Progress and Status of Hydrometallurgical and Direct Recycling of Li-Ion Batteries and Beyond

Abstract

An exponential market growth of Li-ion batteries (LIBs) has been observed in the past 20 years; approximately 670,000 tons of LIBs have been sold in 2017 alone. This trend will continue owing to the growing interest of consumers for electric vehicles, recent engagement of car manufacturers to produce them, recent developments in energy storage facilities, and commitment of governments for the electrification of transportation. Although some limited recycling processes were developed earlier after the commercialization of LIBs, these are inadequate in the context of sustainable development. Therefore, significant efforts have been made to replace the commonly employed pyrometallurgical recycling method with a less detrimental approach, such as hydrometallurgical, in particular sulfate-based leaching, or direct recycling. Sulfate-based leaching is the only large-scale hydrometallurgical method currently used for recycling LIBs and serves as baseline for several pilot or demonstration projects currently under development. Conversely, most project and processes focus only on the recovery of Ni, Co, Mn, and less Li, and are wasting the iron phosphate originating from lithium iron phosphate (LFP) batteries. Although this battery type does not dominate the LIB market, its presence in the waste stream of LIBs causes some technical concerns that affect the profitability of current recycling processes. This review explores the current processes and alternative solutions to pyrometallurgy, including novel selective leaching processes or direct recycling approaches.

Keywords: Li-ion battery; direct recycling; hydrometallurgy; process review; recycling.

Figure 1

Cylindrical cell details ((reproduced with permission from Springer Nature Ref. [26]).

Figure 2

Bill of materials of lithium-cobalt oxide battery (wt.%) (based on data provided by Silveira et al. [27]).

Figure 3

Energy consumption for different synthesis methods and various active materials (reproduced with permission from The Royal Society of Chemistry Ref. [38]); here, NMC, LMR-NMC, LCO, and LFP are lithium-nickel-manganese-cobalt oxide, Li and Mn-rich lithium-nickel-manganese-cobalt oxide, lithium-cobalt oxide, and lithium-iron phosphate, respectively; and SS and HT are solid state and hydrothermal synthesis methods.

Figure 4

Gas emissions for synthesis methods for various active materials (reproduced with permission from The Royal Society of Chemistry Ref. [38]); here, NMC and LMR-NMC are lithium-nickel-manganese-cobalt oxide and Li and Mn-rich lithium-nickel-manganese-cobalt oxide; SS and HT are solid state and hydrothermal synthesis methods; and GHG is greenhouse gas.

Figure 5

Cyclic flow chart of manufacturing, usage, and end-of-life of Li-ion batteries.

Figure 6

Schematic flow and comparison of three approaches for recycling spent Li-ion batteries (LIBs).

Figure 7

Thermogravimetry-differential scanning calorimetry (TG-DSC) curves of spent laptop Li-ion batteries in air (reproduced with permission from Springer Nature Ref. [88]).

Figure 8

H₂SO₄ recycling process of lithium-iron phosphate (LFP) batteries patented by Recupyl (according to Ref. [46]).

Figure 9

Selective leaching process proposed by Li et al. (according to [123]); here, LFP is LiFePO_4.

Figure 10

Selective leaching process proposed by Zheng et al. (according to Ref. [85,126]); here, NMC(OH)₂ and NMC(111) are Ni_1/3Mn_1/3Co_1/3(OH)₂ and LiNi_1/3Mn_1/3Co_1/3O₂, respectively.

Figure 11

HCl leaching process proposed by Laucournet et al. (according to [164]); here LFP, LTO, and PVDF are for LiFePO₄, Li₄Ti₅O₁₂, and polyvinylidene fluoride, respectively.

Figure 12

HNO₃ leaching and electrodeposition process proposed by Li et al. (adapted from [180]); here, LCO and NMP are LiCoO₂ and N-methyl-2-pyrrolidone, respectively.

Figure 13

H₃PO₄ leaching process suggested by Yang et al. (according to [76]); here, LFP and EDTA-2Na are for LiFePO₄ and ethylenediamine tetraacetic acid disodium salt, respectively.

Figure 14

Selective leaching of LFP proposed by Amouzegar et al. (according to [185]); here, LFP is for LiFePO₄.

Figure 15

Selective leaching of LFP proposed by Yang et al. (according to [77]).

Figure 16

LFP dissolution process proposed by Li et al. (according to [207]); here, LFP, PVDF, and NMP are LiFePO₄, polyvinylidene fluoride, and N-methyl-2-pyrrolidone, respectively.

Figure 17

Pilot-scale thermal regeneration process of LFP (according to [97]).

Figure 18

Hydrothermal process proposed by Sloop (according to [218]).

Figure 19

Iodide relithiation process proposed by Ganter et al. (according to [217]).

Figure 20

Electrochemical resynthesis process for LCO (according to [219]).