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The past decades have witnessed the rapid development of lithium-ion batteries (LIBs), which are applied in nearly every aspect of our daily life. However, the increasing number of spent LIBs (S-LIBs) poses a great threat to the environment. Thus, to protect the environment and preserve limited lithium resources, it is necessary to recycle S-LIBs. In this review, we initially provide a brief introduction on the structure and degradation mechanism of LIBs and pretreatment of S-LIBs. Subsequently, we highlight the recent advancements in the development of recycling the cathode of S-LIBs, including its direct, hydrometallurgical, and pyrometallurgical recovery. The advantages and disadvantages of each recycling process are also discussed from the viewpoint of the environment and economy. In addition, we also introduce the recycling of S-LIBs through a green and environmentally friendly process of treating waste with waste. Finally, the overall perspective of this technology and areas requiring particular attention in the future are discussed. [ABSTRACT FROM AUTHOR]

Carbon-based materials have demonstrated excellent thermal, electric, optical, magnetic, and mechanical properties, offering promising application potential in many fields. Corresponding synthetic approaches meeting the requirements of sustainable development goals are always desired. Compared with chemical vapor deposition, solvothermal, conventional pyrolysis, and salt-assisted methods are emerging as advanced synthetic technologies for the fabrication of carbon-based materials since these processes are expected to be more sustainable. Herein, we provide a comprehensive review on the salt-assisted synthesis of carbon-based materials and their typical energy-related applications. First, the properties of carbon and a comparison of various synthetic techniques are briefly introduced. In particular, we highlight the advantages of salt-assisted synthesis in view of sustainable development goals. For convenience, we divide the roles of salt in assisting the synthesis of carbon-based materials into four subclasses: reaction medium, pore-forming agent, morphology control, and precursors. Simultaneously, the applications of these carbon-based materials in energy-related fields are discussed. Lastly, the major challenges in this field are outlined, and future research avenues in salt-assisted synthesis of carbon-based materials for energy-related applications are also highlighted. It is expected that this tutorial review will supply necessary background information to further advance salt-assisted synthesis of carbon-based materials for energy-related applications. [ABSTRACT FROM AUTHOR]

Carbon materials play an important role in supercapacitors due to their structural diversity, rich surface morphology, excellent chemical stability and highly active surfaces. Currently, there are many reports on the synthesis methods for carbon-based materials. The molten salt method stands out among the many methods for its advantages of economy, environmental protection, high efficiency, and maneuverability. Here, we focus on the different roles played by molten salts as templates, sealants, reaction media, and catalysts from the point of view of their functions. The properties and selection principles of the molten salts are discussed in depth, focusing on the morphology, structure, and capacitive properties of the carbon materials prepared using the molten salt strategy. Finally, the current research status of the preparation of carbon-based materials by the molten salt method is summarized, the shortcomings of existing technology are pointed out, and the prospects for its development are envisioned. It is hoped that this review can provide some basic knowledge for the preparation of carbon-based materials by the molten salt method and promote further research on molten salt technology. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) is one of the most important plastics derived from petroleum, which has been extensively used in everyday life for the last few decades due to its superior properties. Without reasonable manageability, the volume of PVC is increasing steadily in the natural world. Owing to its features of non-biodegradability, the traditional disposal of PVC waste by either pouring it into the oceans or landfilling causes serious environmental issues. Due to sustainable development, PVC solid waste can be recycled to obtain products with the same quality as the starting material, reused in other fields, or converted into other high-value chemicals. Over the past decades, great progress has been made in the recycling of PVC. In this review, we initially provide a brief introduction to PVC, including its chemical structure, annual production and application fields, followed by an overview of mechanical approaches, including separation techniques, inclusion in other materials, and non-conventional mechanical recycling. The advantages and disadvantages of these techniques are also considered. Various chemical approaches to converting PVC waste into new products or chemicals to enhance the sustainability of the environment, such as gasification, pyrolysis, and de-chlorination are discussed in detail. Finally, the challenges and future perspectives of recycling PVC solid waste are discussed. [ABSTRACT FROM AUTHOR]