The fuel tanks are compartmentalized and have baffles to prevent sloshing. It's a solved problem. Electric motors are not 98-99% efficient. As you alluded to,

The fuel tanks are compartmentalized and have baffles to prevent sloshing. It's a solved problem. Electric motors are not 98-99% efficient. As you alluded to, battery weight is more than ICE weight. EVs are significantly heavier than ICEs. I'm sure we can expect improvements along the lines you mentioned, but I seriously doubt it will be nearly enough.