In reverse order:
2. We need to build lots more renewables.
1. a) You build more than you need on any particular day so even when the wind is low you get something.
b) when you have more than you need as electricity, which is basically all the time, you make hydrogen to decarbonize the production of steel, fertilizer, avgas etc. (This is something we need to do even if we had lots of cheap nuclear plants)
c) If you are hit by some freak event you didnt plan for, and you can't just import via wires, you burn the hydrogen in fairly standard cheap turbines to provide more power. You have a lot stored as hydrogen anyway that you were going to make stuff with, so just delay that a little. (In the short term, while every bit of electricity is needed to clean the grid, stored natural gas can take this role)
d) do this all over the world, and when convenient, trade hydrogen or things made from it as a way of exporting/importing renewable energy from wherever it's cheapest.
e) lithium batteries for grid use would only be economic for shifting a small amount of power on a daily schedule (e.g. solar peaks to evenings or night wind to mornings) but..
f) the entire vehicle fleet shifting to battery means theres a giant demand response fleet that can absorb energy when its available at no (extra) loss since they were going to charge anyway.
extra: there's no reason to not include nuclear in the above, except for the fact that it's more expensive than the other options for producing electricity and we already need a method to flex demand to meet needs. So new nuclear is mostly useless, unless you need some excuse to talk about how crap renewables are.