Why battery’s internal resistance decreases with temperature?

bobfei

Hi,

Does battery internal resistance obey the general resistance-temperature rule?

For metal, resistance usually increases with temperature (see wikipedia).

For batteries however, its internal resistance decreases with temperature (also see wikipedia).

Could anyone explain the contradiction?


Bob

trollcast

The resistance of any galvanic cell such as a battery decreases as temperature increases due to increased electron mobility at higher temps.

The increased electron mobility means that the electrochemical reactions inside the cell can happen faster or easier (not sure which one it is, someone else might know) which means the internal resistance is effectively reduced.

bobfei

Then they are consistent. Thank you!

Bob

Studiot

Batteries are chemical devices that rely on chemical reactions to produce their 'electricity'.

Chemical reactions mostly obey the Arrhenius equation which says that the rate of reaction increases with temperature.

http://en.wikipedia.org/wiki/Arrhenius_equation

So the faster the reactions the better the current transport and the lower the effective resistance.

Note that the cell voltage is only weakly dependent on temperature.

bobfei

Studiot,

I just read the wiki article and got a better understanding. Thanks!

Bob