Super-capacitors are energy storage devices similar to secondary batteries. Unlike batteries, which use chemical reactions to store energy, super-capacitors generally store energy through the physical separation of electrical charges.
Electrochemical Techniques for
Knowing the exact specifications when testing batteries.
This application note is Part of 2 describing electrochemical techniques for energy-storage devices. It explains Gamry’s PWR800 measurement software and describes techniques to investigate electrochemical capacitors. This application note can also be extended to testing batteries.
This note discusses basics of Electrochemical Impedance Spectroscopy (EIS) and introduces Gamry’s EIS techniques by measurements on single electrochemical capacitors (ECs) and stacks.
Batteries in electric vehicles discharge during acceleration and while maintaining vehicular speed. They are recharged during braking. Driving cycles can therefore reflect significant variations in battery discharging and charging events such that observation of ampere-level current swings may be possible. For example, The US Advanced Battery Consortium (USABC) adapted the Federal Urban Driving Schedule (FUDS) cycle test to electric vehicles and presented it as percent of peak discharge power with time as shown in Figure 1. Negative percentage values refer to a state of discharging whereas positive values refer to a state of charging.