Nowadays, there are many types of batteries. From the perspective of material systems, lithium ions occupy an absolute dominant position. However, the bottleneck caused by the performance of lithium-ion batteries themselves has made the research of other materials more urgent. Among them, sodium-ion batteries, as an emerging technology, have gradually become a hot spot for research and application due to their advantages such as abundant resources and low cost.
Sodium-ion batteries are rechargeable batteries that use sodium ions to move between the positive and negative electrodes of the battery to store and release energy. Similar to lithium-ion batteries, sodium-ion batteries rely on the embedding and de-embedding process of sodium ions in positive and negative electrode materials to achieve charging and discharging. Sodium-ion batteries are mainly composed of positive electrodes, negative electrodes, diaphragms, current collectors, electrolytes, etc. According to whether their constituent materials directly participate in electrochemical reactions, they can be divided into active materials and inactive materials. Active materials include positive electrode materials, negative electrode materials, and electrolyte materials, and inactive materials include diaphragms, current collectors, conductive agents, binders, etc.
Advantages of Sodium-ion Batteries
Compared with lithium-ion batteries, sodium-ion batteries have the following advantages:
Rich resources and low cost: Compared with the scarcity of lithium ions, sodium ions have richer energy storage in the earth’s crust elements, so they are low in cost and can be a good supplement to lithium-ion batteries. The price of sodium carbonate is about 1/200 of that of lithium carbonate. In addition, the positive and negative electrodes of sodium batteries are both made of aluminum foil, which can further reduce costs.
Wide temperature range: Sodium-ion batteries have good capacity retention in the temperature range of -40℃~80℃.
Fast charging and good rate performance: Sodium-ion battery electrolytes of the same concentration have higher ionic conductivity than lithium-ion battery electrolytes. At the same time, sodium ions have lower solvation energy in polar solvents, which makes them have faster kinetic properties in electrolytes and higher conductivity.
Safety: Sodium-ion batteries can be stored and transported at zero voltage, without transportation safety risks. When short-circuited, they have less self-heating heat and no hidden dangers such as fire/explosion.
Production: Sodium-ion batteries have similar working principles and material compositions to lithium-ion batteries, and production experience and equipment can be partially compatible.
History And Development
The concept of sodium-ion batteries can be traced back to the 1970s, but due to the relatively active chemical properties of sodium, its research progress has been relatively slow. It was not until recent years that the performance of sodium-ion batteries has been significantly improved with the advancement of materials science, especially the development of new electrode materials.
Early research stage: Research on sodium-ion batteries began in the 1970s, when researchers began to explore various ions as charge carriers for batteries. Due to the abundance and low cost of sodium, some scientists began to pay attention to the electrochemical properties of sodium ions. From the late 1970s to the 1980s, research focused on the basic electrochemical properties of sodium ions and material screening, exploring suitable positive and negative electrode materials. However, due to the excellent performance of lithium-ion batteries in energy density and cycle life, research on sodium-ion batteries stagnated for a time.
Material exploration stage: From the 1990s to the early 2010s, despite the rapid development of lithium-ion battery technology, research on sodium-ion batteries did not stop completely. Researchers continue to explore suitable positive and negative electrode materials and have accumulated some key technologies and material knowledge. Early research focused on layered oxide materials such as sodium nickel oxide and sodium manganese oxide, which exhibit good sodium ion insertion/deinsertion properties. Hard carbon is considered to be a more ideal negative electrode material for sodium-ion batteries because of its high specific capacity and good cycle stability. In addition, some studies have also explored the possibility of titanium-based materials and tin-based alloys as negative electrode materials.
Technological breakthroughs and performance improvement: In the mid-2010s, with the rise in lithium resource prices and the increasing demand for alternative energy storage technologies, sodium-ion batteries have regained widespread attention. A series of technological breakthroughs have promoted the improvement of sodium ion battery performance. Scientists have developed a variety of new positive electrode materials, such as sodium iron phosphate, sodium manganese nickel oxide, and Prussian blue compounds, which show higher specific capacity and better cycle stability. In terms of negative electrode materials, the performance of hard carbon has been further optimized, and some new materials such as phosphorus, tin, and antimony-based materials have also demonstrated good sodium storage performance. Researchers have developed more stable electrolytes and high-performance separators to improve the overall safety and efficiency of batteries.
Applicable Scenarios of Sodium-ion Batteries
Due to their characteristics, sodium-ion batteries are particularly suitable for use in equipment in the following fields:
Portable electronic products: The low cost and long cycle life of sodium-ion batteries make them an ideal choice for portable electronic products such as smartphones and tablets.
Household appliances: The high safety and environmental protection characteristics of sodium-ion batteries make them the preferred power source for household appliances such as vacuum cleaners and washing machines.
Electric vehicles: Although the charge and discharge rate and energy density of sodium-ion batteries are not as good as those of lithium-ion batteries, their long cycle life and low cost make them suitable for use in light electric vehicles such as electric bicycles and electric motorcycles.
Large-scale energy storage systems: The large-scale energy storage capacity and environmental protection characteristics of sodium-ion batteries make them an ideal energy storage solution for renewable energy facilities such as solar power stations and wind power stations.
Summary
Although sodium-ion batteries have obvious advantages in the above fields, they may not be suitable for use in equipment that requires high energy density, such as electric vehicles and drones, due to their relatively low energy density and charge and discharge rate. However, sodium-ion batteries have been used in some specific fields, such as energy storage systems and electric vehicles. In particular, sodium-ion batteries have the outstanding advantage of low-temperature resistance in extremely cold regions, and lithium iron phosphate batteries and ternary lithium battery technologies cannot make up for this shortcoming in the short term. With the advancement of technology and the reduction of costs, sodium-ion batteries are expected to be more widely used in the future.
As an important direction of new energy technology, the research and industrialization process of sodium-ion batteries is constantly advancing. With the continuous development and improvement of sodium-ion battery technology, its application in various fields will also be more extensive. It is expected that in the next few years, sodium-ion batteries will be more widely used in electric vehicles, household appliances, industrial equipment and other fields, and are expected to become an important supplement and substitute for lithium-ion batteries. At the same time, with the acceleration of the commercialization process of sodium-ion batteries, the related industrial chain will also be further improved and developed. Sodium-ion batteries are expected to play a more important role in the future energy field and contribute to the realization of sustainable energy supply.
