Rechargeable lithium metal anode batteries (RLB) have the potential to meet the Department of Energy’s 500 Wh/kg goal [1]. However, higher cycling efficiency and safety of these cells is challenged by the dendritic Li plating morphology. Li surface protective coating or electrolyte that can promote growth of stable solid electrolyte interphase from the reduction products can prevent dendritic growth of Li during plating. Another way to suppress the dendritic growth and facilitate more uniform Li surface morphologies is by applying the external pressure to the cell [2].

The external cell pressure can influence the Li plating conditions and modify Li surface. The growth of Li dendrites can be suppressed due to the Li surface strain field under external cell pressure. Also the loss due to dead lithium can be minimized by maintaining a good electrochemical contact between Li deposits. A dendrite-free uniform mossy Li surface with good electrochemical contact will improve the cycling efficiency and safety of the cells.

The effect of external cell pressure was studied in cells with nickel rich LiNi_0.6Mn_0.2Co_0.2O₂ cathode and Li metal anode. The cycling performance was analyzed with electrochemical diagnostics tools. The Li surface morphology was characterized with scanning electron microscopy. The effects of various external pressure on cycling efficiency and the Li surface morphology will be illustrated and discussed.

References:

[1] Battery500 Consortium to Spark EV Innovations: Pacific Northwest National Laboratory-led, 5-year $50M effort seeks to almost triple energy stored in electric car batteries, in Office of Technology Transitions Energy.gov (2016).

[2] Gireaud, L., Grugeon, S., Laruelle, S., Yrieix, and B., Tarascon, J. –M., Electrochem. Comm. 8, 1639–1649 (2006)