# What determines the speed of charging of a battery?

I was told on physics.stackexchange that this question belongs to Chemistry, what do you think?

Recently we have seen the surge of superfast mobile phone charging. Just an example: http://www.bbc.com/news/technology-30708945

What underlying physical principle determines the speed of charging of a battery?

There are many factors limiting speed of charging. Here are just a few:

1. Run-away overheating -- some battery chemistries, such Li-ion, may even self-ignite.

2. Spalling of electrodes -- the physical stress of rapid charging can buckle electrodes and cause a composite electrode to break apart.

3. Side reactions -- to increase the charging current, higher voltage is required. This over-voltage causes undesired side reactions, such as lithium plating (and out-gassing in Ni-MH and lead-acid batteries).

To make cells charge more rapidly, each of these potential issues must be analyzed and both the cell and the charging system must be designed to overcome the problem. In some cases, there have been spectacular failures, even when millions have been spent on design.

• In addition to the limits mentioned by DrMoishe Pippik there is also the intercalation rate that determines the charge rate. Oct 17, 2019 at 23:44

As you may know, what determines speed of a chemical reaction is its kinetics.

I didn't read the BBC article, but charging a battery follows a simple reaction :

A + B(+) → A(+) + B

and the rate of this reaction is determined by:

R = K [A][B(+)]

as you can see it depends on K and concentrations.

the thing we can change to make the reaction speed really high is K.

K is determined by three things. first the nature of reaction and second the catalyst we use and we can change both and third the temperature.

so to make a super hell fast recharging battery you need to find the right material for reaction and right catalyst and right temperature.

I hope this was the answer you were looking for.

• The geometry of the involved materials is probably also an important factor in this case. Feb 1, 2016 at 21:44
• Yea, of course, it's part of the nature of reaction.thanks for mentioning Feb 1, 2016 at 21:51