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Summarize with AI
How do batteries work?
Mis à jour le
March 6, 2026
4
Min reading
The battery has profoundly changed our way of life. And for good reason, this technological device is one of the most popular today. It is present in almost all our mobile devices and allows them to work far from an electrical outlet.
So how does she do it? SirEnergies plunges into the heart of these devices to explain it to you.
How does a battery produce electricity?
A battery insures electricity storage for later use. It always contains a positive electrode and a negative electrode, both immersed in an electrolyte bath. Unlike batteries, batteries are based on a system reversible, that is, they are capable of recharging after a discharge.
As soon as a charge is connected to the two electrodes of a battery (thus creating a closed circuit), a chemical oxidation reaction takes place at the level of the negative plate, i.e. a loss of electrons. Conversely, the Positive plate undergoes a reduction, that is to say a gain of electrons at this discharge phase.
The movement of electrochemical charges in the form of ions is facilitated by the presence of the electrolyte. As long as the ions move from one electrode to the other, the constant flow of electrons is maintained, creating the energy needed to operate the devices. During a refill, the opposite process is taking place. The ions then move from the anode to the cathode and the latter loses electrons.
The important characteristics of a battery
All batteries, regardless of their technology, have common characteristics: their voltage, their capacity and their lifespan.
Voltage and capacity
Expressed in volts, the voltage is generally 12 V for small rechargeable batteries. It can also reach 48 V, but in both cases, small elements separated by 2 V are used and assembled in series.
As far as storage capacity is concerned, it is Expressed in Ampere-hours or Ah. It refers to the quantity of energy available instantly. It can be increased by connecting several batteries in parallel.
When we multiply these two parameters, we get the quantity ofstored electricity in kWh. A 12 V - 200 Ah battery, for example, theoretically contains 2,400 Wh, or 2.4 kWh. However, in practice, all this accumulated energy is not accessible for use. The discharge should not exceed 10 to 15% of the battery capacity in order to protect it from rapid degradation.
The lifespan
The batteries can certainly be recharged, but this operation cannot be carried out endlessly. After a certain number of cycles (charge and discharge period), batteries end up losing capacity and need to be replaced. This number of cycles is therefore an important metric relating to the operation of a battery.
The different types of batteries
There are various battery technologies on the market. They all have their own specificities. These include batteries Lithium-ion (Li-ion), batteries at nickel and batteries at pellet.
Lithium-ion batteries
Batteries that incorporate lithium-ion technology are undoubtedly the most popular on the market. This is explained in particular by their higher energy density than that of nickel or lead batteries.
As a result, their miniaturization is much more advanced for equal autonomy. In addition, lithium is themost electropositive chemical element, that is to say the one that loses its electrons the most easily. This characteristic allows it to easily produce a lot of energy. It is not surprising that most electric cars work with batteries designed with this reference technology.
Li-ion batteries also have a very low discharge rate, which means that they lose little energy during their storing. They can also be recharged at any time, even after partial discharge. In addition, the materials that go into their manufacture are much less polluting than those of other types of batteries.
Lead acid batteries
These batteries can be opened with dilute sulfuric acid electrolyte or closed. with a gelled electrolyte. The first are very reliable accumulators. However, they tend to be strongly influenced by the external temperature, which can drastically reduce their capacity.
As for the latter, their handling is easy and their stability is perfectly ensured by the manufacturer. They can provide an average of 400 cycles at 80% discharge.
Nickel batteries
There are generally two types of nickel batteries: nickel metal hydride batteries (NiMH) and nickel-cadmium batteries (NiCd) which have become very rare.
NiMH present a much higher energy density, which ensures them better autonomy. These batteries, unlike the Li-ion variants, only need to be recharged after they are completely discharged. Likewise, their self-discharge rate is very high, which implies a rapid loss of charge in case of storage.
As for nickel-cadmium batteries, their robustness and reliability are proven in hot and cold weather. They also have a long lifespan if they are maintained properly.
In short, batteries work more or less on the same principle: in a closed circuit, a chemical reaction takes place at the level of their positive and negative electrodes ensuring Electron flow. This then provides the energy necessary for the operation of the devices.
To go further, do not hesitate to read our article that answers the question Why is energy storage necessary?
Did you know that?
Today, more than ever, electric mobility is one of the levers for achieving carbon neutrality. As such, businesses have a role to play in the energy transition.
You want to install charging stations and/or convert your company's vehicle fleet to electric? SirEnergies is there to help you and supports you in building an eco-responsible image for your business.
Click below for more information:
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The answers to your questions
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