Air Carrier A320 Captain reported a momentary loss of aircraft control during taxi with the taxiway appearing to be compacted with ice or snow. The event required the Captain to use the thrust reversers in order to avoid a taxiway excursion.

Narrative

After clearing the runway in ZZZ at [Taxiway] 1 on Runway X/XX we were instructed to turn left and proceed north on Taxiway 2. The runway had medium braking action but the taxiway was completely covered in snow and what appeared to be compacted snow or ice. As I started my left turn towards Taxiway 2 at approximately 3 or 4 kts my nose wheel began to slide. I applied the brakes and my main gear wheels began sliding as well. We were drifting towards the edge of the taxiway and due to the snow it was extremely difficult to see where the edge of the taxiway was. In order to keep from sliding further I opened the reversers and applied maybe 40 to 50% reverse thrust to stop the aircraft. After stopping; I continued my taxi into the ramp at about 3 kts the rest of the way in to the ramp. We didn't notice any signs of ingesting anything into the engines or packs. We have a limitation restricting max reverse below 70 kts. Idle reverse is permitted to a stop. I really didn't feel I had any other option than to spool up the reversers to keep the aircraft on the taxiway. I contacted maintenance to ask if any further action was required. After checking their manuals for required inspections they said no further action was required. Although I don't think it made a difference in our braking ability in this situation; I would like to point out my #2 brake was deferred. The weather was quite poor in ZZZ with gusty winds; low ceilings and snow covered runways and taxiways.