Abstract:

Chromium oxides (Cr₈O₂₁) have been extensively studied as cathode materials for lithium primary batteries due to their high specific capacity and stable voltage plateau. However, designing state-of-the-art electrolytes for Li/Cr₈O₂₁ is crucial to ensure applicability under various conditions. In this study, a novel dual-salt electrolyte (FB55-10%) was developed through theoretical calculations and experimental validation. LiBF₄ enhances the low-temperature performance of Li/Cr₈O₂₁, while LiFSI, with its superior stability, compensates for the low ionic conductivity of LiBF₄ at normal temperatures. In addition, methyl butyrate (MB), characterized by low viscosity and a low melting point, was selected as a co-solvent with propylene carbonate (PC) to extend the operating temperature range from the melting point to the boiling point, thereby enabling Li/Cr₈O₂₁ applications across a wide temperature range (-45—65 ℃). Furthermore, the low-temperature (-45 ℃) performance of Li/Cr₈O₂₁ was further improved by incorporating a solid-state electrolyte, Li_1.3Al_0.3Ti_0.7(PO₄)₃ (LATP), into Cr₈O₂₁ composite materials. As a result, the Li/Cr₈O₂₁ coin cell achieved specific capacities of 404 mAh/g, 410 mAh/g, and 223 mAh/g at 25 ℃, 65 ℃, and -45 ℃, respectively, at a current density of 0.02C. In addition, a 3 Ah pouch cell incorporating this novel electrolyte demonstrated excellent electrochemical performance, confirming the superior wide-temperature adaptability of this electrolyte system.

Key words: chromium oxide, wide-temperature electrolyte, solid-state-electrolyte, lithium primary battery