1500mAh is only a 1.5A charge. That's standard for most battery packs, nothing great. My old Motorola P4000 charges at 1.5A.

This Anker 20,100mAh on Amazon is $79.99 (not Prime) and supports up to 2.4A on standard USB and 3A on Type-C.

Here's a similar Anker 20,100mAh one without Type-C for only $45.99 (Prime). It is limited to 2.4A like all standard USB ports though. It does come with the wall adapter too however.

There's also this 20,100mAh one from RavPower for $55.99 (Prime) that's the same capacity and 2.4A USB and 3A Type-C capability (except it also supports QuickCharge2.0)

Or this RavPower 26,800mAh behemoth for only $49.99 (Prime) without Type-C that will charge up to 2.4A via stadard USB.

Both of the RavPower devices have good reviews and I've never had an issue with them or Anker before.