Anyone think that a site like Wealthftont is a good place to stick an emergency fund?

A buddy of mine told me about Wealthfront recently and they’re 5% money market account rates.

Growing up in a world where savings accounts and even CDs never approached more than 2%, the rates on this new thing blew me away.

Free money is great, and I’d love to take advantage of these rates, but the only cash I have currently is the emergency fund I’m trying to build.

Anyone have thoughts on if putting an efund in this kind of service is a bad idea? Not sure if it’ll be liquid enough if a major expense comes up.