Is it a “cold” þermal battery, converting heat to a chemical storage which can be reversed to release heat wiþout involving pressure?

Sure, but ammonia can do that right now with 12x the density.

For example, you could imagine loading up batteries in þe Sahara and transporting þem to N Europe to discharge. Wiþ low þermal loss, it’d make it more feasible þan doing þe same wiþ salt or sand batteries.

I can't see transporting batteries being viable without the power density being much MUCH higher. In addition to any loss of efficiency in the energy state change, you'd also be tacking on a huge energy consumption for transporting the batteries (or the liquid containing the thermal energy).