Multiple Modifications of Li-B Alloy Anodes for Primary Batteries

Lithium-boron (Li-B) alloys have long been applied in thermal batteries and have recently been used in secondary batteries due to their stable three-dimensional (3D) framework. To extend the application of Li-B anodes to primary cells, especially primary cells with high rate performance, we developed a new surface treatment method to modify Li-B. Using silver trifluoromethanethiolate (AgSCF₃) as the single reagent to react with Li to produce metal Ag, LiF, and sulfide species at the surface of Li-B. For the symmetric cell, the resulting multiple modified Li-B shows two orders of magnitude smaller charge transfer impedance than the pristine Li-B (1.10 ohms vs. 205.40 ohms) and improved reaction kinetics in the first cycle. The modified Li-B/MnO₂ primary cells show improved rate performance in the current density range of 0.5 C − 5 C. Specifically, when discharging at 2 C, the full cell using modified Li-B anode show specific capacity of 197 mAh g⁻¹ and specific energy of 485 Wh kg⁻¹, 82% and 103% higher related to the cell using pristine Li-B anode, respectively. This study provides a new way to modify Li-B alloys that may have practical applications in high-power density primary batteries.