A surprising breakthrough could help sodium-ion batteries rival lithium—and even turn seawater into drinking water. Scientists discovered that keeping water inside a key battery material, instead of removing it as traditionally done, dramatically boosts performance. The “wet” version stores nearly twice as much charge, charges faster, and remains stable for hundreds of cycles, placing it among the top-performing sodium battery materials ever reported.
mAh/g (milliamp-hours per gram) is essentially still a measurement of capacity, but in terms of current instead of power.
We can do a little dimensional analysis here to translate between them. Power = Current x Voltage, so you’d multiply this (Current x Time)/(Weight) value by the nominal voltage of the cell to get to (Power x Time)/(Weight).
Phone batteries are often specified in units of Current*Time (e.g. milliamp-hours), but I’m not completely sure why. I think it has to do with voltages being standardized for certain types of cells, so the only real variable in the battery capacity is the current.
Edit: rearranged some ideas to make more sense
I think it’s marketing
5000 mAh is much a bigger number than 19 Wh and marketing loves huge numbers
Kinda like BMW did with the i3.
In 2013 Tesla was selling a model with a 60 kWh battery so BMW had the genius idea to install a 20 kWh battery BUT refer to it as “60 Ah” battery.
Tesla introduced the 90 kWh battery? BMW responds with a 94 Ah battery (28 kWh)
Newest Tesla has 100 kWh battery now? BMW has 120 Ah battery (38 kWh)
“See? Higher number!”, says the marketing
And in order to have a comparable range number they had to implement heavy weight reduction techniques like using carbon fiber for the body, negating any cost saving from the smaller battery AND giving the owner a total loss after small collisions as it shatters instead of bending
That’s an incredibly longwinded way of saying “mahh Tezlur burns three times as much ‘clean coal’ per mile as a commie BMW, yee-haw”.