Battery Basics

What is a Battery?

A battery is a device that stores chemical energy and converts it into electrical energy. It typically consists of one or more electrochemical cells, which include three main components:

1. Negative electrode (colloquially anode)

2. Positive electrode (colloquially cathode)

3. Electrolyte (a substance that conducts electricity through the movement of ions) 

When connected to an external circuit, electrons flow from the anode to the cathode, participating in electrochemical reactions, and producing electricity that powers devices.

Check out our Glossary of Electrochemistry Terms for more battery definitions.

What is Electrochemistry?

Electrochemistry is the branch of chemistry that studies the relationship between electrical energy and chemical reactions. This field encompasses energy storage (batteries), energy conversion (fuel cells), material coating (electroplating), water splitting (electrolysis), and sensors (e.g., pH meters).

Redox Reactions: Reactions involving the transfer of electrons between substances, which are central to electrochemical processes. Redox is short for reduction & oxidation.

• Anode: Where oxidation occurs (loss of electrons).

• Cathode: Where reduction occurs (gain of electrons).

I was taught to remember it as a mnemonic: LEO goes GER.

Loses Electrons is Oxidation. Gaining Electrons is Reduction.

Also Red Cat and Ox An: Reduction occurs at the cathode, oxidation at the anode.

Batteries in Your Daily Life

Alkaline Batteries

• Applications: Remote controls, flashlights, toys (think AA or AAA)

• Chemistry: Zinc anode and manganese dioxide cathode with an alkaline electrolyte (**conversion**)

• Pros and Cons: Affordable, long shelf life, not rechargeable

Lithium-Ion Batteries

• Applications: Smartphones, laptops, electric vehicles

• Chemistry: Lithium ions shuttle between a graphite anode and a lithium metal oxide cathode in an organic electrolyte (**intercalation**)

• Pros and Cons: High energy density, rechargeable, lightweight, expensive, degrades over time, sensitive to temperature

Lead-Acid Batteries

• Applications: Automotive starters (in gas-powered cars), backup power systems

• Chemistry: Lead and lead dioxide electrodes with a sulfuric acid electrolyte

• Pros and Cons: Reliable, inexpensive, heavy, limited energy density

Some Resources We Love:

• Summary of the history of batteries (includes li-ion, flow batteries, metal air)

•  A video that explains how a lithium-ion battery works

Next Up

We will cover intercalation vs. conversion chemistry. Stay tuned.