There is quite a bit of R&D going into negating the need for Cobalt in Li batteries. I would not expect Cobalt to be needed in ~3-5 years (for Li batteries).
The tl;dr is slightly lower energy density (~14%) in exchange for non-toxicity, extremely low self-discharge rates, not prone to runaway thermalling, and great cycle life.
It also has the advantage of being able to be essentially a drop-in replacement for many lead-acid uses.
https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
The tl;dr is slightly lower energy density (~14%) in exchange for non-toxicity, extremely low self-discharge rates, not prone to runaway thermalling, and great cycle life.
It also has the advantage of being able to be essentially a drop-in replacement for many lead-acid uses.