Lithium-Ion batteries aren't all sweetness and light, but it's not a particularly dirty process compared to Ni-Cd, and certainly you have to factor in benefits of reduced generation.
Ni-Cd batteries are so bad for the environment that the EU is forcing companies to phase out their use. Saying that Lithium Ion batteries are better than something that's been banned for most purposes because it's so toxic is not exactly high praise.
> have to factor in benefits of reduced generation
Well the outcome really depends on how long they last before you need to replace them. Plus you have the take in account the recycling cost (for the environment as well).
