Toward the High‐Performance Lithium Primary Batteries by Chemically Modified Fluorinate Carbon with δ‐MnO2

Abstract Li/CF x battery is one of the most promising lithium primary batteries (LPBs) which yields the highest energy density but with poor rate capability. This Achilles'’ heel hinders the large‐scale applications of Li/CF x batteries. This work first reports a facile chemical modification method of CF x with δ‐MnO 2 . Having benefited from the chemical bonding, the electrochemical performance at high‐rate discharge is remarkably enhanced without compromising the specific capacity. The coin cells exhibit an energy density of 1.94 × 10 3 Wh kg −1 at 0.2 C, which is approaching the theoretical energy density of commercial fluorinated graphite (2.07 × 10 3 Wh kg −1 ). A power density of 5.49 × 10 4 W kg −1 at 40 C associated with an energy density of 4.39 × 10 2 Wh kg −1 , which is among the highest value of Li/CF x batteries, are obtained. Besides, the punch batteries achieve an ultrahigh power density of 4.39 × 10 4 W kg −1 with an energy density of 7.60 × 10 2 Wh kg −1 at 30 C. The intrinsic reasons for this outstanding electrochemical performance, which are known as the fast Li + diffusion kinetics guided by thin δ‐MnO 2 flakes and the low formation energy barrier caused by chemical bonding, are explored by the galvanostatic intermittent titration technique (GITT) and theoretical calculations.