A high power workload on a phone might require ~5-10W over 100ms, i.e. ~0.5 joules. At 4V capacitor voltage, you would need ~30mF capacitor. Not likely to fit in a phone.
This assumes you’re powering the phone solely off the cap. Even with a battery you’d still need something in the mF range to make up for the battery’s degradation.
This assumes you’re powering the phone solely off the cap. Even with a battery you’d still need something in the mF range to make up for the battery’s degradation.