Cathode Formulation Research Articles

Life cycle assessment of recycled NiCoMn ternary cathode materials prepared by hydrometallurgical technology for power batteries in China

Power lithium-ion batteries (LIBs) are core components of electric vehicles (EVs), and the cathode material is the key to the performance of LIBs. Nickel-cobalt-manganese oxide (NCM) cathode formulations have emerged as dominant choices in the battery industry. This work presents a life cycle assessment of recycled NCM ternary cathode materials produced from spent batteries in China. The environmental impacts of virgin and recycled material production were compared based on the ReCiPe 2016 method. The results demonstrated that the highest environmental pressure was generated during the leaching and extraction process due to the high consumption of electricity and auxiliary materials, which contributed nearly half to all three endpoint impact categories. Sensitivity analysis revealed that the environmental impacts of the leaching and extraction process could be effectively reduced by optimizing the production process to reduce the consumption of sulfuric acid, electricity, hydrogen peroxide, and sodium hydroxide. The comparative results indicated that the production of recycled NCM materials consumes 74% less energy, and compared to virgin NCM materials, the three endpoint environmental impact categories are reduced by 72%, 59% and 57%. Comparison of the global warming potential (GWP) between different recycling techniques in the literature indicated that the GWP of hydrometallurgical technology is lower. In addition, we estimated the GWP reduction potential per kg under optimized power scenarios. The annual GWP reduction and energy savings benefits of recycling in China from 2021 to 2035 were predicted. Based on the results, it is necessary to maintain high recycling rates through a variety of initiatives. This Chinese case study demonstrated that the adoption of cathode material production by recycling spent power LIBs through cleaner technology is of great practical significance for resource conservation and sustainable development of the EV industry.

Machine-Learning for Li-Ion Battery Capacity Prediction in Manufacturing Process

Battery manufacturing is a highly complicated and multi-stage process with large number of parameters involved in each stage. Understanding the correlation of these factors and their impact on the performance of the cells is crucial and would provide opportunity to improve the quality of cells and reduce the production time and cost. While in traditional battery manufacturing, try and error approach is used to design experiments and reveal the correlations, a smart manufacturing requires advanced and systematic modelling techniques for representing the production line. Motivated by this urgent need, this study focuses on machine-learning models to correlate parameters of the manufacturing chain with the battery performance, i.e., to predict the cell areal capacity given electrode specifications. The study is dedicated to cathode manufacturing process, addresses capacities at various Crates and quantifies the predictability unlike the existing literature.The models here are supervised machine-learning models to classify the range of the cell capacity (mAh/cm2) given the characteristics of the cathode including thickness, and porosity. To prepare the data for training the models a set of experiments were run by altering the control parameters of cathode manufacturing, i.e., comma bar gap, coating ratio and coating line speed advised by an expert. Following the cathode coating process, cathode electrodes were obtained. The experiments led to cathode electrodes with various thickness and porosities all measured via high precision equipment. The cut electrodes were then used to build half coin-cells with lithium metal as the opposite electrode. To minimize the number of free factors, cathode formulation, calendaring control parameters, drying time and temperature were kept unchanged. Then the cells were cycled in controlled temperature of 25 C at various Crates, C/20, C/5, 1C and 5C.The classifier here is a support vector machine with radial basis function kernel. For training the model a set of 110 cell data are used after removing outliers and noisy measurements. The cell capacity data are then labelled by three labels of low, medium, and high for each Crate. The label ranges are selected to distinguish the cells with undesirably low, medium but acceptable, and high or desirable capacities. In order to validate the models single and double cross-validation (CV) approaches are utilised. In CV approach data are split in 5 folds, in each run 4 of those used for training and one for hyperparameter optimisation as well as testing the model, the process is repeated in a one or two loops for single and double validation. The accuracy of the models is considered to be the number of correctly classified items compared to all classified items.The modelling results and analysis reveal that the capacity range (A= low, B = medium and C = high) can be predicted with an accuracy of 96.68% for C/20 capacity, 97.3% for C/5 capacity, 96.67% for 1C capacity and 72.6% for 5C capacity in single CV. A summary of the results as well as the associated accuracies (confusion matrices) are given in Figure for C/20 and 5Crate capacities for single and double CV methods. The classification models confirm that capacities at all Crates are having stronger correlations with thickness compared to porosity (in range above 25%) therefore thickness is considered as a more fundamental feature to classify the batteries according to their performance index. For C/20, C/5 and 1Crate capacities, the values are directly related to cathode thickness, which means that thicker electrodes at almost all porosities are led to cells with higher capacities. However, for 5Crate, it’s the opposite and for thicker electrodes, the capacity drops off accordingly. This is matched with the fact that capacity at higher Crates is limited by electronic conduction in the solid components, ionic conduction in the pores of the electrode, or both. It is also evident that the classification accuracy is lower for higher Crate capacities and suggest that extra features of cathode electrodes should be taken into account for a more accurate classification.The model-based performance prediction discussed here quantifies the accuracy for the capacity prediction at various Crates given cathode characteristics. It is highly significant for performance prediction where physical cycling tests may take hours to be completed. Therefore, it can avoid waste of time and resource and reduce the production cost for the battery manufacturer. Figure 1

Recent Advances in Cobalt-Free Nickel-rich Li-ion Battery Cathode Materials for Next Generation Electric Vehicles

Recently, battery research community has been grappling with the burgeoning question of ensuring sustainability in battery technologies that would enable next generation electric vehicles. In the past decade, extreme cobalt price fluctuations have severely constrained the supply chains of battery manufacturing industries as most mainstream lithium ion batteries still largely employ cobalt containing cathode materials. To keep battery costs low to ~80$/kWh, and to ensure a sustainable future for electric vehicles, a multitude of research efforts have been directed towards exploring nickel rich cathode chemistries boasting high capacities >200 mAh/g. Though the question of sustainability is not completely addressed through the use of nickel rich compositions, these systems still remain the most promising alternatives when considering the performance requirements of modern electric vehicles. In this context, our team has been exploring the development of novel classes of layered lithium ion battery cathode materials with '0' cobalt in their compositions. Our team has systematically investigated new classes of cobalt-free nickel-rich battery cathodes, having the general formula, LiNixM1yM2zO2 (where, M1 and M2 are other metal ions, x + y + z = 1)[1,2] and evaluated their performance in the quest of identifying the best nickel rich variant. These layered nickel-rich cobalt-free cathodes have similar crystal structure and properties to conventional cobalt containing cathodes such as NCMs and NCAs while delivering comparable and in some cases better electrochemical performance. Here, I will present our research efforts in the development of these novel cathode formulations starting from compositional landscape investigations, advanced characterizations followed by electrochemical performance assessments. Specifically, in-situ high temperature X-Ray and Neutron diffraction techniques were employed to investigate the calcination and phase formation behavior while operando investigations using X-Ray diffraction and Mössbauer spectroscopy were employed to obtain a mechanistic understanding of the redox behavior exhibited by these systems. Best performing compositions were upscaled in continuous stirred tank reactors to kilogram levels, following which, slot-die coating process was employed to fabricate electrodes that were later assembled in pouch format full cells for electrochemical performance assessments[3]. The work presented here summarizes recent results of this early stage research and development endeavor to highlight the immense potential that these nickel-rich class of cathodes can offer towards development of next generation cost effective lithium ion batteries for electric vehicle applications in the coming decades.

Self-activated cathode substrates in rechargeable zinc–air batteries

Developing cost-effective and durable air-cathodes is crucial for improving metal-air batteries. Most reports of cathode formulation involve preparing bi-functional electrocatalysts from wet chemistry or solid-state synthesis, followed by pasting onto a substrate. In this work, the cathodes generated from electrochemical activation of normal carbon paper substrates were directly used in Zn-air batteries. The self-activated carbon paper substrate without any additional electrocatalysts exhibits an impressive cycling stability (more than 165 hours for 1,000 cycles) and a small discharge-charge voltage gap. After the activation, the maximum power density and electrochemical surface area were increased by over 40 and 1,920 times respectively. It is discovered that substrates after activation can be directly used as a cathode. The new method is scalable, inexpensive and produces near best in class performance. The mechanism behind this enhancement is due to the creation of oxygen functional groups within the cathode, which overcame slow kinetics, enhanced wettability and enabled optimum three-phase boundaries.

Toward High-Energy-Density Lithium Metal Batteries: Opportunities and Challenges for Solid Organic Electrolytes.

With increasing demands for safe, high capacity energy storage to support personal electronics, newer devices such as unmanned aerial vehicles, as well as the commercialization of electric vehicles, current energy storage technologies are facing increased challenges. Although alternative batteries have been intensively investigated, lithium (Li) batteries are still recognized as the preferred energy storage solution for the consumer electronics markets and next generation automobiles. However, the commercialized Li batteries still have disadvantages, such as low capacities, potential safety issues, and unfavorable cycling life. Therefore, the design and development of electromaterials toward high-energy-density, long-life-span Li batteries with improved safety is a focus for researchers in the field of energy materials. Herein, recent advances in the development of novel organic electrolytes are summarized toward solid-state Li batteries with higher energy density and improved safety. On the basis of new insights into ionic conduction and design principles of organic-based solid-state electrolytes, specific strategies toward developing these electrolytes for Li metal anodes, high-energy-density cathode materials (e.g., high voltage materials), as well as the optimization of cathode formulations are outlined. Finally, prospects for next generation solid-state electrolytes are also proposed.

Environmental life cycle assessment of the production in China of lithium-ion batteries with nickel-cobalt-manganese cathodes utilising novel electrode chemistries

Advances in lithium-ion battery (LIB) technology, offering higher mass specific energies, volumetric energy densities, potential differences and energy efficiencies, are key enablers of the large-scale uptake of electric vehicles (EVs). Nickel-cobalt-manganese oxide (NCM) cathode formulations have emerged as the dominant choice in the battery industry. Further performance improvements are expected from the introduction of silicon-graphite composite anodes and nickel-rich cathodes alongside cost reductions achieved through upscaling the battery manufacturing. This work presents results of life cycle assessments concerning the environmental burdens associated with the production of novel electrode batteries and the impacts of the Chinese domination in lithium-ion battery manufacturing. The production of LIBs in China was shown to come at a high environmental cost of 40% higher Global Warming Potential (GWP) than earlier literature suggests. The novel batteries were shown to exhibit similar threats to humans and ecosystems as the commercialised ones, occurring mainly from the metals used in the battery cells; environmental impact reductions are shown to occur as a result of the increased nominal storage capacities of novel battery technologies. The replicable model presented provides the means to quantify the environmental impacts of production of LIBs including those with novel electrode chemistries and offers robust means of decision making that complement scientific and engineering developments targeting LIB performance improvements and cost reductions.

Performance Improvement in Direct Methanol Fuel Cells by Using CaTiO3-δ Additive at the Cathode

A non-stoichiometric calcium titanate CaTiO3-δ (CTO) was synthesized and used as oxygen reduction reaction co-catalyst (together with Pt/C) in direct methanol fuel cells (DMFCs). A membrane-electrode assembly (MEA), equipped with a composite cathode formulation (Pt/C:CTO1:1), was investigated in DMFC, using a 2 M methanol solution at the anode and oxygen at the cathode, and compared with an MEA equipped with a benchmark Pt/C cathode catalyst. It appears that the presence of the CTO additive promotes the oxygen reduction reaction (ORR) due to the presence of oxygen vacancies as available active sites for oxygen adsorption in the lattice. The increase in power density obtained with the CTO-based electrode, compared with the benchmark Pt/C, was more than 40% at 90 °C, reaching a maximum power density close to 120 mW cm−2, which is one of the highest values reported in the literature under similar operating conditions.

Synergic effect of catalyst/binder in passivation side-products of Li-oxygen cells

While used in minor proportion respect to other components in cathode formulations, binders play a crucial role in lithium batteries cathode. This is particularly true in Li-O2 batteries which represent a very harsh environment mainly because of the formation, upon cycling, of very aggressive superoxide radicals. In such batteries, the use of catalyst in the cathode formulation is quite usual to help oxygen reduction reaction and oxygen evolution reaction (ORR and OER) to proceed rapidly and reversibly. However, the slightest binder degradation upon cycling can hinder the catalyst effects dramatically, modifying them to act on other reactions associated with the generated side-products, thus deteriorating cell performances and preventing researchers from drawing the right conclusions about catalytic properties of new materials. In this work, the influence of different catalysts in the degradation of the PVDF binder, on the performance of Li-O2 batteries, was investigated. The results obtained were compared with the ones of cathodes prepared with the same catalysts but Li-Nafion binder instead (already reported as stable), to further demonstrate that the choice of binder must be strongly linked to the nature of the catalyst. The catalysts employed for this study were α-MnO2, and commercial Co3O4, and Co phthalocyanines (CoPc).

Selective Hydrogenation of Furfural in a Proton Exchange Membrane Reactor Using Hybrid Pd/Pd Black on Alumina

AbstractInvited for this month's cover picture are the groups of Dr. Peter Pintauro (Vanderbilt University, Tennessee, USA), Dr. Levi Thompson (University of Delaware, Delaware, USA), and Dr. William Tarpeh (Stanford University, California, USA). The cover picture shows the controlled variation of furfural hydrogenation product speciation based on varying cathode formulations of hybrid Pd black and Pd on alumina support. Read the full text of the article at 10.1002/celc.201901314.

(Invited) Working Towards a Cost-effective Lithium-ion Battery Recycling Process

Lithium-ion batteries in electric and hybrid-electric vehicles are just now starting to reach their end-of-life. There are several options to address these end-of-life batteries, landfilling or recycling. Recycling is a desirable option because of the benefits it can bring, including reductions in life-cycle costs, reduced energy usage, lower environmental impacts, and decreased dependence on scarce or imported materials. The options available now for recycling of lithium-ion batteries are not optimal, so research and development (R&D) is needed to make economic processes available for use by the time large volumes of batteries from electric vehicles and other uses go out of service. By then these battery materials could be 20 year-old formulations with little residual value from its structure or contained elements. In particular, cathode formulations are evolving towards varied morphologies, emphasizing formulations that contain reduced quantities of cobalt (the valuable element sought in most current recycling operations), reducing the incentive for recycling with standard pyrometallurgical or hydrometallurgical methods. Several key questions must be addressed by R&D. Most of these focus on the cathode, which is the most valuable form of material that can be recovered. How can the cathode get separated from the other cell components? Can they be recovered? How can optimum cathode function get restored? Can we separate one cathode type from another? Can we modify the cathode composition or morphology to update it for reuse? This presentation will provide a summary of Argonne’s work to create a feasible battery recycling system.

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.

A Highly Stable Sodium–Oxygen Battery Using a Mechanically Reinforced Membrane

AbstractSodium–oxygen batteries have drawn considerable attention due to their high specific energy and the high abundance of sodium. However, stable sodium–oxygen batteries currently require complex cathode formulations. Here, the first demonstration of a highly stable sodium–oxygen system comprising a simple carbon cathode, an ultradry electrolyte, and a newly designed separator that is both capable of blocking dendrites and is impenetrable to oxygen is reported. The battery shows remarkable rechargeability of more than 400 cycles at the current density of 0.28 mA m−2 to the capacity of 1.0 mAh cm−2. An oxygen diffusion study using a dye‐assisted visual chemical reaction proves that the separator efficiently restricts oxygen crossover toward the anode. An in situ atomic force microscope study shows that the discharge product (NaO2) is stable against the electrolyte under anhydrous conditions for over 48 h in either argon or oxygen atmospheres. The sodium–oxygen battery also demonstrates small overpotential (<40 mV) upon charging and remarkable oxygen efficiency (>96%).

Improved performance of the rechargeable hybrid aqueous battery at near full state-of-charge

For the first time, a green lignin/silica nanocomposite (LSC) is introduced to the rechargeable hybrid aqueous Zn/LiMn2O4 battery (ReHAB) as additive in the cathode formulation. Lignin acts as a key role to regulate and control the structure of LSC, intending to enhance the stability of the ReHAB by improving the float charge performance while maintaining other electrochemical performances of the battery. The lignin/silica nanocomposites (LSCs) are characterized by X-ray diffraction, scanning electron microscopy, surface area and porosimetry analyzer, and transmission electron microscopy. The results show that amorphous, uniform and mesoporous LSC-1 is prepared at the mass ratio of 1:2 of lignin to silica. LSC-1 used as the cathode additive improves the float charge performance of ReHAB via decreasing the float charge capacity by 57%. To compensate the loss of conductivity caused by LSC-1 and increase the capacity of the battery, graphene (G) is added. Compared to the reference battery, battery using the cathode containing 3 wt% combined additive of LSC-1 and G at mass ratio of 1:1, has 50% lower float charge capacity, higher rate performance and better cyclability. Up to a discharge capacity of 95 mAh g−1 is still obtained after 300 cycles of 100% depth-of-discharge.

Novel Carbon Materials in the Cathode Formulation for High Rate Rechargeable Hybrid Aqueous Batteries

Novel carbon materials, carbon nanotubes (CNTs) and porous graphene (PG), were exploited and used as conductive additives to improve the rate performance of LiMn2O4 cathode for the rechargeable aqueous Zn/LiMn2O4 battery, namely the rechargeable hybrid aqueous battery (ReHAB). Thanks to the long-range conductivity and stable conductive network provided by CNTs, the rate and cycling performances of LiMn2O4 cathode in ReHAB are highly improved—up to about 100 mAh·g−1 capacity is observed at 10 C (1 C = 120 mAh·g−1). Except for CNTs, porous graphene (PG) with a high surface area, an abundant porous structure, and an excellent electrical conductivity facilitates the transportation of Li ions and electrons, which can also obviously enhance the rate capability of the ReHAB. This is important because the ReHAB could be charged/discharged in a few minutes, and this leads to potential application of the ReHAB in automobile industry.

Anode-originated SEI migration contributes to formation of cathode-electrolyte interphase layer

Cathode-electrolyte interphase (CEI) formation is a key process that impacts the performance of lithium-ion batteries. In this work, we characterized the composition and stoichiometry of CEI layer on LiNixMnyCo1-x-yO2 (NMC) cathodes via a novel combination of quantitative correlation analysis of X-ray photoelectron spectra and binder-free cathode formulation. By comparing the CEI formation in NMC-based cells with lithium, graphite and lithium titanate anodes, we demonstrate a CEI formation pathway via migration of surface species that originally formed on the anode side. A case study of cathodes coated by atomic layer deposition with a thin layer of Al2O3 demonstrates that anode-to-cathode migration can be mitigated by ALD cathode coatings. This work highlights the importance of anode-mediated processes in order to correctly interpret surface phenomena on the cathode side and to guide further development of surface protection strategies.

Electrochemical Flow Cell for the Upgrading of Biomass Derived Streams

The upgrading of biomass derived streams (BDS) provides a unique opportunity for the synthesis of fuel and chemicals completely derived from renewable sources. In order to achieve a complete greenhouse gas neutral fuel, the upgrading process needs to comply with high energy efficiencies and be able to totally rely in renewable resources as inputs and feedstock. However, one of the main challenges in the utilization of BDS comes from the nature and composition of the original sources, specifically, from the large oxygen content present in the carbohydrate polymers that compose the lignocellulose biomass in comparison with fossil sources [1]. The high concentration of oxygen, carbonyls, and phenolic groups present, directly translate in instability and poor physicochemical properties for their incorporation in the current refinery infrastructure. This drives the need to develop upgrading processes which are tailored to future energy schemes. Electrochemical reduction is the only technology that can be directly powered by renewable energy sources, and do not require external addition of hydrogen, as this can be generated in-situ. In this work cathode formulations and membrane electrode assembly architectures have being engineered to allow a selective and efficient upgrading of BDS in a flow cell electrolyzer. Experimental results with surrogates and biomass derived streams will be presented.

Improved Performance and Reduced Cost through Advanced Electrode Drying Technology

The commercial success of lithium ion batteries hinges on significant improvements in both cost and energy density. The electrode coating operation presents the highest leverage opportunity to address both challenges. Navitas ASG with Lambda Technologies has recently demonstrated and scaled up a patent-pending advanced drying process (ADP) technology that breaks through the limitations on electrode thickness and drying rate that are inherent in the present coating technology. This technology can improve electrode loading by at least 50% and accelerate coating rates by >2X. The technology is drop-in compatible with capital equipment in operation at battery OEM plants. The technology will enable cathodes that can match emerging high capacity silicon alloy anode materials. The expected impact of this technology will be >20% improvement in the cell level Wh/kg and 8% reduction in the system level EV battery cost. Microwave drying introduces key advantages over radiant and convective cooling for electrode drying (figure 1). Microwaves efficiently transfer energy through selective absorption by polar solvent (e.g. NMP) or water molecules. Microwave energy is also uniformly deposited through the bulk of the coated electrode. Electrode drying, however, introduces two barriers to use of microwave energy: avoiding arcing with the presence of metal foil current collectors, and supporting roll-to-roll coating without leakage of the microwave field through the coating web entry and exit ports. Navitas worked with a microwave processing company Lambda Technologies to resolve these barriers through the use of variable frequency microwaves (VFM). VFM-dried electrodes were validated by Navitas through accelerated life testing and failure analysis of prototype cells. Navitas worked closely with Lambda to design a VFM module able to support continuous web drying operation – a key challenge. Navitas installed a VFM module onto our Toyo WI pilot coating line and performed pilot scale electrode coating validation for several established commercial anode and cathode formulations to demonstrate accelerated drying with the absence of any deleterious effects on the electrode. The work by Navitas also involved the production of state of the art commercial baseline (i.e. non-VFM dried) benchmark electrodes. The VFM process showed significant advantages, with drying acceleration of >2X for NMP and >5X for water borne slurries. Thorough evaluation of adhesion, cohesion, conductivity, binder distribution etc. has shown the VFM electrode physical properties are as good as or better than the baseline (identical electrode coating passed through coater at lower speed with VFM module toggled off). The Navitas pilot coating trials validated potential cost savings and provided data for presentation to prospective commercial partners to establish confidence that existing coating lines can be retrofitted with VFM. In the course of the validation runs the Navitas team observed that VFM electrodes showed significantly less binder segregation than conventionally dried electrodes. This is attributed to the fact that VFM deposits the drying energy more uniformly in the bulk of the electrode. Uniform energy distribution enables transport of the solvent to the surface as vapor phase rather than as a liquid that drags dissolved or suspended binder to the surface where radiant/convective drying energy transfer predominates. Our observation of reduced binder segregation led to the realization that the critical-to-quality features that limit the ability to coat cathodes at loadings >5mAh/cm2 in high volume production are greatly improved in the VFM process. These limitations include poor adhesion to the current collector (binder deprivation), cracking due to residual stress (binder deprivation), and defects or performance limitations associated with excess binder at surface. Data will be presented comparing VFM electrodes to commercial state of the art electrodes for electrode loading ranging from 3 to 8 mAh/cm2 Figure 1

A comparative study of aqueous and organic processed Li1.2Ni0.2Mn0.6O2 Li-rich cathode materials for advanced lithium-ion batteries

The influence of the solvent used in the processing of Li1.2Ni0.2Mn0.6O2 Li-rich electrodes has been thoroughly studied using complementary chemical, structural and electrochemical characterization techniques. Structural characterization has demonstrated that the bulk chemical composition and the structure of the material remain unchanged when processing the electrode in organic and aqueous media. 6Li solid state NMR measurements revealed that no perceptible variations of the signal positions and intensities were observed for the different samples, indicating the absence of H+/Li+ ionic exchange upon water exposition. Full coin-cells with the waterborne and organic processed Li-rich cathodes and graphite anodes delivered exceptional capacity retention during more than 250 cycles at 100% depth of discharge. This study proves that water-based binders can be used both for the anode and the cathode formulations of the next generation of Li-ion batteries.

In situ Formed Li2NaV2(PO4)3: Potential Cathode for Lithium Ion Batteries

The characteristic three plateau electrochemical behavior of Li3V2(PO4)3, criticized as a drawback of the electrode against its practical applications, has been surpassed through the in situ formed rhombohedral Li2NaV2(PO4)3 analogue obtained upon aging, especially when Na3V2(PO4)3 is explored as a cathode in the rechargeable lithium cell assembly. By incorporating an eco-benign and waste driven biocarbon, viz., human hair derived carbon in the cathode formulation, one can demonstrate the potential cathode behavior of the resultant Li2NaV2(PO4)3/HHC composite that exhibits superior electrochemical performance and a negligible polarization of 0.40 V upon extended cycles. Interestingly, Li2NaV2(PO4)3/HHC cathode of the present study exhibits a capacity of 109 mAh g–1 at 0.1 C for 200 cycles and tolerates as high as 20 C rate for about 5000 cycles with excellent capacity retention behavior, thus qualifying itself as a first ever strain free cathode for lithium-ion batteries.

Performance of a Fe-N-C catalyst for the oxygen reduction reaction in direct methanol fuel cell: Cathode formulation optimization and short-term durability

A non-noble metal (NNM) catalyst for oxygen reduction reaction (ORR) was synthesized using Fe(II)-phthalocyanine as unique source of Fe, N, and C, and SBA-15 ordered mesoporous silica as templating agent, resulting in a material with an extremely high specific surface area and a high microporosity (around 50%). FESEM, FTIR and Raman analyses were performed to investigate the morphology and the physicochemical properties of the catalyst. The ORR activity and the methanol tolerance were tested in rotating disk electrode (RDE), and the selectivity towards a complete 4-electrons reduction was investigated by rotating ring disk electrode (RRDE) test and hydrogen peroxide reduction test in RDE, showing very promising results. Thus, the Fe-N-C catalyst was tested at the cathode of a DMFC after determination of the optimal electrode formulation regarding catalyst loading and Nafion® content, showing a maximum power density of 20mWcm−2 at 90°C. A short term durability test to assess the behavior of both the Fe-N-C and the Pt/C catalysts was conducted on the DMFC, showing a better performance of the non-noble catalyst. Thus, the Fe-N-C catalyst is a potential good candidate to be used as catalytic material for DMFC cathode, in alternative to Pt. The performance in a H2/O2 PEMFC was tested as well, showing a power density of 105mWcm−2 at 60°C.