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The effects of electrochemical aging on the mechanical properties of electrodes in lithium-ion batteries are challenging to measure and are largely unknown. Mechanochemical degradation processes occur at different scales within an electrode and understanding the correlation between the degradation of mechanical properties, electrochemical aging, and morphological changes is crucial for mitigating battery performance degradation. This paper explores the evolution of mechanical and electrochemical properties at the layer level in a Ni-rich positive electrode during the initial stages of electrochemical cycling. The investigation involves complementary cross-section analyses aimed at unraveling the connection between observed changes on both macroscopic and microscopic scales. The macroscopic constitutive properties were assessed using a U-shaped bending test method that had been previously developed. The compressive modulus exhibited substantial dependency on both the porous structure and binder properties. It experienced a notable reduction with electrolyte wetting but demonstrated an increase with cycling and aging. During the initial stages of aging, electrochemical impedance spectra revealed increased local resistance near the particle–electrolyte interface. This is likely attributable to factors such as secondary particle grain separation and the redistribution of carbon black. The swelling of particles, compression of the binder phase, and enhanced particle contact were identified as probable factors adding to the elevation of the elastic modulus within the porous layer as a result of cycling. [ABSTRACT FROM AUTHOR]

• Introduces fabrication-scale solvent-free dry electrode process with PTFE binder. • Defines unit process, equipment, intermediate products, and characterization methods. • Interprets the relationship between intermediate products and cell performance. Conventional wet-electrode manufacturing encounters challenges in producing thicker electrodes due to issues related to solvent evaporation. This study introduces a novel method for fabricating solvent-free dry electrodes using polytetrafluoroethylene (PTFE) as a binder, representing a significant advancement in electrode manufacturing processes. By eliminating the use of solvents, this method not only addresses these challenges but also offers a scalable and practical solution for mass production. The process is meticulously structured into sequential unit operations, each specifically tailored for a distinct function, utilizing the distinctive fibrillation properties of PTFE. Intermediate product specifications for each phase are clearly defined, accompanied by a comprehensive analysis of both physical and electrochemical performances. This analysis highlights the influence of varying PTFE contents and properties on the microstructure of the dry electrode. Notably, the study achieves a significant breakthrough with an electrode formulation of NCM811/PTFE/carbon black (CB)/carbon nanotube (CNT) = 96/2.0/1.8/0.2, which demonstrates exceptional discharge rate capability of 80 % at a 0.5 C-rate (5 mA/cm2) under the demanding parameters of 10 mAh/cm2 and 3.8 g/cc. This approach not only enhances the microstructural properties of dry electrodes but also paves the way for environmentally friendly and efficient electrode manufacturing for future energy storage applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Water-based processing of electrodes is associated with an enhanced environmental footprint for lithium-ion battery (LIB) production in conjunction with reduced costs. This trend is accompanied by an increasing demand for electrode dispersion processing in inkjet printing. However, most of the dispersion components show a low inherent dispersibility with poor stability in aqueous formulations. This is particularly important when it comes to qualifying electrode dispersions for use in inkjet printing, since the effect of agglomeration and sedimentation effects must be effectively prevented. Therefore, additives are needed to improve the dispersive behavior. This paper analyzes the suitability of dispersants for organic electrode components, in particular graphite and carbon black. An empirical approach was devised on the basis of comprehensive theoretical considerations. Empirical investigations revealed that the utilization of polyvinylpyrrolidone (PVP) favored the enhanced stabilization of graphite nanoparticles. The addition of Triton X-100 (TX-100) resulted in an improved stabilization of carbon black. Based on these empirical studies, a methodology was derived, which supports the application of suitable dispersants in printable dispersions. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy was used to analyze a 70% Si/C/perfluorooctene-carbon black/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping (CAMP) Facility, Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.83 401 nm). A survey spectrum together with O 1s, C 1s, and Si 2p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor sodium, copper, calcium, and lithium signals and show the expected silicon-carbon, carbon-fluorine, and silicon-fluorine species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy was used to analyze a 70% Si/C/polyvinylidine difluoride/carbon black/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping Facility (CAMP), Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). A survey spectrum together with O 1s, C 1s, and Si 2p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor copper and lithium signals and show the expected silicon-carbon and silicon-fluorine species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy (XPS) was used to analyze a 70% Si/C-carbon black/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping Facility (CAMP), Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). An initial survey spectrum together with O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor copper, nitrogen, calcium, and lithium signals and show the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure as well contributions related to the binder material. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy was used to analyze a 15%Si/C-graphite/carbon black/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping Facility (CAMP), Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.83 401 nm). An initial survey spectrum together with O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor nitrogen and lithium signals and show the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure as well contributions related to the binder material. [ABSTRACT FROM AUTHOR]

Summary: A Fe2O3@C/Co3O4 hybrid composite anode is synthesized via a two‐step hydrothermal method in which the acetylene carbon black component serves as a conductive matrix and as an effective elastic buffer to relieve the stress from Fe2O3@C and Co3O4/C during the electrochemical testing. The crystallinity, structure, morphology, and electrochemical performance of the composites are systematically characterized. Galvanostatic charge/discharge measurements of Fe2O3@C/Co3O4 present the excellent rate performance and cyclic stability. Its reversible capacity reaches 1478 mAh·g−1 after 45 cycles, and it is equal to 1035 mAh·g−1 after 350 cycles at a current density of 200 mA·g−1. Furthermore, the changes after 30, 45, 60, 90, and 120 cycles are investigated. It is found that the electrochemical performance varies with the morphological change of the electrode surface. Correspondingly, the microstructure, cyclic voltammetry curves, and Nyquist plots significantly change as a consequence of cycling. The results of this study provide an understanding of the increased capacity and excellent cyclic performance of a new anodic material for Li‐ion batteries. [ABSTRACT FROM AUTHOR]

Sedimentation of opaque suspensions of carbon black and lithium-iron-phosphate was investigated by spin-echo-based magnetic resonance imaging. Optical methods are usually applied to determine settling velocities, but are limited with respect to high concentrations and optical transparency. The presented method uses intensity data from the noninvasively measured magnetic resonance signal of the sample. The settling velocity is obtained from the evolution of the signal intensity profiles based on the contrast in 1H magnetic resonance imaging between particles and liquid. New insights into the sedimentation in opaque suspensions are provided, since the 1H images uncover the spatial distribution of the particles and its agglomerates, as well as the shape of the settling front. Additionally, the sedimentation was experimentally studied using a sedimentation balance, which gravimetrically measures the increase in mass fraction over time due to the settling of particles. By parallel usage of these two methods, the sedimentation processes of opaque suspensions of lithium-ion-battery electrode materials were investigated. The sedimentation balance covers high, technically relevant concentrations. Limiting factors of the methods are discussed, which are mainly signal intensity in the magnetic resonance imaging and the increasing viscosity of highly concentrated suspensions. [ABSTRACT FROM AUTHOR]

Abstract: Polymer binder plays a critical role in controlling the microstructure of electrode composites. Compared to synthesizing new binder molecules, polymer blends combining the advantages of different polymers represent a low‐cost, facile, and effective strategy for the design of advanced binder systems. In this study, we aim to improve the poly(vinylidene fluoride) (PVDF) binder performance by blending with other functional polymers, including polyethylene‐block‐poly(ethylene glycol) (PE‐PEG) co‐polymer and poly(propylene carbonates) (PPCs). It is found that the PE‐PEG co‐polymer acting as a surfactant for carbon black (CB) can improve the dispersion of CB and, thus, result in a more uniform conductive network in the electrode composites. The addition of PPC, an amorphous polymer with good affinity to liquid electrolytes, can reduce the crystallinity of PVDF and improve the component interactions. Benefiting from the improved structure uniformity, the specific capacity and C‐rate performance of the resultant electrodes were notably improved, as compared with that of pure PVDF binder. These results indicate that polymer blending is a facile method to modify the PVDF binder and improve the uniformity and interfaces of electrode composites. [ABSTRACT FROM AUTHOR]

We report experimental evidence for the specific Li-storage at turbostratic graphene edges of a well-known and cheap Super P ® carbon black (Csp) material, which is usually used as a conductive additive in composite electrodes. Indeed, operando XRD and HR-TEM consistently demonstrate Li insertion occurs with zero expansion of graphene layer up to a composition of Li 0.4 C 6 (150 mA h/g) that is reached at 0.01 V vs. Li + /Li. 7 Li NMR substantiates these results and suggests that the weak electronic transfer from the carbon host to the intercalant could help local reorganization of the layer order as suggested by the unexpected reversible changes of the (002) Bragg peak intensity during the charge-discharge process. Our observations also indicate this insertion mechanism is kinetically favored resulting in remarkable cycling stability over 1000 cycles and power capability allowing to sustain 110 mA h/g at 8 A/g (21 C) in half cell. The capability of Csp as an efficient anode is ultimately demonstrated in a lithium hybrid capacitor against a positive electrode of activated carbon. The full cell delivers a maximum energy of 120 Wh/kg (4.3–2 V) and remarkable capacity retention over 1800 cycles. [ABSTRACT FROM AUTHOR]

Due to its high theoretical capacity, silicon is a promising active material candidate for the negative electrode of lithium ion batteries. One way to reduce the severe degradation of silicon during charge/discharge cycling, is to use blends of different active materials and a well-balanced ratio of active and inactive materials. To ensure high-energy densities while still maintaining good electronic conductivity and ionic mobility, the necessity of nano-scale conductive carbons within a graphite/silicon composite was evaluated in this study. In particular, the correlation of silicon particle size and the presence of conductive additive was studied in electrodes, predominantly consisting of graphite (15 wt% silicon). Carbon black as conductive additive has a high contact surface area, which can enhance the electronic conductivity within the electrode and thus the rate capability, however, it can also propagate parasitic side reactions. It was determined that composite electrodes containing micron-sized silicon particles depend on the addition of conductive additives with regard to electrochemical performance. Due to high contact area and small transport distances, electrodes based on nano-sized silicon showed comparable capacity retention and a higher specific discharge capacity. Omitting conductive particles from these composite electrodes allowed lower binder amounts, while maintaining a good mechanical electrode integrity. [Display omitted] • Optimization of C/Si-based composite electrode formulation. • Impact of different Si particle sizes varying from nano-to micro-scale. • Evaluation of the necessity of conductive additives in C/Si-based electrodes. • Reduction of inactive material content to maximize energy density. [ABSTRACT FROM AUTHOR]

Electrode processing and performance strongly depend on the active material. Maximizing the active material content of positive composite electrodes enables low cost and high energy density. However, this maximization cannot reach 100%, as composite electrodes additionally consist of binder to provide mechanical integrity and conductive additive to enhance electronic conductivity, which in combination create a flexible porous microstructure for appropriate electron and lithium transport. In this study, the influence of three positive active material classes, layered oxide LiNi 0.6 Mn 0.2 Co 0.2 O 2 , spinel-type LiMn 2 O 4 and olivine-type carbon-coated LiFePO 4 , were investigated regarding the optimum amount of polyvinylidene difluoride as binder and carbon black as conductive additive to achieve high mechanical stability as well as high electronic and ionic conductivity within composite electrodes. Formulation optimization was conducted and compared to a reference electrode formulation with regard to physical, mechanical, electronic and electrochemical properties. In a first step, the binder amount was optimized for each active material class by varying the ratio of binder content to surface area of the solid electrode components. In a second step, the critical conductive additive content was determined. Overall, this strategy allows to decipher material class dependent optimized electrode formulations for high energy density composite electrodes with maximized active material content. [Display omitted] • Strategy to develop material class dependent electrode formulations. • Active material particle surface and size affects binder and conductive additive amount. • Carbon-coated LiFePO 4 based composite electrodes show a high SOH with low conductive additive content. [ABSTRACT FROM AUTHOR]

Many studies have been recently conducted on Ni-rich cathodes to increase cell capacity. The improvement of cell capacity is reaching its limit by increasing Ni content of a cathode material. In addition, increasing Ni content of a cathode material is unsafe due to gas evolution. Thus, research on Ni-rich cathode should proceed in parallel with the development of cell design, i.e., thickening electrode. However, during a calendering process, upper layer particles with low mechanical strength can be fractured, which is a problem with a thick electrode. To solve this issue, electrodes were designed using single crystalline lithium nickel cobalt manganese oxides (NCM) of high mechanical strength together with existing polycrystalline NCM in the present study. Four types of electrodes were tested to determine the best design for the electrode. Among them, double layer of upper layer with single crystalline and lower layer with polycrystalline (DB) completely prevented particle fracturing in the upper layer while maintaining sufficient tortuosity within the electrode. The reaction within the electrode was much more uniform than in other samples. As a result, DB had higher capacity of 34.6 mAh g−1 than the pristine after 40 cycles and a higher capacity of 50.5 mAh g−1 at 2C. • Particles on the upper layer of electrode can be fractured by the pressing force. • The carbon black and PVDF of the upper layer can be agglomerated. • The upper layer of the DB was entirely made of SC, there was no upper layer crack. • The DB enabled a uniform reaction within the electrode without upper layer crack. [ABSTRACT FROM AUTHOR]

Conductive additives, like carbon black or graphite, are essential components of lithium ion batteries due to the limited electrical conductivity of most electrode materials. However, there is still a lack of knowledge about the optimized distribution of these materials within the electrode. A dry mixing process is used in order to prepare a conductive coating by depositing carbon black on the surface of Li(Ni 1/3 Mn 1/3 Co 1/3 )O 2 (NMC) cathode particles. It is demonstrated that this – from a theoretically point of view – favorable distribution does not allow the preparation of working electrodes without taking into account the role of the binder. After adding an organic binder to the slurry, the polymer deposits on top of the carbon shell during drying and inhibits the conductive contact between the particles. This can be avoided by a fraction of distributed carbon particles which are associated with the binder phase providing conductive paths through the isolating organic material. It is shown that carbon black and graphite are principally fulfilling this task, but both materials are leading to varying processing behavior and electrode properties. [ABSTRACT FROM AUTHOR]

The conductive network within a lithium-ion battery electrode is mainly influenced by the process parameters chosen for the dry mixing and wet dispersing step during the production of a coatable electrode slurry, consisting of well-defined components. This conductive network, which results from the electrode's microstructure, plays a major role for the resulting battery cell performance, especially for high performance and power applications. Notable differences can be observed in the subsequently manufactured electrodes due to process-related modifications in the carbon black agglomerate size; mechanical, electrical, and, thus, electrochemical properties are significantly changing with the process parameters set. To allow for a direct correlation of these properties with the electrode structure, a characteristic parameter to describe the carbon black structure in electrode coatings is developed. Based on mercury intrusion measurements, the internal porosity of carbon black particles was determined as a characteristic parameter for the conductive microstructure. For a wide variety of lithium-ion battery cathode samples, the carbon black porosity can be well related to important electrode properties. This underscores the relevance of this carbon black-based microstructure parameter for a knowledge-based process and product optimization. [Display omitted] • Carbon black porosity as a structural parameter for LIB is developed and proven. • Wet dispersion and dry mixing can be used to adjust the carbon black porosity. • Carbon black porosity determines C-rate performance in the form of an optimum curve. [ABSTRACT FROM AUTHOR]

For a given proportion of active material, conductive agent, and binder, performance of the lithium ion battery depends on microstructure of the electrode. Uniform distribution of de-agglomerated particles of carbon black on the active material in the slurry is crucial for establishing a conductive network around the active particles and for improving the adhesion of the electrode to the current collector. Herein, we demonstrate that pre-mixing of carbon black and LiFePO 4 via dry ball-milling achieves the desired microstructure in the electrode coating. Homogeneity of slurry of LiFePO 4 in Poly(vinylidene fluoride)/N-methyl -2-pyrrolidone is demonstrated using measurement of viscosity and dynamic light scattering. Dried electrodes are shown to be uniform via SEM imaging and by a novel "linearly resolved electrical resistivity measurement" technique. Through peel tests it is shown that adhesion of the electrode to the current collector is improved. These improvements reflect in the electrochemical characteristics of the electrode such as increased cycling stability, higher exchange current density and ability of the electrode to perform at a higher C-rate. The electrodes prepared with this method, at an optimal composition, give a higher discharge voltage of ~3 V at 10 C compared to values of 2.4–2.8 V reported for unmodified LiFePO 4 so far. Image 1 • Pre-mixing of carbon black-LiFePO 4 for electrode's desired microstructure. • A novel "linearly resolved electrical resistivity measurement" technique. • The homogeneity of the slurry is measured using rheological properties. • Effective transfer of LFP properties to the electrode performance. [ABSTRACT FROM AUTHOR]

We report the preparation of thick ceramic electrodes of the olivine LiFePO 4 (LFP) with high mass loading. These electrodes are preparated by means of Powder Extrusion Moulding (PEM), which is a technology easily scalable and cheap. These LFP cathodes are additive-free (neither binder nor extra carbon black) with ~0.5 mm thickness, allowing to develop very high areal capacity (13.7 mA h cm−2). By means of a strict control of sintering process, the carbon coating of the commercial LFP powder remains and the decomposition of the active material is prevented. The optimized self-supported LFP cathode presents good cyclability over 20 cycles at C/10 with no capacity loss. The good electrochemical performance of these novel LFP thick electrodes and their non-flammability make them interesting candidates for both mobile and stationary applications. Image 1 • Thick ceramic electrodes of LiFePO4 with high areal capacities (13.7 mA h cm-2). • Self-supported LFP cathode with good cyclability at C/10. • New generation of high performances and sustainable ultra-thick electrodes. • Thick electrodes (~500 μm) prepared by an easily scalable manufacturing process. [ABSTRACT FROM AUTHOR]

Lithium-alloying materials are of great interest to improve the gravimetric and volumetric energy density of lithium-ion batteries, though their associated volume fluctuation with cycling often leads to poor cycling performance. Active–inactive alloys and blending alloys with carbon materials are common strategies to accommodate volume fluctuation. Herein we set out to optimize graphite–SiO blend electrode formulations to eliminate rapid capacity fade. Electrodes with highly stable cycling were prepared by simple planetary mixing procedures, enabled by the use of just a fraction of a weight percent of commercial SWCNTs as the only conductive additive, and by the appropriate choice of binder/stabilizing agent. In fact, the use of SWCNTs allowed for graphite-free SiO electrodes with approximately 74% higher volumetric energy density relative to traditional graphite electrodes, and superior capacity retention in coin-type full-cell testing versus NMC532 cathodes. • Capacity retention of graphite–SiO blend electrodes is significantly improved by the use of a commercial single-walled carbon nanotube (SWCNT) product relative to carbon black. • Excellent cycling performance is achieved for a variety of blend formulations using only a fraction of a weight percent of SWCNT, and prepared with simple and scalable planetary mixing procedures. • The use of SWCNT conductive additive enables graphite-free SiO electrodes with 74% higher volumetric energy and superior full-cell cycling compared to graphite electrodes. [ABSTRACT FROM AUTHOR]