Abstract
A rechargeable Zn metal battery (RZMB) is considered a technology of significance that could eliminate the supply chain and cost crisis brought by Li-based chemistries while maintaining comparable energy. However, current Zn metal electrodes are limited to shallow cycling conditions (< 1 mAh cm
−2
) and inefficient utilization (< 10%) because of Zn irreversibility in battery environments. We used MeOH to alter the solvation structure of Zn electrolytes and interphasial chemistries and achieved high utilization (50%) and high Coulombic efficiency (99.5%) of a Zn metal electrode as well as an unprecedented wide service temperature range for the RZMB, down to −40°C. This work opens up a way to tailor the electrochemical behavior of Zn on the molecular level so that emerging battery chemistries can be realized for practical applications.
Rechargeable Zn metal batteries (RZMBs) may provide a more sustainable and lower-cost alternative to established battery technologies in meeting energy storage applications of the future. However, the most promising electrolytes for RZMBs are generally aqueous and require high concentrations of salt(s) to bring efficiencies toward commercially viable levels and mitigate water-originated parasitic reactions including hydrogen evolution and corrosion. Electrolytes based on nonaqueous solvents are promising for avoiding these issues, but full cell performance demonstrations with solvents other than water have been very limited. To address these challenges, we investigated MeOH as an alternative electrolyte solvent. These MeOH-based electrolytes exhibited exceptional Zn reversibility over a wide temperature range, with a Coulombic efficiency > 99.5% at 50% Zn utilization without cell short-circuit behavior for > 1,800 h. More important, this remarkable performance translates well to Zn || metal-free organic cathode full cells, supporting < 6% capacity decay after > 800 cycles at −40 °C.