Against the backdrop of dual carbon emissions, with the large-scale explosion of the new energy vehicle market, large-scale energy storage applications are being put on the agenda in various local plans, and lithium-ion batteries, which are already heavily reliant on imports, will face resource shortages.
Sodium-ion batteries are a type of rechargeable chemical battery with numerous advantages, including abundant resources, low cost, high energy conversion efficiency, long cycle life, high safety, excellent high and low temperature performance, good high-rate charge and discharge performance, and low maintenance costs. They are expected to complement lithium-ion batteries in the fields of large-scale electrochemical energy storage and low-speed electric vehicles.
Currently, both domestic and international companies have begun to develop industrialization plans for sodium-ion batteries, and sodium-ion batteries have already met the market and technological conditions for large-scale industrialization.
So, how is a sodium-ion battery developed?
First, let's understand the composition, working principle, and mainstream technology of sodium-ion batteries.
Sodium-ion batteries consist of positive electrode materials, negative electrode materials, electrolytes, and separators. Their working principle is similar to that of lithium-ion batteries, both belonging to the "rocking chair" type. During charging, sodium ions are released from the positive electrode material, pass through the electrolyte, and embed into the negative electrode material, while electrons move from the positive electrode to the negative electrode via an external circuit, thereby maintaining the charge balance of the system.
Based on the classification of cathode materials, there are currently three promising technological routes for the industrialization of sodium-ion batteries: layered transition metal oxides, polyanionic compounds, and Prussian blue analogues. Among them, layered transition metal oxide materials have the advantages of simple preparation methods, high specific capacity and energy density, and low manufacturing cost. However, they have the disadvantage of being prone to absorbing water or reacting with air, which affects the stability of the material structure and its electrochemical performance.
The design and manufacturing of sodium-ion batteries are basically the same for different material systems and structural types of sodium-ion battery electrodes. The difference lies in the packaging form, internal structure and assembly process of sodium-ion batteries with different technologies.
Taking sodium-ion pouch batteries as an example, the process can be roughly divided into three parts.
1. Front-end electrode manufacturing processes, including electrode slurry preparation, electrode coating, rolling, vacuum drying of electrode sheets, and die-cutting of electrode sheets;
2. Back-end assembly processes, including wafer stacking, welding, casing, vacuum drying, and liquid injection;
3. Formation and sorting process, including pre-sealing, formation, secondary packaging, and capacity screening.
In addition, the key step in the design and manufacturing of sodium-ion batteries, the formation and sorting process, requires different clamps depending on the battery's appearance, structure, and capacity, and under different formation environments.
Sodium-ion batteries and lithium-ion batteries have similar production lines. The difference is that sodium-ion batteries can use aluminum foil as the negative electrode current collector, so both the positive and negative electrode sheets use aluminum tabs. Therefore, under certain circumstances, existing lithium-ion battery production lines can be slightly modified to produce sodium-ion batteries, thereby significantly reducing the initial sodium battery investment costs for battery companies.
