Spent lithium iron phosphate (LFP) is commonly recovered by hydrometallurgy to prepare Li2CO3 and FePO4, but suffering from long process and low value-added products. Hydrothermal method avoids element separation and regenerates LFP materials directly from leaching solution of spent LFP. However, it requires three-time the theoretical amount of lithium. In this study, using LiFePO4(OH) (LFPOH) as a medium, LFP materials were regenerated with theoretical amount of lithium in virtue of energetically favorable reaction of Li-ions into the internal structure. The formation mechanism of LFPOH and LFP materials were investigated, and advanced polycrystal LFP materials with fast ions-diffusion ability and high reversibility were obtained. The capacities of recovered LFP materials are 156.17 mAh g−1, 148.51 mAh g−1, 138.34 mAh g−1, 124.1 mAh g−1 at 0.2 C, 0.5 C, 1 C and 2 C, respectively and their capacity could be remained 139.92 mAh g−1 at 1 C with retention of almost 100 % after 200 cycles. Moreover, with the assistance of economic analysis, the designed regenerated path displayed considerable recycling value-potential, especially the reducing of Li-resources (from three-time to one-time). This study sheds light on designing polycrystal recovered LFP with help of basic medium, whilst provides an effective strategy for preparing high-performance LFP materials.

中文翻译：

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用于废 LiFePO4 的元素利用再生：为先进的多晶电极材料设计的基本前驱体


废磷酸铁锂 （LFP） 通常通过湿法冶金回收以制备 Li2CO3 和 FePO4，但加工时间长，产品附加值低。水热法避免了元素分离，并直接从废 LFP 的浸出液中再生 LFP 材料。但是，它需要的锂含量是理论用量的三倍。在本研究中，以 LiFePO4（OH） （LFPOH） 为介质，LFP 材料凭借锂离子的能量有利反应到内部结构中，用理论量的锂进行再生。研究了 LFPOH 和 LFP 材料的形成机理，获得了具有快速离子扩散能力和高可逆性的先进多晶 LFP 材料。回收的 LFP 材料的容量在 0.2 C、0.5 C、1 C 和 2 C 时分别为 156.17 mAh g-1、148.51 mAh g-1、138.34 mAh g-1、124.1 mAh g-1，它们的容量在 1 C 时可以保持 139.92 mAh g-1，在 200 次循环后保留率几乎为 100%。此外，在经济分析的帮助下，设计的再生路径显示出相当大的回收价值潜力，尤其是锂资源的减少（从三次减少到一次）。本研究阐明了借助碱性介质设计多晶回收的 LFP，同时为制备高性能 LFP 材料提供了一种有效的策略。