Battery powered z-wave rocker remote

There aren’t any exactly like that. The two closest would be the Cooper zwave in the rectangular “decorator” style, the RF 9575:

The Cooper switch that you linked to is the same device but in their “designer” style, which has the curve.

http://www.cooperindustries.com/content/dam/public/wiringdevices/products/documents/spec_sheets2/Anyplace_switch_specsheet.pdf

Or the Lutron pico, Although if you use the official SmartThings/Lutron integration, the Picos are invisible to SmartThings, so they can only be used as a virtual three-way with the Lutron Caseta master switch.

There are a number of other battery powered devices, some designed for wallmount, which work well with SmartThings, but they have very different form factors from a traditional rocker switch: