Cathode Particles Research Articles

Electro-Chemo-Mechanical Modeling of Composite Cathodes in All-Solid-State Li-Ion Batteries

A model-based understanding can assist and accelerate developing all-solid-state batteries (ASSB). In addition to chemo-mechanical influences within electrode particles (e.g., NMC) [1-2], a solid electrolyte (e.g., argyrodites) introduces additional interfacial interactions between electrode and electrolyte phases [3-5]. The present research derives and implements a coupled multi-physics finite-element model that captures electrochemical, transport, and structural behaviors of composite electrode structures. The models incorporate concentration-dependent and anisotropic material properties that are based on previously published combinations of experiment and density functional theory (DFT). These include stiffness and fracture toughness, porosity and crystallographic orientation, and operating conditions such as charge/discharge rates and external pressure.Figure 1 illustrates predicted stresses developed during electrode manufacturing. The relatively complex cathode microstructure is based on replicating scanning electron microscopy (SEM) images [6]. The composite electrode consists of electrode, electrolyte, and pore phases (Fig. 1a). As illustrated in Fig. 1b, the ASSB synthesis process involves applying and removing high compressive pressure, which causes plastic deformation and introduces residual stresses. Figure 1c shows residual von Mises stresses near electrode-electrolyte interfaces that can be on the order of a gigapascal. The synthesis-generated residual stresses serve as initial conditions for modeling the chemo-mechanics during battery cycling.During cell operation, spatially varying Li concentrations cause material deformation and associated stresses. Figure 1d shows predicted crack nucleation and growth during operation. Depending on the stress levels, crack nucleation and growth leads to cell degradation and capacity fade. The models predict interfacial fracture and phase separations using phase-field fracture theory. In phase-field formulation, the sharp cracks are approximated as diffuse cracks using a process-zone. High values of the phase parameter ξ (Fig. 1d) represent cracked surfaces. The structural disintegration and loss of active surface areas increase the tortuous path for Li/Li-ion transport, which eventually manifests as capacity-fade.The simulations are validated using published experimental work. The modeling approach, which combines phase-field and finite-element algorithms, is implemented using the COMSOL Multiphysics software. The models are expected to inform microstructure/manufacturing design and optimal operating conditions that improve cycling performance and limit/prevent mechanical damage.[1] K. Taghikhani, P.J. Weddle, J.R. Berger, and R.J. Kee. Modeling coupled chemo-mechanical behavior of randomly oriented NMC811 polycrystalline Li-ion battery cathodes. J. Electrochem. Soc., 168(8):080511, 2021.[2] R. Xu, Y. Yang, F. Yin, P. Liu, P. Cloetens, Y. Liu, F. Lin, and K. Zhao, Heterogeneous damage in Li-ion batteries: experimental analysis and theoretical modeling. J. Mech. Phys. Solids, 129, 160, 2019.[3] K. Taghikhani, P.J. Weddle, R.M. Hoffman, J.R. Berger, and R.J. Kee. Electro-chemo-mechanical finite-element model of single-crystal and polycrystalline NMC cathode particles embedded in an argyrodite solid electrolyte. Electrochim. Acta, 460:142585, 2023.[4] A. Bielefeld, D.A. Weber, R. Rueß, V. Glavas, and J. Janek. Influence of lithium ion kinetics, particle morphology and voids on the electrochemical performance of composite cathodes for all-solid-state batteries. J. Electrochem. Soc., 169(2):020539, 2022.[5] P. Minnmann, F. Strauss, A. Bielefeld, R. Ruess, P. Adelhelm, S. Burkhardt, S.L. Dreyer, E. Trevisanello, H. Ehrenberg, T. Brezesinski, F.H. Richter, and J. Janek. Designing cathodes and cathode active materials for solid-state batteries. Adv. Energy Mater., 12(35):2201425, 2022.[6] C. Doerrer, I. Capone, S. Narayanan, J. Liu, C.R.M. Grovenor, M. Pasta, and P.S. Grant. High energy density single-crystal NMC/Li6PS5Cl cathodes for all-solid-state lithium-metal batteries. ACS Appl. Mater. & interfaces, 13(31):37809–37815, 2021. Figure 1

Influence of Cathode Calendering Density on the Cycling Stability of Li-Ion Batteries Using NMC811 Single or Poly Crystalline Particles

Calendering of battery electrodes is a commonly used manufacturing process that enhances electrode packing density and therefore improves the volumetric energy density. While calendering is standard industrial practice, it is known to crack cathode particles, thereby increasing the electrode surface area. The latter is particularly problematic for new Ni-rich layered transition metal oxide cathodes, such as NMC811, which are known to have substantial surface-driven degradation processes. To establish appropriate calendering practices for these new cathode materials, we conducted a comparative analysis of uncalendered electrodes with electrodes that have a 35% porosity (industrial standard), and 25% porosity (highly calendered) for both single crystal (SC) and polycrystalline (PC) NMC811. PC cathodes show clear signs of cracking and decrease in rate capability when calendered to 25% porosity, whereas SC NMC811 cathodes, achieve better cycling stability and no penalty in rate performance at these high packing densities. These findings suggest that SC NMC811 cathodes should be calendered more densely, and we provide a comprehensive overview of both electrochemical and material characterisation methods that corroborate why PC and SC electrodes show such different degradation behaviour. Overall, this work is important because it shows how new single-crystal cathode materials can offer additional advantages both in terms of rate performance and cycling stability by calendaring them more densely.

Insight into interaction of electrode particles from spent lithium-ion batteries assisted by pyrolysis

Pyrolysis-assisted dispersion for electrode particles from spent lithium-ion batteries (LiBs) is an extremely effective means to improve subsequent recovery efficiency. The relationship between interaction energy and surface properties of electrode particles has been constructed. The XRD results demonstrated that the mineral phases of both anode and cathode particles, mainly composed of graphite and LiCoO2 respectively, had little changes using a pyrolysis process at 550 ℃ for 30 min. Nevertheless, pyrolysis treatment could remove the organic film of electrode particles to alter the surface properties effectively. With the organic film removal by pyrolysis, the subtraction value on the contact angle of cathode and anode particles was increased from 9.3° to 35.44°, while the difference in charge ability was increased from 0.35 mV to 23.21 mV. The interaction energy calculations also illustrated that the electrostatic repulsion energy and hydrophilic repulsion energy both increased significantly, resulting in the total interaction energy of anode and cathode particles being 1.7 and 3.8 times that before pyrolysis. Furthermore, the total interaction energy, which determined the dispersing of electrode particles in suspension, mainly depended on the hydrophilic force. The findings might propose an alternative means for enhancing particle interaction to improve the recycling efficiency of electrode materials from spent LiBs by flotation.

Photonic Synthesis and Coating of High‐Entropy Oxide on Layered Ni‐Rich Cathode Particles

High‐entropy materials have drawn much attention as battery materials due to their distinctive properties. Lithiated high‐entropy oxide (Li0.33(MgCoNiCuZn)0.67O, LiHEO) exhibits both high lithium‐ion and electronic conductivity, making it a potential coating material for layered Ni‐rich oxide cathodes (Li1+x(Ni1−y−zCoyMnz)1−xO2, NCM or NMC) in conventional Li‐ion battery cells; however, high‐temperature synthesis limits its application. Therefore, a photonic curing strategy is used for synthesizing LiHEO and the non‐lithiated form (denoted as high‐entropy oxide [HEO]), and nanoscale coatings are successfully produced on LiNi0.85Co0.1Mn0.05O2 (NCM851005) particles. To one's knowledge, this is the first report on particle coating with high‐entropy materials using photonic curing. NCM851005 with LiHEO‐modified surface shows good cycling stability, with a capacity retention of 97% at 1 C rate after 200 cycles. The improvement in electrochemical performance is attributed to the conformal coating that prevents structural changes caused by the reaction between cathode material and liquid electrolyte. Compared to bare NCM851005, the coated material shows a significantly reduced tendency for intergranular cracking, successfully preventing electrolyte penetration and suppressing side reactions. Overall, photonic curing presents a novel cost‐ and energy‐efficient synthesis and coating procedure that paves the way for surface modification of any heat‐sensitive material for a wide range of applications.

Core–Shell NCM Cathode Particles Mechanical Failure: Particle Cracking and Interfacial Debonding

Core–Shell NCM Cathode Particles Mechanical Failure: Particle Cracking and Interfacial Debonding

Cryo-STEM and Multiscale Microscopy of Earth-Abundant Cathode Particles

Cryo-STEM and Multiscale Microscopy of Earth-Abundant Cathode Particles

A Plastic-Crystal Electrolyte Layer Promotes Interfacial Stability of Ni-Rich Oxide Cathode in Li6PS5Cl-Based All-Solid-State Rechargeable Li Batteries.

Unfavorable parasitic reactions between the Ni-rich layered oxide cathode and the sulfide solid electrolyte have plagued the realization of all-solid-state rechargeable Li batteries. The accumulation of inactive by-products (P2Sx, S, POx n- and SOx n-) at the cathode-sulfide interface impedes fast Li-ion transfer, which accounts for sluggish reaction kinetics and significant loss of cathode capacity. Herein, we proposed an easily scalable approach to stabilize the cathode electrochemistry via coating the cathode particles by a uniform, Li+-conductive plastic-crystal electrolyte nanolayer on their surface. The electrolyte, which simply consists of succinonitrile and Li bis(trifluoromethanesulphonyl)imide, serves as an interfacial buffer to effectively suppress the adverse phase transition in highly delithiated cathode materials, and the loss of lattice oxygen and generation of inactive oxygenated by-products at the cathode-sulfide interface. Consequently, an all-solid-state rechargeable Li battery with the modified cathode delivers high specific capacities of 168 mAh g-1 at 0.1 C and a high capacity retention >80 % after 100 cycles. Our work sheds new light on rational design of electrode-electrolyte interface for the next-generation high-energy batteries.

Surface atomic arrangement of primary particles through pre-oxidation to enhance the performance of LiNi0.8Co0.1Mn0.1O2 cathode materials

The primary drawback of Ni-rich LiNixCoyMn1-x-yO2 (NCM, x ≥ 0.8) cathodes lies in their capacity and voltage fading, a phenomenon principally attributed to interfacial instability and intergranular cracks. This study introduces a simple pre-oxidation treatment to modify the grain boundary of LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material as an efficient solution to these issues. Spectroscopic analysis and atomic-level imaging affirm that this pre-oxidation treatment facilitates both the conversion of Ni2+ to Ni3+ and the formation of an ordered NiOOH structure on the surface of precursor primary particles. Consequently, the final NCM811 product displays a distinct layered structure with a reduced degree of Li/Ni disorder. Furthermore, a rock-salt phase surface reconstruction layer is in-situ induced on the surface of NCM811 primary particles during the solid-state lithiation process, providing a protective coating against further degradation of the R3¯m-layered phase beneath it. Therefore, this enhanced NCM811 demonstrates superior structural stability regarding phase transition, cathode-electrolyte interface structure, and morphological integrity. When compared to bare NCM811 and modified NCM811 based on secondary particles, this enhanced NCM811 exhibits greater reversible capacity, superior initial coulombic efficiency, and excellent capacity retention. This study thus offers a promising approach to induce the ordered surface reconstruction of primary cathode particles, forming a conformal protective layer that improves electrochemical stability.

Stabilized Li-rich Mn-based oxide cathode particles with an artificial surface in-Situ-preprocessing

The heavy hybrid anion and cation redox contributes to high discharge capacity for Li-rich Mn-based cathode material, but also raises a number of issues including the low initial coulombic efficiency (ICE), rapid attenuation of capacity and voltage and so on, which have prevented its commercialization for more than a decade. Herein, solid-liquid impregnating is conducted to in-situ-build an artificial surface for Li1.2Mn0.54Ni0.13Co0.13O2 (FLLO) particles, which concurrently constructed a anion-redox-free LiMn1.5Ni0.5O4 (LNMO) shell during FLLO synthesis process that completely encloses the FLLO lattice (A-2%-LNMO-FLLO), presents as solid solution structure between FLLO and LNMO coating interface and exhibits stronger bonding between coatings and FLLO cathode material. DSC, TEM and industry computed tomography (ICT) evidence that LNMO coatings is effectiveness in stabilizing the crystal structure of FLLO from macro and micro aspects, leading to the excellent electrochemical properties, such as A-2%-LNMO-FLLO exhibits a discharge capacity of 278mAh/g under 0.1C, and the capacity retention is 98.5 % after 200 cycles under 1C. Furthermore, the enhancement mechanism on electrochemical properties is investigated from aspects of reaction process and crystal structure stability. This paper can provide a theoretical and experimental support for the practical application of FLLO cathode material.

Alleviating the sluggish kinetics of all-solid-state batteries via cathode single-crystallization and multi-functional interface modification

The application of Li-rich Mn-based cathodes, the most promising candidates for high-energy-density Li-ion batteries, in all-solid-state batteries can further enhance the safety and stability of battery systems. However, the utilization of high-capacity Li-rich cathodes has been limited by sluggish kinetics and severe interfacial issues in all-solid-state batteries. Here, a multi-functional interface modification strategy involving dispersed submicron single-crystal structure and multi-functional surface modification layer obtained through in-situ interfacial chemical reactions was designed to improve the electrochemical performance of Li-rich Mn-based cathodes in all-solid-state batteries. The design of submicron single-crystal structure promotes the interface contact between the cathode particles and the solid-state electrolyte, and thus constructs a more complete ion and electron conductive network in the composite cathode. Furthermore, the Li-gradient layer and the lithium molybdate coating layer constructed on the surface of single-crystal Li-rich particles accelerate the transport of Li ions at the interface, suppress the side reactions between cathodes and electrolyte, and inhibit the oxygen release on the cathode surface. The optimized Li-rich cathode materials exhibit excellent electrochemical performance in halide all-solid-state batteries. This study emphasizes the vital importance of reaction kinetics and interfacial stability of Li-rich cathodes in all-solid-state batteries and provides a facile modification strategy to enhance the electrochemical performance of all-solid-state batteries based on Li-rich cathodes.

In Situ Electrochemical Polymerization of Cathode Electrolyte Interphase Enabling High-Performance Lithium Metal Batteries.

Lithium metal batteries (LMBs) with high-voltage nickel-rich cathodes show great potential as energy storage devices due to their exceptional capacity and power density. However, the detrimental parasitic side reactions at the cathode electrolyte interface result in rapid capacity decay. Herein, a polymerizable electrolyte additive, pyrrole-1-propionic acid (PA), which can be in situ electrochemically polymerized on the cathode surface and involved in forming cathode electrolyte interphase (CEI) film during cycling is proposed. The formed CEI film prevents the formation of microcracks in LiNi0.8Co0.1Mn0.1O2 (NCM811) secondary particles and mitigates parasitic reactions. Additionally, the COO- anions of PA promote the acceleration of Li+ transport from cathode particles and increase charging rates. The Li||NCM811 batteries with PA in the electrolyte exhibit a high capacity retention of 83.83% after 200 cycles at 4.3V, and maintain 80.88% capacity after 150 cycles at 4.6V. This work provides an effective strategy for enhancing interface stability of high-voltage nickel-rich cathodes by forming stable CEI film.

Stable and Fast Ion Transport Electrolyte Interfaces Modified with Novel Fluorine- and Nitrogen-Containing Solvents for Ni-Rich Cathode Materials.

Ternary nickel-rich layered oxide LiNi0.8Co0.1Mn0.1O2 (NCM811) is recognized as a cathode material with a promising future, attributed to its high energy density. However, the pulverization of cathode particles, structural collapse, and electrolyte decomposition are closely associated with the fragile cathode-electrolyte interphases (CEI), which seriously affect the electrochemical performances of ternary high-nickel materials. In this paper, fluorine- and nitrogen-containing methyl-2-nitro-4-(trifluoromethyl)benzoate (MNTB) was selected, which was synergistically regulated with fluoroethylene carbonate (FEC) to generate a robust CEI film. The preferential decomposition of MNTB/FEC results in the formation of an inorganic-rich (Li3N, LiF, and Li2O) CEI film with uniformly dense and stable characteristics, which is conducive to the migration of Li+ and the stability of the NCM811 structure and enhances the cycling stability of the battery system. Simultaneously, MNTB effectively suppresses the adverse reaction associated with increased polarization caused by higher interface impedance due to conventional single FEC additives, further improving the rate capability of the battery. Moreover, MNTB/FEC can effectively eliminate HF, preventing its corrosion on the NCM811 cathode. Under the synergistic effect of MNTB/FEC, after 300 discharge cycles at a high cutoff voltage of 4.3 V and a current density of 1 C (2 mA cm-2), the discharge capacity of the NCM811||Li battery was 150.12 mA h g-1 with a capacity retention of 81.10%, while it was only 32.8% for the standard electrolyte (STD). The discharged capacity of the MNTB/FEC-containing battery was about 115.43 mA h g-1 at the high rate of 7 C, which was considerably higher than that of the STD (93.34 mA h g-1). In this study, the designed MNTB as a novel solvent synergistically regulated with FEC will contribute to the enhanced stability of NCM811 materials at high cutoff voltages and at the same time provide an effective modified strategy to enhance the stability of commercial electrodes.

Unveiling the Degradation Mechanism of Sodium Ion Batteries Based on Na4Fe3(PO4)2P2O7 Cathode and Hard Carbon Anode Suggests Anode Particle Size Reduction for Cycling Stability

AbstractTo improve the cycle life of sodium‐ion batteries, it is essential to understand the microscopic processes that lead to cell degradation. The mismatched response time of anode and cathode has profound but poorly understood impact on cycle life. In this work, we combine electrochemical and materials characterization along with electrochemical modeling to investigate the root cause of degradation in sodium‐ion full cells made from Na4Fe3(PO4)2P2O7 (NFPP) cathodes and hard carbon (HC) anode. Our results pinpoint to the slow diffusion of Na in HC as the main cause of diffusional polarization that leads to cathode experiencing high local potentials and ultimately to active material loss over cycling. We demonstrate that by reducing the anode particle size, the diffusional timescales in anode can be matched with that of cathode to improve both extractable capacity as well as cycle life. These observations shed light on non‐intuitive and intricate ways in which cathode and anode can interact with each other to cause degradation in Na‐ion batteries and how microscopic understanding of these cause and effects can help design long lasting batteries.

Fully carbonate‐electrolyte‐based high‐energy‐density Li–S batteries with solid‐phase conversion

AbstractCarbonate‐electrolyte‐based lithium–sulfur (Li–S) batteries with solid‐phase conversion offer promising safety and scalability, but their reversible capacities are limited. In addition, large‐format pouch cells are paving the way for large‐scale production. This study demonstrates the in situ formation of a solid‐electrolyte interphase (SEI) as a protective layer using vinylene carbonate (VC), highlighting its industrial adaptability. A high reversible capacity is achieved by the lithiated poly‐VC SEI formed inside the cathode particles as a nanoscale ionic conduction path, along with the traditional surface protective layer. Furthermore, the severe dissolution of poly‐VC is mitigated by LiF derived from fluorine ethylene carbonate as a co‐solvent, enabling high rate performance and a long cycle life. A large 8 Ah pouch cell is successfully developed, which shows a high energy density of 400 Wh kg−1 based on the cell weight. This work demonstrates the high performance of large‐scale Li–S batteries with the in situ formation of a protective layer as a scalable technique for future applications.

Synergistic effect of hydrogen bond and carbon coating to suppress the capacity and voltage fading in Li-Rich cathode

The voltage and capacity degradation of high-capacity Li-rich Mn-based (LRM) batteries during cycling have been a formidable barrier to their commercial application. In this study, a modified material coated with 15 nm-thick hydroxy-rich carbon layer (C-LRM) is synthesized by hydrothermal method, and C-LRM-PAA electrode is assembled by combining C-LRM with LiPAA binder. The strong hydrogen bond formed by the rich carboxyl group in LiPAA and the hydroxyl group in C-LRM makes the components of the C-LRM-PAA electrode closely connected to avoid electrode cracking, and the coating of the carbon layer avoids the cracking of the cathode particles. Consequently, this unique combination successfully inhibits transition metal dissolution, diminishes charge transfer impedance, and augments the lithium-ion diffusion coefficient, all of which contribute to suppressing the capacity and voltage attenuation. The electrochemical performance shows that after 200 cycles at 1C, the capacity retention rate increases from 40.8 % to 75.5 %, and the voltage decay rate decreases from 2.925 mV per cycle to 2.135 mV per cycle. This provides a new perspective for the electrode design of high energy density LRM batteries.

Liquid‐Phase Preparation of Low‐Tortuosity Composite Cathode for High Active Material Content All‐Solid‐State Lithium Batteries

AbstractThe all‐solid‐state lithium batteries (ASSLBs) stand as a promising candidate for the next generation of high‐energy‐density batteries with superior safety. Nevertheless, achieving high energy density in ASSLBs necessitates the simultaneous realization of high active material content and loading, posing a significant challenge in ensuring effective Li‐ion conduction within the cathode. Notably, the inhomogeneous distribution of cathode particles causes high porosity and tortuosity within the composite cathodes, thereby adversely impacting the electrochemical performance of the battery. Herein, an in situ liquid‐phase method for the fabrication of LiNi0.8Co0.1Mn0.1O2(NCM811) composite cathode is proposed. This strategy ensures the generation of uniformly distributed and densely packed composite cathode, establishing a well‐networked conduction path that ensures exceptional electronic and ionic conductivity. ASSLBs utilizing LP‐cathode exhibit outstanding electrochemical performance. It delivers a high capacity of 233.3 mAh g−1 at 0.05 C with superior rate capability and remarkable long‐term cycling stability. Moreover, ASSLBs manifest exceptional electrochemical performance, even at a high cathode active material content of 80%. This underscores the efficacy of the liquid‐phase method in constructing low‐tortuosity electrodes and accelerating charge transport kinetics, thereby enhancing the overall performance of ASSLBs. This approach holds promise for addressing the challenges associated with achieving high energy density and facilitating the development of ASSLBs.

Enhanced Electrochemical Performance of Disordered Rocksalt Cathodes in a Localized High‐Concentration Electrolyte

Enhanced Electrochemical Performance of Disordered Rocksalt Cathodes in a Localized High‐Concentration Electrolyte

To Enhance the Performance of LiNi0.5Co0.2Mn0.3O2 Aqueous Electrodes by the Coating Process.

The Li+/H+ cation exchange reactions occur when the cathode is exposed to water and can cause the degradation of battery performance, posing a significant challenge in the preparation of cathode aqueous electrodes. In this study, kh570 [3-(trimethoxysilyl)propyl methacrylate] is used to coat and modify the surface of LiNi0.5Co0.2Mn0.3O2 cathode particles. During the coating process, kh570 undergoes hydrolysis to generate silanol groups, which are subsequently bonded onto the surface of cathode particles and undergo self-polymerization through condensation reactions. As a result, a coating layer forms on the surface of the cathode. This change alters the surface properties of the cathode particles from hydrophilic to hydrophobic, thereby increasing their resistance to water. The coating layers reduce direct contact with water and minimizes internal particle microcracks formation in aqueous electrode processing. After the preparation of aqueous electrodes, the modified cathode exhibits lower transfer resistance and lower polarization, improving both the current rate performance and the cycling performance of the battery.

Bifunctional low molecular weight polyacrylic acid as aqueous binder and coating agent enables high performance LiMn2O4 cathode for lithium-ion batteries

LiMn2O4 is considered to be a promising cathode material for lithium-ion batteries due to its decent energy density, low price and environmental benignity. However, the problems of Mn dissolution, migration and deposition during the cycle, seriously affect its lifespan, especially at high temperature. In this study, we developed a strategy by which we killed two birds with one stone. A low molecular weight polyacrylic acid (PAA) mixed with sodium carboxymethyl cellulose (CMC) is applied as binder and coating agent for cathode particles at the same time. The conventional and environmental unfriendly polyvinylidene difluoride (PVDF)-N-methylpyrrolidone (NMP) system is replaced by the cheap and green aqueous binder with improved adhesive effect. Furthermore, the binder-based surface coating layer not only alleviates the side reaction between the electrolyte and the cathode particles, but also chelates the dissolved Mn2+ by the large amount of carboxyl groups in PAA molecules and so prevents the following migration and deposition of Mn2+. In the button half-cell with low molecular weight PAA based binder, the capacity retention reaches 94.1 % after 1000 cycles at room temperature and 92.0 % after 200 cycles at 60 degrees centigrade. Meanwhile, 18650-type cylindrical cells were prepared with this binder, which shows a great high temperature storage performance. After the cell was held at 60 degrees centigrade for 25 days at full charged state, the internal resistance increased by only 1.25mΩ, the voltage decreased by only 0.1 V, the residual capacity retention and recovery capacity retention reaches 85.6 % and 92.2 %. This work shows the great potential of the aqueous binder in dealing with the problem of Mn dissolution during the cycling of manganese-based cathode materials for lithium-ion batteries.

Resource Recovery of Spent Lithium-Ion Battery Cathode Materials by a Supercritical Carbon Dioxide System.

The increasing global market size of high-energy storage devices due to the boom in electric vehicles and portable electronics has caused the battery industry to produce a lot of waste lithium-ion batteries. The liberation and de-agglomeration of cathode material are the necessary procedures to improve the recycling derived from spent lithium-ion batteries, as well as enabling the direct recycling pathway. In this study, the supercritical (SC) CO2 was innovatively adapted to enable the recycling of spent lithium-ion batteries (LIBs) based on facilitating the interaction with a binder and dimethyl sulfoxide (DMSO) co-solvent. The results show that the optimum experimental conditions to liberate the cathode particles are processing at a temperature of 70 °C and 80 bar pressure for a duration of 20 min. During the treatment, polyvinylidene fluoride (PVDF) was dissolved in the SC fluid system and collected in the dimethyl sulfoxide (DMSO), as detected by the Fourier Transform Infrared Spectrometer (FTIR). The liberation yield of the cathode from the current collector reaches 96.7% under optimal conditions and thus, the cathode particles are dispersed into smaller fragments. Afterwards, PVDF can be precipitated and reused. In addition, there is no hydrogen fluoride (HF) gas emission due to binder decomposition in the suggested process. The proposed SC-CO2 and co-solvent system effectively separate the PVDF from Li-ion battery electrodes. Thus, this approach is promising as an alternative pre-treatment method due to its efficiency, relatively low energy consumption, and environmental benign features.