How does a Battery Work

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Energy Storage & Batteries

How does a Battery Work?

Lithium-ion batteries are an important part of our daily lives and are used to power common devices like laptops and cellphones. But how does a battery work? These batteries function by converting chemical energy to electrical energy. This is ho the batter works – Lithium ions move between two electrodes, a graphite one, and a metal oxide one. The lithium ions move from the metal oxide electrode to the graphite electrode when the battery is charged, storing energy. On the other hand, the flow of electrons, which is reversed when the battery is discharged, releases the stored energy as electrical energy. The lithium-ion battery’s engineering is impressive, and it’s no surprise that they power the lives of millions globally.

How-does-a-Battery-work -example 1
How-does-a-Battery-work -example 1
How does a battery work
How does a battery work

As we move towards a more technologically advanced and environmentally conscious world, it’s important to recognize the growing popularity of Lithium-technology. From cell phones, notebooks, and laptops to bikes, hybrids, and electric cars, Lithium-technology is rapidly gaining traction due to its many benefits.

One of the key advantages of Lithium-technology is its light-weight nature, which makes it the perfect choice for portable devices such as phones and laptops. Another key advantage is its high-energy density, which means that it can store a lot of energy in a small amount of space. This makes it an ideal choice for electric cars and other vehicles where space is limited. Additionally, Lithium-technology is known for its ability to recharge, making it a more sustainable and environmentally friendly option.

Overall, the exponential growth of Lithium-technology is a positive step towards a more sustainable future, and we can expect to see continued advancements and applications in the years to come. But how does a battery work?

How does a battery work? 
How-does-a-Battery-work scheme

Many other battery chemistries exist (Lead-acid, alkaline-batteries, flow-Batteries, Lithium-metal-batteries and Lithium-Ion-batteries.

However, the Lithium-ion chemistry is the most popular Battery chemistry these days due to 1) the possibility to recharge them and 2) the high amount of energy the LIB can store per battery mass and battery volume.

Battery Working Principle

The five essential of a battery works:

  1. A battery or accumulator is a device that stores chemical energy and converts it to electrical energy.
  2. The chemical reactions in an accumulator or battery involve the flow of electrons from one material (electrode) to another, through an external electric circuit. 
  3. That flow of electrons provides an electric current I that can be used to do work in another device (e.g. a electric motor in a car)
  4. To balance the flow of electrons, ions also flow through an electrolyte solution that is in contact with both battery electrodes (active materials).
  5. Different electrodes and electrolytes produce different chemical reactions that affect how the battery works, how much energy it can store and its voltage. 
How does a battery work?
How does a battery work?

How a Lithium-Ion Battery Works

How a Lithium-Ion Battery Works:
A battery or accumulator is made from an a) anode, b) cathode, c) separator, d) electrolyte, and e) two current collectors used for the positive cathode and for the negative node).
The anode and cathode store the lithium-ions. The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa through the ion-permeable separator. 

The movement of the lithium ions creates free electrons in the anode, which creates a charge at the positive current collector.  The electric current then flows from the current collector through a device being powered (e.g. laptop, cell phone, headset, etc.) to the negative current collector. The separator, which is an electric insulator, blocks the flow of electrons inside the battery.


See also for further information: “How a Lithium-Ion Battery Work” on the Swiss Battery Site.

Lithium-Ion Batteries should not be confused with Lithium-Metal Batteries, which form lithium-metal-dendrites if recharged.

Charging and Discharging the Battery​

While the battery (under operation) is discharging and delivering an electric current to the device being powered (e.g. cell phone etc…), the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other of the battery cell.

When plugging in the device to charge the battery the opposite happens: Lithium ions are released by the cathode and received by the anode.

Energy Density versus Power Density ​

The two most common physical measures (concepts) associated with lithium-ion batteries are the power-density and energy-density. Energy density is expressed in watt-hours per kilogram (Wh/kg) and is the quantity of energy the battery can store regarding its mass. Power-density is quantified in watts per kilogram (W/kg) and is the quantity of power that can be generated by the battery regarding its mass. In the year 2023 the cathode with the highest energy density for Lithium-Ion is the NMC 811 cathode.

To understand the better, think of draining a water bath: Energy-density is similar to the size of the bath, while power-density is comparable to draining the water bath as quickly as possible. 

Both measures, energy and power, can be related to cost.
For example, the holy grail cost (target for EV batteries of the US Department of energy) of battery storage has been for a long time 100 CHF/kWh.
This means that a Battery which can stores 1 kWh of energy in the form of electricity should not cost more than CHF 100.



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How does a battery work

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Circular Economy, Recycling of Batteries and Product Lifetime

Circular economy, trade in Li-ion batteries waste will remain essential in markets where economically viable recycling can take place. Promoting circular economy and value chains for Li-ion batteries require clear rules on the waste status, transport, storage, safety regulations, trade facilitation, standards for battery design, product lifetime, and regulatory targets for waste collection and recycling rates.

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Wiki Battery is an encyclopedia for battery technologies, which explains technical terms from the field of batteries and energy storage in a simple and understandable way – dummy proof.

More information about Wiki Battery can be found hereWiki Battery is a published Swiss Battery (

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How-does-a-Battery-work -example 1
How-does-a-Battery-work -example 1


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