Why internal resistance of the battery decreases as temperature increases?

R is inversely related to temperature T so as temperature increases resistance decreases.

Specifically, R increases if the T coefficient is pos.(P.T.C) And decreases if T coefficient is neg. (N.T.C) Most conductors have P.T.C and most insulators have (N.T.C) . xept. like carbon. 1 of few conductors that has a N.T.C. But all can be found on a tablet. R.T.C / R mil-foot ,R, millimeter-meter and R.T.C @ 68*F