How do you manage your emergency fund? Typical cash management solutions seem to have 1-3 business day withdrawal period. Are there any liquid instant withdrawal options better than a savings account?

I have reviewed several cash management offerings which have withdrawal time ranging from 1-3 business days. I would like to explore other options to save my emergency funds (6x monthly salary), which is easy to liquidate yet doesn't suffer the low interest rates that a typical savings account offers.