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Preparation of ­FePO4 and ­LiH2PO4 from cathode mixture materials of scrapped ­LiFePO4 batteries Yongzhi Chen2 · Lihua Wang1   · Hao He3 · Jian Li4 · Yimin Li2,3 · Rutie Liu2 · Dongyang Li2 · Zheyu He2 Received: 6 September 2019 / Accepted: 20 January 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract Typically, ­LiFePO4 batteries (LFPBs) contain a shell, cathode mixture materials, anode mixture materials, current collector, electrolyte, separator, and other components. Cathode mixture materials are composed of a binder, conductive additive, and ­LiFePO4/C. After LFPBs are scrapped, their appropriate disposal is necessary to avoid pollution. This study investigated the recovery of Li, Fe, and P by hydrometallurgy from scrapped LFPBs. To remove the binder, conductive additive, and ­ 3PO4 as carbon coating layer, recycled cathode mixture materials are oxidized to L ­ i3Fe2(PO4)3 and ­Fe2O3 at 600 °C. Using H a leaching agent, the optimal leaching efficiencies, i.e., 99.2% and 97.68% for Li and Fe, respectively, can be achieved when the reaction time, temperature, Li in the ­Li3Fe2(PO4)3 and ­Fe2O3 mixture materials to the ­H3PO4 molar ratio (L/P ratio), and ­H3PO4 concentration are 12 h, 95 °C, 1:5, and 0.5 mol/L, respectively. Moreover, Li can be leached into a solution efficiently and recovered as L ­ iH2PO4, while Fe and P can be selectively precipitated as ­FePO4·xH2O. ­FePO4 is prepared by a heat treatment. Furthermore, ­LiFePO4/C is re-synthesized by ­FePO4, ­LiH2PO4, ­Fe2O3, LiOH, and sucrose.

1 Introduction Over time, the incongruity between the environment and economic development is becoming increasingly prominent. Environmental issues have become the focus of social concern. Established green and low-carbon energy sources have become the primary focus for new energy devices and renewable energy development [1–3]. Some countries are accelerating the development of electric vehicles (EVs) and hybrid electric vehicles (HEVs) to protect the environment. * Lihua Wang [email protected] * Hao He [email protected] * Jian Li [email protected] 1



School of Metallurgy and Environment, Central South University, Changsha 410083, Hunan, China

2



State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, People’s Republic of China

3

Research Centre for Materials Science and Engineering, Guangxi University of Science and Technology, Liuzhou 545006, People’s Republic of China

4

School of Materials Science and Engineering, Central South University, Changsha 410083, Hunan, China





Lithium-ion batteries (LIBs) play an important role as a primary energy source and a back-up supply system in EVs [4–8]. Since their first commercial introduction by SONY in 1991, LIBs have developed rapidly [9]. In China alone, the sales of LIBs have rapidly increased from 0.6 GWh in 2011 to 30.5 Gwh in 2016, indicating a more than 50-fold increase. The compounds ­LiFePO4, ­LiNiCoMnO2, ­LiNiCoAlO2, and ­LiMn2O4 are commonly used as the cathode active materia