GB were within a goal of the world’s 10th seeds when Robert Farmer closed the gap to 2-1 with five minutes remaining in the second period, but the hosts – helped by two powerplay markers – scored four unanswered goals to secure a 6-1 victory.
Phillips said: “Slovakia came at us hard in the opening stages but we rode that out and grew into the game the longer it went on.
“I felt we fully deserved our goal and at that stage it was a one-goal game and we felt we were right in it.
“Slovakia showed their class in the third period and took the game away from us, but we can take positives from that performance for sure.
“We certainly now know the standards we are going to have to achieve at this tournament and it was great preparation for us.
“Our training in Slovakia so far has been excellent and we are looking forward to another week of solid practice ahead of our first game.”
GB will now continue their training camp at their base in Michalovce, before moving on to Kosice on Thursday ahead of facing Germany on Saturday in their opening game at the World Championship.