Computers don’t create transient loads that last only a few hundred ms. (The components are already decoupled for that kind of transient). When you open your m

Computers don’t create transient loads that last only a few hundred ms. (The components are already decoupled for that kind of transient). When you open your mail and it has to perform a sync, for example, the transient may last for 10+ seconds and it’s not something you can fix with a supercap. You’d be better off adding more battery at that stage, as a larger battery has lower proportional sag for a given current (coulomb rates). Another thing you can do is size your battery, say 20% larger than you require it, and only charge to 80%. This reduces ageing significantly, BUT consumers would never see this as a feature. They would just complain that the latest Apple phone has 20% less battery than the competitor and is $50 more expensive and heavier than the last model. I’m taking it at a punt that 99% of regular consumers want to change their phone every 2-3 years (to get the latest camera, Face ID or car keys or whatever feature it might be), so that’s what Apple has targeted for the maximum age of their battery. Anything more is making a collective trade-off for the, perhaps, 1% no?