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Lithium-ion batteries (LIBs), in which lithium ions function as charge carriers, are considered the most competitive energy storage devices due to their high energy and power density. However, battery materials, especially with high capacity undergo side reactions and changes that result in capacity decay and safety issues. A deep understanding of the reactions that cause changes in the battery's internal components and the mechanisms of those reactions is needed to build safer and better batteries. This review focuses on the processes of battery failures, with voltage and temperature as the underlying factors. Voltage-induced failures result from anode interfacial reactions, current collector corrosion, cathode interfacial reactions, overcharge, and overdischarge, while temperature-induced failure mechanisms include SEI decomposition, separator damage, and interfacial reactions between electrodes and electrolytes. The review also presents protective strategies for controlling these reactions. As a result, the reader is offered a comprehensive overview of the safety features and failure mechanisms of various LIB components.

The lithium hexafluorophosphate (LiPF6) in spent lithium-ion batteries (LIBs) is a potentially valuable resource and a significant environmental pollutant. Unfortunately, most of the LiPF6 in a spent LIB is difficult to extract because the electrolyte is strongly adsorbed by the cathode, anode, and separator. Storing extracted electrolyte is also challenging because it contains LiPF6, which promotes the decomposition of the solvent. Here we show that electrolytes in spent LIBs can be collected by a less polar solvent dimethyl carbonate (DMC) wash, and LiPF6 can be concentrated by simple aqueous extraction by lowering ethylene carbonate (EC) content in the recycled electrolyte. Due to the similar dielectric constant of EC and water, reducing the content of EC in LIB electrolytes, or even eliminating it, facilitates the separation of water and electrolyte, thus enabling the lithium salts in the electrolyte to be separated from the organic solvent. The lithium salt extracting efficiency achieved in this way can be as high as 99.8%, and fluorine and phosphorus of LiPF6 can be fixed in the form of stable metal fluoride and phosphate by hydrothermal method. The same strategy can be used in industrial waste electrolyte recycling by diluting the waste with DMC and extracting the resulting solution with water. This work thus reveals a new route for waste electrolyte treatment and will also support the development of advanced EC-free electrolytes for high-performance, safe, and easily recyclable LIBs.

Recycling lithium-ion batteries (LIBs) is fundamental for resource recovery, reducing energy consumption, decreasing emissions, and minimizing environmental risks. The inherited properties of materials and design are not commonly attributed to the complexity of recycling LIBs and their effects on the recycling process. The state-of-the-art battery recycling methodology consequently suffers from poor recycling efficiency and high consumption from issues with the cathode and the binder material. As a feasibility study, high-energy-density cathode material LiFeMnPO4 with a water-soluble polyacrylic acid (PAA) binder is extracted with dilute hydrochloric acid at room temperature under oxidant-free conditions. The cathode is wholly leached with high purity and is suitable for reuse. The cathode is easily separated from its constituent materials and reduces material and energy consumption during recycling by 20% and 7%, respectively. This strategy is utilized to fabricate recyclable-oriented LiFeMnPO4/graphite LIBs with a PAA binder and carbon paper current collector. Finally, the limitation of the solubility of the binder is discussed in terms of recycling. This research hopefully provides guidance for recycling-oriented design for the circular economy of the LIB industry.

It is challenging to efficiently and economically recycle many lithium-ion batteries (LIBs) because of the low valuation of commodity metals and materials, such as LiFePO4. There are millions of tons of spent LIBs where the barrier to recycling is economical, and to make recycling more feasible, it is required that the value of the processed recycled material exceeds the value of raw commodity materials. The presented research illustrates improved profitability and economics for recycling spent LIBs by utilizing the surplus energy in lithiated graphite to drive the preparation of organolithiums to add value to the recycled lithium materials. This study methodology demonstrates that the surplus energy of lithiated graphite obtained from spent LIBs can be utilized to prepare high-value organolithiums, thereby significantly improving the economic profitability of LIB recycling. Organolithiums (R–O–Li and R–Li) were prepared using alkyl alcohol (R–OH) and alkyl bromide (R–Br) as substrates, where R includes varying hindered alkyl hydrocarbons. The organolithiums extracted from per kilogram of recycled LIBs can increase the economic value between $29.5 and $226.5 kg−1 cell. The value of the organolithiums is at least 5.4 times the total theoretical value of spent materials, improving the profitability of recycling LIBs over traditional pyrometallurgical ($0.86 kg−1 cell), hydrometallurgical ($1.00 kg−1 cell), and physical direct recycling methods ($5.40 kg−1 cell).

Efficient and reliable energy storage systems are crucial for our modern society. Lithium-ion batteries (LIBs) with excellent performance are widely used in portable electronics and electric vehicles (EVs), but frequent fires and explosions limit their further and more widespread applications. This review summarizes aspects of LIB safety and discusses the related issues, strategies, and testing standards. Specifically, it begins with a brief introduction to LIB working principles and cell structures, and then provides an overview of the notorious thermal runaway, with an emphasis on the effects of mechanical, electrical, and thermal abuse. The following sections examine strategies for improving cell safety, including approaches through cell chemistry, cooling, and balancing, afterwards describing current safety standards and corresponding tests. The review concludes with insights into potential future developments and the prospects for safer LIBs.