supplied there through the elution reaction of a lead current collector 17 continuously supply the route for electronic conduction and can provide stable battery characteristics this is because the carbon particles dispersed in the current collector by mechanical alloying are incorporated in a passivated film layer region due to the elution of lead of a base material in the current collector even if fibrous carbon replaces carbon particles 13 it shows a similar effect in the present embodiment a lead current collector 17 had a material yield strength improved to a 60 mpa level from a 20 mpa level because of having lowered the grain size thereby in the preparation of a wound type battery using a thinned material with a thickness of several tens of microns problems such as the breaking of a thin lead current collector in the middle of an operation disappeared and the winding workability was improved in addition as a result of a corrosion test as will be described later of overcharging a prepared lead current collector 17 in a sulphuric acid solution of 20 u00b0 c having the specific gravity of 1 280 for four weeks the lead current collector 17 showed the effect of greatly improving intergranular corrosion resistance and corrosion elongation compared to a conventional cast and rolled material a lead tin alloy containing calcium because of having decreased the concentration of segregated elements in grain boundaries specifically a current collector made of an ordinary lead tin alloy containing calcium showed intergranular corrosion after.