Cycle Life and Safety Characteristics of Lead Negative Electrodes in Sodium-Ion Batteries

Abstract

The choice of negative electrode plays a significant role in determining the volumetric energy density of a sodium-ion cell. Lead (Pb), along with other alloy materials, has emerged as a promising negative electrode material for sodium-ion batteries (SIBs) due to its potentially high volumetric capacity compared to hard carbon, resulting in higher energy density on a cell level. This study focuses on improving the formulation of Pb negative electrodes and evaluating their capacity retention in half- and full-cell configurations while investigating potential degradation mechanisms in full cells. Additionally, the impact of oxide impurities on the cycling stability of Pb negative electrodes was studied using a controlled heat treatment procedure. The results show that the irreversible formation of Na₂O, a side product of the sodiation reaction of Pb oxide with sodium, leads to sodium inventory loss, decreased first-cycle efficiency, and a detrimental impact on the cell’s long-term cyclability. The thermal stability of fully sodiated Pb in the presence of glyme-based electrolyte indicates that Pb not only offers an energy density advantage but is also marginally more stable at elevated temperatures compared to hard carbon under the applied testing conditions. Overall, this work provides valuable insights into the cyclability, degradation mechanisms, and thermal stability of Pb, offering useful guidance for its future commercialization and deployment in SIBs.