If we consider charging mechanism of electro-chemical cell or battery,it is continuous process of injecting electrons on negative side(-Ve) plate and protons positive side(+Ve) plate. When we see an AC current graph it is sine wave or a pi/2 shifted cosine wave . It changes its direction i.e. the phase from positive to negative continuously with high frequency. so it is difficult to physically change the terminals of the battery with such a high frequency and more over if we use a AC power to charge a battery then during positive half the battery will charge and the next half cycle it will discharge and as a result the net voltage stored in the battery is zero.However AC can be stored in capacitor or inductor with very less output .