"It says it expects its batteries to exceed 400 Wh/kg by 2022"
The 400 Wh/kg level would be 54% higher than roughly 260 Wh/kg that Tesla is using today.
EVs would not weigh that much then, even when having huge battery packs:
75 kWh battery at 400 Wh/kg: 188 kg of cells (compared to 288 kg now)
100 kWh battery at 400 Wh/kg: 250 kg of cells (compared to 384 kg now)
150 kWh battery at 400 Wh/kg: 375 kg of cells (compared to 577 kg now)
200 kWh battery at 400 Wh/kg: 500 kg of cells (compared to 770 kg now)
https://insideevs.com/news/440727/el...cells-not-far/
Lightweight battery packs = better performing and lower cost (other things being equal)