Selenium-regulated band structure engineering in CFx cathodes enables high-power and wide-temperature Li/CFx primary batteries

Li/CF x primary batteries are renowned for their exceptional energy density, yet their practical deployment is hindered by the inherently sluggish kinetics of the CF x cathode. This study addresses this limitation by incorporating selenium (Se) into CF x (denoted as CF x /Se) via a facile low-temperature thermal treatment, significantly enhancing its electrochemical performance. Comprehensive spectroscopic and electrochemical analyses reveal that Se doping induces the formation of C Se bonds, which promote semi-ionic C F bonding, thereby accelerating Li + diffusion and reducing charge transfer resistance. Density functional theory calculations further demonstrate that Se doping modulates the electronic structure of CF x , narrowing its bandgap to establish an efficient conductive network and markedly improving electronic conductivity. The optimized CF x /Se-1 composite (Se:CF x  = 1:9) delivers outstanding performance, achieving a discharge capacity of 383.9 mAh g −1 at a high current density of 20 A g −1 with an energy density of 765.7 Wh kg −1 and a power density of 3.99 × 10 4  W kg −1 . Moreover, CF x /Se-1 exhibits remarkable wide-temperature operability (−35 to 60 °C), retaining a capacity of 485.3 mAh g −1 at 0.5 A g −1 with a stable 2.0 V plateau even at −35 °C. This work underscores the pivotal role of Se doping in tailoring the band structure of CF x , unlocking its potential for high-power and extreme-temperature Li/CF x batteries.