Corrosion of aluminum current collectors in high power lithium-ion batteries for use in hybrid electric vehicles

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Corrosion of aluminum current collectors in high power lithium-ion batteries for use in hybrid electric vehicles

Cohen Hyams, Tzipi / Go, John / Devine, Thomas M.

The aluminum current collectors from six ATD (Advanced Technology Development) cells that were commercially fabricated and cycle-life (charge/discharge) tested at 25 deg C were microscopically inspected for evidence of corrosion. The results clearly show that aluminum covered with porous cathodes of LiNi(0.8)Co(0.15)Al(0.5)O2 of cycle-life ATD cells cycled at 25 deg C is susceptible to significant underdeposit corrosion in LiPF6-containing battery electrolytes. Aluminum current collectors of uncycled ATD cells contain mechanical pits formed during the attachment of the cathode, but with cycling at 25 deg C there is an increase in percentage pit area, in the number of pits, in pit-size-distribution, and in pit depth, which is a strong evidence of corrosion of Al current collectors of ATD cells. The formation of corrosion pits, corrosion of mechanical pits, and the non negligible amount of aluminum that was found in the electrolytes (approx. 2700 ppm) of cycle-life tested ATD cells explain the significant contribution of corrosion to the power fade and capacity fade and the possibility of mechanical degradation of the cathode as well.