What is the Difference Between Electrochemical and Electrolytic Cells?

Electrochemical and electrolytic cells are both types of devices that deal with electrochemical reactions, but they differ fundamentally in their operation: an electrochemical cell converts chemical energy into electrical energy, while an electrolytic cell uses electrical energy to drive a non-spontaneous chemical reaction.

Electrochemical Cell (Galvanic or Voltaic Cell)

Electrochemical cells, also known as galvanic or voltaic cells, harness spontaneous chemical reactions to generate electricity.

• Energy Conversion: Chemical energy to electrical energy.
• Spontaneity: Reaction is spontaneous (ΔG < 0).
• Operation: Involves two half-cells, each containing an electrode immersed in an electrolyte solution. The electrodes are connected by an external circuit, allowing electrons to flow from the anode (where oxidation occurs) to the cathode (where reduction occurs). A salt bridge or porous membrane is used to maintain electrical neutrality in the half-cells.
• Examples: Batteries (e.g., alkaline, lithium-ion), fuel cells.

Electrolytic Cell

Electrolytic cells, on the other hand, use electrical energy to force a non-spontaneous chemical reaction to occur.

• Energy Conversion: Electrical energy to chemical energy.
• Spontaneity: Reaction is non-spontaneous (ΔG > 0).
• Operation: An external voltage source is used to drive the reaction. The anode is positive and the cathode is negative, which is the reverse of an electrochemical cell. Electrolysis involves the decomposition of a substance by passing an electric current through it.
• Examples: Electrolysis of water, electroplating, production of aluminum.

Key Differences Summarized

Conclusion

In essence, electrochemical and electrolytic cells perform opposite functions. Electrochemical cells create electricity from chemical reactions, while electrolytic cells use electricity to make chemical reactions happen.