π-hole driven defluorination for fast kinetics of Li/CFx batteries

Abstract

The intrinsic challenge of C-F cleavage and the electron-insulating nature of LiF accumulation impose severe kinetic barriers in lithium/fluorinated carbon (Li/CFx) batteries, particularly under extreme operating conditions. Existing electrolyte systems are unable to effectively address these coupled obstacles. Here, we introduce a π-hole mediated strategy that leverages the electron-deficient region of isoxazole (IZ) solvents to simultaneously destabilize C-F bonds and facilitate LiF dissolution. The adjacent electronegative N and O atoms in IZ induce a directional π-hole, enabling orbital-specific coordination with F atoms (π-hole•••F interactions). These interactions lower the energy of the σ*(C-F) antibonding orbitals and reduce Li⁺-F⁻ bonding, thereby accelerating defluorination kinetics and facilitating interfacial ion transport. As a result, the industrial-grade 12 Ah Li||CFx (11.82 mAh cm⁻²) pouch cells with lean IZ-based electrolyte (1.5 g Ah⁻¹) deliver high energy densities exceeding 540 Wh kg⁻¹ even under harsh conditions such as -40°C at 1 C, whereas the pouch cells with conventional propylene carbonate and 1,2-dimethoxyethane-based electrolyte fail to discharge under the same conditions. This work redefines the role of solvent molecules in conversion-type batteries by integrating supramolecular orbital engineering with electrolyte design, offering a broadly applicable platform for high-power/energy systems.