Quantification of lithium dendrite and solid electrolyte interphase (SEI) in lithium-ion batteries

The unexpected plating of lithium on the anode is a common issue for lithium-ion batteries (LIBs), which shortens the cycle life by consuming active Li+ and causes the severe safety hazard due to the formation of Li dendrites. However, the quantitive detection of deposited metallic Li is hindered by the lack of feasible and precise method. Herein, we utilized the differential scanning calorimetry (DSC) technique to quantify the deposited metallic Li by measuring the heat of metallic Li melting. This technique provides an accurate quantification method for the “dead Li” and solid electrolyte interphase (SEI) evolution of the graphite electrode. The measured minimum amount of metallic Li reaches 0.19 μg (0.72 μAh). We found that SEI growth consumes more capacity in the period of the nucleation of lithium dendrites than that in the period of the growth of lithium dendrites. The formation of SEI is the main cause for the capacity loss during the Li plating/stripping on both graphite and copper electrodes. Only 1.4–1.6% of capacity loss of the commercial pouch cell aged at low temperature is consumed to form “dead Li”.