This is wrong and I will show you why. Range = total energy / total consumption Total consumption is a constant for both vehicles (lithium and sodium) - same mass Total energy = mass of battery x gravimetric energy density Sodium ion battery has half the energy density of the lithium-ion battery Energy of the sodium battery = mass of battery x (half of lithium battery gravimetric energy density) Energy of the sodium battery = 0.5 x energy of the lithium battery therefore Range of the sodium vehicle = (0.5 x energy of the lithium battery) / total consumption (which is constant as we said) = 0.5 x range of lithium vehicle There is something else you have not considered which is that in order to keep a large lithium battery operational it need to expend energy to heat itself and cool itself to the correct temperature, which a sodium battery doesn't need to. This is a major loss factor in current lithium based EVs. So in fact the sodium vehicle will have more than half the range of the lithium for the same weight, with the difference being more marked the further the ambient temperature is away from the optimal temperature for the lithium battery.