I suppose you could, but why bother? USB power banks are so darn cheap now that you should just buy one. I priced out what it would cost me to build my own power bank out of 18650 Li-ion cells, and by the time I priced out the components, the cells, the enclosure, the connectors and so on, it was cheaper to just buy one.
Lithium titanate batteries are a lot more expensive than the more popular chemistries. The good news about this battery type is that it can recharge more quickly than other lithium battery chemistries, but the bad news is that they are an odd voltage, so that would very likely require a unique circuit design.
Perhaps soon some manufacturer will build power banks from these cells. You will save a lot of money and time by waiting for someone else to build and sell them. But if you like to tinker, go right ahead.