[jsprogrammer]

Lithium ion makes no sense for storage. Something like large-scale flywheels would probably be much better. Using gravity for storage is even more sustainable. Flywheels for night use and stored water for long term use (storms, fog, prolonged winter at poles [would need to keep from freezing]) all powered by solar or other low-ongoing-input sources should provide a pretty nice environment.

[dredmorbius]

Flywheels have proved extremely expensive with massive engineering challenges. When you have to account for precession due to Earth's rotation, things get tough.

For short term very high flux power conditioning they've got uses. For long-term storage not so much.

Seconds to minutes is likely their effective range. Not hours to days.