Significant Advancements in Sodium-Ion Battery Engineering Technology Research

The sodium-ion battery represents a novel form of energy storage technology, succeeding the lithium-ion battery. In contrast to lithium-ion batteries, sodium-ion batteries leverage the abundant sodium resources found on Earth, particularly in salt extracted from seawater, and employ water-soluble electrolytes. This design offers the advantages of tapping into rich raw material sources and eliminating the need for ultra-clean manufacturing environments. As a result, the next generation of energy storage batteries is anticipated to be produced at a lower cost.

Due to the larger ionic radius of sodium ions, sodium-ion batteries often face challenges such as low capacity and inadequate cycle performance. Internationally, numerous scholars have conducted extensive basic research on sodium-ion electrode materials, yielding notable progress. Supported by the National Natural Science Foundation of China (21336003 and 21073120) and the National 973 Program (2014CB239700), Professor Ma Zifeng's research group at Shanghai Jiao Tong University applied graphene oxide to enhance Na2/3[Ni1/3Mn2/3] for industrial applications. They modified the O2 electrode, producing a binder-free flexible electrode with high conductivity characteristics. Remarkably, this electrode exhibited commendable capacity and cycle performance under charge and discharge cycles ranging from 0.1C to 10C (J. Mater. Chem. A, 2 (2014) 6723-6727).

In a recent breakthrough, the research team utilized cost-effective Prussian blue material (NaMFe(CN)6) and optimized its internal molecular structure to develop a high-capacity, long-cycle-life sodium-ion battery cathode material with a specific capacity of up to 118.2 mAh/g (at 10 mA/g). This capacity was comparable to Na2MnFe(CN)6 material. After 800 cycles of charge and discharge at a current density of 100 mA/g, the material demonstrated an impressive capacity retention rate of 83.8%, surpassing Na2MnFe(CN)6 material significantly.

Notably, the research team achieved a groundbreaking milestone by combining this material with a hard carbon negative electrode to create a prototype sodium-ion battery for energy storage. With an energy density reaching 81.72 Wh/kg, double that of a lead-acid battery, it lays a robust technical foundation for the industrialization of energy storage sodium-ion batteries.