Abstract
The corrosion behavior of aluminum, a candidate material for the current collectors of the positive electrodes of lithium‐polymer batteries, in contact with a lithium polymer electrolyte was examined in both batteries and three‐electrode electrochemical cells. The results indicate aluminum is resistant to uniform corrosion in the polymer electrolyte: poly(ethylene oxide)‐
but can be susceptible to pitting corrosion. Localized pitting corrosion occurs on the aluminum current collector during overcharging of the battery. Pitting corrosion only occurred in the electrochemical cells when the aluminum electrode was anodically polarized to potentials that were considerably greater than those that resulted in pitting corrosion in batteries. The greater susceptibility of the aluminum current collectors of batteries to pitting corrosion is attributed to inhomogeneous current flow through the current collector. This results in local breakdown of the passive film on aluminum at sites of locally high current density. The inhomogeneous current density that flows through the aluminum/cathode interface is caused by the presence of discrete paths through the cathode with low electrical resistance. In an effort to improve the localized corrosion behavior of aluminum electrodes, it was found that surfaces impregnated by ion implantation with ∼20 atom % tungsten exhibited enhanced resistance to pitting corrosion in poly(ethylene oxide)‐
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