How do batteries store energy? How do they work in general?
In: Technology
It’s a chemical reaction. There are different kinds but typically you have two pieces of metal called an anode and a cathode. Those pieces of metal are placed in a fluid substance called an electrolyte. The anode is made of a substance that reacts with the electrolyte causing electrons to build up on the anode. The cathode is made of a material that reacts with the electrolyte to pull electrons away. This creates a difference in charge between the anode and the cathode. When a wire circuit connects the two, the negative charges on the anode repel each other, pushing themselves onto the wire. This then pushes electrons already on the wire further down the wire. Eventually the electrolytes chemical ability to produce charge on the anode is depleted. The reaction stops and the battery dies.
For this example, I’m going to look specifically at an alkaline battery (like your everyday AA cell), but what I’m about to say applies generally to every type of battery.
In your typical battery, you have zinc metal at one end and the compound manganese dioxide at the other. They are separated by a paste of (typically) potassium hydroxide to act as an electrolyte and a buffer.
When you connect the battery to an electrical circuit, two chemical reactions occur, one at each end of the battery. At one end, zinc reacts with the hydroxide to release electrons. At the other, manganese dioxide reacts with the hydroxide and absorbs the electrons. This flow of electrons provides the power to the device.
The two ends of the battery are (generally) irreversibly changed as a result of the reaction; they’re slowly turned into forms that can’t release or absorb electrons, and that’s what’s happened when a battery runs out of power.
Other battery types use different materials, and some can be *recharged*; that is, the chemical reactions can be forced to “go backwards,” restoring the battery’s ability to generate power.
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