How Does a Lithium Ion Battery Work?

Lithium-ion batteries power the lives of millions of people every day. From laptops and mobile phones to hybrid and electric vehicles, this technology is becoming more and more popular due to its light weight, high energy density, and strong charging capabilities.

So how does it work?

1. How do lithium-ion batteries store energy?

Lithium-ion batteries consist of the following parts: an anode and a cathode, a separator between the two electrodes; and an electrolyte that fills the remaining space of the battery. The anode and cathode can store lithium ions. When lithium ions move between these electrodes through the electrolyte, energy is stored and released.

When storing energy (during charging), the charger delivers current to the battery. Lithium ions move from the cathode to the anode through the electrolyte. The battery is charged by the potential difference between the two electrodes. When energy is used (during discharge), a discharge loop is formed between the anode and the cathode. The lithium ions stored in the anode move to the cathode, and energy is used.

2. Energy density VS Power density

The two most common concepts related to batteries are energy density and power density. Energy density is measured in watt-hours per kilogram (Wh/kg), which is the energy that a battery can store relative to its mass. The power density is in watts per kilogram (W/kg), which refers to the power that the battery can generate relative to the mass of the battery. In order to draw a clearer picture, think about draining a sink. The energy density is similar to the size of the pool, while the power density is equivalent to draining the pool as quickly as possible.

Lithium-ion batteries have high energy density and high average output voltage. With small self-discharge, good batteries have discharge less than 2% per month (recoverable). There is no memory effect. The wide operating temperature range is -20℃~60℃. Wich excellent cycle performance, fast charging and discharging are available, the charging efficiency is up to 100%, and the output power is high. It has long service life. And since it does not contain toxic and hazardous substances, lithium iron phosphate battery pack is called a green battery.