Experimental Study on Dead-Lithium Formation in Lithium-Ion Battery

The growing demand for renewable energy and energy storage solutions is driven by two significant challenges faced by fossil fuel-based energy generation methods: energy security and greenhouse gas emissions. Electrochemical energy storage technology, particularly lithium-ion batteries (LIBs), offers high energy density and numerous charge/discharge cycles. However, the safety of LIBS has been called into question due to the risk of thermal runaway and fire accidents caused by factors such as lithium dendrite/plating (dead lithium). This research paper investigates the formation of dead lithium in a commercially available 18650 NCM (Nickel Cobalt Manganese) lithium-ion battery under low temperature (−5 °C) with 1C charging rate and 2C discharging rate. The study employs electrochemical impedance spectroscopy to characterize the process and validated through kramers kronig transform (KKT) as well as evaluated with distribution of relaxation time (DRT). The results reveal that during lithium formation at the anode surface, the resistance of the solid electrolyte interface (SEI) layer remains almost constant, but the series resistance significantly increases, indicating the conversion of active lithium-ion into dead lithium on the electrode's surface, while the charge transfer resistance (Rct) increases slightly. This finding could contribute to a better understanding of dead lithium formation and improve battery safety.