Want to replace fossil fuels?

You have two options. Nuclear, or renewables.

Renewables, however, generally don't produce consistent energy output. So, you need a way to store the surplus, and release it at night time.

The most effective way of storing this energy, is currently pumped hydro. However, it has very specific geographical restrictions, and isn't an option in most cases.

The other option, is lithium, until a better alternative is produced.

As well, you need to replace fossil fuel usage for vehicles. The only current suitable alternative with an "OK" energy density, charge rate, and output capacity, is lithium based technologies. Typically uses Li-ion, or LiFePO4.

Have a cell phone? Its powered with lithium batteries. All cell phones, are powered with lithium. Typically LiPO, or Li-ion.

One day, this will change, but, until that day, lithium is needed.