Novel Li3V2-xMox(PO4)3 Electrode Material and Liquid Electrolytes for Lithium-Ion Batteries Cycled at Cryogenic Temperatures

Lithium-ion batteries (LIBs) are widely used owing to their high specific energy and long lifespans. However, cryogenic temperatures can restrict their application considerably—for example, during cold weather (winter) and military and aerospace exploration. Molybdenum (Mo)-doped Li3V2-xMox(PO4)3 has a beneficial tetrahedron and octahedron structure that is stable at low temperatures and shorter distances (for Li+ transmission), which contributes to higher ion conductivity at low temperatures. The theoretical capacity of Li3V2(PO4)3 in the 3.0–4.3 V working range is 132 mAh/g, reaching 197 mAh/g in the 3.0–4.8 V working range. In this study, we first examined the optimal molar ratio of Mo in a commercial electrolyte, the most suitable Mo molar ratio being 0.02 with a specific capacity of 121.3 mAh/g in the 3.0–4.3 V working range under ambient temperature conditions. Subsequently, we developed a novel electrolyte with a volume ratio of 1,3-dioxolane:1,2-dimethoxyethane (DOL:DME) of 8:2. Here, the specific capacity was 102.3 mAh/g at room temperature with a capacity retention of 42.3%; moreover, the specific capacity was 43.3 mAh/g at 223 K with a capacity retention of 0.11% at 193 K.