Battery what is

This list also explains why in Volta's pile, the zinc was the anode, and silver the cathode: the zinc half-reaction has a lower more negative E 0 value Any two conducting materials that have reactions with different standard potentials can form an electrochemical cell, because the stronger one will be able to take electrons from the weaker one. But the ideal choice for an anode would be a material that produces a reaction with a significantly lower more negative standard potential than the material you choose for your cathode.

What we end up with is electrons being attracted to the cathode from the anode and the anode not trying to fight very much , and when provided with an easy pathway to get there—a conducting wire—we can harness their energy to provide electrical power to our torch, phone, or whatever. The difference in standard potential between the electrodes kind of equates to the force with which electrons will travel between the two electrodes.

The greater the difference, the greater the electrochemical potential, and the higher the voltage. We could choose different materials for our electrodes, ones that will give the cell a greater electrochemical potential. Or, we can stack several cells together. Essentially, the force at which the electrons move through the battery can be seen as the total force as it moves from the anode of the first cell all the way through however many cells the battery contains to the cathode of the final cell.

But the electrodes are just part of the battery. The salty water was the electrolyte, another crucial part of the picture. An electrolyte can be a liquid, gel or a solid substance, but it must be able to allow the movement of charged ions. The electrolyte provides a medium through which charge-balancing positive ions can flow. As the chemical reaction at the anode produces electrons, to maintain a neutral charge balance on the electrode, a matching amount of positively charged ions are also produced.

At the same time, the cathode must also balance the negative charge of the electrons it receives, so the reaction that occurs here must pull in positively charged ions from the electrolyte alternatively, it may also release negative charged ions from the electrode into the electrolyte. So, while the external wire provides the pathway for the flow of negatively charged electrons, the electrolyte provides the pathway for the transfer of positively charged ions to balance the negative flow.

This flow of positively charged ions is just as important as the electrons that provide the electric current in the external circuit we use to power our devices. The charge balancing role they perform is necessary to keep the entire reaction running. Now, if all the ions released into the electrolyte were allowed to move completely freely through the electrolyte, they would end up coating the surfaces of the electrodes and clog the whole system up.

So the cell generally has some sort of barrier to prevent this from happening. Show labels during animation Start animation. When the battery is being used, we have a situation where there is a continuous flow of electrons through the external circuit and positively charged ions through the electrolyte. If this continuous flow is halted—if the circuit is open, like when your torch is turned off—the flow of electrons is halted. As the battery is used, and the reactions at both electrodes chug along, new chemical products are made.

These reaction products can create a kind of resistance that can prevent the reaction from continuing with the same efficiency. When this resistance becomes too great, the reaction slows down. The electron tug-of-war between the cathode and anode also loses its strength and the electrons stop flowing.

The battery slowly goes flat. Some common batteries are single use only known as primary or disposable batteries. The trip the electrons take from the anode over to the cathode is one-way. The nifty thing about that flow of ions and electrons as it takes place in some types of batteries that have appropriate electrode materials, is that it can also go backwards, taking our battery back to its starting point and giving it a whole new lease on life. When we connect an almost flat battery to an external electricity source, and send energy back in to the battery, it reverses the chemical reaction that occurred during discharge.

This sends the positive ions released from the anode into the electrolyte back to the anode, and the electrons that the cathode took in also back to the anode. Over the course of several charge and discharge cycles, the shape of the battery's crystals becomes less ordered. High-rate cycling leads to the crystal structure becoming more disordered, with a less efficient battery as a result.

In some cells, it is caused by the way the metal and the electrolyte react to form a salt and the way that salt then dissolves again and metal is replaced on the electrodes when you recharge it.

The way some crystals form is very complex, and the way some metals deposit during recharge is also surprisingly complex, which is why some battery types have a bigger memory effect than others. The imperfections mainly depend on the charge state of the battery to start with, the temperature, charge voltage and charging current.

Over time, the imperfections in one charge cycle can cause the same in the next charge cycle, and so on, and our battery picks up some bad memories. This exchange of electrons allows a difference in potential or voltage difference to be developed between the two terminals—allowing electricity to flow.

There can be a vast number of cells in a battery, from a single cell in an AA battery, to more than 7, cells in the 85 kWh Tesla Model S battery. In these cells a chemical action between the electrodes and electrolyte causes a permanent change, meaning they are not rechargeable. This causes the chemical action to go in reverse, effectively being restored, meaning that they are rechargeable.

Batteries are often rated in terms of their output voltage and capacity. The capacity is how long a particular battery will last in Ah Ampere hours [2] :. Batteries can also be rated by their energy capacity. This is either done in watt-hours or kilowatt-hours.

The University of Colorado has graciously allowed us to use the following Phet simulation. This simulation explores how batteries work in an electric circuit :. DS1 can last from half an hour to three hours running purely on battery power before the batteries need to be recharged from the solar panels.

These batteries are recharged thousands of times over the life of the spacecraft. What are solar panels? What happens to a ship when it runs out of power?

Where does DS1 get its electricity? How do batteries work? What's a circuit? What's an electron?