Cathode Paste Research Articles

THE RECOVERY OF COBALT FROM THE CATHODE-RAY PASTE OF USED Li-ION BATTERIES IN THE FORM OF COBALT BLUE

Used Li-ion batteries through recycling allow the recovery of deficient and expensive elements such as cobalt, nickel and lithium. The work presents the possibilities of recovering cobalt from the cathodic paste of worn Li-ion batteries. The method applied for the recovery of cathode paste is the one with ultrasonication in acidic medium. Citric acid was used as a fainting medium. The method is viable and environmentally friendly. The cathode paste obtained by processing in the oven mixed with alumina leads to the obtaining of a blue cobalt pigment.

Dry Extrusion Process for Manufacturing of High-Energy Cathodes for Lithium-Ion Batteries

For a sustainable production of lithium ion batteries, more environmentally friendly, energy saving and faster strategies are required. For cathode production NCM/NCA layered oxides are commonly used as active materials. Nevertheless, application of the very toxic and teratogenic solvent N-methylpyrrolidone (NMP) is still common for the industrial production of these cathodes. Besides the high toxicity, the NMP recovery after coating is very energy-, time- and cost-intensive.As an alternative, to conventional NMP-based cathode production, we developed a dry extrusion process coupled with slot-die coating, to manufacture high-energy cathodes. The extrusion process offers continuous production, alongside a very good scalability to industrial demands and a significant reduction of mixing time. Since the process is NMP-free and the drying step is saved, it overcomes typical shortcomings of the wet coating as crack formation or binder migration occurring during solvent evaporation. In addition, producing high-energy electrodes leads to lower material costs and space savings, since less layers of Al/Cu foil and separator are required on cell level, compared to a battery of the same capacity and lower electrode mass loading.Herein, we present the development of a dry cathode manufacturing process, a suitable recipe for dry processing, consisting of NCM622, PVdF, carbon black and a superplasticizer, as well as the optimization of the formulation in terms of processability and active material content. We also discuss the influence of process parameters such as temperature or rotation speed on the viscosity of the cathode paste. As a proof of concept, we processed powder mixtures, corresponding to our optimized formulation with about 90 % of NCM, in a pilot scale twin-screw extruder. By melt extrusion through a slot die, we create a thin film from the cathode composite that we directly apply on an Al current collector. We show a schematic representation of the process in the attracted graphic. By repositioning of the electrode coil, we also produce double-sided coatings. After calendaring, we characterize the dry processed electrodes electrochemically in half-cells. The electrochemical performance data is comparable to state of the art cathodes and results are promising that even higher active material contents can be reached. Therefore, the solvent free extrusion of cathodes is highly relevant for industrial applications.AcknowledgementThe presented work was financially supported by BMBF within the project Tropex under the reference number 03XP0235C. Figure 1

Life cycle assessment of a lithium-ion battery with a silicon anode for electric vehicles

New lithium-ion battery generations for electric vehicles are constantly being developed. Currently, batteries with silicon and graphite anode enter the market as third-generation batteries, with limited knowledge of their environmental impacts. This life cycle assessment study evaluates the impacts of the entire life cycle of a prototype lithium nickel manganese cobalt oxide (LiNi0.6Mn0.2Co0.2O2) battery with a silicon-rich anode using the ReCiPe 2016 method. This prototype battery is compared to a state-of-the-art graphite-based battery. A sensitivity analysis is carried out, and the uncertainty of the results is quantified using Monte Carlo analysis. The battery emits 265 gCO2eq/kWh delivered over its life cycle (95 % confidence interval = [219;322]). The energy use in the cell manufacturing phase is critical for all environmental impact categories grouped with climate change. The new silicon-based anode does not contribute more than 7 % to the environmental impact categories. The cathode paste production is the main contributor to ozone formation, human non-carcinogenic toxicity, fine particulate matter, terrestrial acidification, mineral resource scarcity and ecotoxicity (terrestrial, freshwater and marine). The results are sensitive to the carbon intensity of the electricity mix used in the manufacturing phase and during charging. Switching to an electricity mix based on renewable energy sources reduces the impact by up to 53 % (for freshwater eutrophication). The impact categories climate change and ozone formation have the lowest coefficient of variation, while water consumption and human carcinogenic toxicity have the highest. Third-generation batteries can be environmentally beneficial, as soon as their cycle life is sufficient: at least 180,000 km.

Studies on Spinel-Layer Composite Cathode for Lithium-Ion Battery

The development of rechargeable lithium-ion batteries with higher energy density is of technological importance for applications. In this context, the use of active spinel cathode LiMn2O4 materials has attracted attention due to its robust stable structure and layer cathode LiMn0.50Ni0.25Co0.25O2 materials known due to high capacity at moderate rates during intercalation of the lithium ions. We report studies on compound of xLiMn2O4 - (1-x) LiMn0.50Ni0.25Co0.25O2 composite cathode, where (x =0.1, 0.2, 0.3 and 0.4) for high energy density and high-capacity retention for hybrid applications. Sol-gel route has been employed for synthesis of the layer and spinel compound for cathode composite and Intimate mixing of two compound materials was achieved by a ball milling for a cathode paste. The key challenges and corresponding strategies for these materials will be discussed, with an emphasis placed on the intrinsic structural properties and energy storage electrochemistry with respect to the redox reactions. The gravimetric energy density of our composite cathode materials will carry out in comparison with the LiMn2O4 and LiMn0.50Ni0.25Co0.25O2 electrodes used in lithium-ion batteries and provide a new alternative material for applications where weight, rather than volume is a critical factor. Preliminary data of electrochemical studies revealed high capacity and cycle retentions of composites.

Optimization of Contact Cathode Composition Based on La0.8Sr0.2MnO3±δ for SOFC Stacks

A stack based on planar solid oxide fuel cells (SOFCs) is an assembly of ceramic plates - membrane-electrode assemblies (MEA) and metal current collectors, which play the role of the distribution of gas mixtures over the electrode area, as well as current collection. In order to organize the high-quality current collection it’s necessary to provide a reliable electrical contact between the MEA’s electrodes and contact surfaces of the current collectors. Electrical contact between MEAs’ anode electrode and the collector is achieved by pressing the contact nickel meshes. Metal-based conductive adhesives are also used to reduce the contact resistance at the anode electrode. Despite this in order to ensure contact between the MEA’s cathode electrode and the collector this approach is not applicable due to the rapid oxidation of contact meshes in air atmosphere at high temperatures. In turn, contact pastes based on conductive ceramics do not have such a drawback and make it possible to ensure reliable contact under the conditions of the SOFC cathode chamber.Materials for the contact adhesive for the SOFC cathode chamber must be chemically and thermomechanically compatible with the materials of the SOFC cathode and bipolar plate along with high electrical conductivity. These requirements are met by materials based on lanthanum strontium manganite oxide (LSM) materials, which are widely used as cathode materials for SOFCs. It should be noted that the contact adhesive must also correspond to the limitations of technological processes of SOFC stack manufacturing. SOFC stacks are sealed with glass in a temperature range of 930-950°C, so it’s necessary to use a material that forms a conductive contact at temperatures not higher than 950°C, which is significantly lower than typical sintering temperatures of LSM-based cathode.The synthesis of single-phase highly dispersed powders with the composition of La0.8Sr0.2MnO3±δ (LSM) and (La0.8Sr0.2)0.97MnO3±δ (LSM-d) was carried out by the glycine-nitrate method. After synthesis some of the obtained materials were ball-milled in ethanol using 5 mm ceramic milling bodies at a speed of 600 rpm for 300 and 600 min. A mixture of polyvinyl butyral, toluene, and butanol was used as the basis for the contact paste.Tests of the electrical conductive properties of contact pastes were carried out in air in temperature range of 600-950°C. Samples were kept for 2 hours before cooling at the maximum temperature. Figure shows the results of resistivity measurements: the dashed lines represent the values obtained when the sample was cooled.The maximum values of the resistivity at a temperature of 850°C were obtained for contact adhesive samples based on non-activated stoichiometric (LSM) and A-deficient (LSM-d) powders. Low electrical conductivity can be associated with weak intergranular contact due to the strong agglomeration of the material after synthesis. Grinding for 300 minutes results in a noticeable reduction in the resistivity of the contact adhesive (LSM-300). Change in resistivity after holding at maximum temperature, as well as the change in the slope of the temperature dependence of the resistivity of the adhesive based on LSM-300 indicates the sintering of the contact adhesive powder into a ceramic compact, which is confirmed by SEM results. In turn, holding at a temperature of 950°C of contact adhesive based on LSM-600 (600 min grinding pre-activated) powder does not lead to its sintering.Grinding of the initially single-phase LSM powder results in the appearance of additional reflections in the XRD-spectrum corresponding to the Sr(OH)2 and MnCO3 phases. An increase in the grinding time leads to an increase in the proportion of impurity phases that prevent the contact adhesive from sintering at temperatures <950°C.Thus, the best results were shown by a contact adhesive based on stoichiometric LSM powder, pre-activated by grinding for 300 minutes. Holding at a temperature of 950°C leads to sintering of LSM-300 powder into ceramics, which makes it possible to form a reliable electrical contact under the conditions of the SOFC cathode chamber.We have proposed a method for the manufacture and deposition of a contact cathode composition based on La0.8Sr0.2MnO3±δ. It is shown that the initial powders obtained by the glycine-nitrate method according to the Pechini modification are preliminary prepared. The optimal grinding parameters have been determined. The sintering modes of the contact paste are selected, which are consistent with those for the sealing glass. An experimental SOFC assembly was made using a contact cathode paste. It is shown that the electrochemical characteristics of individual MEAs correspond to the declared ones and the specific power reaches 0.25W/cm2.This work was carried out with financial support from the Russian Scientific Foundation, grant no. 17-79-30071. Figure 1

Greenhouse Gas Emissions of Stationary Battery Installations in Two Renewable Energy Projects

The goal to decrease greenhouse gas (GHG) emissions is spurring interest in renewable energy systems from time-varying sources (e.g., photovoltaics, wind) and these can require batteries to help load balancing. However, the batteries themselves add additional GHG emissions to the electricity system in all its life cycle phases. This article begins by investigating the GHG emissions for the manufacturing of two stationary lithium-ion batteries, comparing production in Europe, US and China. Next, we analyze how the installation and operation of these batteries change the GHG emissions of the electricity supply in two pilot sites. Life cycle assessment is used for GHG emissions calculation. The regional comparison on GHG emissions of battery manufacturing shows that primary aluminum, cathode paste and battery cell production are the principal components of the GHG emissions of battery manufacturing. Regional variations are linked mainly to high grid electricity demand and regional changes in the electricity mixes, resulting in base values of 77 kg CO2-eq/kWh to 153 kg CO2-eq/kWh battery capacity. The assessment of two pilot sites shows that the implementation of batteries can lead to GHG emission savings of up to 77%, if their operation enables an increase in renewable energy sources in the electricity system.

Researches on the recovery of useful metals from spent Li-Ion batteries

The present and future importance of Li-Ion batteries is immeasurable; this is evidenced by the awarding of the Nobel Prize in chemistry in 2019, to the team of John Goodenough - director, M Stanley Whittingham and Akita Yashino, who developed the technology to make this type of rechargeable battery. Used at the beginning (1990-2000) in applications such as portable electronic equipments (mobile phones, laptops, electric tools, energy storage systems, etc.), these batteries are considered the most suitable battery for powering electric vehicles. Today the number of electric cars in the world has exceeded 4 million units and the future estimates are among the most optimistic. Recycling of Li-Ion batteries is mainly done in China and South Korea, countries that have a large share in their production, but things can change. Intense research for the recovery and reuse of useful metals contained in these batteries is carried out in many research laboratories. The paper presents the current state of the research undertaken for the recovery of the cathodic paste with high content of Cobalt of waste LIBs, by ultrasonography in lactic acid solution. The hydrometallurgical method uses a non-polluting organic (lactic) acid. The working technique, the results obtained and the investigations carried out on the recovered materials are presented (analysis of optical and electron microscopy, EDX, X-ray diffraction). The paper also includes data regarding the optimization of the separation process of the active cathode paste from the aluminium foil using the orthogonal central-compositional programming of the second order.

Environmental Life Cycle Impacts of Automotive Batteries Based on a Literature Review

We compiled 50 publications from the years 2005–2020 about life cycle assessment (LCA) of Li-ion batteries to assess the environmental effects of production, use, and end of life for application in electric vehicles. Investigated LCAs showed for the production of a battery pack per kWh battery capacity a median of 280 kWh/kWh_bc (25%-quantile–75%-quantile: 200–500 kWh/kWh_bc) for the primary energy consumption and a median of 120 kg CO2-eq/kWh_bc (25%-quantile–75%-quantile: 70–175 kg CO2-eq/kWh_bc) for greenhouse gas emissions. We expect results for current batteries to be in the lower range. Over the lifetime of an electric vehicle, these emissions relate to 20 g CO2-eq/km (25%-quantile–75%-quantile: 10–50 g CO2-eq/km). Considering recycling processes, greenhouse gas savings outweigh the negative environmental impacts of recycling and can reduce the life cycle greenhouse gas emissions by a median value of 20 kg CO2-eq/kWh_bc (25%-quantile–75%-quantile: 5–29 kg CO2-eq/kWh_bc). Overall, many LCA results overestimated the environmental impact of cell manufacturing, due to the assessments of relatively small or underutilized production facilities. Material emissions, like from mining and especially processing from metals and the cathode paste, could have been underestimated, due to process-based assumptions and non-regionalized primary data. Second-life applications were often not considered.

Preparation of Resin Added Graphite Sheet As Current Collector of Lead Acid Batteries

Introduction Lead Acid Batteries(LAB) have been widely used for more than 100 years. Conventionally, LAB cannot be recharged after over-discharged, and its performance is greatly declined. We found that the deterioration after deep-discharge is caused by local cell reaction between lead current collector and cathode active material.[1] We also revealed that the decline of the battery performance can be prevented by using gold or graphite material current collector.[2-3] In that case, the LAB can be recharged even after over-discharge. Graphite sheet is practical as current collector, however, it was revealed that raw graphite sheet absorbs sulfuric acid electrolyte, and the properties deteriorates. In this study, to prevent the property degradation, we tried to mix resin materials into raw graphite sheet and investigated the characteristics improvement as a function of type and amount of additive resins. Experimental We used four kinds of resin material(polyethylene(PE), polypropylene(PP), ethylene-propylene copolymer(EPM) and polyvinylidene fluoride(PVDF)) and dispersed it by 5, 10, and 15wt% into expanded graphite. Then we made graphite sheet from expanded graphite mixed with resin by a rolling mill. Next, in the heat treatment process, we carried out preheating at 100°C for 10 minutes, and raised the temperature to various appropriate high temperature for each resin, then hold for 10 minutes.For characterization of resin added graphite sheet, we measured the tensile strength of longitudinal direction and contact angle of pure water. The test piece size was 100×20×0.5mm for tensile strength measurement. We also conducted charge/discharge experiments by using 5%PP or 5%PE added graphite sheet as current collector. The cathode paste was prepared by mixing β-PbO2 powder as active material, acetylene black as conductive additive, and PTFE as binder at the ratio of 80:15:5 in weight. We constructed the cathode by pressing the cathode paste on each current collector. We used 35% H2SO4 as electrolyte and lead plate as the anode. Results and discussion We conducted characterization for PP or PE resin dispersed graphite sheet, because it was found that resin was not dispersed uniformly into graphite even after heat treatment at 200℃ for EPM or PVDF. The tensile strength of raw graphite sheet was 4.8 MPa, and graphite sheet with PP was 7.5, 9.7, and 10.8 MPa for the 5, 10, and 15% additive amount, respectively. The Tensile strength of graphite sheet with PE was 6.2, 4.1, and 4.4 MPa for the 5, 10, and 15% respectively. It was confirmed that addition of PP gives higher tensile strength than raw graphite sheet. Graphite sheets with PE showed the highest value at 5%PE addition, but when 10 or 15% was added, the tensile strength was reduced due to inhomogeneous force concentration.The contact angle of pure water was about 40° for raw graphite sheet, and over 80° for each resin dispersed graphite sheet regardless of kind or amount of resin. This means that dispersion of resin makes water repellency increase for graphite sheet.Figure 1 shows the weight increase of graphite sheet with resin when immersed in 47% sulfuric acid at around 70°C. It is indicated that graphite sheets containing 5%PP and 15%PE showed no mass increase due to sulfuric acid absorption even after 14 d.Figure 2 shows the charge-discharge results of LAB using graphite sheet with 5%PP or 5%PE or raw graphite sheet for reference, as the current collector. It is shown that the charge/discharge cycle was restarted after complete discharge to 0 V and 48 h open circuit rest, for all three cases. This result is very much consistent with our previous study that graphite material current collector prevents degradation of cathode active material by local cell reaction control.[4] In the case of raw graphite sheet, cell voltage was fluctuating. For PP or PE cases, the voltage fluctuation is well suppressed. It is thought that this is due to graphite sheet degradation by absorption of sulfuric acid and addition of PP or PE is effective to prevent the degradation.From these results, especially in the improvement of tensile strength and discharge potential, it is concluded that 5% polypropylene addition to raw graphite sheet is most suitable for use as a cathode current collector of LAB.

Graphene modulated LiMn1.5Ni0.4Cr0.1O4 spinel cathode for lithium ion battery

We report the development of a rechargeable lithium ion battery with homogeneous mixing of 10% of graphene oxide in active LiMn1.5Ni0.4Cr0.1O4 cathode material for enhanced electrochemical performance. The redox behavior of the cell, which is normally too slow for practical applications, is accelerated with highly conductive graphene. Intimate mixing of the two materials is achieved by a slurry maker using an organic solution for a cathode paste. The fabricated electrode is repeatedly charged/discharge at C/10 and C/2 rates without any significant degradation in the electrochemical capacity. The gravimetric energy density of the composite cathode material exceeds that of the LiMn1.5Ni0.4Cr0.1O4 oxide electrode in lithium-ion batteries, and the addition of graphene in active material is likely to prove advantageous in applications where weight, rather than volume, is a critical factor.

Performance of Lead Acid Battery Using Graphite Based Composite As Cathode Current Collector

Introduction Lead acid batteries have been widely used for more than 100 years. They are used for vehicles and backup power supplies. However, when overdischarged, lead acid battery cannot be recharged and its performance is greatly declined. Recently, Iwai et al. had revealed that the cause of not being able to be recharged is the nucleation of α-PbO2 on cathode material, β-PbO2, and that, when gold or platinum is used as the current collector, formation of α-PbO2 is prevented due to local cell reaction, then that lead acid battery can be recharged even after overdischarge [1,2]. In this study, we investigated the possibility of realizing the lead acid battery with high resistance to overdischarge using graphite materials, such as natural expanded graphite sheet as a current collector. We think that graphite materials will be advantageous for cost reduction, weight reduction and improvement of processability for lead acid batteries. Experiment We developed graphite based composite material as a current collector which was prepared by the following procedure, in order to improve water repellency. Resin materials such as polyethylene, polypropylene (PP), ethylene propylene copolymer and fluororesin were dispersed with graphite sheet, preheated in air at 100 degrees for 10 minutes, and then heated at 160 degrees to 200 degrees for 10 minutes. Then, the graphite-based composite material was immersed in sulfuric acid (H2SO4) and the weight variation was measured. Also, the surface electric resistance of the graphite composite material was measured by four-terminal method. We decided to use PP as resin for graphite based composite materials, because graphite based composite material using PP have a low electric resistance and PP is easily dispersed in graphite sheet. Then, we chose PP contents of 5% from the viewpoint of water resistance. We used two-electrode glass cell for charge-discharge experiments. The cathode paste was prepared by mixing purchased β-PbO2 powder as an active material, acetylene black as a conducting additive and PTFE as a binder at the ratio of 80:15:5 in weight. The cathode was fabricated by pressing the paste on a current collector. In this study, we tested three kinds of current collectors, Pb plate, graphite sheet and graphite-based composite material. Each current collectors were used in 35 wt% H2SO4. Lead plate and 35 wt% H2SO4 were employed as anode and electrolyte, respectively. Firstly, we discharged the cell at 9 mAg-1 for 30 min and charged at 180 mAg-1 for 20 min. We repeated this cycle 20 times in order to stabilize the charge-discharge reaction. Secondly, we deeply discharged the cell down to 0 V at 9 mAg-1 and opened the circuit for 48 h. Finally, we once again charged the cell at 180 mAg-1 for 60 min, then we discharged the cell at 9 mAg-1 for 30 min and charged at 180 mAg-1 for 20 min and repeated the cycle to study the cell performance. Results and discussion Figure 1 (A) and (B) show the charge-discharge curves for the lead acid battery using Pb plate and graphite sheet as a current collector, respectively. In the case of Pb plate, the lead acid battery cannot be recharged after the open circuit. On the other hand, in the case of graphite sheet, it can be recharged even after the open circuit. Electrode potential does not come out for carbon, so it is thought that carbon has a role of stopping the local cell reaction. From this reason, it can be explained that the formation of α-PbO2 is prevented on cathode β-PbO2 then that the similar performance was shown when using gold or platinum as a current collector. In figure 2, performance of lead acid battery using graphite based composite as cathode current collector is shown. We discharged the cell at 9 mAg-1 to 0 volt and charged at 180 mAg-1 for 60 min and repeated the cycle between 0 volt and 2 volt. Between 1.9 V and 1.3 V, potential flat area is clearly observed. Just only inserting a thin graphite based composite, lead acid battery repeating charge / discharge cycles between 0 volt and 2 volt so many times without decay was realized. This result may be caused by improvement of water repellency of current collector by impregnate with PP into graphite sheet.

Cradle-to-gate environmental impacts of sulfur-based solid-state lithium batteries for electric vehicle applications

In this study, we investigate the cradle-to-gate environmental impacts of a pre-production sulfur-based solid-state lithium pyrite battery suitable for electric vehicle applications. We apply process-based attributional life cycle assessment methodology, utilizing laboratory data, literature, U.S. patents, and US-EI 2.2 life cycle inventory database to estimate the materials and energy required for the battery and its anticipated manufacturing and assembly processes. We estimate a mass of 440 kg and a specific capacity of 182 Wh kg−1 for a battery with 80 kWh energy capacity and 100 kW power, capable of powering a full-size battery electric vehicle with a 200-mile range. The estimated cumulative energy demand (CED) and global warming potential for a 100-year time horizon (GWP100) are 3300 MJ kWh−1 and 199 kg CO2 eq. kWh−1, respectively. The combination of direct and upstream energy associated with clean dry-room operation accounts for the biggest share of the total CED (75%) and GWP100 (73%), followed by the cathode paste (10% and 6%, respectively). The energy demand and environmental impacts of the clean dry-room and cathode paste present opportunities to improve production processes and reduce costs. CED and GWP100 impacts associated with battery production are lower than well-to-wheel energy consumption and emissions for a vehicle with the same size and range. The pyrite battery delivers higher specific capacity than the current Li-ion battery chemistries while its CED and GWP100 environmental impacts are comparable.

Fully edible biofuel cells.

The first example of a fully edible biofuel cell (BFC), based solely on highly biocompatible food materials without any additional external mediators, is described. The new BFC energy-harvesting approach relies on a variety of edible plant/mushroom extract/vegetable oil/charcoal paste biocatalytic electrodes and represents an attractive route for energy harvesting towards ingestible biomedical devices. The edible BFC anode and cathode paste materials consist of biocatalytic rich mushroom, apple, plum and banana plant tissues, along with dietary activated charcoal and water-immiscible olive oil, corn oil, and sesame oil for creating the paste matrix. The ethanol/O2 BFC relies on a bioanode, based on ethanol oxidation induced by the intrinsic biocatalytic activity of its mushroom component, along with a biocathode based on oxygen-reducing apple extract containing polyphenol-oxidase and phenolic compounds. The integrated natural catalytic system and selective biocatalytic activity of the natural extracts offer successful operation of BFCs without any extra mediators or membrane separating the anode and the cathode. The mushroom/apple/olive oil-based BFC displays a favorable power density of 282 μW cm-2 with an open circuit voltage (OCV) of 0.24 V. The power and OCV signals are linearly proportional to ethanol levels and indicate promise for self-powered alcohol sensing. The food-based BFCs were reproducible and able to maintain a power performance of over 80% of their initial output for four hours. These edible energy-harvesting BFCs hold great promise for the next-generation of ingestible devices and smart self-powered biosensors for monitoring health and the digestive system.

Conductive Cellulose Composites with Low Percolation Threshold for 3D Printed Electronics

We are reporting a 3D printable composite paste having strong thixotropic rheology. The composite has been designed and investigated with highly conductive silver nanowires. The optimized electrical percolation threshold from both simulation and experiment is shown from 0.7 vol. % of silver nanowires which is significantly lower than other composites using conductive nano-materials. Reliable conductivity of 1.19 × 102 S/cm has been achieved from the demonstrated 3D printable composite with 1.9 vol. % loading of silver nanowires. Utilizing the high conductivity of the printable composites, 3D printing of designed battery electrode pastes is demonstrated. Rheology study shows superior printability of the electrode pastes aided by the cellulose’s strong thixotropic rheology. The designed anode, electrolyte, and cathode pastes are sequentially printed to form a three-layered lithium battery for the demonstration of a charging profile. This study opens opportunities of 3D printable conductive materials to create printed electronics with the next generation additive manufacturing process.

A Recovery Process of Active Cathode Paste from Spent Li-Ion Batteries

In this work, the depleted active paste from spent lithium–ion batteries was separated from cathode by means of ultrasonic vibration. First the unit cells were discharged in brine at room temperature, for safety reasons. Then anode, separator, electrolyte and cathode were separated. Spent Li-Ion batteries were introduced into a washing container to separate electrode materials from their support substrate: active paste (lithium cobalt oxide – LiCoO2) from cathode (Al foil) and graphite from anode (Cu foil). The Al foil and Cu foil were also recovered. A cleaning efficiency of 91% was achieved using a solution of 1.5 M acetic acid after a 6 minute time of exposure into an ultrasonic washing container with a frequency and electric power of 50 kHz and 50 W, respectively. The XRD patterns and the morphology of LiCoO2 powder were presented.

High performance screen printable lithium-ion battery cathode ink based on C-LiFePO4

Lithium-ion battery cathodes have been fabricated by screen-printing through the development of C-LiFePO4 inks. It is shown that shear thinning polymer solutions in N-methyl-2-pyrrolidone (NMP) with Newtonian viscosity above 0.4Pas are the best binders for formulating a cathode paste with satisfactory film forming properties. The paste shows an elasticity of the order of 500Pa and, after shear yielding, shows an apparent viscosity of the order of 3Pas for shear rates corresponding to those used during screen-printing. The screen-printed cathode produced with a thickness of 26μm shows a homogeneous distribution of the active material, conductive additive and polymer binder. The total resistance and diffusion coefficient of the cathode are ∼450Ω and 2.5×10−16cm2s−1, respectively.The developed cathodes show an initial discharge capacity of 48.2mAhg−1at 5C and a discharge value of 39.8mAhg−1 after 50 cycles. The capacity retention of 83% represents 23% of the theoretical value (charge and/or discharge process in twenty minutes), demonstrating the good performance of the battery. Thus, the developed C-LiFePO4 based inks allow to fabricate screen-printed cathodes suitable for printed lithium-ion batteries.

Mobilty of Sr in Gadolinia Doped Ceria SOFC Chemical Barrier Layers Prepared Using Spray Pyrolysis, Pulsed Laser Deposition and Magnetron Sputtering Methods

For application of highly active La0.6Sr0.4CoO3- d (LSCO) and Pr0.6Sr0.4CoO3- d (PSCO) cathodes in the systems with yttria stabilized zirconia (YSZ) membrane the ceria based chemical barrier layers have been used to prevent active reaction between Sr containing cathode and YSZ. However, even in thin chemical barrier layer the Sr has some mobility. The aim of this study was to clarify how the microstructure of chemical barrier layer influences the Sr mobility and how the electrochemical parameters of SOFC are related with these properties.Gadolinium doped ceria Ce0.9Gd0.1O2- d (GDC) chemical barrier layers with thickness approximately 0.7 mm were deposited to the YSZ electrolyte using pulsed laser deposition (PLD), magnetron sputtering (MS) and spray pyrolysis (SP) method. One set of chemical barrier layers were studied as prepared (PLD GDC prepared at 600 °C; MS GDC prepared at 300 °C; SP GDC pre-sintered at 950 °C) and other set of samples were sintered for 30 h at 1300 °C before printing and sintering of the cathode paste. PSCO and LSCO cathodes were used to compare the Sr mobility in chemical barrier layer. Both cathodes were sintered at two different temperatures, at 950 °C and at 1100 °C, supported onto differently synthesized and thermally treated GDC layers. Concentration profiles of Zr ion in GDC, Ce in YSZ, Sr in GDC and in YSZ were recorded using TOF-SIMS analysis. XRD, SEM and electrochemical studies were also used to establish formation of new phases, GDC layer thickness and effective electrical parameters of studied systems, respectively. Systematic analysis of TOF-SIMS data demonstrated that thermal treatment has a significant influence on the behavior of chemical barrier layers. If non-sintered GDC chemical barrier layer was used, then at both cathode sintering temperatures (at 950 °C and 1100 °C) mobility of Zr, Sr and Ce ions was detected, less at lower and more pronounced at higher sintering temperatures. Very slight accumulation of Sr onto the interface of YSZ and GDC was detected in the case of SP layer, which is, without correct sintering, most nonhomogeneous. When cathode sintering at 1100 °C was carried out, the mobility of ions increased which led to intensive accumulation of Sr onto the interface between YSZ and GDC layers. In addition, a slight increase of thickness of chemical barrier layer was observed when high cathode sintering temperature was used, most likely caused by the formation of SrZrO2 crystallites in GDC film. This phenomenon was also confirmed with analysis of XRD and HR-SEM data. When GDC barrier layer, deposited on YSZ, was sintered for 30h at 1300 °C, the mobility of Zr ions in GDC and Ce ions in YSZ was caused. When Sr containing cathode was sintered at 1100 °C on top of GDC layer contaminated with Zr ions, an intensive increase of GDC layer thickness occurred caused by the formation of SrZrO2, but no Sr accumulation at interface between GDC and YSZ has been established. When cathode sintering at 950 °C was carried out, a slight Sr mobility in highly sintered GDC layers was observed in the case of LSCO cathode, but not in the case of PSCO if PLD and MS layers were applied. However, in SP layers some Sr mobility was observed in the case of both cathode materials studied. Electrochemical tests have been carried out using LSCO | CGO | YSZ | Ni-YSZ system using impedance spectroscopy method. High frequency resistance Rex, dominantly characteristic for electrolyte and interlayers, depends significantly on synthesis method and sintering temperature of layer (microstructure of layer) and cathode. Results of electrochemical tests confirm the result obtained using TOF-SIMS analysis and show that better homogeneity of layer prevents the mobility and accumulation of Sr onto the interlayer between GDC and YSZ. The growth of SrZrO2 crystallites inside of the GDC layer seems to be less harmful compared with the accumulation of Sr onto the interlayer of GDC and YSZ initiating formation of relatively dense SrZrO2 film.

Studies on LiMn1.5Ni0.4Cr0.1O4 Cathode Spinel Combined with Graphene for Lithium Ion Batteries

The low-cost development of rechargeable lithium ion batteries is of considerable technological importance. In this context, the use of active cathode LiMn1.5Ni0.4Cr0.1O4 material has attracted much attention due to its stable structure while intercalation and de-intercalation of lithium ions. The necessity of such battery material is that the energy density stored electrochemically in the electrodes is quite high. They combine high theoretical energy storage capability with low weight and good mechanical strength. Here we report the development of a rechargeable lithium ion battery with homogeneous mixing of graphene powder (with 10, 15 and 20%) in active cathode materials for high energy applications. The reduced graphene oxide was synthesized using modified Hummers method with high purity concentrated of H2SO4 (50 ml), oriented pyrolytic graphite, KMnO4 (7 g) and H2O2 (30 wt %). The resultant mixture was stirred well and then filtered with the help of a glass filter. The obtained precipitates were dried for 30 h in a vacuum oven at room temperature. Highly conducting reduced graphene powder was obtained using hydrazine treatment. The redox behavior of the cell, which is normally too slow for practical applications, is accelerated with highly conductive powder of the graphene (which itself functions as an active cathode material). Intimate mixing of the two materials is achieved by a slurry maker using an organic solution for a cathode paste. The resulting electrode can be repeatedly charged to near its theoretical limit and discharged. The gravimetric energy density of our composite cathode materials exceeds that of the LiMn1.5Ni0.4Cr0.1O4 oxide electrodes in lithium-ion batteries, a feature that is likely to prove advantageous in applications where weight, rather than volume, is a critical factor. The aforementioned results will be discussed.

Performance Comparison Between Iridium Oxide and Iridium-Ruthenium Oxide As Electro-Catalysts for PEM Electrolyzers

Water electrolysis is a well-established technology and one of the most widely used methods for producing high purity hydrogen. Among the different technologies available for water electrolysis, solid polymer electrolyte membrane (SPE)-based electrolyzers are one of the most promising, given their high efficiencies and suitable current density, even at low temperatures. Besides they present ecological cleanliness, considerably small mass-volume characteristics and a high degree of hydrogen purity [1-3].The rate determining step in SPE water electrolysis is associated with the oxygen evolution reaction (OER), occurring at the anode. The most common electrocatalysts for the OER are noble metal oxides such as IrO2, RuO2, etc, given that exhibit high corrosion resistance and high activity for OER [4].One of the main drawbacks of several IrO2 preparation methods is the presence of chlorine contaminants as residues of chloride-based precursors. Chlorine species poisons the surface of the IrO2 catalyst also causing contamination of the electrolyzer components, such as the polymer electrolyte, leading to loss of catalytic activity.In this work, iridium oxide and iridium-ruthenium oxide were synthesized by a sulphite complex route in order to avoid the above-mentioned problem. Membrane electrode assemblies (MEAs) were prepared with these catalysts and electrochemically tested for the oxygen evolution reaction in an SPE electrolyzer.Iridium sodium sulfite was decomposed with H2O2 to form an amorphous iridium oxide; subsequently calcined at 450 ºC. In the case of iridium-ruthenium oxide, corresponding sulfites were mixed, decomposed and calcined in the same way, as previously described.Physico-chemical characterization included X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). XRD was performed on the dry catalysts powders with a Philips X-Pert diffractometer equipped with a CuKa as radiation source. The diffraction patterns were fitted to Joint Committee on Powder Diffraction Standards (JCPDS). The morphology of the iridium and iridium-ruthenium oxide catalysts were investigated by Transmission Electron Microscopy in a Philips CM12 microscope.For the MEA preparation, a Nafion 115 (Ion Power) membrane was used as the solid polymer electrolyte. The oxygen evolution catalysts based on iridium and iridium-ruthenium oxide were directly deposited onto one side of the Nafion 115 by a spray-coating technique. Inks were composed of aqueous dispersions of catalyst, deionized water, NafionÒ solution (5% Aldrich) and Ethanol (Carlo Erba); the anode catalyst loading was 2.5 mg·cm-2. A Ti mesh was used as backing layer. A commercial 30% Pt/Vulcan XC-72 (E-TEK, PEMEAS, Boston, USA) was used as the catalyst for the H 2 evolution. The cathode electrode was prepared by directly mixing in an ultrasonic bath a suspension of Nafion ionomer in water with the catalyst powder. The obtained cathode paste was spread on carbon cloth backings (GDL ELAT from E-TEK) with a Pt loading of 0.6 mg·cm-2. The ionomer content in both electrodes was 33 wt% in the catalytic layer after drying. MEAs (5 cm2 geometrical area) were directly prepared in the cell housing by tightening at 9 N·m using a dynamometric wrench.Electrochemical characterization included linear voltammetry, impedance spectroscopy and chrono-amperometric measurements. The electrochemical activity of these MEAs was analyzed in a temperature range from 25 °C to 80 °C.The results have demonstrated promising performance and stability of these catalysts for their application in an SPE electrolyzer. Acknowledgement The authors acknowledge the financial support of the EU through the FCH JU ELECTROHYPEM Project. “The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2010-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement Electrohypem n. 300081”.

Planar Double-Sided Anode Supported SOFC—Novel Design

The paper presents the innovative design of a ceramic high temperature solid oxide fuel cell (SOFC) in which the anode consists of two parts: the bottom supportive part with microchannels for fuel distribution and the upper operating part which takes part in the electrochemical reaction in the cell. Both parts of the anode are made of cofired yttrium-stabilized zirconia (Ni/YSZ) foils. Microchannels as well as the manifold for combustion products are engraved mechanically in the isostatic pressed stack of Ni/YSZ foils before their firing. The electrolyte and the cathode are set on the upper functional part of the anode by successive screen printing and firing of the electrolyte paste and the cathode paste. The paper reveals details of the fuel cell processing, test fixture and measurement setup for testing the cells, as well as the results of open circuit voltage and short-circuit current measurements.