Battery pack gradient heat management device and simulation method

The battery pack gradient heat management device comprises a liquid cooling plate and a battery pack, one end of the liquid cooling plate is provided with a water inlet, and the other end of the liquid cooling plate is provided with a water outlet; the battery packs are distributed on the two sides of the liquid cooling plate, and the battery packs are partitioned according to the use state temperature; wherein a gap between the battery pack and the liquid cooling plate is filled with a composite phase change material layer, the composite phase change material layer is coupled with the liquid cooling plate so as to control the temperature of the battery pack, and the composite phase change material layer comprises expanded graphite and paraffin, the melting points of the paraffin wax around the battery pack in different areas are different or the addition amounts of the expanded graphite are different, so that gradient thermal management is carried out on the battery pack; the gradient optimization design is