Recovering valuable materials from spent lithium-ion batteries is an important task because of the asymmetry in resource distribution, supply, and demand around the world. A lithium-ion battery is a combination system of various elements and their oxides. Current recovering technologies focus on the separation of valuable metal elements. They can inescapably bring secondary contamination and cost to the environment due to the addition of leachants and precipitants. To recover valuable materials, in situ recombination of elements in spent lithium-ion batteries can be a more economical and environment-friendly solution. Herein, we developed a technology based on in situ aluminothermic reduction and interstitial solid solution transformation to recover high-value γ-LiAlO 2 and LiAl 5 O 8 under vacuum and high-temperature (1723 K) conditions. It was found that the process of Li 2 O filling into the lattice of O−Al−O structure is an energy-reducing process, while LiAl 5 O 8 was an existing high-energy transition-state matter. Since there was no wastewater generated, the process brought a new environment-friendly method for recovering valuable metals from spent lithium-ion batteries. This study also provides new comprehension regarding the design for high-value products' recovery from multi-element mixed wastes on an atomic scale.

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We demonstrated a domain reversal mechanism on Z-cut congruent-grown lithium tentalate (LiTaO3) composed of nickel (Ni) diffusion followed by pulse field poling. Domain nucleation and forward growth were found confined to the nondiffused regions, where the commonly observed serrated domain fronts in poled LiTaO3 were absent in this work. These observations are ascribed to the formation of domain nucleation barrier by the depolarization field and reveal the divergence effect in the ferroelectric spontaneous polarization at the domain boundary due to Ni diffusion. This mechanism simplifies the fabrication of periodically poled LiTaO3 for second-harmonic generation in the blue spectral regime.

The recovery of spent lithium-ion batteries is a hot issue in the field of social sustainable development. At present, vacuum reduction is encouraged to be used in the resource recovery of spent lithium-ion batteries. However, the occupational threat of their recovery process has not been studied. This paper investigated the occupational threat of recovering spent lithium-ion batteries during vacuum reduction. The PM 10 (0.065 mg/m 3 ) and heavy metals in the gas have no occupational threat, whereas the gas contains dozens of toxic pollutants, such as ethanolamine, carbon monoxide, and 1,4dioxane. Among them, the content of 1,4-dioxane reaches 5.67%, which have carcinogenic risk (ILCR = 2.28 × 10 −3 ) and noncarcinogenic risk (HQ = 155.94). Molecular dynamics results indicate that the formation of pollutants is caused by NH 2• , and so forth. Organic residues also contain pollutants, but they are easy to collect and are harmless. Therefore, it is necessary to monitor and control the pollutant gas. The occupational threat can be avoided by reducing the organic substances involved in the reaction and increasing the activated carbon to absorb the gas. This paper might be the first time to provide environmental information about the vacuum reduction process of recovering spent lithium-ion batteries.

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