The Bosch battery does indeed use silver in its construction (Bosch website)
But a quick google search on the price resulted in a definitive gasp! £100+ for a battery?????? Ok, maybe if it's a seriously high capacity unit, but for the vast majority of cars a much, much cheaper unit will do just fine. I'd take your existing battery to a local motorfactor, ask them to test it (making sure it's not the alternator at fault) then get a direct replacement.