Electrochemical Stabilization of Non-magnetic Copper Impurities for Internal Short-Circuit Prevention in Lithium-Ion Batteries

Abstract

Metallic foreign particles introduced during lithium-ion battery manufacturing, particularly non-magnetic Cu contaminants, pose severe safety risks by inducing internal short circuits. Conventional separation and non-destructive detection methods are largely ineffective for these microscopic impurities. Herein, we present a scalable, software-integrable electrochemical deactivation strategy that stabilizes Cu contaminants during the initial formation stage. By applying a thermodynamically tailored constant-voltage step （0.4 V） followed by a kinetically regulated pulse-rest sequence, macroscopic Cu particles are selectively dissolved and uniformly immobilized as stable inorganic CuF2 within the anode solid electrolyte interphase. This protocol effectively suppresses both immediate and latent short-circuit risks under severe contamination （100 ppm） and in practical 4 Ah cells, while fully preserving the long-term cycling performance （77% retention after 700 cycles） and bulk structural integrity of the NCM622 cathode. This active safety-assurance mechanism offers a practical, hardware-free route to enhance battery manufacturing safety and production yield.