The paper analyzes the prospects of using a heat-accumulating material consisting of metallized polyethylene granules. X-ray diffraction analysis has been used to study the influence of the number of heating and cooling cycles of the heat-accumulating material on the change in the degree of crystallinity of polyethylene. It was shown that the proposed heat-accumulating material showed a low resistance and a significant decrease in the degree of crystallinity of polyethylene under the experimental conditions. The crystal structure of polyethylene did not change during cyclic heating and cooling. Grounded on the obtained experimental results, it was determined that a high degree of polyethylene crystallinity is being kept for 200–300 heating-cooling cycles.