Spent lithium iron phosphate (SLFP) batteries recycling is increasingly being researched. In this study, an electrochemical recycling method for SLFP is proposed based on solid-phase electrolysis; in reference to that, the technology exhibits complex procedures, extra secondary wastes, and high cost, resulting in reduced risk of secondary pollution and improved yield, and lower price. Phosphoric acid electrolysis system and stepwise precipitation method were adopted to prepare FePO4·2H2O and Li3PO4. The study covers parameter optimization in the electrolysis process and factor analysis for the precipitation separation. It analyzes the effect of parameters such as cell voltage, H3PO4 electrolyte concentration, and soaking time before electrolysis on Fe and Li leaching rates. After 60 min of soaking, with 30 min electrolysis in 0.6 mol/L H3PO4 electrolyte at 2.5 V, the Fe and Li leaching rates were 91.3% and 95.6%, respectively. The solution pH was controlled by stepwise addition of ammonia water to precipitate FePO4·2H2O and Li3PO4, of which a corresponding 98.8% and 99.4% recovery rates were achieved. respectively.
WANG Zixuan. Resource recovery technology of spent lithium iron phosphate cathode material[J]. Energy Storage Science and Technology, 2022, 11(1): 45-52
Fig. 4
Effects of electrolysis voltage on electrolysis current and integrated electricity (a) current change during electrolysis, (b) electricity obtained by direct integration of electrolysis current, (c) electricity in b is corrected with background current and waste load quality, (d) comparison of final power consumption and power consumption after background deduction
Fig. 7
Leaching rates of Li and Fe under direct immersion and constant pressure electrolysis in different concentrations of phosphoric acid electrolyte
PADHI A K, NANJUNDASWAMY K S, GOODENOUGH J B. Phospho-olivines as positive-electrode materials for rechargeable lithium batteries[J]. Journal of the Electrochemical Society, 1997, 144(4): 1188-1194.
DELACOURT C, POIZOT P, TARASCON J M, et al, The existence of a temperature-driven solid solution in LixFePO4 for 0≤x≤1[J]. Nature Materials, 2005, 4(3): 254-260.
WANG W, WU Y F. An overview of recycling and treatment of spent LiFePO4 batteries in China[J]. Resources, Conservation and Recycling, 2017, 127: 233-243.
WU Y, PEI F, JIA L L, et al. Recovery of aluminum, iron and lithium from spent lithium iron phosphate batteries[J]. Chinese Journal of Power Sources, 2014, 38(4): 629-631.
WANG T Y, SONG D M, HE W Z, et al. Recycling strategies and economic efficiency analysis of waste electric vehicle lithium-ion batteries[J]. Shanghai Energy Conservation, 2019(10): 814-820.
OMAR H, ROHANI S. Treatment of landfill waste, leachate and landfill gas: A review[J]. Frontiers of Chemical Science and Engineering, 2015, 9(1): 15-32.
KANG D H P, CHEN M, OGUNSEITAN O A. Potential environmental and human health impacts of rechargeable lithium batteries in electronic waste[J]. Environmental Science & Technology, 2013, 47(10): 5495-5503.
ZHAO G J, HE M, TANG G P, et al. Study on leaching and recovery of cathode material for spent lithium iron phosphate battery[J]. Chinese Journal of Power Sources, 2019, 43(3): 442-444, 452.
CAI G Q, FUNG K Y, NG K M, et al. Process development for the recycle of spent lithium ion batteries by chemical precipitation[J]. Industrial & Engineering Chemistry Research, 2014, 53(47): 18245-18259.
WU D Y, LIU Z Q, RAO S, et al. Research progress in recycling technology of cathode materials for spent lithium iron phosphate batteries[J]. Nonferrous Metals (Extractive Metallurgy), 2020(10): 70-78.
LÜ W, WANG Z H, CAO H B, et al. A critical review and analysis on the recycling of spent lithium-ion batteries[J]. ACS Sustainable Chemistry & Engineering, 2018, 6(2): 1504-1521.
LIU C W, LIN J, CAO H B, et al, Recycling of spent lithium-ion batteries in view of lithium recovery: A critical review[J]. Journal of Cleaner Production, 2019, 228: 801-813.
LI H Y, YE H, SUN M C, et al. Process for recycle of spent lithium iron phosphate battery via a selective leaching-precipitation method[J]. Journal of Central South University, 2020, 27(11): 3239-3248.
HAN X Y, XU J Q. Recover of iron and lithium from spent lithium iron phosphate batteries by precipitation process[J]. Guangdong Chemical Industry, 2017, 44(4): 12-16.
WANG B N, WANG Y, LIU J, et al. Recovery technology of lithium in waste lithium iron phosphate battery[J]. Chinese Journal of Power Sources, 2019, 43(1): 57-59+116.
LI H, XING S Z, LIU Y, et al. Recovery of lithium, iron, and phosphorus from spent LiFePO4 batteries using stoichiometric sulfuric acid leaching system[J]. ACS Sustainable Chemistry & Engineering, 2017, 5(9): 8017-8024.
WANG X, WANG X, ZHANG R, et al. Hydrothermal preparation and performance of LiFePO4 by using Li3PO4 recovered from spent cathode scraps as Li source[J]. Waste Management, 2018, 78: 208-216.
YANG Y X, MENG X Q, CAO H B, et al. Selective recovery of lithium from spent lithium iron phosphate batteries: a sustainable process[J]. Green Chemistry, 2018, 20(13): 3121-3133.
LI L, LU J, ZHAI L Y, et al, A facile recovery process for cathodes from spent lithium iron phosphate batteries by using oxalic acid[J]. CSEE Journal of Power and Energy Systems, 2018, 4(2): 219-225.
LI L, BIAN Y F, ZHANG X X, et al. A green and effective room-temperature recycling process of LiFePO4 cathode materials for lithium-ion batteries[J]. Waste Management, 2019, 85: 437-444.
YADAV P, JIE C J, TAN S, et al. Recycling of cathode from spent lithium iron phosphate batteries[J]. Journal of Hazardous Materials, 2020, 399: doi: 10.1016/j.jhazmat.2020.123068.
LAROUCHE F, TEDJAR F, AMOUZEGAR K, et al, Progress and status of hydrometallurgical and direct recycling of Li-ion batteries and beyond[J]. Materials, 2020, 13(3): doi: 10.3390/ma13030801.
ZHU H S, SUN J F, HU Q Y, et al. Application of phosphoric acid system in positive electrode material recovery from invalid lithium iron phosphate batteries[J]. Journal of Chemical Engineering of Chinese Universities, 2017, 31(5): 1238-1244.
YANG Y X, ZHENG X H, CAO H B, et al. A closed-loop process for selective metal recovery from spent lithium iron phosphate batteries through mechanochemical activation[J]. ACS Sustainable Chemistry & Engineering, 2017, 5(11): 9972-9980.
BI H J, ZHU H B, ZU L, et al. Combined mechanical process recycling technology for recovering copper and aluminium components of spent lithium-iron phosphate batteries[J]. Waste Management & Research, 2019, 37(8): 767-780.
LI Z, LIU D F, XIONG J C, et al. Selective recovery of lithium and iron phosphate/carbon from spent lithium iron phosphate cathode material by anionic membrane slurry electrolysis[J]. Waste Management, 2020, 107: 1-8.
BAE H, KIM Y. Technologies of lithium recycling from waste lithium ion batteries: A review[J]. Materials Advances, 2021, 2(10): 3234-3250.