The role of Cu impurity on the structure and electrochemical performance of Ni-rich cathode material for lithium-ion batteries

It is a challenge to completely eliminate copper (Cu) from an anode collector by an acid-leachate and results in Cu impurities in the regenerated Ni-rich materials. To investigate the effect of Cu impurities on Ni-rich cathode material, the present study successfully synthesized Li (Ni_0.8Co_0.1Mn_0.1)_1-xCu_xO₂ (x = 0, 0.005, 0.01 and 0.02) cathode material via co-precipitation. The results determine that the dopant of Cu promote to form surface like coral thicket and stomas. Moreover, while Cu replaces Mn and Ni in the cathode material with different Cu concentrations, a resulting increase in Ni³⁺ content is apparent and in turn, when the x = 0.01, the cathode material performs the lowest amount of cation mixing and provides the best electrochemical properties. The capacity retention of LiNi_0.8Co_0.1Mn_0.09Cu_0.01O₂ after 100 cycles is >90% at 1C, resulting from a higher Li⁺ diffusion coefficient and lower charge-transfer resistance due to the generation of porous structure for Cu impurity. And the incorporation of Cu could effectively inhibit discharge capacity decrease and alleviate the voltage reduction. These findings provide an opportunity to exhibit copper as a beneficial dopant in the recycling and regeneration processes of spent lithium-ion batteries.