Upcycling spent cathode materials from Li-ion batteries to precursors: Challenges and opportunities

Upcycling of lithium cobalt oxide to LiNi1/3Mn1/3Co1/3O2

“…However, in recent years, larger focus has been placed on developing the hydrometallurgical methods to increase the recycling yield of lithium and decrease energy use, among other aspects. 4,18,19 In most of these hydrometallurgical processes, the black mass is subjected to strong inorganic acids that dissolve the metals which then are recovered via different purification and recovery techniques. 4,17,19,20 NH 3 or NaOH could also be applied in the process to control the pH or as precipitation agents.…”

“…The successful integration of these downstream processes into the synthesis of materials would significantly simplify the flowsheet for cathode recycling while improving the upstream production. As several studies discuss various processes, 18,27–29 we here highlight two relevant synthesis methods. Co-precipitation is a common practice of NMC cathode material synthesis using materials recovered from spent LIBs, in which transition metal precursors (often either in the form of hydroxides or carbonates) are mixed in desired proportions.…”

“…A chelating or precipitation agent such as NH 3 or NaOH is added while monitoring the pH. 18,27,28,30,31 However, for primary production of NMC cathodes or in the form of supplements, transition metal sulfate salts could be applicable. 32–36 Sintering is then applied after a lithium source is added (often in the form of carbonates obtained directly from LIB recycling or in the form of hydroxides originating from primary resources as well as converted precipitates from LIB recycling) followed by calcination.…”

“…32–36 Sintering is then applied after a lithium source is added (often in the form of carbonates obtained directly from LIB recycling or in the form of hydroxides originating from primary resources as well as converted precipitates from LIB recycling) followed by calcination. 18,28 Advantages with co-precipitation are cost-effectiveness and scalability as well as the production of well-defined round agglomerates where the shape, morphology and particle shape are tunable by several parameters. 27,28…”

“…27,29 As an example, Çetin et al 37 utilized citric acid as a chelating agent and transition metal acetates when preparing an NMC material by the sol–gel method. While co-precipitation is a better solution than the sol–gel method for upscaling in general, 18,27–29 the citrate concentration for the former has an optimal ratio of max 0.01 (citrate to metal ions) 23 whereas the latter can tolerate up to 2 equivalents. 37 In fact, when using organic acids as leaching agents, the sol–gel method is more applicable as the organic acid also acts as a chelating agent.…”