Cathode Components Research Articles

Facile interfacial adhesion enabled LATP-based solid-state lithium metal battery

As a low-cost fast lithium ionic conductor with high shear modulus and ionic conductivity, Li1.3Al0.3Ti1.7(PO4)3 (LATP) is supposed to be one of the most promising ceramic electrolytes for high-energy solid-state batteries. However, the chemical reaction with lithium metal and the high interfacial impedance with solid electrodes make the ceramic electrolyte difficult to straightly apply to lithium metal batteries. Herein, a facile interfacial adhesion strategy is proposed to solve the addressed issues. The sticky polyethylene oxide (PEO) thin layer is served as interfacial adhesive to link the compact LATP ceramic electrolyte and the solid electrodes in consideration of its acceptable Li+ conducting capability and perfect compatibility with the tailored materials. Meantime, the PEO adhesive instead of PVDF binder is employed to glue the cathode components, enhancing the affinity to the PEO interlayer. As a result, the solid/solid interfacial resistance is decreased by two orders of magnitude. The solid-state Li/LATP/LiFePO4(LFP) cell with PEO adhesion is successfully activated, and exhibits steady cycling performance with high reversible capacity at the current no more than 0.5 C. As proposed interfacial adhesion strategy is simple but efficient to enable solid-state lithium metal batteries.

Correlation between manganese dissolution and dynamic phase stability in spinel-based lithium-ion battery

Historically long accepted to be the singular root cause of capacity fading, transition metal dissolution has been reported to severely degrade the anode. However, its impact on the cathode behavior remains poorly understood. Here we show the correlation between capacity fading and phase/surface stability of an LiMn2O4 cathode. It is revealed that a combination of structural transformation and transition metal dissolution dominates the cathode capacity fading. LiMn2O4 exhibits irreversible phase transitions driven by manganese(III) disproportionation and Jahn-Teller distortion, which in conjunction with particle cracks results in serious manganese dissolution. Meanwhile, fast manganese dissolution in turn triggers irreversible structural evolution, and as such, forms a detrimental cycle constantly consuming active cathode components. Furthermore, lithium-rich LiMn2O4 with lithium/manganese disorder and surface reconstruction could effectively suppress the irreversible phase transition and manganese dissolution. These findings close the loop of understanding capacity fading mechanisms and allow for development of longer life batteries.

The Effect of Sputter Cathode Design on Deposition Parameters

SummaryRecent advances in the classic magnetron sputter cathode design have enabled higher quality thin films and improved deposition rates. New designs that have eliminated traditional sputter target hold down fixtures and the retraction of the dark space shield have greatly increased the available sputter target surface area while reducing the probability of re‐deposition of target material on cathode components that could lead to shorting and contamination. Hermetic sealing strategies have mitigated gas permeation through the sputter cathode and enabled lower operating pressures which substantially reduces process gas inclusions in sputtered films.

(Invited) The Processing Science and Engineering Research Portfolio for Advanced Vehicle Batteries at the U.S. Department of Energy

The widespread adoption of electric vehicles using advanced battery technologies and the development of their manufacturing base in the United States are critically important for the US economy and therefor a major focus of research and development sponsored by DOE’s Office of Energy Efficiency and Renewable Energy. Materials development is often touted as the most important enabling activity, however in a rank of major cost items, manufacturing costs ranks just below the cathode components. In addition to the need to reduce costs, US R&D should also focus on new, yet-to-be-scaled processing technologies that, when developed and implemented in the US provide both a strong component of US energy security and US-based employment in the production of electric vehicle batteries. This presents a major economic opportunity to the USA, as the global electric vehicle market is expected to grow to over $100 billion in the next ten years. Advances in battery processing science and technology could lead directly to the displacement of the established non-US-based manufacturing base via creative destruction--new innovative technologies lead to new manufacturing facilities, facilities that could be built and run in the USA. Processing science and engineering has traditionally been underrepresented in federally funded electrochemical energy storage R&D. Over the last nine years, the Vehicle Technologies Office (VTO) has been building an advanced processing R&D portfolio. This includes competitively funded research at universities, small businesses, and large corporations as well as programs supported across the national laboratory complex. Processing science and technology projects organize into two general activities: scaling-up materials production and developing innovative electrode fabrication approaches. This presentation will provide an overview of the sub-program’s history and several example successes. Future research directions and scenarios for possible funding opportunities will also be discussed.

Study of Corrosion Behaviour of Carbon Steel in Evian Derived Solution from Electrochemical Techniques

Marine structures and buried pipelines are constantly exposed to extreme conditions with elements such as temperature variation, soil ion content and dissolved metals posing a continuous threat on the integrity and lifespan of the structures. Quantification of these elements has been limited to studying only a few of the parameters, with the resulting corrosion behaviour not fully understood. The purpose of this study was to investigate the corrosion behaviour of carbon steel in Evian derived solution using the anodic component attained from modelled polarisation curves. The behaviour of the metal/electrolyte interface was studied using a combination of voltammetry and X-ray diffraction analysis of the mineral layer. The expression for the anodic and cathodic component of the current as a function of potential was attained from log|j| vs. potential plots. Mathematical modelling of the experimental polarisation curves was done using OriginPro Data Analysis & Graphing Software. Voltammetry around open circuit potential (VAOCP) showed the necessity for corrosion protection as the adopted electrochemical system resulted in a progressively corrosive environment. Kinetics and mechanism of the anodic and cathodic process indicated corrosion processes similar to aerated soil conditions.

Surface Stabilization of O3-type Layered Oxide Cathode to Protect the Anode of Sodium Ion Batteries for Superior Lifespan.

SummaryEven though the energy density of O3-type layer-structured metal oxide cathode can fully reach the requirement for large-scale energy storage systems, the cycling lifespan still cannot meet the demand for practical application once it is coupled with a non-sodium-metal anode in full-cell system. Transition metal dissolution into the electrolyte occurs along with continuous phase transformation and accelerates deterioration of the crystal structure, followed by migration and finally deposition on the anode to form a vicious circle. Surface engineering techniques are employed to modify the interface between active materials and the electrolyte by coating them with a thin layer of AlPO4 ion conductor. This stable thin layer can stabilize the surface crystal structure of the cathode material by avoiding element dissolution. Meanwhile, it can protect the anode from increased resistance by suppressing the dissolution-migration-deposition process. This technique is a promising method to improve the lifetime for the future commercialization.

The Development of Redox-Active Helical Polypeptides for Battery Application

This work seeks to develop polypeptide nanocomposites containing redox-active moieties as cathode and anode components to circumvent the drawbacks of conventional lithium ion batteries, e.g., use of scarce resources, high carbon emissions, and high-cost recycling. Polymer frameworks carrying 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) and viologen moieties are recognized as viable materials for next-generation battery cathodes and anodes, respectively, due to their stabilities and redox processes. Anticipating that the secondary structures adopted by polypeptides will provide opportunities to control the placement of radicals in three-dimensional space by tuning the distribution of radicals along polymer backbones, polypeptides containing TEMPO and viologen were designed for utilization in electrodes. This presentation will highlight the synthetic processes, followed by investigation of the physical and electrochemical properties of the materials, and their secondary structures, by utilizing a variety of thermal, spectroscopic, and imaging techniques. It is anticipated that the synthetic development of radical polypeptide nanocomposites will address needs in the advancement of high-performance and sustainable alternative energy sources (e.g., supercapacitors, and biosensors) towards a greener and more sustainable world, which is facing a never-ending demand for energy technologies. Figure 1

A Multi-Physics Study on High-Power Li-O2 Batteries for Electric Aircrafts

Commercialization of lithium-air batteries faces many challenges, such as electrolyte decomposition, short cycle life, low energy and power density, etc. However, commercialization of Li-O2 batteries for aeronautics is much more challenging due to additional safety constraints on cyclability and performance (high specific power and specific energy). For this presentation, we will discuss inter-related aspects of physics-based modeling of a pack: cell and battery model calibration; and parameter estimation using statistical methods. In addition, we will evaluate and present optimal battery designs for high discharge current density, high discharge time, and low battery mass using simulation-based optimization. The Finite Element Model (FEM) used to simulate a Li-O2 cell is based on the work of Bevara [1]. The different aspects of the model are based on: porous electrode theory and concentrated electrolyte theory; quantum tunneling model for the resistance of conformal layer of discharge product (Li2O2) [1]; Butler-Volmer kinetics for electrochemical reaction; Fick’s diffusion for oxygen transport; and an oxygen dissolution model is applied at the air/electrolyte interface [2]. The electrolyte properties such as ion conductivity, ion diffusion, oxygen diffusion, and mass density of the electrolyte were taken from Molecular Dynamics (MD) simulations [3]; while the other model parameters, which includes mass of cell components, were calibrated to match experiments at high discharge current densities. The cell mass includes the anode, cathode, separator, electrolyte, and other components (such as current collector). This calibrated model is used to perform parametric studies on cathode thickness, porosity, tortuosity, carbon particle size, electrolyte transport and material properties, partial pressure of oxygen, discharge time, and discharge current density to study optimal designs for high specific power and energy. Traditionally, pack (several cells are connected in series and/or parallel) simulations are performed using equivalent circuit, analytical expressions, or empirical models. Here, we develop a multi-physics model to include cell level variations in pack by considering factors such as difference in pressure drop, temperature variation, and variation in manufacturing. Using “accurate” cell power and mass estimates from the multi-physics model, optimal pack design solutions will be explored and presented at the meeting. Continuum model parameters are usually taken from experiments, from first principle simulations, or are assumed. They include errors such as model error, which arise from using a simplified model, from neglecting unknown processes or interactions, or from using wrong assumptions. Bayesian inversion techniques [4] will be used to find probability distributions in parameter values such as reaction rate, reaction active area, and Li2O2 resistance and the resulting error in the predicted values of specific power will be presented.

Biomass Based Porous Carbons As Promising Composite Cathodes for Lithium Sulfur Battery

The lithium sulfur battery is the one of the promising alternative rechargeable battery system to replace the conventional lithium ion battery system. It has a high capacity and energy density of 1,675 mA h g−1 and 2,500 Wh kg−1, respectively. The energy density is about five times higher compared to lithium ion batteries. Furthermore, sulfur is cheap, naturally abundant and safe . One of the main constraints is related to the poor electrical conductivity of sulfur which needs addition of high amount of conductive carbon, Another main problem is the high solubility of the intermediate polysulfides in the organic solvent electrolytes during discharge/charge process. Dissolved polysulfide components are moving back and forward between Li Anodes and Sulfur Cathodes, causing a rapid capacity loss and a low coulombic efficiency. The common approach to solve the problem was using the concept of sulfur encapsulation in the porous carbon structure. This strategy is the most popular study for cathodes in lithium sulfur battery in the last few years. It has been shown to solve the problems of low conductivity and dissolution of polysulfides simultaneously. As the results, the electrochemical performance of sulfur cathodes has been improved due the better electronic conductivity and the inhibation of polysulfide dissoltion. In this current works, biomass based porous carbons have been synthesized by using chemical activation of tropical salacca fruit peel with potassium carbonate and used as sulfur cathode component for lithium-sulfur batteries. The motivation was to obtain carbon with specific morphology and structures used for the application in composite sulfur cathodes for lithium sulfur battery. As shown by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption isotherms, the porous carbon material has microporous-mesoporous structures with honeycomb morphology. Composite sulfur cathode has shown a large initial discharge capacity of 802 mAh g−1 at current density of 0.1 C , which remained stable during 50 charge-discharge cycles . This stable and reversible cycleability of this composite cathode has been contributed by a unique combination of micro and mesoporosity, as well assurface functional groups, which could allow the retention of the intermediate polysulfides within the carbon porous structures, without enormous dissolution in the electrolyte.

Understanding the Effect of Interlayer on the Performance of All-Solid-State Li2s Batteries

Li−S batteries are considered a promising technology for next generation batteries, due to their high energy density and low cost of sulfur. The traditional liquid Li−S batteries, however, suffer from severe capacity fading and low Coulombic efficiency owing to processes occurring at the sulfur cathode. The electrochemical conversion reaction between S8 and Li2S involves a phase change where soluble lithium polysulfide intermediates are produced, causing so-called polysulfide shuttle phenomena. In order to mitigate the issues related to polysulfides, various approaches such as physical confinement of polysulfides or fabricating protective layer on Li anode were employed. However, the shuttle reaction still remains, affecting the cycling performance of the battery. One promising approach to proceed the Li−S battery chemistry without producing polysulfide intermediates is to utilize non-solvating electrolyte such as inorganic solid electrolytes (SE). The use of solid electrolyte eliminates the possibility of polysulfide dissolution, improving the energy efficiency of Li−S batteries. In addition, sulfide solid electrolyte such as Li7P­3S­11­ exhibits an ionic conductivity of ~10-3 S cm-1 comparable to that of the conventional 1 M ethereal electrolytes. Despite these advantages, the performance of all-solid-state Li−S battery (ASSLSB) incorporating inorganic solid electrolyte is much worse than Li−S cells with liquid electrolytes in terms of active material utilization and rate capability. The biggest challenge lies in constructing sufficient Li+ ion transport channel within the composite cathode, since SEs do not infiltrate into cathodes as liquid electrolytes. There have been considerable research efforts to improve the ionic conductivity of the cathode, such as ball-milling S8 (or Li2S), conductive carbon, and SE to prepare the composite cathode. However, only limited improvement was achieved on increasing active material utilization by simply ball-milling the three components. This is likely due to the poor physical contact between SE and cathode active material, leaving the active material electrochemically inactive (Figure 1a). In an effort to improve the interfacial contact and increase the capacity, we report a strategy of using an interlayer between the electrode/electrolyte interfaces (Figure 1b). Our solid-state cell with interlayers exhibits much higher capacity compared to that of bare sample without interlayers, achieving ~80% active material utilization at cycle 60 with dramatically reduced impedance relative to the bare cell. The interlayer in ASSLSB infiltrates into void space in composite cathode creating contact between the active material and SE resulting in high active material utilization. This increased contact leads to smaller cell impedance due to the decreased interfacial resistance. Additionally, the interlayer provides buffer space for volume contraction and expansion during electrochemical cycling, thereby preventing the physical delamination of cathode components. Figure 1

Low-Threshold Field Electron Emission from Two-Dimensional Carbon Structures

Particles of multilayer graphene obtained by the method of self-propagating high-temperature synthesis are proposed as an active cathode component for field electron emission. It is shown that this material makes it possible to implement a new technology for creating efficient field emitters with a developed surface. It has been established that the effect of low-threshold field electron emission is observed in this material. In pulsed electric fields, the possibility of obtaining high-current electron beams with currents up to hundreds of amperes has been confirmed.

(Invited) Improvements in High Energy Density Silver-Zinc Button Cells for Wearable Devices

The silver (Ag)-zinc (Zn) system has the highest theoretical specific (Wh/kg) and volumetric energy density (Wh/L) amongst all rechargeable batteries with the added benefit of safety and non-flammability compared to lithium-ion or lithium metal batteries, which makes it a good and ideal candidate for portable applications like hearing-aids. However, historically, the Ag-Zn battery has suffered from poor rechargeability and low energy utilization. At ZPower, we have tailored the chemistry and engineered a new Ag-Zn battery system, which is highly energy dense and rechargeable, thus making it possible to use it portable applications and giving more power to the consumer to allow them to contribute to a greener future. As aforementioned, enhancing the capacity of the active materials is paramount for high energy density, which we achieved by developing proprietary additives and methods. For the cathode, silver oxide (AgO) was used in our system. We developed novel proprietary conductive coatings for AgO, which allowed high capacity utilization and retention for many cycles. We conducted gassing tests, where we found the coatings considerably reduced oxygen generation. The role of these coatings was further studied through charge algorithm cycling, where we found that it reduced AgO cathode’s impedance compared to the control tests and maintained its active surface area. More importantly, we found that the morphology of the proprietary conductive coatings played a crucial role in efficiently utilizing the AgO cathode’s capacity. For the anode, Zn was used, where it has a theoretical specific capacity of 820 mAh/g; however, Zn has a long history of poor rechargeability due to problems like shape change (zinc redistribution), dendrite formation and passivation. In the past, previous researchers tried altering the Zn formulation to increase utilization; however, these attempts were not fruitful. We have engineered a new Zn anode that can access 94% of its theoretical capacity in a single primary discharge and 56% of its theoretical capacity rechargeably for over 300 cycles. We achieved this breakthrough by developing proprietary additives and methods that localize the Zn to the current collector and prevent dendrite formation. We will comment on the anode performance further in the talk. Finally, we will present impedance models and data of the ZPower Ag-Zn system measured with respect to state of charge, storage time and temperature, which is vital from a manufacturing standpoint to understand cell properties and make future cell and electrode improvements. We will comment on our future work of identifying impedance contribution from the cathode and anode components of the battery and using this data as a guideline for improving electrode composition and cell performance.

Theoretical simulation of the optimal relation between active material, binder and conductive additive for lithium-ion battery cathodes

The cathode formulation for lithium-ion batteries has been optimized taking into consideration different active material, polymer binder and conductive additive ratios. Theoretical simulations have been carried out to evaluate the influence of different materials relative contents in the electrode performance, at various discharge rates. Simulations were performed by the finite element method applying the Doyle/Fuller/Newman model for two different active materials (C-LiFePO4 and LiMn2O4) and some results were compared with experimental data. The optimization of the electrode formulation is dependent on the maximum value of n, defined as the ratio polymer binder/conductive additive. The electrical conductivity of the cathode depends on the conductive material, thus it is dependent on the ratio n. The optimum balance of the cathode components is reported considering the performance and the mechanical stability.

Eu2SrCo1.5Fe0.5O7 a new promising Ruddlesden–Popper member as a cathode component for intermediate temperature solid oxide fuel cells

A new oxide of the Ruddlesden–Popper series in the (Eu,Sr)n+1(Co,Fe)nO3n+1 system has been isolated and structurally characterized.

Diffusion Phenomenon of Cathode Components in YSZ Electrolyte and Effect on Mechanical Properties of SOFC

At present, SOFC research mainly focuses on the development of new medium and low temperature cathode materials or the improvement of existing cathodes, as well as the development of new anodes resistant to carbon deposition and sulfur poisoning. However, during the discharge state, the diffusion of metal elements in the electrolyte caused by the constant current is rarely studied. In order to analyze whether there is a diffusion of electrode elements at the electrode-electrolyte interface, and the effect of this diffusion on the mechanical properties of the SOFC. Polarization test of the half-cell of YSZ electrolyte and LSM cathode was carried out at 950°C with the current load of -300 mA·cm-2 in an air atmosphere, and the polarization time was different. The powders were analyzed by XRD. A post-test analysis of the cathode-electrolyte interface was tested by using SEM, EDX and EPMA. Finally, the Vickers hardness was used to measure the mechanical properties of YSZ electrolyte. The results show that the Mn element has diffused into the YSZ electrolyte after constant current. In addition, it has a certain impact on the mechanical properties of the cell.

Enzymatic glucose/oxygen biofuel cells: Use of oxygen-rich cathodes for operation under severe oxygen-deficit conditions

A glucose/oxygen biofuel cell (BFC) that can operate continuously under oxygen-free conditions is described. The oxygen-deficit limitations of metabolite/oxygen enzymatic BFCs have been addressed by using an oxygen-rich cathode binder material, polychlorotrifluoroethylene (PCTFE), which provides an internal oxygen supply for the BFC reduction reaction. This oxygen-rich cathode component mitigates the potential power loss in oxygen-free medium or during external oxygen fluctuations through internal supply of oxygen, while the bioanode employs glucose oxidase-mediated reactions. The internal oxygen supply leads to a prolonged energy-harvesting in oxygen-free solutions, e.g., maintaining over 90% and 70% of its initial power during 10- and 24-h operations, respectively, in the absence of oxygen. The new strategy holds considerable promise for energy-harvesting and self-powered biosensing applications in oxygen-deficient conditions.

Activated porous carbons originated from the Indonesian snake skin fruit peel as cathode components for lithium sulfur battery

Activated porous carbons originating from the Indonesian snake skin fruit peel has been prepared by carbonization process followed by the ZnCl2 activation process. This porous carbon was then applied as cathode component along with sulfur in lithium sulfur (Li–S) batteries. The carbon materials possessed a high surface area of 2247 m2 g−1 and a large pore volume of 1.97 cm3 g−1 with sulfur loading of 63%. From the x-ray diffraction (XRD) patterns, Raman analysis, and SEM observation of the composites, it was shown that the sulfur was uniformly encapsulated inside the carbon pores, which was beneficial for the optimum utilization of sulfur and the confinement of soluble lithium polysulfides. The fabricated carbon-sulfur composite electrodes demonstrated an initial specific capacity of 945 mAh g−1 and good capacity retention until the 100th cycle at 0.1 C rate. At high C rate (1 and 2 C), the composite electrodes exhibited specific discharge capacity of 538 and 466 mAh g−1 until the 100th cycle, respectively. Those excellent electrochemical performances were attributed to the high surface area, combination of micropore/mesopore structures and low average pore diameter of porous carbons.

Cathodic Component of Corrosion Process: Polarization Curve with Two Tafel Portions

A method for the analysis of corrosion process involving two cathodic reactions and one anodic reaction is proposed. By way of example, this method is used to calculate a particular cathodic polarization curve with two Tafel portions. The calculated polarization curve coincides with the experimental curve measured on stainless steel in 0.5 M HCl solution.

Intermediate Temperature Na-ZnCl2 Battery

Sodium-metal halide (Na-MH) batteries have been considered as one of the most attractive energy storage systems for stationary applications. Significant progress has been achieved in the Na-MH technologies during the past a few of decades. However, the batteries are still facing challenges in battery performance and cost. Recently, we have been working on advanced planar type Na-MH batteries with operating temperatures below 200oC. It was found that the low-temperature operation dramatically improved the battery performance (e.g., cycle life). Meanwhile, we have put efforts to replace the major cathode component of Ni in the Na-NiCl2 chemistry with Zn, which potentially can cut down around 46 and 20% of the cell material and overall battery costs. In this study, we further investigated the performance of the Na-ZnCl2 battery at intermediate-temperatures (e.g., 190oC). It was found the Na-ZnCl2 chemistry has significant higher rate capability over the Na-NiCl2 counterpart under similar operating conditions. The mechanisms for the higher rate capability could be related to the improved mass or charge transfer rate in the Na-ZnCl2 cathode. We believe this high-performance, low-cost, and safe Na-ZnCl2 battery will bring it one-step closer for broad market penetration of the Na-MH technologies. Figure 1

Coin-Type Cell Design and Engineering of Its Compartments for Rechargeable Seawater Battery

Seawater battery is a new concept energy storage device that uses seawater as a cathode material, one of the most abundant resources on the earth. It is crucial to design cells and optimize key components for the high performance rechargeable seawater batteries. Seawater batteries, which utilize natural seawater as the active material in an open-structured cathode, require a new platform for building and testing the cells other than existing Li-ion coin-type or pouch-type cells. So, we designed the coin-type seawater battery of a new platform, and we would like to introduce new findings based on our optimized cell. Engineering the cathode components—improving the wettability of cathode current collector and seawater catholyte flow—improves the voltage efficiency. In order to get reliable data from the materials that are the key elements in seawater batteries, a coin-type cell, a flow-cell tester, and their key compartments were designed and fabricated by trial and error and the testing environment was also determined. We examined the wettability of seawater on the carbon felt (CF) cathode current collector and its effect on the charge-discharge cycling performance. The air-heating process of CFs made the surface hydrophilic, resulting in a reduced ΔV of the cell (~1.4 V) at a current rate of 0.025 mA cm-2, compared to the cell using a pristine CF (~1.6 V). We also showed that the flow of the seawater reduced ΔV (~0.7 V) by 36% from ~1.1 V under no flow state. Through these various experiments, we optimized the key factors affecting the seawater battery. Therefore, further experiments on promising materials in seawater batteries can be conducted using the customized coin-type cell, which is an essential prerequisite for the practical implementation of seawater batteries as the next generation Energy storage system (ESS).