What’s lithium plating?
Lithium-ion batteries work by exchanging lithium ions from positive to negative electrodes during a charge period. A current through the battery terminal provokes these lithium ions to diffuse through the electrolyte at a rate controlled by the injected current and the diffusion path of the battery. For a more in-depth explanation, see this video here.
When completing a “fast charge” for a lithium-ion battery, which is completed almost daily for many consumer electronics (ex. your phone) and electric vehicles, the goal is to push the battery to its limit and charge as fast as possible. This limit is very often defined as the current at which irreversible lithium plating tends to occur. Lithium plating happens when those lithium ions deposit themselves on the anode surface instead of intercalating into the anode structure, removing cyclable lithium ions from the cell and increasing the internal resistance. This makes lithium plating a very important degradation mode for lithium-ion batteries.
Current-voltage (IV) data and cell dissection images are key research components for investigating lithium plating in lithium-ion batteries. To give the consumer the fastest charging experience without compromising the battery due to lithium plating, firmware charge profiles are also optimized for all charge ranges of the battery (0%-20%, 60%-100%, etc.); for example, by mapping how much current the battery pack can handle at each closed-circuit voltage.
Now you know why your phone battery needs some time to recharge!
