287 / 2024-03-14 21:17:47

Application of a High Entropy Electrolyte to Fluorinated Carbon Batteries in a Wide Temperature Domain

Li/CFx batteries, High entropy electrolyte, Co-intercalation, Second discharge platform, High energy densities

7、矿物与先进能源材料 > 5、新能源材料与器件

Fluorinated carbon (CF_x) is considered to be a very promising cathode material for lithium primary batteries, with an ultra-high theoretical energy density of 2180 Wh kg^-1. However, the C-F bonds in CF_x materials are strongly covalent, which means that CF_x materials have a very low intrinsic conductivity. In this paper, a high entropy electrolyte (HE) is investigated, and while maintaining the original discharge platform, a second discharge voltage platform is found to appear around 1.7 V, which effectively improves the capacity of Li/CF_x batteries. This huge improvement can be attributed to the chelation of the dioxygen atoms in the solvent with the Li⁺, and finally, the solvated Li⁺ are co-intercalated into the lamellar structure of the graphite. Especially at low and high temperatures, the HE electrolyte exhibits superior performance to the electrolyte with a single lithium salt. This is mostly because of the high entropy, which changes the point at which the electrolyte solidifies. This avoids capacity loss caused by solid-phase electrolyte clogging the electrode holes. This work will provide a simple and reliable method for the design of Li/CF_x batteries with high capacity and high energy density.