A sustainable approach to cathode delamination using a green solvent

Direct Regeneration of Spent Lithium-Ion Battery Cathodes: From Theoretical Study to Production Practice

Direct regeneration method has been widely concerned by researchers in the field of battery recycling because of its advantages of in situ regeneration, short process and less pollutant emission. In this review, we firstly analyze the primary causes for the failure of three representative battery cathodes (lithium iron phosphate, layered lithium transition metal oxide and lithium cobalt oxide), targeting at illustrating their underlying regeneration mechanism and applicability. Efficient stripping of material from the collector to obtain pure cathode material has become a first challenge in recycling, for which we report several pretreatment methods currently available for subsequent regeneration processes. We review and discuss emphatically the research progress of five direct regeneration methods, including solid-state sintering, hydrothermal, eutectic molten salt, electrochemical and chemical lithiation methods. Finally, the application of direct regeneration technology in production practice is introduced, the problems exposed at the early stage of the industrialization of direct regeneration technology are revealed, and the prospect of future large-scale commercial production is proposed. It is hoped that this review will give readers a comprehensive and basic understanding of direct regeneration methods for used lithium-ion batteries and promote the industrial application of direct regeneration technology.

A comprehensive review of emerging technologies for recycling spent lithium-ion batteries

Along with the increasing demand for lithium-ion batteries (LIB), the need for recycling major components such as graphite and different critical materials contained in LIB is also reaching a peak in the research community. Several authors review the different LIB recycling methodologies, including pyro- and hydrometallurgy processes. However, the characteristics, main stages, and achievements of LIB emerging recycling are still missing. This study reviews the diverse emerging approaches for recycling critical materials from spent LIB in the last five years. A classification for emerging recycling technologies is provided, including terms like development stage and eco-friendly status. The main stages of recycling LIB are opening, phase separation, and materials recovery. Among the emerging proposals with the highest industrialization potential are direct recycling techniques due to low costs and simple procedures. Concerning phase separation, froth flotation and ultrasound-assisted methods are discussed. The former divides black mass into pure anodic and cathodic materials, while ultrasonication is employed to physically detach active materials from foils or enhance binder degradation. As to materials recovery, several recent approaches show high recovery efficiency for different elements, mainly in leaching. The use of new organic acids, deep eutectic acids, and some salts are worth noting as leaching agents due to their low environmental impact. In addition, leaching methods assisted by ultrasound and microwave irradiation increase valuable metal recovery, reducing time consumption and the number of leaching reactants. As a part of the hydrometallurgy process, metallic ion purification is performed by solvent extraction and ion exchange, while selective precipitation can be achieved by specific chemical agents or electrochemical processes.

Challenges in Recycling Spent Lithium-Ion Batteries: Spotlight on Polyvinylidene Fluoride Removal

In the recycling of retired lithium-ion batteries (LIBs), the cathode materials containing valuable metals should be first separated from the current collector aluminum foil to decrease the difficulty and complexity in the subsequent metal extraction. However, strong the binding force of organic binder polyvinylidene fluoride (PVDF) prevents effective separation of cathode materials and Al foil, thus affecting metal recycling. This paper reviews the composition, property, function, and binding mechanism of PVDF, and elaborates on the separation technologies of cathode material and Al foil (e.g., physical separation, solid-phase thermochemistry, solution chemistry, and solvent chemistry) as well as the corresponding reaction behavior and transformation mechanisms of PVDF. Due to the characteristic variation of the reaction systems, the dissolution, swelling, melting, and degradation processes and mechanisms of PVDF exhibit considerable differences, posing new challenges to efficient recycling of spent LIBs worldwide. It is critical to separate cathode materials and Al foil and recycle PVDF to reduce environmental risks from the recovery of retired LIBs resources. Developing fluorine-free alternative materials and solid-state electrolytes is a potential way to mitigate PVDF pollution in the recycling of spent LIBs in the EV era.

Mesoporous TiO2 Microparticles with Tailored Surfaces, Pores, Walls, and Particle Dimensions Using Persistent Micelle Templates

Mesoporous microparticles are an attractive platform to deploy high-surface-area nanomaterials in a convenient particulate form that is broadly compatible with diverse device manufacturing methods. The applications for mesoporous microparticles are numerous, spanning the gamut from drug delivery to catalysis and energy storage. For most applications, the performance of the resulting materials depends upon the architectural dimensions including the mesopore size, wall thickness, and microparticle size, yet a synthetic method to control all these parameters has remained elusive. Furthermore, some mesoporous microparticle reports noted a surface skin layer which has not been tuned before despite the important effect of such a skin layer upon transport/encapsulation. In the present study, material precursors and block polymer micelles are combined to yield mesoporous materials in a microparticle format due to phase separation from a homopolymer matrix. The skin layer thickness was kinetically controlled where a layer integration via diffusion (LID) model explains its production and dissipation. Furthermore, the independent tuning of pore size and wall thickness for mesoporous microparticles is shown for the first time using persistent micelle templates (PMT). Last, the kinetic effects of numerous processing parameters upon the microparticle size are shown.