidic condition for vertical porous alignment, is utilized for assembling this nanocomposite anodic film. During the microfluidic assembly process, we achieved the desirable flowrate, flow patterns, and alignments of the integrated TiO2-rGO layers while forming porous microstructures through freeze drying. The porous and aligned TiO2-integrated rGO film exhibits a significantly enhanced specific capacity of 400 mAh/g at 0.2 A/g, which is a drastic increase compared to traditional TiO2 and carbon black electrodes possessing <50 mAh/g capacity, attributed to the anisotropic alignment and porous microstructure of rGO in combination with TiO2 grafting. The developed TiO2-rGO composite film provides a promising application of Ti-based electrodes in LIBs for commercial battery industries.

Controllable Growth of Crystal Facets Enables Superb Cycling Stability of Anode Material for Potassium Ion Batteries

AbstractTo enrich the crystal growth strategies for the booming applications concerning lattice structure, a preferred facet‐growth method is proposed for solvothermal synthesis of target (BiO)2CO3 in the two‐phase system. The dominant crystal phase can be regulated from α‐Fe2O3 to (BiO)2CO3 by properly increasing dosage of Bi feedstock, and the optimized composite is composed of (BiO)2CO3 nanocrystal (≈10 nm) and amorphous iron oxide (defined as “FOB‐50”). Based on experimental characterizations and theoretical calculations, the highly matched lattice between (006)/(0012) facets of α‐Fe2O3 and {010} facet group of (BiO)2CO3 involving orientation of Fe─O─Fe bond and Bi─O─Bi bond is verified to facilitate the interaction between the above facets, resulting in preferred growth of {010} dominated by (040) facet in (BiO)2CO3 and its composites. The structural merits can not only enable the FOB‐50‐based electrodes to achieve a high capacity and unprecedentedly stable cyclic performances for 1500 cycles/a long time‐span of 32 months as anode materials, but also ensure the full‐cell to well inherit the electrochemical features of the cathode in potassium ion batteries (PIBs). This work can provide new insight into lattice regulation for bismuth‐based materials and expand their application as electrodes for high performance PIBs and lithium ion batteries.

The timescale identification and quantification of complicated kinetic processes in lithium-ion batteries based on micro-reference electrodes

The lack of reliable methods for acquiring accurate and stable electrochemical impedance spectroscopy (EIS) data at both the cathode and anode makes overlapping kinetic processes in commercial lithium-ion batteries (LIBs) with enhanced capacity and size indistinguishable. Micro-reference electrodes offer an elegant solution for obtaining accurate and stable EIS data for both the cathode and anode. The proposed selection model ensures that the mean absolute percentage error between the EIS of the combined cathode and anode and the battery remains below 3.5 % under varying temperatures and states of charge (SOCs). Different SOCs, temperatures, and pressures are utilized on the timescale to identify and quantify the kinetic processes of the cathode and anode. The results indicate that under varying temperature conditions, the process of Li+ traversing the solid electrolyte interphase dominates the total impedance of the battery, contributing over 75 %. At −10 °C, polarization resistance from this process exceeds a 2500 % increase compared to 20 °C. Moreover, the variations in the kinetic processes of LIB cathodes and anodes with temperature are revealed on the timescale, with potential reasons for the overlap of kinetic processes provided. This study offers new insights into LIB electrode kinetics and lays a theoretical groundwork for enhancing battery design and performance.

Experimental and Modeling Analysis of Mechanical Response of Composite Electrodes in Lithium Batteries.

The mechanical response is one of the main factors that influence the capacity and number of cycles of lithium batteries, which hinder its wide application. Therefore, it is crucial to perform an in-depth investigation of the electro-chemo-mechanical coupling performance and work mechanism of battery electrodes during the electrochemical reaction process. Usually, graphite is the main active material used in commercially used batteries, while silicon is gaining worldwide attention because of its large energy density. Here, graphite and silicon composite electrodes were prepared to obtain the electro-chemo-mechanical response during electrochemical cycling by an in situ bending deformation measurement. The findings indicate that the composite electrodes could induce a large bending deformation, with an increase in the state of charge (C-rate). And, with an increase in the C-rate, the deformation degree of the silicon composite electrode increases, while that of the graphite composite electrode decreases due to the hardening properties of the graphite particles. In addition, increasing the thickness ratio could induce an increase in the peak stress for both composite electrodes. This work gives a detailed analysis of the mechanical properties of composite electrodes and finds the working mechanism of the C-rate and thickness ratio, which can supply suggestions for the development of high-performance batteries.

Barrel effect of high-rate capability determined by anode for LiNi0.5Co0.2Mn0.3O2/graphite lithium-ion battery

To date, charging time remains a critical issue that impedes the widespread application of lithium-ion batteries (LIBs). A comprehensive understanding of the attenuation mechanism of LIBs at high (dis)charging rates is essential for clarifying application strategies for extreme operating conditions and environments, thereby enhancing battery control, and guiding the design of advanced batteries with superior rate capability. In line with this focus, particular commercial NCM/graphite batteries were explored under various high-rate (dis)charging procedures, alongside the investigation of the impact of constant voltage steps on battery performance. This exploration revealed that capacity degradation occurs in three stages, and the rate of capacity decay is directly proportional to the (dis)charging rate. Furthermore, the in-situ temperature and stress of the battery during cycling, primarily caused by side reactions, were monitored to confirm the thermal effects and stress variations under high-rate conditions. By characterizing the morphology and composition of the electrode surface after post-mortem analysis, the “barrel effect” of high-rate capability determined by the anode electrode for LIBs is proposed. This research aims to establish optimal guidelines for designing batteries with excellent high-rate properties and to provide solutions for improving the safety and reliability of batteries applied in high-rate conditions.

Polymer-Supported Graphene Sheet as a Vertically Conductive Anode of Lithium-Ion Battery.

The increasing demand for electric vehicles necessitates the development of cost-effective, mass-producible, long-lasting, and highly conductive batteries. Making this kind of battery is exceedingly tricky. This study introduces an innovative fabrication technique utilizing a laser-induced graphene (LIG) approach on commercial Kapton film to create hexagonal pores. These pores form vertical conduction paths for electron and ion transportation during lithiation and delithiation, significantly enhancing conductivity. The nongraphitized portion of the Kapton film makes it a binder-less, free-standing electrode, providing mechanical stability. Various analytical techniques, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, and atomic force microscopy (AFM) are utilized to confirm the transformation of a 3D porous graphene sheet from a commercial Kapton film. Cross-sectional SEM images verify the vertical connections. The specific capacity of 581 mAh g-1 is maintained until the end, with 99% coulombic efficiency at 0.1C. This simple manufacturing method paves the pathway for future LIG-based, cost-effective, lightweight, mass-producible, long-lasting, vertically conductive electrodes for lithium-ion batteries.

Multilayer Ti3C2Tx-loaded CoOHF composite structures for high-performance lithium-ion batteries

Research into new composites to enhance the performance of lithium-ion battery electrode materials has become a trendy area of study. Cobalt-based composites are particularly prominent due to their exceptional electrochemical performance and unique physicochemical properties. Additionally, Ti3C2Tx MXenes materials are anticipated to replace graphene and other carbonaceous materials since they possess an open structure and low lithium-ion diffusion barrier. In this work, we employed simple hydrothermal method to combine layered Ti3C2Tx with needle-shaped CoOHF. The resulting nanosheets showed an even dispersion of CoOHF in the surface, leading to a remarkable increase in specific capacity. Furthermore, Ti3C2Tx provided a higher number of lithium-ion active sites and improved the lithium-ion migration rate, while also ensuring the structure and stability of CoOHF. This composite material enables stable cycling for 1000 cycles at high current densities of 2 A g−1 and ultimately shows a large capacity of 802.4 mAh g−1 stably. Additionally, CoOHF/MXene composites display exceptional performance rate and cycling stability. This study highlights new feasible strategies for using multilayer Ti3C2Tx in lithium-ion batteries, along with metal hydroxyfluorides in new, highly efficient lithium-ion battery anode materials.

Toxicological evaluation of copper oxide nanoparticles following their intraperitoneal injection to Wistar rats.

Copper oxide (Cu2O) nanoparticles (CO NPs) are in extensive use during our everyday life as antimicrobial agent, lubricant, in manufacturing electrodes of lithium ion batteries as well as for photo catalytic degradation of organic pollutants. Due to extensive and diverse use Cu2O NPs, they are likely to accumulate in the environment and to affect the live forms. Present investigation was aimed to report the biocompatibility of CO NPs in Wistar rats in sex specific manner. CO NPs, having average diameter of 14.06nm, were synthesized by co-precipitation method and scanning electron microscopy and X ray diffraction were used for their characterization. For 14 consecutive days, Wistar rats (6weeks old) of both sexes were intraperitoneally injected with 10mg/mL saline/Kg body weight of CO NPs, while the control groups intraperitoneally received saline solution for same duration. Behavioral tests (open field and novel object recognition), complete blood count, selected biomarkers of oxidative stress and Copper concentration in brain and liver were determined in all subjects. High mortality rates [male 40% and female 60%] were observed in rats exposed to CO NPs. A sever decrease in body weight was also observed in both male and female rats exposed to CO NPs. Female rats treated with CO NPs spent significantly more time with novel object as compared to control [P=0.05] during second trial of novel object test. CO NPs treated female rats had higher mean corpuscular hemoglobin [P<0.001] levels and Copper concentration in liver [P=0.04] than control. Male rats exposed to CO NPs had significantly higher mean corpuscular volume [P=0.02] and superoxide dismutase [SOD] [P=0.04] in lungs than their control group. All other studied parameters non significantly varied upon comparison between CO NPs treated and untreated rats of both sex. In conclusion, we are reporting that intraperitoneal injections of CO NPs for 14days can disturb complete blood count and biomarkers of oxidative stress in lungs of Wistar rats.

Modeling Rate Dependent Volume Change in Porous Electrodes in Lithium-Ion Batteries

Automotive manufacturers are working to improve individual cell, module, and overall pack design by increasing the performance, range, and durability, while reducing cost. One key piece to consider during the design process is the active material volume change, its linkage to the particle, electrode, and cell level volume changes, and the interplay with structural components in the rechargeable energy storage system. As the time from initial design to manufacture of electric vehicles decreases, design work needs to move to the virtual domain; therefore, a need for coupled electrochemical-mechanical models that take into account the active material volume change and the rate dependence of this volume change need to be considered. In this study, we illustrated the applicability of a coupled electrochemical-mechanical battery model considering multiple representative particles to capture experimentally measured rate dependent reversible volume change at the cell level through the use of an electrochemical-mechanical battery model that couples the particle, electrode, and cell level volume changes. By employing this coupled approach, the importance of considering multiple active material particle sizes representative of the distribution is demonstrated. The non-uniformity in utilization between two different size particles as well as the significant spatial non-uniformity in the radial direction of the larger particles is the primary driver of the rate dependent characteristics of the volume change at the electrode and cell level.

Nanotechnology applied in lithium-ion battery electrode

Abstract Lithium-ion batteries (LIBs) are the device that are widely used to store energy for various applications such as electric vehicles. However, the application of the LIBs still faces limitations such as energy density, durability, charging speed and safety. Nanomaterials, which have at least one dimension under nanoscale, can offer some solutions to these challenges by modifying the properties and performance of the electrode materials. In this research, recent progresses and challenges of using nanomaterials as electrode materials for LIBs are analyzed. The advantages and disadvantages of different types of nanomaterials are being discussed, such as nanoparticles, nanocoating, nanotubes, and nanocomposites, and their effects on the electrochemical behavior of the LIBs. On the other hand, some of the key issues and future directions for the development of nanomaterials-based LIBs are also being highlighted. This research aims to provide a comprehensive overview and perspective on the application of nanomaterials for better performance LIBs.

Diffusion-induced stress amplification in phase-transition materials for electrodes of lithium-ion batteries

This work sheds the light on the stress amplification in active material particles of electrodes caused by the localized lithium concentration inhomogeneity due to phase transitions. This is a significant issue usually neglected in the literature, as generally the ideal Fickian diffusion model is used to describe the lithium diffusion, which particularly fails when dealing with phase change materials, resulting in the underestimation of the stress. In turn, this results in the underestimation of the fracture behavior of the electrode and the battery degradation, ultimately.To overcome these limitations, this work proposes a mechanical-transport model where the lithium transport is modeled according to the non-ideal solution theory with an equivalent diffusion coefficient depending on the potential of the host material vs Li/Li+. The results show that the proposed model correctly describes the concentration distribution within the particle of phase-change materials (graphite is chosen as a case study), in agreement with the existent experimental measurements. The differences with respect to the traditional Fickian diffusion model is substantial as the stress is up to 85% higher with the proposed model and the concentration distribution can capture the inhomogeneity caused by phase transitions.

Optimizing porous medium electrode suspension drying: A numerical simulation

The drying process of porous medium electrodes is crucial for optimizing the performance of lithium-ion batteries. Among various drying methods, convection drying has been proven to be an effective double-sided and contactless technique for these electrodes, enhancing manufacturing quality and efficiency. This study investigates the impact of different drying parameters on the drying process of porous medium electrodes by establishing a coupling model for convective drying. The particle swarm algorithm optimized the drying parameters to minimizing drying time and energy consumption. As a result of this optimization, the optimal drying temperature and Reynolds number were found to be 104.77 °C and 3082.55, respectively. Furthermore, implementing a multi-stage drying process effectively prevents internal binder migration within the porous medium and ensures even distribution of components, thereby enhancing electrode performance. This study examines the effects of different multi-stage drying schemes on the drying time and energy consumption of porous medium electrodes based on the optimal drying parameters. The optimal multi-stage drying scheme, characterized by temperature profiles of 104.77 (0–15 s) − 90 (15–44 s) − 104.77 (&amp;gt;44 s) °C, was proposed to achieve both reduced drying time and low energy consumption. With this scheme, the drying process of porous medium electrodes achieved a suitable drying time of 137.50 s and a low energy consumption of 285 110.09 kJ/m3. The proposed model explores the drying process and provides valuable theoretical guidance for establishing appropriate drying parameters in the actual production of lithium-ion battery electrodes.

Micrometer Scale X-ray CT-Informed Optimization of Heterogeneous Pore Distribution in Double Layered Thick LiNCM 811 Cathode

The pore structure of lithium-ion battery electrodes heavily influences ion transport and thus their deliverable capacity, especially at higher rates. Ideally, a gradient pore distribution favoring higher porosity near the separator side can enable faster ion transport at higher cycling rates. We present here a two-layer heterogenous cathode design using traditional NCM 811 material featuring a three-dimensional design space of this cathode design. An efficient characterization technique that combines fast micrometer-scale X-ray computed tomography and pore network modeling was developed, providing critical information regarding the ion transport pathways inside the cathode. Based on the X-ray CT data and performance characteristics obtained, we created a comprehensive profile of cathode rate performance as a function of their pore distribution with easily identifiable advantaged configurations for different cycling scenarios.

Wettability and plasticizing effect of CO2 on Si/C electrode in lithium-ion batteries

Wettability and plasticizing effect of CO2 on Si/C electrode in lithium-ion batteries

Boosting the intercalation reaction of FeOF-based cathode toward highly reversible lithium storage

FeOF as an intercalation-conversion cathode features a high theoretical capacity toward high energy density lithium-ion batteries (LIBs). However, the inadequate intercalation process and poor reversibility of redox reaction deteriorate its practical capacity and cycling stability. Herein, a S-substitution strategy in FeOF (FeOF-S) is proposed to boost the intercalation reaction and enhance the reaction kinetics, achieving a record-high capacity of 668 mAh g−1 at 0.05 A g−1 and a long cycling stability up to 1500 cycles at 0.5 A g−1. Under this strategy, the Li+ intercalation energy of FeOF-S is remarkably reduced in thermodynamics, promoting the intercalation capacity to 230 mAh g−1 which is 50% higher than that of FeOF. Furthermore, a nearly zero band gap with superior electronic conduction is achieved in FeOF-S, leading to excellent rate capability with much enhanced pseudo-capacitance contribution. This work presents new insights into the regulation of thermodynamics and kinetics toward the boosted electrochemical performance of conversion-type electrodes for high energy density LIBs.

Purification of Spherical Graphite as Anode for Li-Ion Battery: A Comparative Study on the Purifying Approaches.

Graphite is a versatile material used in various fields, particularly in the power source manufacturing industry. Nowadays, graphite holds a unique position in materials for anode electrodes in lithium-ion batteries. With a carbon content of over 99% being a requirement for graphite to serve as an electrode material, the graphite refinement process plays a pivotal role in the research and development of anode materials for lithium-ion batteries. This study used three different processes to purify spherical graphite through wet chemical methods. The spherical graphite after the purification processes was analysed for carbon content by using energy-dispersive X-ray (EDX) spectroscopy and was evaluated for structural and morphological characteristics through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses. The analyses results indicate that the three-step process via H2SO4-NaOH-HCl cleaning can elevate the carbon content from 90% to above 99.9% while still maintaining the graphite structure and spherical morphology, thus enhancing the surface area of the material for anode application. Furthermore, the spherical graphite was studied for electrochemical properties when used as an anode for Li-ion batteries using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements. The results demonstrated that the purification process significantly improves the material's capacity with a specific capacity of 350 mAh/g compared to the 280 mAh/g capacity of the anode made of spherical graphite without purification.

An Efficient FEniCS implementation for coupling lithium-ion battery charge/discharge processes with fatigue phase-field fracture

Accurately predicting the fatigue failure of lithium-ion battery electrode particles during charge–discharge cycles is essential for enhancing their structural reliability and lifespan. The fatigue failure of lithium-ion battery electrode particles during charge–discharge cycles poses a significant challenge in maintaining structural reliability and lifespan. To address this critical issue, this study presents a mathematical formulation for fatigue failure in lithium-ion batteries, utilizing the phase-field approach to fracture modeling. This approach, widely employed for fracture failure analysis, offers a comprehensive framework for capturing the complex interplay between mechanical deformation, chemical lithium concentration, and crack formation. Specifically, an additive decomposition of the strain tensor is employed to account for the swelling and shrinkage effects induced by lithium diffusion. Moreover, open-source code (https://github.com/noiiG) is provided, constituting a convenient platform for future developments, e.g., multi-field coupled problems. The developed chemo-mechanical model undergoes fatigue failure package is written in FEniCS as a popular free open-source computing platform for solving partial differential equations in which simplifies the implementation of parallel FEM simulations. Several numerical simulations with two different case studies corresponding to monotonic charge process and fatigue charge/discharge process are performed to demonstrate the correctness of our algorithmic developments.

Ferrocene-Based Polymer Organic Cathode for Extreme Fast Charging Lithium-Ion Batteries with Ultralong Lifespans.

To meet the growing demand for energy storage, lithium-ion batteries (LIBs) with fast charging capabilities has emerged as a critical technology. The electrode materials affect the rate performance significantly. Organic electrodes with structural flexibility support fast lithium-ion transport and are considered promising candidates for fast-charging LIBs. However, it is a challenge to create organic electrodes that can cycle steadily and reach high energy density in a few minutes. To solve this issue, accelerating the transport of electrons and lithium ions in the electrode is the key. Here, it is demonstrated that a ferrocene-based polymer electrode (Fc-SO3Li) can be used as a fast-charging organic electrode for LIBs. Thanks to its molecular architecture, LIBs with Fc-SO3Li show exceptional cycling stability (99.99% capacity retention after 10 000 cycles) and reach an energy density of 183Wh kg-1 in 72 seconds. Moreover, the composite material through insitu polymerization with Fc-SO3Li and 50 wt % carbon nanotube (denoted as Fc-SO3Li-CNT50) achieved optimized electron and ion transport pathways. After 10000 cycles at a high current density of 50C, it delivered a high energy density of 304Wh kg-1. This study provides valuable insights into designing cathode materials for LIBs that combine high power and ultralong cycle life.

Establishing Li-acetylide (Li2C2) as functional element in solid-electrolyte interphases in lithium-ion batteries

Previously, lithium-acetylide (Li2C2) had been identified as electrolyte degradation product on lithium-metal based electrodes using Raman spectroscopy. This raised the question, if Li2C2 is also be formed on graphitic electrodes in lithium-ion batteries without lithium metal present. In order to shed light on this research question, we performed a series of in situ Raman experiments with graphitic electrodes in half- and full-cell configuration. The recorded cell potential dependent spectra clearly prove the presence of Li2C2 in the lithiated state of the electrodes, but the according peak vanishes when delithiating. This observation indicates a somewhat reversible process involving Li2C2. Several chemical/electrochemical reactions are in question to contribute to this effect. With respect to its properties and potential role in the solid-electrolyte interphase (SEI) DFT calculations of Li2C2-nanoclusters were performed, which revealed an exceptionally low energy band gap, hence a remarkable electric conductivity. In conjunction with a relatively high ionic conductivity, Li2C2 appears to play a key role in the degradation of lithium-ion batteries, which had not yet been revealed nor taken into account in simulations of the interphase.