[nardi]

Li-ion batteries are only dead after 2 years if they are abused or their charge/discharge life is used up. Properly cared for real world Li-ion batteries last for 10 years or more (in spite of Isador Buchmann's claim to the contrary).

Note that he explicitly confirms that Li-ion batteries have a limit on the number of charge/discharge cycles they can handle. That's precisely the problem this technology is supposed to fix.