Compared to lithium-ion batteries, sodium ion batteries have the following advantages:
1. Compared with lithium, sodium has similar physical and chemical properties, abundant reserves, and low prices;
2. In principle, the charging time of sodium ion batteries can be shortened to 1/5 of that of lithium-ion batteries;
3. Due to the characteristics of sodium salts, low concentration electrolytes are allowed to be used, which can reduce costs;
4. Sodium ions do not form alloys with aluminum, and aluminum foil can be used as the current collector for the negative electrode, which can reduce costs and battery weight.
It is understood that the current energy density of sodium ion batteries can only reach 120 watt hours per kilogram. So, in terms of energy density, sodium ion batteries cannot be compared to lithium-ion batteries because lithium-ion batteries have an energy density of over 300 watt hours per kilogram.
From the perspective of energy density, current sodium ion batteries can only reach less than half of lithium-ion batteries. Therefore, sodium ion batteries can only be used in low-speed electric vehicles, electric boats, household energy storage and other fields with low energy density requirements. Currently, sodium batteries cannot be used to make high-speed electric vehicles.
The main differences between lithium-ion batteries and sodium batteries are:
1. The difference in charge carriers within batteries is that lithium-ion batteries charge and discharge through the movement and conversion of lithium ions between the positive and negative electrodes, while sodium ion batteries charge transfer through the insertion and extraction of sodium ions between the positive and negative electrodes. In fact, the working principles of the two are the same.
2. The two have different ionic radii, which results in the performance of sodium ion batteries being far inferior to that of lithium-ion batteries; The negative electrode of lithium ions can make graphite, but sodium ions can hardly be removed/embedded in graphite, resulting in a small capacity; Other carbon materials can reach a maximum of about 300 milliampere hours after treatment; The capacity of ions in the positive electrode is very small, only over 100 milliampere hours; The insertion/deintercalation resistance of sodium ions in the positive and negative electrodes is high, due to the large radius; Poor reversibility and significant irreversible capacity loss.