The cost of replacing electric car battery packs is enough to convince many drivers to keep topping up with gasoline. Today we consider the causes of electric car battery aging, and explain how this process is inevitable. Although, as The Naked Scientists point out, there are things we can do to delay the process.
Just Why Do Electric Car Batteries Age?
Lithium-ion batteries power most electric cars, and so we will use them as our example. Drivers can influence the performance of their vehicles, by the way they use them and their batteries. The three main factors to consider are (a) the operating temperature (b) the state of charge, and (c) the rate at which drivers charge and discharge them.
Electric car batteries deliver their energy, by moving ions from their negative electrodes to their positive cathodes. This process reverses when their users recharge them, which essentially involves returning the ions from where they came. During this process the ions insert and remove from the electrodes, and this causes large volume changes.
This repeated expansion and contraction can cause cracking, exposing more surface, and loss of some of active material as electric car battery aging proceeds. Moreover, the graphite anodes may be unable to accept all the lithium ions while the temperature is low, and / or during fast charging. This may in turn cause the rogue ions to accumulate on the surface, and result in dendrites.
How These Factors Influence Battery Life
To complete the picture we should first mention the role of the liquid electrolyte. Its molecules can also suffer damage, and decompose at high voltages during recharging. This can increase the resistance in the surface layers in the battery. That just leaves the behavior of the user to complete the picture.
Our first, and most important conclusion is moderation is the key to extending electric car battery age. Since degradation happens during high rates of charge / discharge, it makes sense to drive slowly and not allow the battery to drop below half its capacity. However, this is impractical when driving long distances, and so battery degradation is a fact of life that we can manage to an extent.
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