Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth

Owing to the high abundance and gravimetric capacity (1165.78 mAh g^-1 ) of pure sodium, it is considered as a promising candidate for the anode of next-generation batteries. However, one major challenge needs to be solved before commercializing the sodium metal anode: The growth of dendrites during metal plating. One possibility to address this challenge is to use additives in the electrolyte to form a protective solid electrolyte interphase on the anode surface. In this work, we introduce a diamondoid-based additive, which is incorporated into the anode to target this problem. Combining operando and ex situ experiments (electrochemical impedance spectroscopy, optical characterization, and cycling experiments), we show that molecular diamondoids are incorporated into the anode during cycling and successfully mitigate the growth of dendrites. Furthermore, we demonstrate the positive effect of the additive on the operation of sodium-oxygen batteries by means of increased energy density.