Why we can’t use a big capacitor instead of batteries to store energy?
While capacitors can store energy like batteries, they have different characteristics and are typically not used as direct replacements for batteries. Capacitors discharge energy rapidly and have lower energy density compared to batteries.
A battery uses electrochemical processes to store energy, while a capacitor simply stores charge. As such, capacitors are able to release the stored energy at a much higher rate than batteries.
Capacitors are less common (and probably less familiar) alternative to batteries.
They store energy in an electric field². In either case, the stored energy creates an electric potential. Electric potential, as the name might suggest, can drive a flow of electrons. Such a flow is called an electric current.
That current can be used to power electrical components within a circuit.
A new type of capacitor known as a supercapacitor is capable of storing electric energy much like batteries, but more research needs to be done on this technology.