Electrochemical process for recovery of metallic Mn from waste LiMn₂O₄-based Li-ion batteries in NaCl−CaCl₂ melts

Abstract

A new method is proposed for the recovery of Mn via the direct electrochemical reduction of LiMn₂O₄ from the waste of lithium-ion batteries in NaCl−CaCl₂ melts at 750°C. The results show that the LiMn₂O₄ reduction process by the electrochemical method on the coated electrode surface occurs in three steps: Mn(IV) → Mn(III) → Mn(II) → Mn. The products of this electro-deoxidation are CaMn₂O₄, MnO, (MnO) _x(CaO)_1−x, and Mn. Metal Mn appears when the electrolytic voltage increases to 2.6 V, which indicates that increasing the voltage may promote the deoxidation reaction process. With the advancement of the three-phase interline (3PI), electric deoxygenation gradually proceeds from the outer area of the crucible to the core. At high voltage, the kinetic process of the reduction reaction is accelerated, which generates double 3PIs at different stages.

Keywords

lithium-ion-battery waste / electrochemistry of melts / Mn recovery / electro-deoxidation / lithium manganate

References

[1] Guan PY, Zhou L, Yu ZL, Sun YD, Liu YJ, Wu FX, Jiang YF, Chu DW. Recent progress of surface coating on cathode materials for high-performance lithium-ion batteries. J. Energy Chem., 2020, 43, 220.

[2] Xu YN, Dong YY, Han X, Wang XF, Wang YJ, Jiao LF, Yuan HT. Application for simply recovered LiCoO₂ material as a high-performance candidate for supercapacitor in aqueous system. ACS Sustainable Chem. Eng., 2015, 3(10): 2435.

[3] Gao GL, Luo XM, Lou XY, Guo YG, Su RJ, Guan J, Li YS, Yuan H, Dai J, Jiao Z. Efficient sulfuric acid-Vitamin C leaching system: Towards enhanced extraction of cobalt from spent lithium-ion batteries. J. Mater. Cycles Waste Manage., 2019, 21(4): 942.

[4] Li L, Bian YF, Zhang XX, Yao Y, Xue Q, Fan E, Wu F, Chen RJ. A green and effective room-temperature recycling process of LiFePO₄ cathode materials for lithium-ion batteries. Waste Manage., 2019, 85, 437.

[5] M. Roshanfar, R. Golmohammadzadeh, and F. Rashchi. An environmentally friendly method for recovery of lithium and cobalt from spent lithium-ion batteries using gluconic and lactic acids, J. Environ. Chem. Eng, 7(2019), No. 1, art. No. 102794.

[6] Setiawan H, Petrus H T B M, Perdan I. Reaction kinetics modeling for lithium and cobalt recovery from spent lithium-ion batteries using acetic acid. Int. J. Miner. Metall. Mater., 2019, 26(1): 98.

[7] Chen XP, Kang DZ, Cao L, Li JZ, Zhou T, Ma HR. Separation and recovery of valuable metals from spent lithium ion batteries: Simultaneous recovery of Li and Co in a single step. Sep. Purif. Technol., 2019, 210, 690.

[8] Xiao JF, Li J, Xu ZQ. Recycling metals from lithium ion battery by mechanical separation and vacuum metallurgy. J. Hazard. Mater., 2017, 338, 124.

[9] Wang WY, Yen CH, Lin JL, Xu RB. Recovery of high-purity metallic cobalt from lithium nickel manganese cobalt oxide (NMC)-type Li-ion battery. J. Mater. Cycles Waste Manage., 2019, 21(2): 300.

[10] Q. Liang, H.F. Yue, S.F. Wang, S.Y. Yang, K. Lam, and X.H. Hou, Recycling and crystal regeneration of commercial used LiFePO₄ cathode materials, Electrochim. Acta, 330(2020), art. No. 135323.

[11] Y. Zhou, W. Shan, S.F. Wang, K. Lam, Q. Ru, F.M. Chen, and X.H. Hou, Recovery Li/Co from spent LiCoO₂ electrode based on an aqueous dual-ion lithium-air battery, Electrochim. Acta, 332(2020), art. No. 135529.

[12] Chen GZ, Fray DJ, Farthing TW. Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride. Nature, 2000, 407(6802): 361.

[13] Jiao SQ, Zhu HM. Electrolysis of Ti₂CO₃ solid solution prepared by TiC and TiO₂. J. Alloys Compd., 2007, 438(1–2): 243.

[14] Maha Vishnu DS, Sanil N, Shakila L, Sudha R, Mohandas KS, Nagarajan K. Electrochemical reduction of TiO₂ powders in molten calcium chloride. Electrochim. Acta, 2015, 159, 124.

[15] Liu XY, Hu ML, Bai CG, Lv XW. Effect of electrical conductivity and porosity of cathode on electro-deoxidation process of ilmenite concentrate. Rare Met. Mater. Eng., 2017, 46(5): 1176.

[16] Jiao HD, Wang QY, Ge JB, Sun HB, Jiao SQ. Electrochemical synthesis of Ti₅Si₃ in CaCl₂ melt. J. Alloys Compd., 2014, 582, 146.

[17] Yang X, Ji L, Zou XL, Lim T, Zhao J, Yu ET, Bard AJ. Toward cost-effective manufacturing of silicon solar cells: electrodeposition of high-quality Si films in a CaCl₂-based melts. Angew. Chem., 2017, 56(47): 15078.

[18] Sakanaka Y, Goto T. Electrodeposition of Si film on Ag substrate in molten LiF−NaF−KF directly dissolving SiO₂. Electrochim. Acta, 2015, 164, 139.

[19] Sakanaka Y, Murata A, Goto T, Hachiya K. Electrodeposition of porous Si film from SiO₂ in molten BaCl₂−CaCl₂−NaCl. J. Alloys Compd., 2017, 695, 2131.

[20] Weng W, Wang MY, Gong XZ, Wang Z, Wang D, Guo ZC. Electrochemical reduction behavior of soluble CaTiO₃ in Na₃AlF₆−AlF₃ melt for the preparation of metal titanium. J. Electrochem. Soc., 2017, 164(9): D551.

[21] Kartal L, Daryal M B, Şireli G K, Timur S. One-step electrochemical reduction of stibnite concentrate in molten borax. Int. J. Miner. Metall. Mater., 2019, 26(10): 1258.

[22] Weng W, Wang MY, Gong XZ, Wang Z, Wang D, Guo ZC. Direct electro-deposition of metallic chromium from K₂CrO₄ in the equimolar CaCl₂−KCl melts and its reduction mechanism. Electrochim. Acta, 2016, 212, 162.

[23] Wang L, Liu WZ, Hu JP, Liu Q, Yue HR, Liang B, Zhang GQ, Luo DM, Xie HP, Li C. Indirect mineral carbonation of titanium-bearing blast furnace slag coupled with recovery of TiO₂ and Al₂O₃. Chin. J. Chem. Eng., 2018, 26(3): 583.

[24] Ge XL, Wang XD, Seetharaman S. Copper extraction from copper ore by electro-reduction in molten CaCl₂−NaCl. Electrochim. Acta, 2009, 54(18): 4397.

[25] Kartal L, Timur S. Direct electrochemical reduction of copper sulfide in molten borax. Int. J. Miner. Metall. Mater., 2019, 26(8): 992.

[26] Zhang BL, Xie HW, Lu BH, Chen X, Xing PF, Qu JK, Song QS, Yin HY. A green electrochemical process to recover Co and Li from spent LiCoO₂-based batteries in meltss. ACS Sustainable Chem. Eng., 2019, 7(15): 13391.

[27] H. Li, D.B. Wang, J.L. Liang, H.Y. Yan, Z.Y. Cai, and R.G. Reddy, Electrochemical mechanism for the preparation of Fe−Si alloys by melts electrodeposition, Int. J. Chem. React. Eng., 18(2019), No. 2, art. No. 20190112.

[28] Liang JL, Li H, Huo DX, Yan HY, Reddy RG, Wang LG, Wang LQ. Electrochemical characteristics of TiO₂ in NaCl−KCl−NaF melts system. Ionics, 2018, 24(10): 3221.

[29] H. Li, L.S. Zhang, J.L. Liang, R.G. Reddy, H.Y. Yan, and Y.H. Yin, Electrochemical Behavior of Fe₃O₄ in NaCl−CaCl₂ Melts, Int. J. Chem. React. Eng., 17(2019), No. 10, art. No. 0190017.

[30] G.Z. Chen and D.J. Fray, Understanding the electro-reduction of metal oxides in molten salts, [in] Light Metals Symposium, Charlotte, NC, 2004, p. 881.

[31] Weng W, Wang MY, Gong XZ, Guo ZC. Thermodynamic analysis on the direct preparation of metallic vanadium from NaVO₃ by molten salt electrolysis. Chin. J. Chem. Eng., 2016, 24(5): 671.

[32] Tang DY, Yin HY, Xiao W, Zhu H, Mao XH, Wang DH. Reduction mechanism and carbon content investigation for electrolytic production of iron from solid Fe₂O₃ in molten K₂CO₃−Na₂CO₃ using an inert anode. J. Electroanal. Chem., 2013, 689, 109.