Batteries made out of gold nanowires and electrolyte gel last 400 years

Any advances in energy production or energy storage make me very excited because I consider those are the most important challenges for human race survival, because we are destroying the climate using fossil fuels. Advances in energy storage would allow us to make better use of solar and wind energy production.

I also can't help but dream with how advances in energy technologies could maybe put us close to building self-replicating robots to explore and colonize other planets!

Any ideas if it would be expensive to produce batteries using this technology?