What is a sodium-ion battery?

What is a sodium-ion battery?

Sodium batteries, also known as sodium-ion batteries (SIBs or Na-ion batteries), are reversible, rechargeable, “rocking chair” rechargeable battery systems.

Their working principle relies on the insertion and extraction of sodium ions (Na⁺) between the positive and negative electrodes to store and release electrical energy. The core structure of sodium batteries is highly similar to that of lithium-ion batteries, except that sodium is used instead of lithium.

Compared to lithium batteries, sodium batteries have advantages such as low cost, abundant resources, and high thermal stability, and are expected to achieve price competition with low-cost lithium batteries by 2030 through technological iterations.

A detailed explanation of sodium-ion batteries

With the acceleration of the global energy transition and the booming development of the new energy vehicle market, the production scale of lithium-ion batteries has increased significantly, but the shortage of lithium resources is becoming increasingly prominent.

Compared to lithium, sodium has a higher abundance in the Earth’s crust, resulting in a significant cost advantage. Furthermore, sodium batteries offer the closest overall performance to lithium batteries, and their architecture and packaging processes are highly similar to those of lithium batteries. Therefore, sodium batteries maintain a cost advantage over lithium batteries in the medium to long term, making them a highly anticipated new energy storage technology in recent years.

However, compared to lithium ions, sodium ions have a larger ionic radius, a characteristic that becomes a key factor affecting the performance of sodium batteries. The larger ionic radius results in a slower diffusion rate of sodium ions in the electrode material, thus affecting the rate performance and cycle stability of sodium batteries, and potentially shortening their lifespan.

To overcome these performance challenges, researchers have conducted extensive research and optimization work on the core components of sodium batteries to improve their performance. For example, in terms of positive and negative electrode materials, they are developing positive electrode materials with special crystal structures, high specific capacity, and good structural stability, and searching for low-cost negative electrode materials with excellent sodium storage performance. In terms of electrolytes, they are developing novel electrolyte systems, such as solid-state electrolytes and ionic liquids, to improve the performance and safety of sodium batteries.

Application areas and development prospects of sodium-ion batteries

Sodium-ion batteries have broad application prospects in large-scale energy storage systems, electric vehicles, and backup power supplies for communication base stations due to their advantages, such as low cost and abundant resources.

In large-scale energy storage systems, sodium-ion batteries can be used for grid peak shaving, load balancing, and the storage and dispatch of renewable energy. Compared to lithium-ion batteries, sodium-ion batteries are less expensive and suitable for large-scale deployment.

In the field of electric vehicles, sodium-ion batteries are suitable for low-speed electric vehicles, logistics vehicles, and urban public transportation due to their lower cost and longer cycle life. Although their energy density is lower than that of lithium-ion batteries, they remain competitive in cost-sensitive applications.

In the field of backup power for communication base stations, sodium-ion batteries are suitable for backup power systems due to their long service life and low maintenance costs. With the continuous development of communication networks, the demand for backup power is constantly increasing, and sodium-ion batteries have broad application prospects in this area.

With the continuous development of sodium-ion battery technology, significant progress has been made in energy density, cycle life, and low-temperature performance. In the future, with advancements in materials science, electrochemistry, and engineering technology, sodium-ion batteries are expected to find applications in more fields, becoming a powerful complement to lithium-ion batteries.

Challenges in the green application of sodium-ion batteries

Sodium batteries, as a green energy storage technology to replace lithium batteries, still face multiple environmental and sustainability challenges in their development.

The mining and refining of sodium resources can pollute soil and water sources. Meanwhile, if battery production lacks effective control, it can also generate pollutants such as wastewater and exhaust gases. Improper recycling and disposal of batteries after they are scrapped can lead to the leakage of heavy metals and other harmful substances, causing secondary pollution.

Furthermore, the safety and reliability of sodium batteries still require further verification. Although sodium batteries theoretically possess good safety, their performance in practical applications still needs extensive testing and validation. Therefore, in the research and development, and application of sodium batteries, it is necessary to strengthen research on safety and reliability to ensure their safe application in various fields.

Currently, China’s sodium battery industry is experiencing rapid development. Leveraging abundant raw materials and policy support, China’s sodium battery industry has entered the mass production stage and is gradually expanding into two-wheeled vehicles, micro electric vehicles, and energy storage markets. However, significant problems remain: energy density still lags behind LFP lithium batteries; initial efficiency is low and cold-start performance needs optimization; the core materials and recycling system of the industrial chain are still incomplete; and technical standards and evaluation platforms urgently need to be established. These challenges, to some extent, restrict its breakthrough in the high-end market.