How the Magical Sodium Ion Battery Works
Overview of Sodium Ion Batteries
The concept of sodium-ion batteries started in the 1980s and started almost at the same time as lithium-ion batteries. The working principle of sodium ion battery is similar to that of lithium ion. When charging, Na+ is extracted from the positive electrode material and inserted into the negative electrode material through the electrolyte. At the same time, electrons are transferred to the negative electrode through the external circuit to maintain charge balance; the opposite is true during discharge.
In principle, the charging time of sodium ion batteries can be shortened to 1/5 of that of lithium ion batteries. The main feature of sodium ion batteries is to use Na+ instead of expensive Li+. In order to adapt to sodium ion batteries, the positive electrode material, negative electrode material and electrolyte must be changed accordingly. Compared with lithium, the advantage of sodium ion batteries is that they are rich in resources. Sodium resources account for about 2.64% of the earth's crust reserves. In addition, the method for obtaining sodium is very simple, so compared to lithium-ion batteries, sodium-ion batteries will have more advantages in cost.
Although the energy density of sodium-ion batteries is not as good as that of lithium-ion batteries, in view of the current high price of lithium carbonate, sodium-ion batteries still have very broad application prospects: for areas where energy density is not high, such as energy storage in power grids, Peak shaving, wind power storage and other applications are very broad. In the future, sodium-ion batteries will gradually replace lead-acid batteries and be widely used in various low-speed electric vehicles, complementing lithium-ion batteries.
Working Principle of Sodium Ion Battery
The working principle of the sodium ion battery is similar to that of the lithium ion battery, which uses the intercalation and deintercalation process of sodium ions between the positive and negative electrodes to achieve charge and discharge. During charging, Na+ is removed from the positive electrode and inserted into the negative electrode through the electrolyte, while the electronic compensation charge is supplied to the negative electrode through an external circuit to ensure the balance of the positive and negative electrodes. The opposite is true when discharging. Na+ is released from the negative electrode and inserted into the positive electrode through the electrolyte. Under normal charge and discharge conditions, the insertion and extraction of sodium ions between the positive and negative electrodes does not destroy the basic chemical structure of the electrode material.
Advantages of Sodium Ion Batteries
(1) The sodium salt raw material reserves are abundant and the price is low. Compared with the ternary cathode material of lithium-ion battery, the iron-manganese-nickel-based cathode material is used, and the raw material cost is reduced by half;
(2) Due to the characteristics of sodium salt, it is allowed to use low-concentration electrolyte (with the same concentration of electrolyte, the conductivity of sodium salt is about 20% higher than that of lithium electrolyte) to reduce costs;
(3) Sodium ions do not form an alloy with aluminum, and the anode can use aluminum foil as the current collector, which can further reduce the cost by about 8% and the weight by about 10%;
(4) Since sodium ion batteries have no over-discharge characteristics, sodium ion batteries can be allowed to discharge to zero volts.