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

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-MnO₂ . 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 × 10³  Wh kg^-1 at 0.2 C, which is approaching the theoretical energy density of commercial fluorinated graphite (2.07 × 10³  Wh kg^-1 ). A power density of 5.49 × 10⁴  W kg^-1 at 40 C associated with an energy density of 4.39 × 10²  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 × 10⁴  W kg^-1 with an energy density of 7.60 × 10²  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-MnO₂ flakes and the low formation energy barrier caused by chemical bonding, are explored by the galvanostatic intermittent titration technique (GITT) and theoretical calculations.