Polyvinylidene Fluoride Binder Research Articles

Eco-friendly aqueous binder derived from waste ramie for high-performance Li-S battery

Even the sulfur cathode in lithium-sulfur (Li-S) battery has the advantages of high theoretical energy density, wide source of raw materials, no pollution to the environment, and so on. It still suffers the sore points of easy electrode collapse due to large volume expansion during charge and discharge and low active materials utilization caused by the severe shuttle effect of lithium polysulfides (LiPSs). Therefore, in this work, ramie gum (RG) was extracted from ramie fiber degumming liquid and used as the functional binder to address the above problems and improve the Li-S battery's performance for the first time. Surprisingly, the sulfur cathode using RG binder illustrates a high initial capacity of 1152.2 mAh/g, and a reversible capacity of 644.6 mAh/g after 500 cycles at 0.5 C, far better than the sulfur cathode using polyvinylidene fluoride (PVDF) and sodium carboxymethyl cellulose (CMC) binder. More importantly, even if the active materials loading increased to as high as 4.30 mg/cm2, the area capacity is still around 3.1 mAh/cm2 after 200 cycles. Such excellent performances could be attributed to the abundant oxygen- and nitrogen-containing functional groups of RG that can effectively inhibit the shuttle effect of LiPSs, as well as the excellent viscosity and mechanical properties that can maintain electrode integrity during long-term charging/discharging. This work verifies the feasibility of RG as an eco-friendly and high-performance Li-S battery binder and provides a new idea for the utilization of agricultural biomass resources.

Biodiesel production from the Scenedesmus sp. and utilization of pigment from de-oiled biomass as sensitizer in the dye-sensitized solar cell (DSSC) for performance enhancement

Dye-sensitized solar cell (DSSC) using algal photosynthetic pigments has got rampant attention as it converts sunlight into electricity. Therefore, in this present research, the neutral lipid extracted from the green alga Scenedesmus sp. was used for biodiesel production, and concurrently, pigments extracted from the de-oiled biomass cake were used as a sensitizer in DSSC to evaluate its performance efficacy with and without PVDF (Polyvinylidene fluoride). Initially, neutral lipids extracted from the Scenedesmus sp. were converted to biodiesel with a yield of 72.9%, and the de-oiled biomass was subjected to pigment extraction (17.65 mg/g) to use as a sensitizer in DSSC. This study proposes two DSSC test models, i.e., PVDF (Polyvinylidene fluoride) - bound cell and cell without any PVDF binder. For the PVDF-coated DSSC, the average energy conversion efficiency reached about 14.3%, the open circuit voltage was 0.55 V, and the short circuit current was 144.5 mA. The unbound cells showed a reduction in efficiency, voltage, and current, and notably, efficiency of 10.44% on day 1 was decreased to 3.32%, and the open circuit voltage and short circuit current of 0.38V and 144 mA were decreased to 0.24V and 130 mA after 10 days, under 40 mW/cm2 input power. The PVDF-coated solar cell has maintained its efficiency range of 16.32%–11.22%, which is higher than the PVDF-unbound cell for a tested timeline of 30 days. The fill factor of 0.47 was observed in PVDF- unbound DSSC under 40 mW/cm2 as input power, while it was increased to 0.577 when PVDF was used as a binder. The PVDF-coated cell has low degradation compared with the PVDF-uncoated cell. These results offer dual benefits as the production of biodiesel from microalgal lipids and electricity generation from the DSSC using the pigments of biodiesel-extracted algal biomass.

Nitrogen-ion-irradiated defective tin oxyhydroxide nanoparticle anode for ultrafast and highly stable lithium-ion storage

High-performance lithium-ion batteries require high energy density, long cycle life, and fast (dis)chargeability. Despite several accomplishments in increasing capacity under normal operation, maintaining high capacity under fast charging and discharging remains a challenge. To achieve such performance, we have applied nitrogen-ion (N+) irradiation to an anode material comprising tin oxyhydroxide nanoparticles (Sn6O4(OH)4 NPs) active material, carbon black conducting agent, and polyvinylidene fluoride (PVDF) binder. Sn6O4(OH)4 NPs have high capacity and fair rate capability due to their layered structure with a large interlayer spacing of 0.455 nm and a small particle size of < 5 nm. N+ irradiation induces multiple defects including implanted N+ and oxygen vacancies in the anode material. The defects provide more Li-ion active sites in the Sn6O4(OH)4 NPs and lead to amorphization of carbon black as well as increasing the conductivities of Sn6O4(OH)4 NPs. Additionally, N+ irradiation brings about cross-linking of PVDF, enhancing the binding property. As a consequence, the N+-irradiated anode shows significantly improved performance: a capacity maintains 2306 mA h g−1 after 500 cycles at 0.5C and 1053 mA h g−1 after 300 cycles at 5C. Moreover, the anode exhibits outstanding rate capability even under ultrahigh-rate operation: 65.1 % capacity retention at 50C.

Improving LiFePO4 cathode stability in lithium-ion batteries by hybridizing activated tannic with PEDOT:PSS binders

The conventional binder polyvinylidene fluoride (PVDF) exhibits substantial polarization resistance at high magnification because of its inertness to Li+ and electrons. In addition, 1-methyl-2-pyrrolidinone (NMP) solvents are toxic, expensive, and environmentally harmful. In this study, we enhanced the poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) binder by incorporating varying ratios of tannic acid (TA) to develop a water-soluble TA-PEDOT:PSS (TAPE) binder. TAPE1,1 with a TA to PEDOT:PSS ratio of 1:1, designated as TAPE1,1, exhibited high tensile strength (7.55 N/m), low impedance (61 Ω), remarkable cycling stability of 121 mAh g−1 (retaining 83.6 % capacity over 1000 cycles), and excellent rate performance (95 mAh g−1 at a 10C rate). Consequently, this study provides valuable insights into the design of high-performance lithium batteries.

Modelling Binder Degradation in the Thermal Treatment of Spent Lithium-Ion Batteries by Coupling Discrete Element Method and Isoconversional Kinetics

Developing efficient recycling processes with high recycling quotas for the recovery of graphite and other critical raw materials contained in LIBs is essential and prudent. This action holds the potential to substantially diminish the supply risk of raw materials for LIBs and enhance the sustainability of their production. An essential processing step in LIB recycling involves the thermal treatment of black mass to degrade the binder. This step is crucial as it enhances the recycling efficiency in subsequent processes, such as flotation and leaching-based processing. Therefore, this paper introduces a Representative Black Mass Model (RBMM) and develops a computational framework for the simulation of the thermal degradation of polymer-based binders in black mass (BM). The models utilize the discrete element method (DEM) with a coarse-graining (CG) scheme and the isoconversional method to predict binder degradation and the required heat. Thermogravimetric analysis (TGA) of the binder polyvinylidene fluoride (PVDF) is utilized to determine the model parameters. The model simulates a specific thermal treatment case on a laboratory scale and investigates the relationship between the scale factor and heating rate. The findings reveal that, for a particular BM system, a scaling factor of 100 regarding the particle diameter is applicable within a heating rate range of 2 to 22 K/min.

Failure Modes of Flexible LiCoO2 Cathodes Incorporating Polyvinylidene Fluoride Binders with Different Molecular Weights.

Understanding the mechanical failure modes of lithium-ion battery [Li-ion batteries (LIBs)] electrodes is exceptionally important for enabling high specific energy and flexible LIB technologies. In this work, the failure modes of lithium cobalt oxide (LCO) cathodes under repeated bending and the role of the polymer binder in improving the mechanical durability of the LCO electrodes for use in flexible LIBs are investigated. Mechanical and electrochemical evaluations of LCO electrodes (areal capacity of ≥2.5 mA h cm-2) employing poly(vinylidene fluoride) (PVDF) binder were carried out, followed by extensive optical and electron microscopies. We find that the molecular weight (MW) of the PVDF significantly influenced the surface and bulk microstructure of the LCO electrodes, particularly the distribution of carbon additive and binder, which plays a crucial role in affecting the mechanical and electrochemical properties of the electrodes. Multiple mechanical failure modes (e.g., surface scratches and microcracks) observed in the LCO electrodes subjected to repeated bending originated from the use of low MW PVDF; these failure modes were successfully mitigated by using a high MW PVDF. Remarkably, the optimized flexible LCO electrode incorporating high MW PVDF showed comparable discharge capacity retention during galvanostatic cycling after repeated bending (7000 cycles at 50 mm bending diameter) to electrodes not subjected to the repeated bending. This study highlights the importance of carrying out a comprehensive investigation of the failure mechanisms in flexible electrodes, which identified the pivotal role of the PVDF MW in the electrode microstructure and its effects on the electrode resilience to failure during repeated bending.

Hydrophilic and Hydrophobic Composite Microporous Layer Coated Gas Diffusion Layers for Performance Enhancement of Polymer Electrolyte Fuel Cells

A novel microporous layer (MPL) coated gas diffusion layer (GDL) is developed to improve water management of polymer electrolyte fuel cells (PEFCs) by incorporating hydrophobic and hydrophilic pores within the same layer. This MPL expels excess water at the interface between the catalyst layer and MPL through hydrophilic pores while maintaining efficient oxygen transport through hydrophobic pores, reducing oxygen transport resistance under high humidity conditions. The water permeability and relative oxygen permeance tests demonstrate the presence of separate hydrophobic and hydrophilic pores in the appropriate composite MPL. The effects of combinations of hydrophilic and hydrophobic binders used in the composite MPLs on the oxygen transport resistance are evaluated. The hydrophobic polytetrafluoroethylene (PTFE) binder and the hydrophilic polyvinyl alcohol (PVA) binder cannot enhance performance due to mismatched sintering temperatures. Although the hydrophobic polyvinylidene fluoride (PVDF) and PVA binders have the same sintering temperature, the performance was degraded due to the strong hydrophilicity of PVA. Another combination of composite MPL incorporates hydrophobic PVDF and Nafion binders. Hydrophilic TiO2 particles are introduced in the Nafion binder to reinforce the hydrophilicity. The appropriate composite MPL significantly reduced the total oxygen transport resistance compared to those obtained with the hydrophobic MPL.

Degradation of cathode in air and its influences on direct recycling

Delamination has been widely used in direct recycling of spent lithium-ion batteries (LIBs) as the first step to harvest cathode materials from cathodes. The variations of the recycling performance have been documented in many studies. The main mechanism of delamination is the inactivation of bonding forces provided by the polyvinylidene fluoride (PVDF) binder. It is believed that the storage environment (air exposure time) will affect the performances of delamination to some extent. Three representative methods (direct calcination, pressure washing, and NMP solvent extraction) for delamination were studied to elucidate the effect of air exposure time on delamination efficiency. The peel-off efficiency (98–99%) of the direct calcination method was barely influenced by air exposure time. The pressure washing system or NMP solvent extraction method also exhibited high peel-off efficiency using samples after a long air exposure time (1 month), however these methods may have problems regarding Al contamination, i.e., 11.5 mg/g of pressure washing system and 134.4 mg/g of NMP solvent extraction. Results suggest that enhanced adhesion (0.11 MPa/month) could be a potential reason why air contact time affects delamination, with O2 and/or H2O acting as contributors. This finding may help to maximum performance of delamination, as it highlights the importance of storage conditions of the spent LIBs prior to direct recycling.

Understanding the Drying Process and Mud Cracking of Li-Ion Battery Electrodes through Synchrotron X-Ray Computed Tomography

The drying process of slurry cast Li-ion battery electrodes is a subject with significant impacts on the performance of the battery but where detailed understanding is lacking(1). Mud cracking, opening of cracks in the surface due to stress from the slurry shrinking as it dries, is the most dramatic phenomenon during the process. Cracks may be detrimental to electrode performance due to delamination, which makes sections of the electrode unusable, or generally poor electrode cohesion. However, cracks could provide channels for ion transport to deeper levels of the electrode, similar to templated electrodes (2) but without the extra manufacturing steps. Cracking is prominent in thick (3-5) or water processed electrodes (3), which are desirable for greater energy density and replacement of the toxic solvent N-methyl pyrrolidone (NMP), respectively. Thus, understanding mud cracking during drying can lead to more energy dense (thicker), greener (without toxic NMP), and better performing electrodes (fast charging).Li-ion electrodes are industrially produced by casting a slurry on a metal foil current collector by a slot die or doctor blade method in a roll-to-roll machine. In the case of the positive electrode this slurry typically contains active metal oxide (e.g. LiNiMnCoO2, LiNi0.6Mn0.2Co0.2O2) particles, polyvinylidene fluoride (PVDF) binder, and carbon black. Drying is composed of three stages illustrated in Fig. 1 a-d, with the binder, carbon black settling and migrating at random (1),(6, 7). Crack formation is thought to occur during the third stage when capillary forces cause stress in the drying slurry opening cracks as solvent menisci form between particles. However, the process of crack nucleation and their 3-dimensional growth has never been directly observed in-situ(1),(4). X-ray computed tomography (Fig. 1 f-j) is able to show the morphology of cracks in an electrode and can be used to characterize properties like delamination, crack volume, crack network connectedness or crack network tortuosity, which can be linked to electrode performance. However, to understand how these crack networks form requires observation of the time evolution of the cracks and the movement of active material particles near the cracks, which requires fast measurements. Here, we present synchrotron x-ray computed tomography of drying electrode which enable the fast measurements required and allows us to more fully explain mud cracking in drying electrodes, and the drying process in general.References Y. S. Zhang, N. E. Courtier, Z. Zhang, K. Liu, J. J. Bailey, A. M. Boyce, G. Richardson, P. R. Shearing, E. Kendrick and D. J. L. Brett, Advanced Energy Materials, 2102233 (2021). C. Huang, M. Dontigny, K. Zaghib and P. S. Grant, Journal of Materials Chemistry A, 7, 21421 (2019). Z. Du, K. M. Rollag, J. Li, S. J. An, M. Wood, Y. Sheng, P. P. Mukherjee, C. Daniel and D. L. Wood, Journal of Power Sources, 354, 200 (2017). B. Lu, C. Ning, D. Shi, Y. Zhao and J. Zhang, Chinese Physics B, 29, 026201 (2020). R. Sahore, D. L. Wood, A. Kukay, K. M. Grady, J. Li and I. Belharouak, ACS Sustainable Chemistry & Engineering, 8, 3162 (2020). S. Jaiser, L. Funk, M. Baunach, P. Scharfer and W. Schabel, Journal of Colloid and Interface Science, 494, 22 (2017). Y. S. Zhang, A. N. Pallipurath Radhakrishnan, J. B. Robinson, R. E. Owen, T. G. Tranter, E. Kendrick, P. R. Shearing and D. J. Brett, ACS Applied Materials & Interfaces, 13, 36605 (2021). Figure 1

Laser-Induced Printing of Next Generation Silicon-Graphite Anodes for the Development of Advanced Lithium-Ion Batteries

The expansion of renewable causing a rising demand for affordable and improved energy storage systems. Lithium-ion batteries (LIB) are one of the most promising technologies for this achievement, with further improvements to be made in terms of new materials and an advanced electrode architecture. As a new generation electrode material to be included in LIB, silicon is in the focus of the today’s investigations. Silicon offers one order of magnitude higher theoretical specific capacity (3579 mAh/g) compared to the state-of-the-art material graphite (372 mAh/g). However, during lithiation of silicon a volume expansion of up to 300 % takes place. Due to the huge volume expansion tremendous mechanical degradation of the anode occurs, resulting in a drop in capacity and a shorten lifetime.Laser induced forward transfer (LIFT) is applied in this study as printing technology to develop enhanced silicon-graphite electrode compositions and electrode architectures. LIFT was performed using a pulsed nanosecond UV-laser with a maximum power of 10 W and repetitions rate of up to 30 kHz. For the LIFT process of anodes, polyacrylic acid (PAA) is used as binder, in contrast to the polyvinylidene fluoride (PVDF) binder commonly used for LIFT assisted printing of electrodes. PAA is a more appropriate binder for silicon-containing anodes than PVDF. In addition, also a customized architecture using subtractive and additive laser process techniques is introduced for an increase in lifetime of batteries containing silicon-based electrodes. For this purpose, graphite electrodes were structured with an ultrashort pulse laser with pattern widths of 100 µm. Subsequently, silicon rich slurry was printed into the patterns to increase the areal capacity. The as-prepared electrodes have spatially separated graphite and silicon regions. The respective electrodes were electrochemically cycled in half-cells and charged at different C-rates up to 5C to investigate their lithiation capability. After the rate capability analysis, the cells were cycled at C/2 to investigate the long-term degradation. The cells with the printed electrodes were cycled for more than 450 cycles with a capacity fade of 5 %. At their end-of-life, the cells were analyzed post-mortem. Finally, full-cells were assembled with cathodes containing NMC 622 as the active cathode material. Subsequently to the cell priming a lifetime analysis was performed at a C-rate of C/2 and cycle stability as well as lithium loss during cycling were evaluated.

Fluorides coated Ni-rich cathode materials with enhanced surficial chemical stability for advanced lithium-ion battery

Ni-rich cathode materials (LiNixCoyMnzO2 denoted as NCM, where x ≥ 0.8 and x + y + z = 1) with high energy density are considered as next-generation promising cathodes for lithium-ion batteries (LIBs). However, the high surface chemical sensitivity against CO2 and H2O in air triggers serious surface degradation. Meanwhile, the notorious surficial residual lithium compounds are often prone to react with polyvinylidene fluoride (PVDF) binder, resulting in slurry gelation, and further deteriorating electrochemical performance. Herein, a facile solvothermal strategy is proposed to construct thin and uniform fluoride coating layers on NCM surface (NCM-F) via in-situ reacting trifluoroethanol with residual lithium compounds. This fluoride protective layer not only significantly suppresses the surface deterioration by inhibiting Li+/H+ exchange, but also avoids the side reactions between NCM and electrolyte. As a result, NCM-F with low pH value of 11.2 exhibits highly chemical stability against ambient air, excellent processing performance and superior cyclic stability. More importantly, even after 4 weeks air aging, NCM-F demonstrates high initial capacity and low electrode polarization compared to pristine NCM (P-NCM). This work not only opens up new perspectives on surface modification of NCM cathodes, but also provides guidance on improving air stability for other functional materials.

A Solvent-Free Process Enabled by Polytetrafluoroethlyene/Carbon Black Composites for Fabricating Electrodes for Lithium-Ion Batteries with a High Volumetric Energy

Manufacturing electrodes for lithium-ion batteries (LIBs) consists of making a slurry, coating the slurry onto a current collector, drying the slurry to remove the solvent, and calendaring the electrode. Cathodes for LIBs are fabricated by a wet process using a toxic chemical, N-methyl-2-pyrrolidone (NMP). However, it is preferable to use a dry process without toxic chemicals, and with fewer manufacturing operations, which saves money. However, the powder-mixing step of the dry process makes it difficult to ensure a uniform distribution of the carbonaceous conducting agents and binder used, which agglomerate in the dry mixed product. To solve this problem, we fabricate a composite of polytetrafluoroethylene (PTFE) and carbon black (CB) nanoparticles. The electrode fabricated using the PTFE/CB composite has a 98 wt% active material content and 3.8 g cc−1 of electrode density. An electrode produced by the conventional wet process using a polyvinylidene fluoride (PVDF) binder and NMP solvent has a 96 wt% active material content and an electrode density of 3.4 g cc−1. The dry-processed electrode has a higher volumetric capacity (760 mAh cc−1) as well as a higher discharge rate capability and cycle life than a conventional wet-processed electrode.

Mitigating first charge overpotential of Li2S-based lithium-sulfur batteries by leveraging PVDF reaction with the LiOH/Li2O layer

The high overpotential observed during the first charging process of Li2S-based lithium sulfur batteries (Li2S-LSBs) poses a challenge for their development, as it leads to irreversible side reactions. One possible cause for this overpotential is the high hygroscopic nature of Li2S, which results in the formation of a highly insulating LiOH/Li2O layer on the surface of Li2S particles. This study proposes a novel method to reduce the first charge overpotential of Li2S-LSBs by utilizing the reaction between the polyvinylidene fluoride (PVDF) binder and the LiOH/Li2O layer on the surface of the Li2S particles. Model reactions demonstrate that LiOH or Li2O can readily react with PVDF through dehydrofluorination at room temperature. While a battery made with a Li2S cathode slurry containing PVDF, prepared using conventional grinding for 30 min, displays high charging voltages with an overpotential spike of 3.74 V during the first charge, a battery prepared using a slurry stirred for 48 h exhibits significantly reduced first charge voltages, with an overpotential spike of only 2.75 V. The study also reveals that PVDF can undergo similar dehydrofluorination with Li2S, which leads to a decrease in discharge capacity due to the consumption of some Li2S. This study provides new insights into the origin of overpotential during the first charging process of Li2S-LSBs and suggests that stirring Li2S cathode slurry in the presence of PVDF can effectively reduce the first charge overpotential of Li2S-LSBs.

Effects of incineration and pyrolysis on removal of organics and liberation of cathode active materials derived from spent ternary lithium-ion batteries

Removing organics via thermal treatment to liberate active materials from spent cathode sheets is essential for recovering lithium-ion batteries. In this study, the effects of incineration, N2 pyrolysis, and CO2 pyrolysis on the removal of organics and liberation of ternary cathode active materials (CAMs) were compared. The results indicated that the organics in the spent ternary cathode sheets comprised a residual electrolyte and polyvinylidene fluoride (PVDF) binder. Moreover, the organics could be removed to promote the liberation of CAMs via incineration, N2 pyrolysis, and CO2 pyrolysis. When the temperature was <200 °C, the chemical properties of the volatilized ester electrolyte remained unchanged during both N2 and CO2 pyrolysis, indicating that the electrolyte can be collected by controlling the pyrolysis temperature and condensation. Furthermore, PVDF binder decomposition occurred at 200–600 °C. The optimal temperatures of incineration, N2 pyrolysis, and CO2 pyrolysis were 550, 500, and 450 °C, respectively, and these treatments increased the liberation efficiency of CAMs from 81.49 % to 98.75 %, 99.26 %, and 97.98 %, respectively. In addition, heat-treated CAMs required less time to achieve adequate liberation. Following three thermal treatment processes, the sizes of the CAM particles were mainly concentrated in the ranges of 0.075–0.1 mm and <0.075 mm. Furthermore, for all types of CAMs examined, the Al concentration decreased from 1.09 % to <0.35 %, which increased the separation efficiency and improved the chemical metallurgical performance.

Simple Estimation of Creep Properties of Negative Electrode for Lithium-Ion Battery

The macroscopic creep properties of negative electrodes in lithium-ion batteries and their estimation methods have been investigated based on the microscopic structure of the electrode. Tensile and creep tests were conducted on a negative electrode consisting of carbon powder and polyvinylidene fluoride (PVDF) binder. The stress-strain curve, the time history of the tensile strain, and the creep rupture time were measured in these tests and estimated using the simple model proposed in this study. The proposed model approximates the alignment of carbon particles as body-centered cubic (bcc) or face-centered cubic (fcc). The external load on the model was supported by a PVDF binder located between carbon particles. The test results showed that PVDF binder mechanical properties affect the macroscopic mechanical properties of the negative electrode, including the creep properties. The stress-strain curve and time history of the tensile strain were located between the upper and lower limits of the proposed model. The tensile strength and creep rupture time agree with the lower limit of the proposed model.

Gum based functional binder for high-performance artificial graphite anode for lithium-ion batteries

Artificial graphite (AG), in contrast to natural graphite, has received much attention due to its superior rate capabilities and stability under high current density. Although the rate capabilities can be enhanced by employing artificial graphite, there is room for improvement in the cycle retention characteristics of artificial graphite. In particular, further optimization on the binder type on anodes is necessary, as commercially used polyvinylidene fluoride (PVdF) has limitations in long-term cycling stability. Furthermore, PVdF is dissolved in N-Methyl-2-pyrrolidone (NMP), which is not environmentally- and eco-friendly. In this work, we have introduced a water-soluble binder based on deacetylated kondagogu gum (KG) for AG anodes, which are derived from the gum tree. Upon deacetylation, kondagogu gum can be dissolved in water, which can be directly used together with active materials and conductive agents in a slurry. Replacing a PVdF binder with a KG binder results in an enhanced cycle retention and comparable rate capabilities, without the changes in the overall redox reactions with Li+. Postmortem analysis reveals that the improved electrochemical performance of the AG anode contributed to the excellent structural integrity of the KG binder compared with the PVdF binder.

Advancing radioactive material research method: the development of a novel in situ particle-attached microfluidic electrochemical cell

Introduction: This study aims to develop a microgram-scale microfluidic electrochemical cell (E-cell) for investigating the redox behavior of uranium oxide (UO2). The traditional bulk electrochemical methods may require shielded facilities to investigate the hazardous materials, e.g., spent nuclear fuel, due to high radiation levels. Microfluidic E-cells offer advantages such as reduced radiation exposure, control over fluid flow rates, and high-throughput capabilities.Methods: The design of the E-cell considers electrode morphology, adhesion to a thin membrane, electrode configuration, and vacuum compatibility. Three techniques, including FIB-SEM lift-out, Au coating, and polyvinylidene fluoride (PVDF) binder, are explored for fabricating and attaching microgram quantities of UO2 as working electrodes. The PVDF binder method proves to be the most effective, enabling the creation of a vacuum-compatible microfluidic E-cell.Results and discussion: The PVDF binder method demonstrates successful electrochemical responses and allows for real-time monitoring of UO2 electrode behavior at the microscale. It offers chemical imaging capabilities using in situ SEM/EDS analysis. The technique provides consistent redox outcomes similar to bulk electrochemical analysis.Conclusion: The development of a microgram-scale microfluidic electrochemical cell using the PVDF binder technique enables the investigation of UO2 redox behavior. It offers a low-risk approach with reduced radiation exposure and high-throughput capabilities. The technique provides real-time monitoring and chemical imaging capabilities, making it valuable for studying spent nuclear fuel systems and material characterization.

Development of a More Sustainable Hybrid Process for Lithium and Cobalt Recovery from Lithium-Ion Batteries

Lithium-ion batteries are widely used as a power source for portable devices and electrical vehicles (EVs). After their useful life, they can provide a secondary source from which to obtain some materials which make them up, such as lithium and cobalt. However, the metallurgical route which will be used to recover them must be considered. Therefore, is crucial that many efforts to develop more environmentally favorable recovery processes be pursued. Due to this, the present work aimed to use 1.5 M DL-malic acid and compare it to 2 M sulfuric acid, employing heat pretreatment of 1 h and 3 h to remove the powder cathode binder polyvinylidene fluoride (PVDF); for all conditions, experiments were carried out with and without adding the oxidizing agent hydrogen peroxide. The PVDF temperature degradation occurred at 630 °C. The best yields occurred in the presence of H2O2 10% v/v and heat pretreatment. With sulfuric acid (1 h) it was possible to recover 33.49% Co and 4.63% Li, and (3 h) 36.36% Co and 4.64% Li. With DL-malic acid it was possible to recover (1 h) 29.78% Co and 3.44% Li, and (3 h) 32.73% Co and 3.99% Li.

In-situ pyrolysis based on alkaline medium removes fluorine-containing contaminants from spent lithium-ion batteries

Pyrolysis is an effective method for removing organic contaminants (e.g. electrolytes, solid electrolyte interface (SEI), and polyvinylidene fluoride (PVDF) binders) from spent lithium-ion batteries (LIBs). However, during pyrolysis, the metal oxides in black mass (BM) readily react with fluorine-containing contaminants, resulting in a high content of dissociable fluorine in pyrolyzed BM and fluorine-containing wastewater in subsequent hydrometallurgical processes. Herein, an in-situ pyrolysis process is proposed to control the transition pathway of fluorine species in BM using Ca(OH)2-based materials. Results show that the designed fluorine removal additives (FRA@Ca(OH)2) can effectively scavenge SEI components (LixPOFy) and PVDF binders from BM. During the in-situ pyrolysis, potential fluorine species (e.g. HF, PF5, and POF3) are adsorbed and converted to CaF2 on the surface of FRA@Ca(OH)2 additives, thereby inhibiting the fluorination reaction with electrode materials. Under the optimal experimental conditions (temperature = 400 °C, BM: FRA@Ca(OH)2 = 1: 4, holding time = 1.0 h), the dissociable fluorine content in BM was reduced from 3.84 wt% to 2.54 wt%. The inherent metal fluorides in BM feedstock hinder the further removal of fluorine with pyrolysis treatment. This study provides a potential strategy for source control of fluorine-containing contaminants in the recycling process of spent LIBs.

Conversion-type Ni2.5Co0.5(PO4)2 phosphate as negative electrode material for rechargeable Li-ion batteries

The production of clean energy requires efficient energy storage systems, such as Lithium-ion batteries, to store wind and solar energy. To meet this demand, suitable electrode materials must be chosen. Conversion-type negative electrode materials are considered promising candidates due to their high reversible capacity. In this study, pure Ni2.5Co0.5(PO4)2 (NCP) orthophosphate was synthesized using a solid-state reaction at 900 °C in air and its electrochemical behavior was studied for the first time as a negative electrode material. Carboxymethyl cellulose (CMC) and polyvinylidene fluoride (PVDF) binders were used and the obtained performances were compared. The electrochemical properties were explored over a voltage range of 0.5 – 3.0 V and 0.01 – 3.0 V. The results showed that NCP exhibits the best electrochemical properties, delivering a high reversible discharge capacity of 200 mAh g−1 after 30 cycles at a C/5 current rate over 0.01 – 3.0 V voltage range, using a water-based CMC binder. Additionally, NCP@C delivers a reversible discharge capacity of 211 mAh g−1 after 400 cycles at a 2 C rate with a coulombic efficiency of 100 %