Sodium-ion batteries are also a type of rechargeable battery, primarily relying on the movement of sodium ions between the positive and negative electrodes to function, similar to the working principle of lithium-ion batteries. During charging and discharging, Na+ ions repeatedly insert and extract between the two electrodes: during charging, Na+ ions are extracted from the positive electrode and inserted into the negative electrode via the electrolyte; the reverse occurs during discharging.
Sodium-ion batteries primarily use sodium salts as electrode materials, which are more abundant and cheaper than lithium salts. Because sodium ions are larger than lithium ions, sodium-ion batteries are a cost-effective alternative when weight and energy density requirements are not critical.
Compared to lithium-ion batteries, sodium-ion batteries have the following advantages:
(1) Sodium salt raw materials are abundant and inexpensive. Compared with ternary cathode materials for lithium-ion batteries, the raw material cost of using iron-manganese-nickel-based cathode materials is reduced by half.
(2) Due to the properties of sodium salts, it is permissible to use low-concentration electrolytes (for the same concentration of electrolyte, sodium salt conductivity is about 20% higher than that of lithium electrolytes), thus reducing costs;
(3) Sodium ions do not form alloys with aluminum, and aluminum foil can be used as the current collector for the negative electrode, which can further reduce the cost by about 8% and the weight by about 10%;
(4) Sodium-ion batteries have no over-discharge characteristics, allowing them to discharge to zero volts. Sodium-ion batteries have an energy density greater than 100Wh/kg, comparable to lithium iron phosphate batteries, but with a significant cost advantage, and are expected to replace traditional lead-acid batteries in large-scale energy storage.
Recently, Chen Liquan, an academician of the Chinese Academy of Engineering, pointed out at the 2021 China EV100 Cloud Forum: "If all cars in the world use lithium-ion batteries and all the world's electricity is stored in lithium-ion batteries, then lithium-ion batteries will not be enough. Therefore, we must consider new batteries, and sodium-ion batteries are the first choice."
Sodium-ion batteries are becoming the energy storage battery that countries are vying to develop. Both domestic and foreign research institutions and companies are trying to seize the commanding heights of the sodium-ion battery industry before it takes off.
Currently, Chinese companies are in a leading position internationally in terms of basic research, technology development, and the speed of industrialization of sodium-ion batteries. Therefore, China has the opportunity to gain international dominance in the industrialization of sodium-ion batteries, lead the development trend of sodium-ion battery technology, and be the first in the world to achieve the industrialization of sodium-ion batteries.
