Impact of Oxide Growth on Lead Negative Electrodes for Sodium-Ion Batteries

Lead (Pb), along with other alloy materials has emerged as a promising negative electrode material for sodium-ion batteries (SIBs) due to its high volumetric capacity. However, the presence of oxide impurities in Pb negative electrodes has been found to negatively impact cell performance. This study investigates the impact of oxide content on the initial capacity and cycling stability of Na/Pb half cells. A controlled heat treatment procedure enabled the formation of varying oxide amounts with increased exposure time, confirmed by X-ray diffraction to be Pb oxide (PbO). When PbO reacts with Na upon first charge, Na 2 O is irreversibly formed, which consumes active Na inventory, decreases the first cycle efficiency, and leads to capacity fade. Long term cycling of oxidized Pb electrodes suggests that there is a permissible level of oxides in Pb-based Na-ion cells without severe impact on performance; specifically, in this study, this threshold was found to be ∼0.13 moles of PbO per 1 mol of Pb. Understanding the impact of PbO on cell performance can guide material selection and design of these relatively inexpensive, high capacity Pb-based negative electrodes for SIBs.