Question

When modeling Lithium-ion battery degradation, which specific internal electrochemical state parameter is directly responsible for limiting the allowable charge current to prevent lithium plating?

Accepted Answer

The specific internal electrochemical state parameter directly responsible for limiting the allowable charge current to prevent lithium plating is the anode surface potential. Lithium-ion batteries function by moving lithium ions between a cathode and an anode. During charging, these ions are forced into the anode, a process called intercalation. If the charging current is too high or the temperature is too low, the potential at the surface of the anode particles can drop below the potential of metallic lithium. When this occurs, the lithium ions arriving at the anode surface cannot intercalate into the graphite structure fast enough and instead deposit as solid metallic lithium on the surface of the anode, a phenomenon known as lithium plating. This plating is dangerous because it consumes active lithium, reduces battery capacity, and can form needle-like structures called dendrites that may pierce the separator and cause internal short circuits. Therefore, battery management systems monitor the anode surface potential relative to the lithium reference potential; to prevent plating, the charging current must be restricted whenever this potential approaches or crosses the zero-volt threshold relative to lithium metal.

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When modeling Lithium-ion battery degradation, which specific internal electrochemical state parameter is directly responsible for limiting the allowable charge current to prevent lithium plating?