Lithium-ion batteries are everywhere these days – in mobile phones, electric bikes, laptops, electric cars, and even in large systems based on renewable energy sources. They power our everyday lives and allow us to use technology in a convenient and mobile way. But few people wonder how a lithium-ion battery is built, what happens inside during charging and discharging, and why these small systems are so important in today's world.
Today we take a look inside this technological marvel. Because the ion battery is not just a buzzword – it is a fascinating combination of the laws of physics, materials chemistry and engineering that enables safe and efficient storage of electrical energy.
What is a lithium-ion battery made of?
In simple terms, a lithium-ion battery consists of a set of lithium-ion cells that work together to store and release energy. Each of these cells acts as a separate miniature power plant – made up of a few basic elements:
1. Positive electrode (cathode)
The cathode in lithium-ion batteries is most often made of cobalt oxide, iron phosphate or nickel manganese oxide. This is where the lithium ions are located, which move towards the second electrode during discharge. The cathode is of particular importance for the battery capacity and its voltage - therefore, the material used at this stage determines, among other things, how long the battery "lasts".
2. Negative electrode (anode)
The anode is usually made of graphite, deposited on copper foil. This is where lithium ions arrive during charging and are "stored" before flowing through the cell again. Proper anode design prevents over-discharge and affects the aging process of the battery.
3. Electrolyte
It is a carrier that allows lithium ions to flow between electrodes. It usually consists of lithium salts dissolved in a mixture of organic solvents. The electrolyte does not conduct electrons, but allows the free flow of ions, which drives the entire charging and discharging process.
4. Separator
A separator is a thin layer of material (often plastic, such as polyethylene or polypropylene) that separates the electrodes, preventing a short circuit but allowing the lithium ions to move freely. Separators are made of high-temperature resistant materials because in the event of a threat they should close and stop further flow – protecting the cell from overheating or ignition.
5. Cell housing
Lithium-ion cells can be placed in a metal housing (e.g. cylindrical 18650 cells) or in the form of flexible pouch cells. The housing protects the interior of the battery from mechanical damage, moisture and the influence of the external environment.
How does a lithium-ion battery work?
During charging, lithium ions move from the positive electrode (cathode) to the negative electrode (anode), accumulating in its structure. During use (discharging), the direction is reversed – ions return to the cathode, generating electric current that powers portable devices, electric cars, electric bikes, and even entire buildings.
During this time, chemical reactions occur, which must be strictly controlled. Lithium-ion batteries do not accept overcharging, are sensitive to too high temperature, and also to uncontrolled voltage fluctuations. Therefore, batteries based on lithium-ion technology require the presence of a management system - BMS, which monitors and controls the entire process.
Why are lithium-ion batteries so popular?
Lithium-ion batteries combine many advantages: low production cost, high energy density, the ability to be recharged multiple times, no memory effect and a relatively long service life. As a result, they are used practically everywhere – from mobile phones, through bicycles and electric cars, to large-scale energy storage.
Importantly, this technology is still developing – capacities are growing, safety is improving, and battery chargers are becoming more and more intelligent, adjusting the current and voltage to the cell condition.
What's inside a lithium-ion battery?
If you’ve ever wondered how a lithium-ion battery is made, the answer is: electrodes, an electrolyte, a separator, and a healthy dose of advanced engineering. All of them work in tight sync to safely and efficiently store and release electrical energy.
Although lithium-ion cells are just one part of a larger system, their correct design has a significant impact on the safety, durability and efficiency of the entire system. And because we know more and more about their structure, we can use them longer, more efficiently and safely - in portable devices, electric vehicles and modern power systems.
