Water-soluble Binder Research Articles

Locust bean gum as green and water-soluble binder for LiFePO4 and Li4Ti5O12 electrodes

Locust Bean Gum (LBG, carob bean gum) was investigated as an environmentally friendly, natural, and water-soluble binder for cathode (LFP) and anode (LTO) in lithium-ion batteries (Li-ion). For the first time, we show LBG as an electrode binder and compare to those of the most popular aqueous (CMC) and conventional (PVDF) binders. The electrodes were characterized using TGA/DSC, the galvanostatic charge–discharge cycle test, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Thermal decomposition of LBG is seen to begin above 250 °C with a weight loss of about 60 wt% observed at 300 °C, which is sufficient to ensure stable performance of the electrode in a Li-ion battery. For CMC, weight loss at the same temperature is about 45%. Scanning electron microscopy (SEM) shows that the LFP–LBG system has a similar distribution of conductive carbon black particles to PVDF electrodes. The LTO–LBG electrode has a homogeneous dispersion of the electrode elements and maintains the electrical integrity of the network even after cycling, which leads to fast electron migration between LTO and carbon black particles, as well as ion conductivity between LTO active material and electrolyte, better than in systems with CMC and PVDF. The exchange current density, obtained from impedance spectroscopy fell within a broad range between 10−4 and 10−2 mA cm−2 for the LTO|Li and LFP|Li systems, respectively. The results presented in this paper indicate that LBG is a new promising material to serve as a binder.Graphic abstract

Enhanced electrochemical properties of Co3O4 anode with PEDOT:PSS/CMC binder for lithium-ion batteries

A superior electrochemical performance of Co3O4 anode with water-soluble binder consisting of a combination of intrinsically conducting polymer poly-3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS) dispersion and carboxymethyl cellulose (CMC) is presented. This type of electrode material shows ultrahigh capacity value of 1200 mA·h·g−1. It also demonstrates an excellent stability during continuous cycling at 0.2 C (capacity loss is near 4–5%) and has no significant capacity fading at high current densities. Cyclic voltammetry measurements show that Co3O4-electrode containing conducting polymer has smaller changes in shape of the curves than in the case of anode material where polyvinylidene fluoride (PVDF) binder was used.

Study on Different Water-Based Binders for Li4Ti5O12 Electrodes.

In this study, Li4Ti5O12 (LTO) electrodes with different types of water-soluble binders are successfully coated upon aluminum foil. Electrodes containing solely sodium alginate (SA) as a binder or a mixed PVDF/carboxymethyl cellulose (CMC) binder show the most stable performance in 1 M LiPF6 in EC/DMC 1:1 in half cell vs. Li, with respect to cycle stability over 100 cycles at 1 C. The electrodes processed with a mixture of PVDF/SA show considerable fading and slightly worse values for rate capability. Each one of the different binders used is eco-friendly, and the whole processing can be performed without the use of organic solvents. Further advantages covering the whole production and recycling process, as well as safety issues during operation, encourage deeper research in this area.

Understanding the role of water-soluble guar gum binder in reducing capacity fading and voltage decay of Li-rich cathode for Li-ion batteries

The practical application of high-capacity Li-rich cathode materials is hindered by capacity fading and voltage decay. The capacity fading and voltage decay could be effectively overcome by using water-soluble guar gum (GG) binder instead of traditional polyvinylidene fluoride (PVDF). However, the specific role of the GG binder is not clear yet, though the GG binder can significantly improve the electrochemical performance of Li-rich cathode. To understand the effect of GG binder on the morphology, microstructure of electrode and electrode/electrolyte interfaces, ex-situ scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray adsorption near edge spectroscopy (XANES), in-situ electrochemical impedance spectroscopy (EIS) were applied to comparatively study the charge-discharge processes of Li-rich Li1.2Ni0.2Mn0.6O2 cathode when using GG and PVDF as binders. The results indicate that the GG binder can prevent electrode crack and active material loss, ascribing to the strong mechanical adhesion of GG binder with active material particles and current collector. It has found that the GG binder can also induce the formation of a uniform layer on Li1.2Ni0.2Mn0.6O2 particles’ surface. As a consequence, both the electrolyte decomposition and the electrode corrosion were significantly inhibited. The strong chelation between Mn2+ and polar OH group restrain Mn ion dissolution, which contributes to surface structural transformation mitigation. The present study reveals the role of water-soluble GG binder in reducing capacity fading and voltage decay of Li-rich material and is of great importance in design functional binders for high-performance Li-rich electrodes.

Water-Based Electrode Manufacturing and Direct Recycling of Lithium-Ion Battery Electrodes-A Green and Sustainable Manufacturing System.

SummaryIt is critical to develop a low-cost and environmentally friendly system to manufacture and recycle lithium-ion batteries (LIBs) as the demand on LIBs keeps increasing dramatically. Conventional LIB cathodes are manufactured using N-methyl-2-pyrrolidone as the solvent, which is expensive, highly toxic, flammable, and energy intensive to produce and recover. Ideally, a close-loop industrial supply chain should be built, in which the batteries are manufactured, market harvested, and recycled with minimal external toxic solvent through the whole system. This work demonstrates a green and more sustainable manufacturing method for LIBs where no hazardous organic solvent is used during electrode manufacturing and recycling. The electrodes fabricated via water-based processing demonstrate comparable rate performance and cycle life to the ones from conventional solvent-based processing. Utilization of a water-soluble binder enables recovering the cathode compound from spent electrodes using water, which is successfully regenerated to deliver comparable electrochemical performance to the pristine one.

Role of elongational viscosity of feedstock in extrusion-based additive manufacturing of powder-binder mixtures

The 3D printing of metals and ceramics by the extrusion of a powder/thermoplastic binder feedstock is an extrusion-based additive manufacturing (EAM) technique and has received significant interest. EAM feedstocks are generally characterized by their shear viscosity. A quantitative comparison with the shear flow data, through an estimation of the Trouton ratio, indicates that the extensional viscosities are three orders of magnitude greater than their shear flow viscosity at a comparable shear rate obtained in three different high loaded polymers retained for this study. This experimental study addresses the unsolved issue of the role of elongational viscosity in the modelling of EAM of highly viscous melts. The study was conducted using three feedstocks with a water-soluble binder and high powder loading. The different powder materials used for this study are stainless steel, alumina and zirconia. Initially, the rheological properties of the feedstocks were assessed using capillary rheometers. A pressure drop model based on the shear and elongational components of the viscosity was proposed to predict the extrusion pressure during capillary tests. The model was adapted to develop a specific EAM machine, namely, an EFeSTO, equipped with a pellet extrusion unit. Experimental EAM tests were conducted, and the pressure drops were analytically predicted and experimentally measured. A total of 31 different combinations of extrusion velocities, nozzle diameters, 3D printed shapes and materials were tested through a total 184 experimental runs. The model predicts well the experimental pressures for the steel feedstock, whereas it underestimates the pressure for the two ceramic feedstocks owing to their different thermal properties. The results of this study clearly demonstrate that the pressure, and therefore the material flow during the EAM processes of viscous materials, cannot be modelled well without considering the elongational viscosity.

Toward More Sustainable Rechargeable Aqueous Batteries Using Plasma-Treated Cellulose-Based Li-Ion Electrodes

The use of water-soluble biobased binders (e.g., carboxymethylcellulose, CMC) in electrodes for aqueous Li-ion battery systems is typically impossible due to their inherent hydrophilicity that lead...

A Preliminary Study Upon the Applicability of the Direct Water Cooling with the Lost Foam Casting Process

Direct water cooling (DWC) application with the lost foam casting (LFC) process was inspired by the ablation casting technique. Ablation casting is designed to combine the controlled filling property of sand mold casting and the rapid cooling of the high-pressure die casting. Briefly, in this method, sand casting is followed by the removal of the mold by water spray and cooling of the part within a short time. The use of special water-soluble inorganic binders facilitates the mold breakdown. However, due to no use of binder materials in the LFC method, the DWC process may become more effective. In this study, similar cooling techniques were applied to the lost foam castings of A356 alloy by two techniques. In the first one, cooling was achieved by tipping the mold content over into a container with a sufficient amount of water after the casting process. The second process was carried out by pouring a sufficient amount of water onto the mold following the casting process. These two developed methods were named as “quench casting” and “splash casting,” respectively. It was seen that both methods changed the traditional casting microstructure and properties considerably. A serious decrement in secondary dendritic arm spacing with accompanying modification of the eutectic silicon was observed for the specimens produced via both methods. Hardness values increased significantly, and the results indicate that splash casting is preferable than quench casting because it exhibits better and more stable properties.

Preparation of pectin-based dual-crosslinked network as a binder for high performance Si/C anode for LIBs

The modification of pectin polysaccharide through grafting with polyacrylamide and crosslinking is newly proposed as a powerful candidate for a water-soluble binder of high-capacity Si anodes in lithium ion batteries. The grafting of pectin with polyacrylamide enhances adhesion in the electrode and contributes to the good wettability of the carbonate electrolyte. Herein, dual-crosslinking of pectin-g-polyacrylamide was achieved by the ionic crosslinking of pectin with divalent calcium ions and the chemical crosslinking of polyacrylamide with a bisacrylamide. As a result, the dual-crosslinked binder improves further the cycling performance of the Si/C composite anode with a 1.2 mg cm−2 loading, which retains a specific capacity of 729 mAh g−1 after 300 cycles. In contrast, the Si/C electrode containing dual-crosslinked alginate with polyacrylamide shows a specific capacity of 515 mAh g−1 after 300 cycles.

Beneficial effect of green water-soluble binders on SiOx/graphite anode for lithium-ion batteries

The electrochemical performance of SiOx/graphite anode have been improved by using water-soluble binder. When using sodium carboxymethyl (CMC) as binder, the initial Coulombic efficiency, rate capability and charge transfer impedance have been improved. The first discharge specific capacity of SiOx/graphite can reach to 686.2 mAh g−1 when using guar gum (GG) as binder. In addition, various hybrid binders of CMC/GG are investigated to improve the cycle stability and reversible specific capacity synchronously. The results reveal that mixing two water-soluble binders in an appropriate proportion can give play to the respective advantages of the two components.

A Method to Measure the Swelling of Water-Soluble PVDF Binder System and Its Electrochemical Performance for Lithium Ion Batteries

Water-soluble CMC/PVDF binder systems were used to prepare graphite anodes and compared mechanically and electrochemically with CMC/SBR binder systems. The effect of crystallinity of PVDF binder on the mechanical and electrochemical performance of the anodes is studied. A contact free method easy to operate and equipped with high accuracy was developed by using capacitance measurement. The swelling of graphite electrodes was controlled and showed different results for different binder crystallinities (no swelling of binder with high crystallinity vs 12% for medium crystallinity and 17% for low crystallinity binder). The discharge capacity depends on the crystallinity of the binders and half-cells delivered a capacity in the range of 230–360 mAh g−1. The binder with medium crystallinity in particular exhibited the best mechanical and electrochemical performance and showed an excellent C-rate stability with specific capacities up to 10 C. Full cell tests showed good cycling stability over 180 cycles. The water-based PVDF binders seem to be a promising alternative to solvent-based binders.

Chitosan-grafted-poly(aniline-co-anthranilic acid) as a water soluble binder to form 3D structures for Si anodes.

We graft an electrically conductive poly(aniline-co-anthranilic acid) (PAAA) polymer capable of interacting with Si particles onto chitosan, a natural hydrophilic polymer, to form a chitosan-grafted-PAAA (CS-g-PAAA) copolymer, and use it as a new water soluble polymeric binder for Si anodes to relieve the physical stress resulting from Si volume change during charge/discharge cycles. The carboxylic acid functional groups within the PAAA structure, as well as the chitosan functional groups, bind to silicon particles to form a stable 3D network, resulting in high adhesion. Because the binder is conductive, the electrode using the CS-g-PAAA-8 : 1 with an optimal composition ratio of CS to PAAA of 8 : 1 shows a high initial capacity of 2785.6 mA h g−1, and maintains a high capacity of 1301.0 mA h g−1 after 300 cycles. We also extract chitosan directly from crab shells, and fabricate a Si@ECS-g-PAAA electrode by grafting PAAA onto the extracted-chitosan (ECS). This electrode records an initial capacity of 3057.3 mA h g−1, and maintains a high capacity of 1408.8 mA h g−1 with 51.4% retention after 300 cycles. Overall, we develop a polymeric binder with outstanding cell properties, ease of fabrication, and high water solubility for Si anodes by grafting a conductive PAAA onto chitosan.

Si@S‐doped C anode with high cycling stability using PVA‐g‐PAA water soluble binder for lithium‐ion batteries

ABSTRACTThe nanostructured Si@S‐doped C (Si/C) hybrid is synthesized via a mild hydrothermal process of glucose and the simultaneous polymerization of 3,4‐ethylenedioxythiophene and poly(sodium‐4‐styrene sulfonate) on the surface of nano‐Si powders, then followed by a calcination process. A new water soluble polymer of poly(vinyl alcohol) (PVA) grafted with poly(acrylic acid) (PAA) is synthesized via a free‐radical polymerization of acrylic acid (AA) in a 1:1 weight ratio in PVA water solution. The Si/C anode using PVA‐g‐PAA binder, exhibits improved lithium storage properties and cycling stability than that of the parallel electrode with carboxymethyl cellulose binder, which exhibits an initial coulombic efficiency (82.0%), even a reversible capacity of 487 mAh g−1 after 300 cycles with 81.2% capacity retention at 0.4 A g−1. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48764.

Instigation of Low Cost, Non-Toxic and Environmentally Benign Binders for Mild Aqueous Zn/MnO2 Systems

In recent years, zinc has gained significant attention due to its wide availability (fourth-most mined material on the Earth), low-cost nature and recyclability. Moreover, it allows water-based batteries (i.e. Zn/MnO2) that could compete with LIBs for both transportation and stationary applications without safety issues. However, they are not considered rechargeable in practice yet due to the capacity limitation from the cathode materials and the detrimental zinc dendrite formation. Most of the electrode preparations are currently based on the use of fluorine-containing polymer binders, such as polyvinylidene difluoride (PVDF) and poly-tetrafluoroethylene (PTFE) with N-methyl-2-pyrrolidone (NMP) as a solvent/dispersant due to its good electrochemical stability and high adhesion to the electrode materials and current collectors. However, the fluorinated binders are relatively expensive and NMP is considered to be a hazardous and toxic substance. Therefore, switching to alternate electrode processing routes with non-toxic binders is crucial to providing a fully sustainable and environmentally friendly electrochemical energy storage device. In this study, various water-soluble binders have been evaluated in mild aqueous electrolyte conditions for Zn/MnO2 systems and are compared with the conventional MnO2/PVDF systems. We observed water-soluble binders can be stable and offer desirable adhesion at certain pH levels (3.5~5) without any decomposition. Electrochemical data also indicates that higher capacity utilization and lower cell overpotential is achieved in the cells with aqueous binders versus the cells with PVDF binder. In summary, our work suggests that the implementation of water-soluble binders can lead to substantial improvements for efficient and effective aqueous battery systems.

Maintaining structure and voltage stability of Li-rich cathode materials by green water-soluble binders containing Na+ ions

As high-capacity cathode materials for lithium-ion batteries, Li-rich materials still suffer from structure transformation during cycling, resulting in serious voltage fading. The improved properties achieved by traditional modification methods, such as surface coating and ion doping, are unsatisfactory. Here, two water-soluble binders, sodium carboxymethyl cellulose and sodium alginate, are employed to prepare electrodes in order to alleviate voltage fading of both Li1.2Ni0.2Mn0.6O2 and Li1.2Co0.13Ni0.13Mn0.54O2 during cycling. Besides the environmental friendliness, these two water-soluble binders have better bonding ability with active particles and conductive agent than that of conventional PVDF binder. Moreover, Na+ ions in water-soluble binders are speculated to occupy lithium vacancies in crystal structure during cycling and play an important role as a pillar in lithium layer, leading to good structure stability of Li-rich materials. Accordingly, the electrodes based on water-soluble binders exhibit improved electrochemical performances, including high reversible discharge specific capacity, excellent cycling stability, and good rate capability. Importantly, voltage fading as a stubborn issue of Li-rich materials is significantly alleviated by using these water-soluble binders to prepare electrodes. Exploring suitable binders for specific electrode materials is considered as an effective strategy to improve electrochemical properties of electrode materials for lithium-ion batteries.

Extrusion of metal powder-polymer mixtures: Melt rheology and process stability

The mixture of metal powder and a viscous polymeric binder (often referred to as feedstock) is commonly used for Metal Injection Moulding (MIM) applications. Recently, the interest towards the extrudability of metal/binder feedstocks is increasing, especially because of the growth of additive manufacturing techniques based on the vertical extrusion and layered deposition of filaments. In this experimental work, a feedstock prepared as a mixture of stainless steel 316 L powder with water-soluble binder was tested. The rheological behaviour of different mixtures (with powder loading between 50 and 63% in volume) was assessed using a capillary rheometer. The theoretical window of optimal extrudability was determined, in terms of temperature, shear rate and powder loading. Then, a specially designed CNC controlled extrusion system was used for performing vertical extrusion tests. The analysis of extrusion pressure profiles and the dimensional variability of the filaments was used to correlate the theoretical extrudability predicted by the rheological model with the actual extrusion tests. All results indicate that the conditions which yield better stability of the extrusion process are those that allow higher viscosity of the mixtures.

Solid Air—Low Temperature Manufacturing of Ultra-Low Permittivity Composite Materials for Future Telecommunication Systems

The frequency spectrum to be used by future wireless telecommunication systems such as 5G and beyond requires novel materials which are environment-friendly, are low cost and, most importantly, have low dielectric loss and permittivity when approaching higher frequencies. In this work, the development of all-inorganic composites with a relative permittivity of ~1.2 and loss tangents in the range of 10-3 is presented. The composites were fabricated at the exceptionally low temperature of 120 °C and were based on lithium molybdate (Li2MoO4) ceramic as a water-soluble binder reinforced by quartz fibers. The relative permittivity was further decreased by the addition of hollow micron-sized glass spheres beads tekstissa esitelty sanalla sphere having very low dielectric loss. A simple manufacturing method through filtration, stencil printing and drying is presented. The microstructure of the composites was investigated with FESEM microscopy and the dielectric properties by SPDR. Printing tests were carried out in order to evaluate the possibility of using the proposed composites in, for example, printed antenna applications.

Effects of binders on electrochemical sodium storage performance with porous CoFe2O4 nanocubes derived from metal-organic frameworks

Porous CoFe2O4 nanocubes (PCFO-NCs) was prepared simply by annealing metal-organic frameworks Prussian blue and used as anode with different binders for sodium ion batteries (SIBs). The water-soluble binders (carboxyl methyl cellulose, CMC and polyacrylic acid, PAA) significantly improve the cycling stability of PCFO-NCs, especially for the electrode with CMC binder. The electrodes with CMC and PAA binders show the capacities of 394 and 310 mAh g−1 after 50 cycles with good cycling stability. Electrochemical impedance spectroscopy shows that the CMC binder delivers the highest sodium diffusion coefficient, the lowest Rct and Ea, which facilitates the reactions at the electrode/electrolyte interface. These advantages highlight the potential applications of CMC binder in SIBs.

Hybrid humics/sodium carboxymethyl cellulose water-soluble binder for enhancing the electrochemical performance of a Li-ion battery cathode

A hybrid water-soluble humics-based binder (humics/sodium carboxymethyl cellulose (CMC)) was studied to enhance the electrochemical performance of a Li-ion battery cathode (LiFePO4) in this work. Molecular dynamics simulations of binder active fractions with related materials (LiFePO4 and Al) were performed to explore the binding mechanisms. Humics serve to connect the active material and provide a conducting bridge in the cathode. To improve the adhesion between the particles and current collector, CMC is added as an auxiliary fraction with a mass ratio of humics to CMC of 3:1. The scanning electron microscope results indicate that the morphology of the electrode with the hybrid humics/CMC binder is more uniform than that of electrodes with conventional polyvinylidene fluoride and CMC binders. The electrochemical performance and cycling stability of the cathode materials are obviously enhanced. The reversible specific capacity can reach 152.3 mAh g−1 at 0.5 °C after 100 cycles. The rate capability is greatly improved, with a specific capacity as high as 105 mAh g−1 at 8 °C. The humics/CMC composite can be regarded as a novel, environmentally friendly and high-efficiency binder for application in Li-ion batteries.

An environmental friendly cross-linked polysaccharide binder for silicon anode in lithium-ion batteries

Silicon is a promising anode material for the next generation of lithium-ion batteries. Binder plays an essential role in maintaining electrode integrity when Si undergoes dramatic volume change during lithiation/delithiation processes. Herein, an environmental friendly water-soluble binder of oxidized starch cross-linked sodium carboxymethyl cellulose (OS-CMC) possessing three-dimensional (3D) network structure is designed. The abundant hydroxyl and carboxyl groups and the 3D structure of the cross-linked binder not only enhance the bonding with Si nanoparticles surface but also greatly alleviate the mechanical stress, thus maintaining the integrity of electrode and conductive network. In addition, it can facilitate faster lithium-ion transportation at the interface of Si/OS-CMC. As a result, the Si anodes with OS-CMC binder show good electrochemical stability and better mechanical properties than that of Si anodes with OS or CMC binder. The Si anodes with OS-CMC binder exhibit a discharge capacity of 1922 mAh g−1 after 100 cycles at a current density of 0.4 A g−1 with a high initial discharge capacity of 3424 mAh g−1 and maintain a superior capacity of 1667 mAh g−1 at a high current density of 8 A g−1. Our work provides a novel binder design for high-performance Si-based anodes.