Improved energy and power density of a Li/CFX primary battery through control of the C-F bonds with thermobaric modifications

Abstract

Although Li/CFX batteries are widely applied primary batteries, the inherent electrical conductivity of CFX is lowered by the highly polar C-F bonds due to the strong electronegativity of fluorine. Here, we have improved the electrochemical performance of Li/CFX batteries by applying an easy and simple new method to control the C-F bonds and induce surface defluorination. Through this method, the microporosity of CFX was increased, and an intermediate CFX was prepared. In addition, the method increased the concentration of semi-ionic C–F bonds (by approximately 3.2 times) compared to the pristine CFX and reduced the relative proportions of inactive covalent C–F and C–F2 bonds (by approximately 3.5 times). In addition, the numbers of sp3 hybridized C–C and sp2 hybridized C = C bonds increased (by approximately 4.4 times). These results improved the electrochemical performance of the Li/CFX battery. In particular, the T-500 showed a specific capacity of 534.80 mAh/g, an energy density of 1264.75 Wh/kg, and a power density of 10,024.67 W/kg at 7.0 C. In addition, a significant decrease in internal resistance (Rct value 45.19 to 7.62 Ω) and improved lithium diffusion were confirmed with galvanostatic intermittent titration.