The limits of batteries, and how they will improve

I was recent­ly asked a ques­tion about bat­tery life in mod­ern devices, and coin­ci­den­tal­ly I’ve been read­ing a few arti­cles about inter­est­ing devel­op­ments in bat­tery tech­nol­o­gy. So here’s a post giv­ing a very super­fi­cial intro­duc­tion to bat­ter­ies in mod­ern con­sumer elec­tron­ics.

Tech­nol­o­gy is being held back because we can’t make bet­ter bat­ter­ies. Ten years ago a mobile phone hand­set might have last­ed a week on a full charge, while your new smart­phone doesn’t even last an entire day; this is because your phone is capa­ble of doing so much more thanks to the fact that every­thing about it has got small­er and more pow­er­ful in recent years – except for the bat­tery.

The gen­er­al prin­ci­ple is that the big­ger a bat­tery is, the more charge it holds. That’s why your tablet can keep a charge for days, where­as your phone needs a dai­ly charge. But phones have a lim­it imposed by their porta­bil­i­ty — car­ry­ing a heavy bat­tery around would make it longer-last­ing, but much less use­ful.

The Lithi­um-ion bat­tery, invent­ed in 1991 and used in the major­i­ty of portable con­sumer elec­tron­ics, is about as good as it gets at the moment. Even Tes­la’s cars (and recent­ly announced home bat­tery) run on Li-ion bat­ter­ies, albeit thou­sands of them in a larg­er bat­tery case.

Man­u­fac­tur­ers are get­ting very good at squeez­ing per­for­mance increas­es from Li-ion, but major improve­ments aren’t hap­pen­ing. The next step is not to make Li-ion bat­ter­ies bet­ter, but to make them cheap­er. Tes­la are build­ing a huge new fac­to­ry that will more than dou­ble world­wide pro­duc­tion of Li-ion, and although all of those will go into their own prod­ucts, the net effect should be cheap­er bat­ter­ies over­all (they esti­mate a 30% reduc­tion). New start­up 24M have also announced that they’ve rein­vent­ed the man­u­fac­tur­ing process to cut devel­op­ment time by 80%, and costs by 50% (they claim per­for­mance ben­e­fits too, but these have yet to be quan­ti­fied).

A promis­ing new entrant to the are­na is Sakti3, who claim to have invent­ed a new sol­id state bat­tery that can store twice as much ener­gy as the Li-ion. The bat­tery is cur­rent­ly only at pro­to­type stage, but they recent­ly received a large invest­ment from Dyson to bring it into pro­duc­tion.

In any case, it will take a few years for these new devel­op­ments to come to mar­ket, so don’t expect your smart­phone to get cheap­er, lighter, or to hold a charge longer, any time in the near future.


Also pub­lished on Medi­um.