Recently, Tang Yongbing, a researcher at the Functional Thin Film Materials Research Center of the Institute of Advanced Technology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, and his research team successfully developed a high-performance sodium ion battery with multi-ion design strategy through design innovation. Related research results A Multi -Ion Strategy towards Rechargeable Sodium-Ion Full Batteries with High Working Voltage and Rate Capability ("Multi-Phase Design Strategy for High Voltage, High Magnification Sodium Ion Full Battery") published online in the international chemical journal Angewandte Chemie International Edition ("German Applied Chemistry" 》) (DOI: 10.1002/anie.201810575).
Among the alkali metal elements, sodium has the advantages of abundant reserves and low price. Therefore, sodium ion batteries have broad application prospects in the fields of large-scale energy storage. However, the standard electrode potential of sodium (-2.71 V vs. SHE) is high. In lithium (-3.04 V vs. SHE), the sodium ion battery has a lower operating voltage. In addition, due to the larger sodium ion radius (Na: 0.98 angstrom vs. Li: 0.69 angstrom), the transmission kinetics are poor. And it is easy to cause larger electrode material to expand, which limits the rate and cycle performance of sodium ion battery.
Based on the above considerations, Tang Yongbing and his team members Jiang Chunlei, Fang Yue et al. successfully developed a novel sodium ion full cell with a multi-ion design strategy (Na+/Li+/PF6-). The positive electrode material is expanded graphite, and the negative electrode can be used simultaneously. A metal material that alloys with Na and Li, and integrates the current collector/active material design, and uses a multi-ion designed Na+/Li+/PF6-organic electrolyte. This multi-ion design strategy has two major advantages: On the one hand, the use of anion (PF6-) intercalated graphite has a high potential, which significantly improves the operating voltage of the sodium ion battery; on the other hand, the multi-ion design strategy can effectively improve the reaction kinetics of the battery and reduce the metal negative electrode. The volume expansion during alloying greatly improves the rate performance and cycle life. The results show that the sodium ion battery designed by this strategy has an operating voltage of up to ~4.0 V; and up to 30 C (2 min charge and discharge) The rate performance and cycle life of 500 cycles (capacity retention rate 95%, 5 C rate). The research results provide a new way to improve the electrochemical performance of sodium ion batteries. Never thinking.
The research was funded by the National Natural Science Foundation of China, the STS project of the Chinese Academy of Sciences, and the Shenzhen Science and Technology Project.
(a) charge and discharge curves of tin negative electrode; (b, c) Na, Li and Sn undergo reversible co-alloying reaction; (d) anion (PF6-) intercalated graphite has good reversibility; (e) tin negative electrode The electrochemical stress test proves that the alloying reaction has good mechanical reversibility; (f) the diffusion path of Na and Li atoms in the Sn lattice and the corresponding diffusion energy barrier (g); the alloy phase NaSn (h) and Density map of Li2Sn5 (i).
