Battery Build: A Simple Voltaic Cell
Electrochemistry, from a lemon battery to the EV packs built at Factory ZERO.
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Standards
HS-PS1-2 — Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms.
Why Does This Matter?
Detroit's Factory ZERO plant builds EVs powered by lithium-ion battery packs. Every one of those batteries works on the same core idea you'll build today at a much smaller scale: two different metals, an electrolyte, and a reaction that pushes electrons through a circuit.
Objective
Build a simple voltaic cell, measure its voltage, and explain the electron flow in terms of oxidation and reduction.
Materials
- 1 lemon or potato, or a cup of saltwater, per group
- 1 zinc-coated (galvanized) nail or strip
- 1 copper wire or penny (post-1982, copper-coated)
- 2 alligator-clip wires
- Multimeter
Safety: Do not taste or eat lab materials. Wash hands after handling metals and electrolyte solutions.
Procedure
- Insert the zinc nail and copper wire/penny into the lemon (or saltwater cup), keeping them close but not touching.
- Connect the multimeter's leads to each electrode using the alligator clips.
- Set the multimeter to read voltage (DC volts) and record the reading.
- Try swapping which electrode connects to the positive vs. negative multimeter lead. Note what happens to the reading.
- Connect two lemon cells in series (copper of one to zinc of the next) and measure the combined voltage.
- Record all voltage readings in the data table.
Data Table
| Setup | Voltage reading (V) | Notes |
|---|---|---|
| Single cell | ||
| Single cell, leads reversed | ||
| Two cells in series |
Analysis Questions
- Which metal is the anode (loses electrons/oxidizes) and which is the cathode (gains electrons/reduces) in your cell? How do you know?
- What happened to your voltage reading when you reversed the leads, and why?
- How did connecting two cells in series change the voltage? Predict what would happen with three cells in series.
- A real lithium-ion EV battery uses lithium instead of zinc/copper and a solid or gel electrolyte instead of lemon juice. What is the same about the underlying chemistry, and what is different?