How to make your own battery

Homemade battery from pencil and bolt

In this ex­per­i­ment, we’ll show you how to make a bat­tery a clock can run on!

Safe­ty pre­cau­tions


Reagents and equip­ment

  • plas­tic cap;
  • graphite rod (pen­cil graphite);
  • sil­i­cone tub­ing;
  • 0.5 g graphite pow­der;
  • 0.5 g man­ganese(IV) ox­ide;
  • cot­ton ab­sorbent;
  • salt so­lu­tion (am­mo­ni­um chlo­ride so­lu­tion, 5 mol/L);
  • zinc-plat­ed bolt.

Step-by-step in­struc­tions

In­sert the graphite rod into the plas­tic cap and at­tach the con­struc­tion to the sil­i­cone tub­ing. Add 1 g of a 1:1 mix­ture of graphite pow­der and man­ganese(IV) ox­ide. In­sert the cot­ton ab­sorbent and add 1 mL of am­mo­ni­um chlo­ride so­lu­tion. In­sert the zinc-plat­ed bolt. Your bat­tery is ready!

Process de­scrip­tion

Elec­tro­chem­i­cal cells are de­vices in which the en­er­gy from chem­i­cal re­ac­tions is turned into elec­tri­cal en­er­gy. An or­di­nary bat­tery is an ex­am­ple of a sim­ple elec­tro­chem­i­cal cell. Its pos­i­tive ter­mi­nal con­sists of man­ganese(IV) ox­ide mixed with graphite, its neg­a­tive ter­mi­nal con­sists of metal­lic zinc, and am­mo­ni­um chlo­ride acts as its elec­trolyte (a sub­stance that con­ducts elec­tric­i­ty). When the cir­cuit is closed – for ex­am­ple, when you in­sert the bat­tery into the clock – an ox­i­da­tion-re­duc­tion re­ac­tion be­gins in­side the bat­tery, and elec­tric cur­rent be­gins to flow through the cir­cuit.

The ox­i­da­tion-re­duc­tion re­ac­tion goes as fol­lows:

Zn - 2e = Zn²⁺

2M­nO₂ + 2N­H₄­Cl + 2e = Mn₂O₃ + 2NH₃ + H₂O + 2Cl⁻

Such a bat­tery can pro­duce up to 1.5 volts of steady elec­tric cur­rent.