Search

Lithium iron phosphate battery recycling is enhanced by an eco-friendly N 2 H 4 ·H 2 O method, restoring Li+ ions and reducing defects. Regenerated LiFePO 4 matches commercial quality, a cost-effective and eco-friendly solution. [Display omitted] • Low-temperature liquid-phase direct regeneration of LiFePO 4 with high efficiency. • Li+ ions anti-site defects being repaired Using N 2 H 4 ·H 2 O. • Regenerated LiFePO 4 showing good electrochemical performance. Lithium iron phosphate batteries, known for their durability, safety, and cost-efficiency, have become essential in new energy applications. However, their widespread use has highlighted the urgency of battery recycling. Inadequate management could lead to resource waste and environmental harm. Traditional recycling methods, like hydrometallurgy and pyrometallurgy, are complex and energy-intensive, resulting in high costs. To address these challenges, this study introduces a novel low-temperature liquid-phase method for regenerating lithium iron phosphate positive electrode materials. By using N 2 H 4 ·H 2 O as a reducing agent, missing Li+ ions are replenished, and anti-site defects are reduced through annealing. This process restores nearly all missing Li+ ions at 80 °C/6h. After high-temperature sintering at 700 °C/2h, the regenerated LiFePO 4 matches commercial LiFePO 4 in terms of anti-site defects and exhibits excellent performance with a 97 % capacity retention rate after 100 cycles at 1C. Compared to high-temperature techniques, this low-temperature liquid-phase method is simpler, safer, and more energy-efficient, offering a blueprint for reclaiming discarded LiFePO 4 and similar materials. [ABSTRACT FROM AUTHOR]

By systematically regulating the Fe-O coordination number of feroxyhyte (δ-FeOOH), we disclosed the structure–activity relationship and developed a highly efficient Fenton-like catalyst. [Display omitted] • Coordination number of Fe atoms were regulated through tuning δ-FeOOH thickness. • 5-coordinated Fe sites accelerate the rate-limiting step and facilitate the PMS activation. • The PMS utilization efficiency achieved as high as 78.40%. • The catalytic mechanism of low coordination Fe sites were proposed. • Fe-O 5 nanosheets were assembled into laminar membrane for micropollutants treatment. Efficient purification of water is essential to remove organic micropollutants for human and environmental health. The development of catalysts with high activity and peroxymonosulfate (PMS) utilization efficiency for removal of organic micropollutants remains challenging. Inspired by natural enzymes, we designed δ-FeOOH nanosheets with abundant 5-coordinated iron sites, which are responsible for the formation of iron-peroxy (FeIII-O-O-FeIII) species with PMS. The iron-peroxy species can directly oxidize and degrade electron-rich micropollutants (e.g. BPA) with an ultra-high PMS utilization efficiency of 78.4%. A laminar membrane constructed from a stack of δ-FeOOH nanosheets, replete with an abundance of 5-coordinated iron sites. The laminar membrane can degrade multiple micropollutants by almost 100% due to nonlinear transport between the δ-FeOOH nanolayers, compared with the dispersed catalyst. This work would motivate the community to focus more on the diversified behavior of the coordination number of active centers in the design of efficient catalysts for water purification. [ABSTRACT FROM AUTHOR]