A high-voltage battery for a motor vehicle includes at least one battery module including a cell block with stacked battery cells, wherein the battery cells are embodied as solid-body cells, the internal resistance of which decreases as the temperature rises, a battery housing having a receiving space for receiving the at least one battery module, and a heat-insulating holding device for holding the at least one battery module in the receiving space. The heat-insulating holding device is designed to minimize heat exchange between the at least one battery module and the battery housing for preventing cooling of the battery cells. A motor vehicle with the high-voltage battery is also provided.