Closed-loop resynthesis of LiNiCoAlO2 cathode active materials from the industrial leachate of spent li-ion batteries

The burgeoning electric vehicle market is significantly leading to a substantial increase in spent lithium-ion batteries (LIBs), emphasizing the need for efficient recycling to address raw material supply challenges. The resynthesis of cathode active materials, one of emerging efficient LIB recycling methods, refers to the synthesis of precursors from the leachate of spent LIBs without the separation of each element. While the resynthesis of LiNixCoyMnzO2 (NCM) from the Mn-rich industrial leachate of spent LIBs becomes popular nowadays, there is no practical approach for the resynthesis of LiNixCoyAlzO2 (NCA) from the industrial leachate. For the resynthesis of NCA, an additional purification step of solvent extraction with di(2-ethylhexyl) phosphoric acid for Mn removal is necessary. NCA is resynthesized from the Mn-removed leachate, after adjusting the Ni:Co ratio of precursors and sintering with Li and Al sources. While the initial discharge capacity of resynthesized NCA is slightly reduced to the electrochemically inactive impurities of Mg and Mn, its rate capability and cyclability are improved compared to pristine NCA from virgin materials. The effects of major impurities of Mg and Mn on the crystal structure and electrochemical properties of resynthesized NCA are further elucidated. Whereas the controlled Mg/Mn doping positively impacts both rate capability and cyclability, excessive Mn leads to degraded cyclability. Overall, our study expands the scope of resynthesis process of cathode active materials from spent LIBs, highlighting the intricate role of impurities and their impact on LIB performance.