Binder For Anode Research Articles

Assessment of Nanofiber Electrode MEA Durability By Analytical Electron Microscopy

Carbons typically used as the support for Platinum catalysts in proton-exchange membrane fuel cells (PEMFCs) are vulnerable to electrochemical corrosion, especially during potential excursions generated by startup/shutdown cycling and local anode starvation [1]. Pintauro and coworkers have shown that an electrospun nanofiber cathode, composed of Pt/C particles and a binder of NafionÒ+ poly(acrylic acid), performs remarkably well in a hydrogen/air PEMFC, with high power output at low Pt loading and excellent durability, as determined from end-of-life polarization curves after an accelerated start-stop voltage cycling (carbon corrosion) test. For example, after 1,000 simulated start-stop cycles (voltage cycling between 1.0 and 1.5 V), a nanofiber membrane electrode assembly (MEA) with a Johnson Matthey Pt/C nanofiber catalyst maintained 53% of its initial power at 0.65 V and 85% of its maximum power, as compared to a 28% power retention at 0.65 V and 58% maximum power for a sprayed electrode MEA [2]. In another study [3], constant power output, or even and increase in power, was observed after a carbon corrosion voltage cycling test with a nanofiber electrode MEA, where the cathode Pt/C catalyst binder was a blend of Nafion + poly(vinylidene fluoride) (PVDF). For a Nafion-poly(acrylic acid) binder, the superior end-of-life performance of the nanofiber MEA after a carbon corrosion test was tentatively attributed to the combined effects of a high initial electrochemical cathode surface area, the retention of the nanofiber structure after testing (no collapse of the cathode), and the rapid/effective expulsion of product water from the cathode, which minimizes/eliminates flooding. Nafion-PVDF binders appear to suppress corrosion by increasing the nanofiber hydrophobicity, thus decreasing the concentration of water at the catalyst surface. The unusual but desirable behavior of nanofiber cathodes during a carbon corrosion voltage cycling test warranted further studies, in particular imaging and chemical analysis using scanning transmission electron microscopy (STEM), of cathodes at beginning-of-life (BOL) vs. end-of-life (EOL) (after 1,000 voltage cycles, triangular wave at 1.0 V to 1.5 V at a scan rate of 500 mV/s). Characterization experiments were performed at Oak Ridge National Laboratory using nanofiber MEAs prepared and tested for power output at Vanderbilt University. All MEAs were made with Johnson Matthey HiSpec® 4000 (40% Pt on Vulcan carbon) catalyst at an electrode loading (anode and cathode) of 0.1 mgPt/cm2. The anode binder was always Nafion + poly(acrylic acid) whereas the cathode nanofiber binder was either Nafion + poly(acrylic acid) or Nafion + poly(vinylidene fluoride) (PVDF), where the Nafion/PVDF weight ratio was varied from 80/20 to 20/80. We were particularly interested in understanding how the nanofiber electrode morphology and/or binder composition (e.g., PVDF content and binder hydrophobicity) affected cathode carbon corrosion and power output. In this presentation, results of STEM imaging and compositional analysis of nanofiber MEAs at BOL and EOL will be presented, along with fuel cell polarization curves for the same MEAs. References C. A. Reiser, et al. Electrochemical and Solid State Letters, 8(6): A273-A276 (2005)M. Brodt, T. Han, N. Dale, E. Niangar, R. Wycisk, and P. Pintauro, , J. Electrochem. Soc., 162, F84-F91 (2015).M. Brodt, R. Wycisk, J. Slack, and P. N. Pintauro, “New Developments in Electrospun Nanofiber Electrodes for Hydrogen/Air Fuel Cells” paper #1250, Electrochemical Society Meeting, Cancun, Mexico (2014).

Interpenetrated Gel Polymer Binder for High Performance Silicon Anodes in Lithium-Ion Batteries

Silicon has attracted ever-increasing attention as a high-capacity anode material in Li-ion batteries owing to its extremely high theoretical capacity.1 However, practical application of silicon anodes is seriously hindered by its fast capacity fading as a result of huge volume changes during the charge/discharge process.2, 3 The situation becomes even worse when making it for practical application where high mass loading of active-materials (mg-Si/cm2) on current collectors is necessary for high energy density batteries.4, 5 Polymer binder, one of major components in electrode, is used to bind active materials and conducting particles together onto the current collector. The properties of polymer binders play an important role on the electrochemical performance of the electrodes, especially for the cycle life and irreversible capacity losses.6, 7 Poly(vinylidene fluoride) (PVDF) is a conventional binder and widely used in traditional LIBs because of its acceptable adhesion and wide electrochemical window. However, the non-functionalized linear chain structure of the PVDF binder can’t afford sufficient binding to high-capacity anode particles that exhibit huge volume changes.6 This requires improved binding characteristics of binders to enable the integrity of the electrodes for long-cycle life. Thus, novel polymer binders with the ability to accommodate this substantial volume changes during lithiation/delithiation of Si anodes are highly desirable. Here, we report an interpenetrated gel polymer binder for high performance silicon anode through in-situ crosslinking of water soluble poly(acrylic acid) (PAA) and polyvinyl alcohol (PVA) precursors. This gel polymer binder with deformable polymer network and strong adhesion on silicon particles can effectively accommodate the large volume change of silicon anodes upon lithiation/delithiation, leading to an excellent cycling stability and high Coulombic efficiency even at high current densities. Moreover, high areal capacity of ~4.3 mAh/cm2 was achieved based on the silicon anode using the gel PAA-PVA polymer binder with a high mass loading. In view of simplicity in using the water soluble gel polymer binder, it is believed that this novel binder has a great potential to be used for high capacity silicon anode in the next generation Li-ion battery, but also for other electrode materials with large volume change during cycling. Acknowledgements This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-EE0006447.

Millipede-inspired structural design principle for high performance polysaccharide binders in silicon anodes

The millipede's extraordinary adhesion provides a design principle for silicon anode binders with emphasis on the superstructure and electrostatic charge.

Producing anode binders by compounding

Alternative binders for nonferrous metallurgy and the power industry are considered. Information regarding existing methods of binder production from coal, oil, and hybrid materials is analyzed. Binder production by compounding is discussed, in theoretical and practical terms. Data, used in article, was obtained during research in frame of government contract 16.2541.2014/K “Development of extraction technology of nanomodifyed ferrum, concentrates of rare-earth metals and titanium, vanadium and scandium oxides from rebellious ore and man-made materials”.

Chitosan oligosaccharides: A novel and efficient water soluble binder for lithium zinc titanate anode in lithium-ion batteries

Chitosan oligosaccharides (COS) as a new, environmentally and water-based organic compound, is firstly applied as the electrode binder for Li2ZnTi3O8 electrode in lithium-ion batteries. Compared with conventional polyvinylidene fluoride (PVDF) binder, the COS binder is used for Li2ZnTi3O8 electrode significantly improves the electrochemical performances in terms of the first Columbic efficiency, cycling behavior, rate capability and long life cycle. At 0.1Ag−1, the initial discharge capacity of 215.6mAhg−1 can be obtained for Li2ZnTi3O8 with COS binder system and the Columbic efficiency is as high as 93.6%, which are apparently better than PVDF binder system. Moreover, 66.1mAhg−1 can be remained after 1000 cycles and the retention is 33.6% for COS binder system, while the PVDF binder system has only 37.9mAhg−1 (22.8%). In addition, the cycling stability of Li2ZnTi3O8 electrode has been improved after using COS as binder. The elevated electrochemical performances of Li2ZnTi3O8 electrode with COS binder system can be ascribed to the characters of COS binder, which not only provide numerous hydroxyl groups formed strong hydrogen binds with both active materials and copper current collector, but also suppress swelling of electrode with electrolyte solution.

Alginate Nanofibers as a Binder in Lithium-Ion Cells

It is well known that the volume expansion upon Li-alloying, followed by pulverization, deleterious side reaction, and electronic isolation limits the commercial use of high-capacity anode materials such as silicon and tin. Despite these challenges, researchers aspire to discover means to integrate high-capacity materials into electrodes. The electrode binder, one of the least investigated components in a lithium-ion battery, is posited as a potential remedy to many of the issues that lead to cell failure. Manipulating the composition and morphology of the binder impacts the longevity of the cell as well as the capacity retention. Here we show that alginate nanofibers as an anode binder can be used to enhance the performance of Si anodes for lithium-ion batteries.Alginate is an anionic polysaccharide derived from brown algae [1]. Although it has many industrial uses such as a textile processing and a thickening agent in foods, alginate has recently been reported [1] as an eco-friendly alternative to the conventional PVDF binder. Sodium alginate has been shown to protect the active material by forming an inert passivating layer with common organic carbonate electrolyte solvents while providing ample Li conductivity [1]. Recently, our group has shown that alginate nanofibers can be formed via electrospinning alginate-PEO blends [2]. PEO, albeit electrochemically stable, can be leached away to form porous alginate nanofibers (Figure 1). Electrospinning provides a desirable fiber extrusion technique because it allows for a continuous and facile method to produce multi-component nanofibers. The small size scale of these fibers can further enhance the electronic and ionic transport through the cell.Here we report physical and electrochemical characteristics of alginate fibers as the binding component in both graphite and silicon anodes. X-ray diffractograms and energy-dispersive x-ray spectroscopy are used to determine the phase and location of the electrochemically active materials, respectively. Cyclic voltammetry test are employed to observe reversibility of the cell. Lithium diffusion rates into the anode materials are also determined. Charge and discharge curves demonstrate alginate fibers may be used in lieu of PVDF as a binding material in Li-ion cells. Figure 1: SEM image showing alginate fibers. The fibers were not sputter-coated and slight charging effects are evident.[1] I. Kovalenko et al., Science 334, 75 (2011)[2] C. A. Bonino et al., Carbohydrate Polymers 85, 111(2011)

A Modified Water Soluble Binder for Graphite Anode in Li-Ion Battery: Towards a Better Binding Performance

In the secondary lithium ion batteries, polymeric binders provide sufficient mechanical strength to the electrodes. The type and amount selection and optimization of the binder may affect the mechanical properties and the electrochemical performance of anodes and may allow significant improvements in the electrochemical capacity, efficiency, charging-discharging rate and cyclic life of battery. Poly(vinylidene difluoride) (PVDF) which is the most widely used binder for Li-ion cells has good electrochemical stability and binding capability but has only solubility in an organic solvent. Poly-methacrylic acid (PMAA) is a water soluble binder which is environmentally friendly has been widely used in industry.However, because of the rigidness of the PMAA polymer, the electrodes go through delamination during production process. We modified the PMAA polymer structure, while maintaining the water solubility, change it to a flexible material. Peel tests show that the graphite laminates using the modified-PMAA material have better binding performance compared to PMAA polymer. Further gain includes improvement of the electrolyte uptake property and improved cell performance for graphite half cells.

산화전극 결합제로서 나피온용액에 혼합된 에폭시가 미생물연료전지의 성능에 미치는 영향

The composite anodes of exfoliated graphite (EG) and multiwall carbon nanotube (MWCNT) were fabricated by using the binders with different content of epoxy in Nafion solution. The influence of the epoxy content in the anode binder on the performance of microbial fuel cell (MFC) was examined in a batch reactor. With the increase in the epoxy content in the anode binder, increase in physical binding force was observed, but at the same time an increase in the internal resistance of MFC was also observed. This was due to the increase in activation and ohmic resistance. For the anode binder without epoxy, the maximum power density was 1,892 mW/m, but a decrease in maximum power density was observed with the increase in the epoxy content in the anode binder. With the epoxy content of 50% in the anode binder, a decrease in the maximum power density to 1,425 mW/m was observed, which about 75.3% of the anode binder without epoxy is. However, the material consisting of the same amount of epoxy and Nafion solution is a good alternative for anode binder in terms of durability and economics of MFC.

Carboxymethyl chitosan: A new water soluble binder for Si anode of Li-ion batteries

Carboxymethyl chitosan (C-chitosan) is investigated as a new water soluble binder for Si anode of Li-ion batteries. The Fourier transformation infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements reveal that the strong hydrogen bonding is formed between the hydroxylated Si surface and the polar groups (–OH, –COOH and –NH2) of C-chitosan. The Si/C-chitosan anode (Si:carbon black:C-chitosan = 62:30:8 in weight ratio) exhibits a high first discharge capacity (4270 mAh g−1) with a first coulombic efficiency of 89%, and maintains a capacity of 950 mAh g−1 at the current density of 500 mA g−1 over 50 cycles.

Mussel‐Inspired Adhesive Binders for High‐Performance Silicon Nanoparticle Anodes in Lithium‐Ion Batteries

Conjugation of mussel-inspired catechol groups to various polymer backbones results in materials suitable as silicon anode binders. The unique wetness-resistant adhesion provided by the catechol groups allows the silicon nanoparticle electrodes to maintain their structure throughout the repeated volume expansion and shrinkage during lithiation cycling, thus facilitating substantially improved specific capacities and cycle lives of lithium-ion batteries.

Effect of Anode Binders on Low-Temperature Performance of Li-Ion Batteries

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Parametric Investigations of Direct Methanol Fuel Cell Electrodes Manufactured by Spraying

Key processing steps in the thin-film process of manufacturing catalyst layers for direct methanol fuel cells are catalyst ink formulation and its application. The catalyst ink is typically composed of supported or unsupported catalysts, binder (ionomer), solvents, and additives. Rheological properties of the ink, amount of binder, and choice of solvents are tuned to match the particular ink application process used to fabricate the electrode, as each coating process has its own unique requirements. Besides affecting the coating process, the choice and ratios of these components can significantly affect the electrochemical performance of the electrode. In this study, catalyst inks are designed and investigated for the spraying process, for utilization in the continuous fabrication of DMFC electrodes. For this purpose, the effect of the binder (ionomer) content on the performance of the electrodes is studied in detail. Decal-transfer electrodes are fabricated on a custom-built automated spraying apparatus with individually specified anode and cathode binder contents, and assembled to form a catalyst coated membrane (CCM) type membrane electrode assembly (MEA). These electrodes are rigorously tested to specifically identify their electrochemical performance, catalyst utilization and electrode morphology.

Conductive Polymer Binder for High Capacity Alloy Anode

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Effect of high adhesive polyvinyl alcohol binder on the anodes of lithium ion batteries

High molecular weight (MW) polyvinyl alcohol (PVA) was synthesized by two-step polymerizations and employed as an anodic binder of lithium ion batteries (LIBs). Numerous hydroxyl groups in PVA formed strong hydrogen bonds with both active materials and the current collector. These strong hydrogen bonds led to an increase in the amount of binder covering the surface of active materials and significantly enhanced the adhesion strength of electrodes. The high MW PVA binder showed much better cyclic performance for silicon/carbon anodes than polyvinylidene fluoride (PVDF) and polyacrylic acid (PAA) binders.

A high performance direct borohydride fuel cell employing cross-linked chitosan membrane

A cross-linked chitosan (CCS) membrane has been prepared by a solution casting method using sulfuric acid as cross-linking agent. The CCS membrane was used as the polymer electrolyte and separator in a direct borohydride fuel cell (DBFC). Ionic conductivity and borohydride crossover rate have been measured for the CCS membrane. The DBFC used in this study employed nickel-based composite as anode catalyst and Nafion® as anode binder. The power performance of the CCS membrane-based DBFC was compared with a similar DBFC employing Nafion® 212 (N212) membrane as electrolyte /separator. The CCS membrane-based DBFC exhibited better power performance as compared to N212 membrane-based DBFC. Encouraged by this result, chitosan chemical hydrogel (CCH) was prepared and used as binder for anode catalysts. A DBFC comprising CCS membrane and CCH as anode binder was studied and found to exhibit even better power performance at all temperatures in this study. A maximum peak power density of 450mWcm−2 was observed at 60̊C for DBFC employing CCS membrane and CCH binder-based anode. The chitosan-based DBFC was operated continuously for 100h and its performance stability was recorded.

Low Temperature Charging Performance and Mechanism of Different Anode Binder in Lithium-Ion Battery

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Optimum Binder for High Capacity SiO Anode

not Available.

Ni-YSZ Cermet Supported Thin Ceria-Based Electrolyte Solid Oxide Fuel Cell for Reduced Temperature (500–600°C) Operation

A Ni-YSZ cermet supported thin ceria-based electrolyte solid oxide fuel cell based on tape casting, screen-printing and co-firing technologies has been fabricated and characterized. Studies were made of the anode substrate, paste solvent and binder, powder loading, co-firing profiles as well as cathode composition and firing conditions. Interaction between YSZ and SDC was investigated by EDX analysis. Cell performance of different electrolyte thicknesses and cathode firing conditions at low temperatures are also presented.

Evaluation on a water-based binder for the graphite anode of Li-ion batteries

Abstract We evaluate poly(acrylamide-co-diallyldimethylammonium chloride) (AMAC) as a water-based binder for the graphite anode of Li-ion batteries. It is shown that AMAC has a similar bonding ability as the conventional poly(vinylidene fluoride) (PVDF) binder, and that the graphite electrodes bonded by AMAC and PVDF have nearly the same cyclability. Advantages of AMAC binder include: (1) it assists in forming a more conductive solid electrolyte interface (SEI) on the surface of graphite and (2) organic liquid electrolyte exhibits better penetration on the AMAC-bonded electrode. Impedance analysis shows that formation of the SEI on the surface of graphite includes two stages. The first stage takes place above 0.15 V and the second stage between 0.15 and 0.04 V. The SEI formed in the first stage is relatively resistive, while that formed in the second stage is highly conductive. For the first stage, the presence of AMAC may enhance the conductivity of the SEI. We performed a storage test on the AMAC-bonded graphite by monitoring the change of open-circuit voltage (OCV) of fully lithiated Li/graphite cells and by comparing their capacity change before and after storage. We observed that OCV of the cell increased gradually, and that capacity loss during the storage recovered in the subsequent lithiation process. Therefore, the OCV increase could be considered a self-delithiation process, which does not consume permanently Li+ ions.

Poly(acrylonitrile-methyl methacrylate) as a non-fluorinated binder for the graphite anode of Li-ion batteries

Poly(vinylidene fluoride) (PVDF) has been a choice of the binder for both cathode and graphite anode in stateof-the-art Li-ion batteries [1, 2]. However, there is currently a demand to replace PVDF with non-fluorinated binder since at elevated temperatures the fluorinated polymers react with lithiated graphite (LixC6) and metal lithium to form more stable LiF and >C@CF– double bonds. In particular, the reaction of PVDF and metal lithium produces an enthalpy as high as 7180 J (g PVDF) [1]. It has been reported that in the presence of electrolytes, PVDF and lithiated graphite undergo a series of exothermic reactions, including (i) temperature-induced degradation of the solid electrolyte interface (SEI) at 120–140 C, (ii) reactions of lithiated graphite and electrolyte at 210–230 C, and (iii) dehydrofluorination of PVDF initiated by LixC6 at >260 C [1, 2]. Among these reactions, the last one is known to be very exothermic and is believed to be a potential source for the thermal runaway of Li-ion batteries under abuse conditions. Therefore, safety concerns with Li-ion batteries may arise from the use of PVDF in the graphite anode. To replace the rather reactive PVDF, we attempt to evaluate poly(acrylonitrile-methyl methacrylate) (AMMA) as a non-fluorinated binder for the graphite anode of Li-ion batteries. Differential scanning calorimetry (DSC) study has shown that the heat of reaction of the lithiated graphite and electrolyte can be reduced significantly by using AMMA instead of PVDF [3]. That is, total enthalpies for the reactions (as indicated by two exothermic peaks in DSC curves) of the fully lithiated graphite (MAG-10, Hitachi Chemical) and electrolyte (1.2 M LiPF6 3:7 EC/EMC) in the temperature range 280–340 C can be reduced to 1211 J (g AMMA) from 2699 J (g PVDF). In this paper, we will electrochemically evaluate AMMA as a binder of the graphite anode of Li-ion batteries. 2. Experimental details