Researchers in China have developed bimetallic Bi-Sn microparticles (μ-BiSn)for use as high-performance anode materials for sodium-ion batteries (SIBs) using ether-based electrolytes.

In an open-access paper in the RSC journal Chemical Communications, they report that the μ-BiSn material exhibits superior electrochemical performance, such as high initial Coulombic efficiency (90.6%), good cycling stability (541 mAh g⁻¹ after 3000 cycles at 2 A g^-1) and excellent rate capability (393 mAh g⁻¹ at 10 A g⁻¹).

Alloy-based anode materials (Sn, Bi, Sb, etc.) have attracted extensive attention as high performance anode materials for sodium-ion batteries.

Among them, Sn stands out with the advantages of high theoretical capacity (847 mAh g^-1), low discharge voltage (~0.4 V vs. Na⁺/Na), high electronic conductivity, and non-toxicity. However, its poor cycling and rate performances hinder its practical applications. In contrast, Bi exhibits excellent rate and cycle performances due to its unique layered structures, but its theoretical specific capacity is only 386 mAh g^-1. Thus, it is highly desirable to combine the advantages of Sn (high theoretical capacity) and Bi (good cycling/rate performance).

—Zhu et al.

The team synthesized the μ-BiSn by ultra-sonication of molten metal at a low temperature. (Bi and Sn beads can be melted at a low temperature, which effectively reduces energy consumption during preparation.)

(a-d) Electrochemical performances of μ-BiSn in SIBs. (a) Galvanostatic charge/discharge curves at 0.1 A g^-1 between 0.01 and 1.5 V. (b, c) Rate and cycling performances of μ-BiSn, μ-Bi, μ-Sn and μ-Bi/Sn. (d) Long-term cycling performance of μ-BiSn at 2 A g^-1. (e-g) Electrochemical performances of μ-BiSn thick electrodes. (e) Galvanostatic discharge/charge curves of μ-BiSn with different mass loadings. (f) The specific and areal capacity of μ-BiSn electrodes with different mass loadings. (g) The cycling performance with a mass loading of 7.6 mg cm^-2. Zhu et al.

Resources

• Y. Zhu, C. Wang, Z. Cheng, Q. Yao, J. Su, B. Chen, J. Yang and Y. Qian (2022) “Bimetallic Bi-Sn Microspheres as High Initial Coulombic Efficiency and Long Lifespan Anodes for Sodium-Ion Batteries” Chem. Commun. doi: 10.1039/D2CC00833E.