Recovery of Lithium and Heavy Non-Ferrous Metals from Spent Lithium-Ion Batteries

When compared with nickel-cadmium or nickel-hydride batteries, lithium-ion batteries (LIBs) provide significant advantages as a power source for electric vehicles and for small mobile devices. However, LIBs contain a variety of toxic and ecologically harmful substances, such as heavy metals, organic and inorganic compounds, thereby creating a challenge for clean end-of-life (EoL) disposal. But why throw away EoL LIBs when the grade of cobalt and lithium in the complex lithium/cobalt oxide cathodes is higher than that in pristine lithium and cobalt ores? Recycling these valuable metals efficiently and with minimal environmental impact has therefore become an effort of significant economic, health and ecological importance, as well as of reducing tense international relations. To this end, we have worked to develop a (laboratory–scale) procedure for recycling EoL laptop LIBs containing LiCoO₂, LiNiCoO₂, and/or lithium-nickel-cobalt-aluminum oxide without the necessity of using acid/bases or costly reagents and without generating hazardous liquid waste. Following removal of the non-metallic container, the battery elements undergo crushing/milling; no other component separation procedure is performed or required. One hour dilute natural gas (4 vol.% in N₂) sintering under reducing conditions (673– 1123 K), followed by ice-water leaching, is used to efficiently separate Li from the heavy metals in the form of lithium carbonate at high yield and purity; 0.5 h smelting (1773 K) of the remaining metal clinker in air with sodium tetraborate as flux, allows recovery of the heavy, non-ferrous metals (Ni, Co, Cu and their alloys) as mm-size ingots (39% Co, 32.2% Ni, 26.3% Cu). Iron compounds, remanent Li, Al and unburnt graphite are removed as slag. Neither corrosive acids nor costly reagents are required, and hazardous liquid waste is not generated.