Litchfield's match-winning knock included the fastest 50 ever in the women's competition.
She told Sky Sports: "You die by the sword at times but putting the pressure back on the bowlers is the way to go in T20 or Hundred cricket.
"Momentum in cricket is an amazing thing, as all cricketers know."
Hosts Phoenix were restricted to a paltry total of 9-107 after Deepti Sharma claimed 3-11 for Sunrisers.
After England batters Davina Perrin, Tammy Beaumont and Alice Capsey were dismissed cheaply, another Aussie, Ellyse Perry, led the fightback with 31 before Emma Lamb hit 47, but 108 never seemed enough at Edgbaston.
It proved the case with Litchfield in imperious form and brushing off the dismissal of opener Bryony Smith for 12.
Litchfield struck 13 fours in a 33-ball innings of 71 and put on 87 for the second wicket with Lauren Winfield-Hill to inspire Sunrisers to a comfortable victory with 31 balls to spare in Birmingham.
Sunrisers' victory, which leaves them in fourth place, means Birmingham, MI London and London Spirit can no longer progress to the knock-out stages of the competition.
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