500 Wh/kg means Sulphur cathode, which also explains the solid electrolyte. Roughly speaking, it'll be 3x as energy dense but only a 1/2 as volumetrically efficient (so, a given capacity battery will weigh 1/3 less but take up twice as much space). There are other approaches to Li-S (and Al-S and Mn-S) which will be less expensive. Grats to CATL for bringing this to market, but the race for sure isn't over yet.
It would weigh 1/3, not 1/3 less.