Electrochemical vs Electrolytic Cells: Key Differences Explained
Electrochemical cells convert chemical energy into electrical energy spontaneously (like a battery). Electrolytic cells do the opposite, using external electricity to drive non-spontaneous chemical reactions (like plating jewelry).
People confuse them because both involve electrodes, ions, and redox reactions. The twist: one powers your phone, the other coats your earbuds in gold. Same parts, opposite energy flow—like a video playing forward vs. in reverse.
Key Differences
Electrochemical cells have positive Gibbs free energy; electrolytic cells negative. In the former, the anode is negative and cathode positive; in the latter, it’s reversed. Salt bridge vs. external power source completes the circuit.
Which One Should You Choose?
Need portable power? Use an electrochemical cell (alkaline, lithium-ion). Need to refine aluminum or electroplate chrome? Hook up an electrolytic cell. Match the process to the goal: spontaneous energy out or forced reaction in.
Examples and Daily Life
AA batteries and smartphone packs are electrochemical cells. Laptop gold-plated USB ports and chrome-plated car trims come from electrolytic cells. One keeps devices alive, the other makes them shiny and corrosion-resistant.
Why does an electrolytic cell need a battery?
Because its reaction is non-spontaneous; the battery supplies the energy to push electrons uphill, splitting compounds or depositing metals.
Can one device act as both?
Yes. Rechargeable lithium-ion batteries operate as electrochemical cells when discharging and switch to electrolytic mode during charging.