The use of strong acids and low atom efficiency in conventional hydrometallurgical recycling of spent lithium-ion batteries (LIBs) results in significant secondary wastes and CO
2
emissions. Herein, we utilize the waste metal current collectors in spent LIBs to promote atom economy and reduce chemicals consumption in a conversion process of spent Li
1-
x
CoO
2
(LCO) → new LiNi
0.80
Co
0.15
Al
0.05
O
2
(NCA) cathode. Mechanochemical activation is employed to achieve moderate valence reduction of transition metal oxides (Co
3+
→Co
2+,3+
) and efficient oxidation of current collector fragments (Al
0
→Al
3+
, Cu
0
→Cu
1+,2+
), and then due to stored internal energy from ball-milling, the leaching rates of Li, Co, Al, and Cu in the ≤4 mm crushed products uniformly approach 100% with just weak acetic acid. Instead of corrosive precipitation reagents, larger Al fragments (≥4 mm) are used to control the oxidation/reduction potential (ORP) in the aqueous leachate and induce the targeted removal of impurity ions (Cu, Fe). After the upcycling of NCA precursor solution to NCA cathode powders, we demonstrate excellent electrochemical performance of the regenerated NCA cathode and improved environmental impact. Through life cycle assessments, the profit margin of this green upcycling path reaches about 18%, while reducing greenhouse gas emissions by 45%.
Multicomponent lead compounds, including lead (Pb), lead oxide (PbO), lead dioxide (PbO 2 ), and lead sulfate (PbSO 4 ), in spent lead−acid batteries (LABs), if not properly disposed of and recycled, will cause serious pollution and damage to the ecological environment. Pyrometallurgical smelting performed above 1000 °C often incurs high energy consumption and lead pollution. In this study, a low-temperature (300 °C), oxygen-free roasting process was proposed. With potassium bisulfate (KHSO 4 ) as the roasting reagent, the uniform conversion of multicomponent lead compounds from spent lead paste (SLP) to PbSO 4 was successfully realized in one step. We observed that PbO 2 species were relatively chemically stable, during the oxygen-free roasting. However, the decomposition of PbO 2 into PbO can be achieved by heating to 300 °C, resulting in an effective conversion to PbSO 4 . The optimal conditions for PbSO 4 production were a heating temperature of 300 °C, an SLP/KHSO 4 mass ratio of 1:1, and a holding time of 10.0 min. Life cycle assessment results show that the recycling of 1.0 t spent LABs can reduce carbon emissions of 2.45 t CO 2 and smog of 0.13 t. Our research provides an emission-free, low-temperature, and negative-carbon strategy for facile and cost-effective recycling of spent LABs, as an alternative to traditional pyrometallurgical smelting.
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