A traction battery thermal plate assembly may include a structure having edge portions defining a cavity and configured to support a battery cell array, a thermal plate disposed within the cavity and adjacent to the array, and a spring assembly disposed within the cavity between the structure and the plate. The spring assembly may be configured to exert a force against the plate such that plate contacts the array to transfer heat between the array and the plate. The thermal plate disposed within the cavity may be below the array. The spring assembly may include a body defining a plurality of tabs configured to extend outward from a plane defined by the body. The spring assembly may include a base portion and an upper portion configured to support one or more compression springs therebetween.