First of all, we simply understand what the energy density of a battery is. There are two types of energy density, weight energy density and volume energy density. At present, the most referenced one is weight energy density. Its calculation formula is: weight energy density = battery capacity & times; discharge platform/weight, in Wh/kg (watt hour) /Kg); and the volume energy density calculation method only needs to change the weight of the above formula into volume, and the unit is Wh/L (watt hour/liter).

Simply put, energy density is an evaluation of the battery's storage capacity. At first, this evaluation was not used to determine the quality of electric vehicles, but the policy requirements for the company's power storage capacity of lithium batteries. According to the requirements, the company needs to exceed 300 watt-hours/kg of power lithium battery cell specific energy in 2020, and the system's specific energy strives to reach 260 watt-hours/kg. From a marketing perspective, since this is a policy-making standard, it must be attractive to consumers, so it has become a gimmick in the sales process of some pure electric vehicles.