Skip to main content

How Do Batteries Work?

Oxidation and Reduction

  • A metal oxidizes and sends electrons out → a substance reduces and regains electrons
  • Once most of the metal oxidizes the battery dies
  • Rechargeable Batteries: electricity from a wall outlet reverses the flow of electrons and regenerates oxidized metal

Battery Design

  • PVC Wrapper: displays product details/brand
  • Cathode: positive end of the battery
  • Anode: negative end of the battery
  • Steel Casing: stops internal contents from interacting with the atmosphere
  • Layer 1: Cathode
    • Manganese Oxide + Graphite
    • Graphite increases conductivity and energy density
  • Layer 2: Fibrous Barrier
    • Prevents the anode and cathode material from having direct contact
    • Allows the battery to last longer when not in use
    • An electrolyte liquid of Potassium Hydroxide is sprayed on the inside of the fibrous barrier during manufacturing and Alkaline Electrolyte is soaked in
    • Specialty material allows ions to pass through
  • Layer 3: Anode
    • A paste made from Zinc powder and a gelling agent
    • Powder form increases the surface area of the material which lowers internal resistance, increasing electron transfer
  • Nylon Plastic Cap: seals the steel capsule
  • Brass Pin: inserted into the Zinc, results in the negative terminal


  • The flow of electrons through a complete circuit
  • Electrons want to get back to their source → they will pursue the optimal route
  • Batteries create Direct Current (DC) electricity – electrons flow in one direction from negative to positive
    • Alternating Current (AC): electrons flow both ways
    • Occurs with wall outlets for example
  • Ion: An atom with an unequal amount of electrons and protons
    • Positive Ion: more protons than electrons
    • Negative Ion: more electrons than protons
  • Conductors: allows electrons to easily flow through
    • Copper is the most commonly used conductor
  • Insulators: does not allow electrons to flow through at all
    • Rubber is the most commonly used conductor

Battery Mechanics

  • Inside the capsule, Manganese, Electrolyte, Zinc, Water are combined together to create a chemical reaction where atoms start to interact with each other
  • Hydroxide Ion atom within the electrolyte will join with Zinc atom inside the Anode
    • This chemical reaction is called Oxidation
    • Creates Zinc Hydroxide which releases electrons that are collected on the brass pin
  • Manganese Oxide atom will join with Water atom within the electrolyte and a free electron
    • This chemical reaction is called Reduction
    • Manganese Oxide atom undergoes changes and ejects the Hydroxide Ion atom into the electrolyte
    • The Water atom is replaced by the one ejected from the Oxidation reaction
    • Hydroxide Ion is free to pass through the separator
  • Results in a build-up of electrons in the negative terminal → results in the voltage difference between the two ends
  • Electrons want to move to somewhere with fewer electrons → since there are fewer electrons in the positive terminal it will try to go there → but the capsule is blocked off → electrons need a different route → when a copper wire is hooked up to two ends electrons will pass through and do work

Lithium-Ion Batteries

Koko Xu

Lover of international cuisines and Class B chess player.