Li plating as unwanted side reaction in commercial Li-ion cells - A review

摘要

Deposition of Lithium metal on anodes contributes significantly to ageing of Li-ion cells. Lithium deposition is connected not only to a drastic limitation of life-time, but also to fast-charging capability and safety issues. Lithium deposition in commercial Li-ion cells is not limited to operation conditions at low temperatures. In recent publications various types of commercial cells were investigated using complimentary analysis methods. Five cell types studied in literature (18650, 26650, pouch) serve as a basis for comparison when and why Li deposition happens in commercial Li-ion cells. In the present paper, we reviewed literature on (i) causes, (ii) hints and evidences for Li deposition, (iii) macroscopic morphology of Li deposition/plating, (iv) ageing mechanisms and shapes of capacity fade curves involving Li deposition, and (v) influences of Li deposition on safety. Although often discussed, safety issues regarding Li deposition are not only limited to dendrite growth and internal short circuits, but also to exothermic reactions in the presence of Lithium metal. Furthermore, we tried to connect knowledge from different length scales including the macroscopic level (Li-ion cells, operating conditions, gradients in cells, electrochemical tests, safety tests), the microscopic level (electrodes, particles, microstructure), and the atomic level (atoms, ions, molecules, energy barriers).