The total will be all kinds of batteries and supercapacitors, made from a variety of materials - each suited for the purpose they'll be used for.. it's not an all or nothing solution. As each solution develops they'll become less deadly and more environmentally sound, leading to better recycling. Much like when we were first contemplating the Internet in the 1980s, will it be fiber or wireless, ATM or Ethernet..? well, here we are and it's a mix of technologies made for their specific purpose.