Sodium-metal cathode annealing at near room-temperature for long life batteries

In the process of charging a sodium (Na) metal battery, the electrons of the positive Na⁺ are reduced into metal and deposited on the surface of the cathode. With the cycle of the battery, the sediment continuously increases and gradually forms the dendrite, limiting the battery life. In this study, the Na metal cathode was worked at near room temperature (35 ℃) at an annealing condition for recrystallization. Due to the low melt point (97 ℃), the metallic Na with dendritic-free plated on the cathodes was obtained. Accordingly, the sodium vanadium phosphate (NVP)||Na full cell indicated a discharge-specific capacity of 83.8 mAh/g even after 300 cycles at a C-rate of 1C. The results show that the working condition of 35 ℃ near room-temperature thermal treatment eliminates the dentrites and forms a cathode surface without the dentrite, thus improving the battery's electrochemical performance.