Electrodes For Rechargeable Lithium-ion Batteries Research Articles

Advanced electrodes for electrochemical energy storage and conversion devices fabricated by reactive spray deposition technology

While different electrochemical devices require electrodes with different microstructures, thicknesses, and catalyst compositions, the reactive spray deposition technology (RSDT) process has been able to demonstrate flexibility to provide what is needed for each application. From developing porous electrodes with platinum group metal catalysts for fuel cell and electrolysis applications, to the fabrication of dense ceramic thin films for solid oxide fuel cell electrolytes, to the fabrication of novel electrodes for rechargeable lithium-ion batteries, the RSDT can be modified to fabricate these layers in a one-step process. Using a combustion flame, the heat generated from the flame is used to provide the energy for sintering ceramic particles into a dense layer and it can be used to decompose a precursor solution into a catalyst particle that contains the desired stoichiometry. The RSDT process has been shown to be an effective method for the development of electrode thin films.

In Situ Analytical and Spectroscopic Characterizations of the Electrode-Electrolyte Interfacial Chemistry in Lithium-Ion Batteries with Next-Generation Electrodes

Next-generation electrodes for rechargeable lithium-ion batteries (LiBs) promise higher energy and power storage at lower cost. For example, silicon has a theoretical capacity approximately 10 times higher compared to current state-of-the-art anodes based on graphite, 3580 mAhg-1 vs 372 mAhg-1, respectively.1 On the other side of the cell, it has been shown that increasing the Ni content in cathodes based on lithium nickel manganese cobalt oxide (LiNi1-x-yMnxCoyO2 or NMC) increases their specific capacity up to 280 mAhg-1.2, 3. Unfortunately, the improvements in energy storage provided by these next-gen materials is currently offset by their rapid degradation due to the undesirable (electro)chemical reactions, taking place at electrode surface in contact with a reactive liquid organic electrolyte, which form the unstable electrode-electrolyte interphase (EEI).2, 4-8 Understanding the complex reactions taking place in each phase, as well as the compositional, morphological, and structural formation and evolution of the EEI is essential to the development of mitigation strategies enabling longer battery life. Over the decades of battery R&D, many spectroscopic and analytical techniques have been developed to characterize the properties of battery components and understand cell capacity fade, but most often, these techniques are applied ex situ to a component of the battery that has been harvested from a disassembled cell after testing.9, 10 While informative, ex situ measurements cannot elucidate changes happening to the cell during testing, thus potentially failing to provide critical information about correlated processes underpinning the cell performance.Here we present a summary of our recently-developed in situ Raman and FTIR spectroscopic techniques and in situ gas chromatography-mass spectrometry-flame-ionization detection (GC-MS-FID) analytical methods applied to custom battery cells under test11-13. By monitoring the EEI “in real-time” during cell charging and discharging cycles, we gain a better understanding of the critical mechanisms occurring near the electrode surfaces. For example, with our in situ FTIR spectroscopic methods, we have investigated the voltage dependent electrolyte solution structure changes at the interface, electrode changes correlated to redox chemistry, and the electrode/electrolyte interfacial layer evolution in LiBs employing high-Ni cathodes. In an electrochemical cell, gas evolution from electrolyte degradation is controlled by many factors, including the electrolyte’s physical and (electro)chemical properties, electrode compositions, and the applied stress to the cell (voltage, current, temperature, etc.), and we have used GC-MS-FID to elucidate mechanistic relationships between gas evolution/interface formation in novel Si-anode LiBs. Our various in situ cell designs provide both sensitive detection and reliable electrochemical device testing. Ultimately, we aim to develop in-situ gas analysis tools to be coupled with in situ spectroscopic techniques enabling a holistic understanding of the battery.

A Green Route for Preparation of Nickel-Vanadate-Nanoparticles as Negative Electrode for Rechargeable Lithium-Ion Batteries

A low-cost for large-scale production, it is still a big challenge for high capacity and good cycling ability of anode materials. Herein, we approve a facile green route to synthesize nickel-vanadate (Na3V2O8) nanoparticles (NPs) using an inexpensive universal solvent, water. An intermediate precipitate of Ni-V-ZIF (Zeolitic Imidazolate Framework) was obtained, which transformed into phase pure Ni3V2O8 NPs by slow annealing process in air, without affecting the original morphology. As an anode material for Li-ion batteries (LIBs), the Ni3V2O8 NPs with uniform spherical shapes can provide an extraordinary retained capacity of 1024 mA h g-1 after 525 cycles, at the current densities of 2 and 0.5 A g-1, which were alternated for every 100 cycles. Additionally, the electrode showed stable specific capacities of 940 and 305 mA h g-1 at 1 and 5 A g-1, respectively after 400 and 1000 cycles. Thus, the fine Ni3V2O8 NPs-based anode can withstand high current densities, indicating that this facile green route revealed an economically applicable and efficient preparation for the large-scale production of nanostructured-electrode materials for high energy density rechargeable batteries.

Structure evolution of azo-fused conjugated microporous polymers for high performance lithium-ion batteries anodes

Redox polymers as electrodes for rechargeable batteries have gained much attention because of their tunable chemical structures and designable electrochemical performance. Herein, a class of azo-fused conjugated microporous polymers with distinct electronic structures is reported as anode materials of rechargeable lithium-ion batteries. The structure-performance correlation revealed by the comparative study in this work demonstrates that the lowest unoccupied molecular orbital energy level and the band gap play significant roles in enhancing the capability of Li ions storage for the azo-fused conjugated microporous polymer electrodes. The polymer of AzoBT comprising azo and benzothiadiazole units delivers a high reversible capacity up to 1543 mAh g−1 at 50 mA g−1, outstanding rate capability (366 mAh g−1 at 3 A g−1) and stable cycling performance of 1000 cycles at 2 A g−1, demonstrating that the newly developed azo-fused conjugated microporous polymers are potential candidate anodes for energy storage. The result underlines the key role of electronic structures in the structure design of high-performance organic electrodes for rechargeable lithium-ion batteries.

A stable 2D nano-columnar sandwich layered phthalocyanine negative electrode for lithium-ion batteries

A porous material composed of nano-columnar Tetra-β-(4-nitro) yttrium phthalocyanine (TNY-Pc) with a sandwich-type layered structure is synthesized and characterized as a negative electrode for rechargeable lithium-ion batteries. The X-ray diffraction and transmission electron microscopy measurement confirmed that the sandwich layer structure has a stable interlayer spacing of 3.07 Å. The TNY-Pc negative electrode is stable during charge/discharge, and the lithium cell with the TNY-Pc negative electrode exhibits a high reversible capacity of 730 mAh g−1 with a high initial coulombic efficiency of 96%; the capacity remains 610 mAh g−1 after 1150 cycles. The cell shows a good rate performance with a capacity of 370 mAh g−1 at 3 A g−1. The XRD, TEM and XPS analysis results suggest that N=O double bond on a substituted nitro group of phthalocyanine ring and C=C double bond on phthalocyanine conjugate structure are the two major contributors to the large capacity of lithium intercalation.

Insights into Li+, Na+, and K+ Intercalation in Lepidocrocite-Type Layered TiO2 Structures

A lamellar lepidocrocite-type titanate structure with ∼25% Ti4+ vacancies was recently synthesized, and it showed potential for use as an electrode in rechargeable lithium-ion batteries. In addition to lithium, we explore this material’s ability to accommodate other monovalent ions with greater natural abundance (e.g., sodium and potassium) in order to develop lower-cost alternatives to lithium-ion batteries constructed from more widely available elements. Galvanostatic discharge/charge curves for the lepidocrocite material indicate that increasing the ionic radius of the monovalent ion results in a deteriorating performance of the electrode. Using first-principles electronic structure calculations, we identify the relaxed geometries of the structure while varying the placement of the ion in the structure. We then use these geometries to compute the energy of formations. Additionally, we determine that all ions are favorable in the structure, but interlayer positions are preferred compared to vacancy posi...

Enhancement of electrochemical performance of tin-based anode in lithium ion batteries by polyimide containing amino benzoquinone

To study the effect of different polymer binders on the electrochemical performance of tin electrodes for rechargeable lithium-ion batteries, poly(vinylidene fluoride) (PVDF), conventional polyimide (PI-OB), and synthesized polyimide containing amino benzoquinone (PI-AQOB) were used as the polymer binders for electrodes consisting of commercial powdered Sn particles and Super P. PI-AQOB was converted from polyamic acid (PA-AQOB) synthesized from 2,5-bis(4,4’-oxydianiline)-1,4-benzoquinone (AQODA) and 4,4’-biphthalic dianhydride (BPDA) by condensation polymerization and characterized by Fourier-transform infrared analysis. Compared to the electrode employing the traditional PVDF binder, those with the PI-AQOB binder exhibited significantly enhanced electrochemical performance in terms of rate capability, specific capacity, and cycling behavior. PI-AQOB provided a high initial lithiation capacity of 1529 mAh/g at a current density of 50mA/g. After 50 cycles, the PI-AQOB electrode maintained a higher specific capacity of 332 mAh/g than the Sn/PVDF electrode (only 65 mAh/g at a current density of 200mA/g). Furthermore, the Sn/PI-AQOB electrode exhibited good volume restoration compared to the electrodes with Sn/PVDF and Sn/PI, as indicated by scanning electron microscopic analysis. The PI-AQOB binder increased the mechanical and adhesive strength of the electrode by suppressing pulverization of the Sn anode during expansion/contraction of Sn particles in the lithiation/delithiation process.

High-voltage materials for positive electrodes of lithium ion batteries (review)

The main publications of recent years devoted to functional materials for positive electrodes of rechargeable lithium-ion batteries destined to work at the potential more positive than that of conventional lithiated oxides of cobalt and manganese are considered. The problem of electrolytes stable at these potentials is discussed briefly.

Study of Lithium Migration Pathways in the Organic Electrode Materials of Li-Battery by Dispersion-Corrected Density Functional Theory

Organic materials have been considered a promising alternative as electrodes for rechargeable lithium-ion batteries. However, there are some obvious shortcomings, especially poor dynamics performance. Approaches to understand the reason for the poor dynamic performance are the main point of the present work. In this paper, an organic electrode material,C12H4N4, is selected as a sample, and studied by dispersion-corrected density functional theory (DFT-D2). The calculation results show that the band gaps of delithiated and lithiated states are about 0.9 and 1.0 eV, respectively, which is consistent with the conventional conjugated organic materials implying the good electronic conductivity. The Li-ion migration pathway forms a complicated three-dimensional (3D) network. The migration energy barrier is higher than 0.53 eV, which is obviously higher than that of the inorganic electrode material, demonstrating the poor ionic conductivity. In organic materials, although the steric hindrance is lowered due to t...

Pyro-Synthesis of Nanostructured Spinel ZnMn2O4/C As Negative Electrode for Rechargeable Lithium-Ion Batteries

Commercially available lithium-ion batteries comprised of LiCoO2 as the cathode and graphite as the anode. Graphite is being considered for use as the anode material for lithium-ion batteries for several reasons, such as the fact that the Li+ ions can easily intercalate/de-intercalate into/from the graphite structure, low irreversible capacity at the first cycle, a flat and low potential profile, a long cycle life, abundant and relatively low cost. However, in spite of its advantages, graphite has several drawbacks, such as its low energy density, low theoretical capacity (372 mAh g-1), easy exfoliation and safety issues related to lithium deposition. These drawbacks limit its application to electric vehicles, hybrid electric vehicles and plug-in hybrid electric vehicles. Therefore, searching for new electrode materials which can act as an alternative to graphite with a high specific capacity and excellent electrical conductivity is an urgent task in building the next-generation high-power lithium-ion batteries, in order to fulfill the ever-growing demand in various consumer electronic devices. Recently, ZnMn2O4 has been considered as one of the most attractive compounds, because of the low oxidation (delithiation) potential of zinc and manganese nanoparticles: 1.2 V and 1.5 V, respectively, which ultimately increase the battery output voltage compared to that provided by simple binary metal oxides. Furthermore, zinc and manganese are abundant, environmentally friendly, and relatively inexpensive compared to nickel and cobalt. Interestingly, ZnMn2O4 can store Li+ions through both conversion and alloying reactions, because Zn, one of the products of the conversion reaction. However, as in the case of other anodes, the poor electric conductivity and large volume change of the ZnMn2O4 nanostructures during the electrochemical reaction lead to a fast capacity decrease. However, a few attempts have been made to overcome the aforementioned drawbacks of ZnMn2O4 by focusing on controlling the morphology accompanied with synthesis of nano-sized particles and graphene based nanocomposites using expensive and tedious methods. Nanostructured materials have become a subject of great interest in a variety of mechanical, electrical and optical applications, due to their unique physico-chemical properties. Therefore we are synthesized ZnMn2O4/C nanoparticles by one step polyol assisted pyro-synthesis for use as the anode in rechargeable lithium ion batteries without any post heat treatment. The as-prepared ZnMn2O4/C is tetragonal with a spherical particle size in the range of 10–30 nm. Electrochemical measurements were performed using the as-prepared powders as the active material for a lithium-ion cell. The nanoparticle electrode delivered an initial charge capacity of 666.1 mAh g1 and exhibited a capacity retention of 81% (539.4 mAh g-1) after 50 cycles. The capacity enhancement in the as-prepared ZnMn2O4/C may be explained on the basis of the polyol medium that enables to develop a sufficient carbon network that can act as electrical conduits during electrochemical reactions. The carbon network appears to enhance the particle-connectivity and hence improve the electronic conductivities.

A review on porous negative electrodes for high performance lithium-ion batteries

Today’s lithium(Li)-ion batteries (LIBs) have been widely adopted as the power of choice for small electronic devices through to large power systems such as hybrid electric vehicles (HEVs) or electric vehicles (EVs). However, it falls short of meeting the demands of new markets in the area of EVS or HEVs due to insufficient energy density, poor rate capability, and low cyclic life. Introduction of porous electrode materials represents one of the most attractive strategies to dramatically enhance battery performance such as capacity, rate capability, cycling life, and safety. In this paper, the applications of porous negative electrodes for rechargeable lithium-ion batteries and properties of porous structure have been reviewed. Porous carbon with other anode materials and metal oxide’s reaction mechanisms also have been elaborated. The purpose of this review is to give a broad overview of the recent scientific researches and developments of porous negative electrodes and indicate future trends in anode development of porous materials as a replacement for graphite in LIBs.

Pyro-Synthesis of Nanostructured Spinel ZnMn2O4/C as Negative Electrode for Rechargeable Lithium-Ion Batteries

ZnMn2O4/C nanoparticles are synthesized by one step polyol assisted pyro-synthesis for use as the anode in rechargeable lithium ion batteries without any post heat treatment. The as-prepared ZnMn2O4/C is tetragonal with a spherical particle size in the range of 10–30nm. Electrochemical measurements were performed using the as-prepared powders as the active material for a lithium-ion cell. The nanoparticle electrode delivered an initial charge capacity of 666.1mAhg−1 and exhibited a capacity retention of ∼81% (539.4mAhg−1) after 50 cycles. The capacity enhancement in the as-prepared ZnMn2O4/C may be explained on the basis of the polyol medium that enables to develop a sufficient carbon network that can act as electrical conduits during electrochemical reactions. The carbon network appears to enhance the particle-connectivity and hence improve the electronic conductivities.

Effect of binder and composition ratio on electrochemical performance of silicon/graphite composite battery electrode

A comparative study was conducted to examine the effect of two different polymer binders and composition ratio of active material on electrochemical performance of silicon-graphite (Si-Gr) composite electrode in rechargeable lithium-ion batteries (LIBs). Polyacrylic acid (PAA) and polyvinylidene fluoride (PVDF) were utilized as binders for composite electrode that was fabricated using Si powder, graphite and super P black (SPB) by varying composition ratios of active material. The electrochemical performance was investigated by galvanostatic charge/discharge tests at room temperature. The results revealed that composite electrode fabricated with PAA binder using maximum contents of Si powder (20wt%) showed high specific capacity around 1000mAhg−1 with excellent capacity retention. The enhanced electrochemical performance can be attributed to high mechanical strength and adhesive capability provided by PAA binder to composite electrode.

Reason analysis for Graphite-Si/SiOx/C composite anode cycle fading and cycle improvement with PI binder

Designed Graphite-Si/SiOx/C composite electrodes for rechargeable lithium-ion batteries are prepared with different binder of carboxymethyl cellulose-styrene butadiene rubber (CMC-SBR) and polyimide (PI). Electrode performance of composites highly depends on the selection of binder. The Si-based/graphite composite electrode containing PI binder shows very stable cycle stability with the retention higher than 95 % after 30 cycles; however, the capacity of composite electrode with CMC-SBR binder fades to less than 80 % after 20 cycles. The improvement mechanism of PI binder is characterized by SEM, EDS mapping, adhesive strength test, and electric performance test. The surface of anode film does not show crack after several cycles, and the SEI on the surface of Si/SiOx/C particle is characterized. It is found that anode film peeing off strength matches well with the composite cycle stability. This result is further supported with cell disassembly result. We believe that improvement of anode film adhesion strength is an effective way to get stable long cycle life.

Tortuosity of Binder-Free and Carbon-Free High Energy Density LiCoO2 Electrodes for Rechargeable Lithium-Ion Batteries

Conventional electrodes, by volume, contain a large amount of electrochemically inactive material such as binder and carbon. This lowers the overall capacity of a battery and makes it difficult to realize high volumetric energy. Researchers have been actively pursuing methods which will enable the fabrication and full utilization of thick electrodes (≥200µm) with a minimal amount of inactive material. One approach which has emerged is to fabricate thick sintered electrode structures which are free of binder and carbon. However, these structures do not adhere to conventional assumptions about tortuosity. This paper aims to correlate John Newman’s macrohomogeneous porous electrode model to thick high energy density, carbon-free and binder-free sintered electrode samples fabricated at PARC. We examine how assumptions about tortuosity affect model predictions of capacity. Our efforts focus on understanding the model parameters which can be used in Newman’s existing model without modification to the underlying equations.

Nanosized Ge@CNF, Ge@C@CNF and Ge@CNF@C composites via chemical vapour deposition method for use in advanced lithium-ion batteries

Three distinct Ge nanoparticle-filled carbon nanofiber (CNF) composites, Ge@CNF, Ge@C@CNF and Ge@CNF@C, were fabricated by chemical vapor deposition (CVD) and electrospinning techniques. These different structures were prepared by: 1) dispersing Ge nanoparticles into CNF, 2) adding carbon-coated Ge nanoparticles (Ge@C) prepared by CVD into CNF, and 3) depositing CVD carbon onto Ge@CNF, respectively. Compared with the Ge@CNF composite, both Ge@C@CNF and Ge@CNF@C had additional amorphous carbon coating fabricated by the CVD method. The three composites were studied as binder-free electrodes for rechargeable lithium-ion batteries. Raw Ge anode materials suffered from serious volume changes and nanoparticle aggregations during cycling, resulting in pulverization and capacity loss. However, carbon nanofiber and the supplemental CVD carbon layer in these nanofiber composites could help preserve the structural integrity of the alloy anode materials during repeated cycling, and consequently, lead to improved cycling stability. In this work, it was found that among the three composites, Ge@CNF@C exhibited the highest capacity retention of 89% at the 50th cycle due to the structurally-durable thorn-like Ge morphology and the additional CVD carbon confinement. Ge@CNF and Ge@C@CNF encountered rapid capacity loss because large Ge clusters were formed and jeopardized the integrity of the electrode structure during cycling.

Templated spinel Li4Ti5O12 Li-ion battery electrodes combining high rates with high energy density

High power and high energy density electrodes for rechargeable lithium-ion batteries are required for electrical mobility applications. Though nano-structuring of electrode materials generally improves the kinetics of the charge transport, thereby increasing the power density, the drawback is the low density of these electrodes compromising the energy density. Combining high power density with high energy density requires dense electrodes with optimal ionic and electronic wiring throughout the electrode microstructure. Here we present a facile and low cost templating method using carbonate salts creating 3D interconnected ionic pathways that improve the ionic charge transport without compromising the electrode density significantly. The method was demonstrated for C/Li4Ti5O12 electrode material resulting in excellent capacity retention reaching ~90% at 5C and ~50% at 200 C rate combined with high active material electrode densities around 1.45 gm/cm3.

Lithium storage in amorphous TiNi hydride: Electrode for rechargeable lithium-ion batteries

In this study, amorphous TiNi phase was successfully prepared using mechanically milling for a very short time of 8 h. HRTEM confirms the formation of amorphous phase with the presence of nanocrystalline Fe particles. After hydrogenation (30 bars of H2 for a duration of 2 h), the electrochemical reaction shows that TiNi hydride/Li cell discharges at a current of one Li for 10 h between 3 V and 0.005 V. The discharge of TiNiH electrode around x = 1 Li corresponds to a capacity of 251 mAh g−1 and a hydride composition of TiNiH1.0 at an average voltage of 0.4 V. Ex-situ X-ray diffraction pattern collected at the end of the discharge shows a mixture of amorphous TiNi compound and LiH. A general mechanism for the electrochemical reaction is then proposed: α-TiNiH + Li+ + e− → α-TiNi + LiH. The results from DFT calculations yield an average cell voltage of 0.396 V, which is in good agreement with the experimental pseudo-plateau occurring at 0.4 V.

Order-aligned Mn3O4 nanostructures as super high-rate electrodes for rechargeable lithium-ion batteries

We demonstrate the synthesis of order-aligned Mn3O4 nanostructures by electrochemically depositing Mn3O4 on a pre-fabricated Cu nanowire array current collector. When used as an electrode for lithium-ion batteries, it exhibits a capacity up to 637 and 494 mA h g−1 after 100 cycles at a current rate of 10 C and 20 C (10 C = 9.4 A g−1), respectively. The excellent cycling performance and superior rate capability can be attributed to the good electrical contact, fast electron transport and good strain accommodation of the order-aligned nanostructured electrodes. The relationship between the thickness of the Mn3O4 film and its electrochemical performance has also been investigated.

Energy storage in composites of a redox couple host and a lithium ion host

The quest for new positive electrodes for rechargeable lithium-ion batteries has been escalating in recent years. Until now, candidates of positive electrode were limited to crystals that contain both redox-active element (usually transition-metal) and lithium ion in the open framework with few exceptions. Here, we demonstrate lithium-free compounds, a material with little activity by itself, can be activated electrochemically by addition of LiF after the first charging. This general strategy is exemplified in various lithium-free iron compounds. Reversible lithium ion extraction and reinsertion take place for Fe2+F2, Fe2+SO4, and Fe22+P2O7, when blended with LiF in nanoscale, in which a simultaneous valence change of Fe2+/3+ occurs above 3V. FeF2–LiF could deliver 190mAhg−1 (∼3.53V) at 50mAg−1 which is even higher energy density than that crystalline LiFePO4 can offer. Various combinations of blending are possible using this approach, which can bring a new branch of material group for positive electrodes in lithium-ion batteries.