"Do you have any idea how much an appropriate battery costs?
an average house uses over 20kws a night, thats anywhere up to $20,000 for the battery that loses up to 50% capacity over 10 years."
There's always incentives and rebates available that can help lower costs of installing a battery.
https://www.energysage.com/energy-storage/benefits-of-storage/energy-storage-incentives/
"If you then add electric cars the cost doubles."
There is currently not a lot of supply in the electric car market, which when electric cars are mandated, prices would become cheaper.
"There's also realistically not even enough lithium on earth to build enough batteries for all the cars and houses in america, let alone every nation on earth."
Lithium can actually be mined sustainably, just look at direct lithium extraction. Innovations in DLE technology have promised greater yield and purity of lithium...
https://www.innovationnewsnetwork.com/how-direct-lithium-extraction-can-ensure-sustainable-mining/35334/