Multi‐Level Regulation of Electrostatic Microenvironment With Anion Vacancies for Low‐Lithium‐Gradient Polymer Electrolyte

Solid‐state lithium‐metal batteries based on poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVH) are frequently proposed to address the detrimental safety issue of conventional lithium‐ion batteries by eliminating the use of flammable solvents, but still face a key challenge: low capacity and sluggish charge/discharge rate due to the intrinsic large‐gradient Li + distribution across the ionically‐inert PVH matrix. Herein, Te vacancies in form of Bi 2 Te 3−x are proposed to polarize the PVH unit to realize efficient decoupling of lithium salts at the atomic level in PVH‐based solid polymeric electrolyte. Te vacancies in the PVH electrolyte doped with Bi 2 Te 3−x (PVBT) induce a high‐throughput and homogenous Li + flow within the PVH matrices and near the Li metal. Theoretical calculations show that Te vacancies own high adsorption energy with bis(trifluoromethanesulfonyl)imide anions (TFSI − ), repulsive effect on Li + , and localized electron distribution, giving rise to a lithium‐ion concentration gradient of 30 mol m −3 , the smallest among the PVH‐based inorganic/organic composite electrolytes. Consequently, the polarized electrolyte owns an unprecedented high‐rate battery capacity of 114 mAh g −1 at ∼700 mA g −1 and also superior capacity performances with a cathode loading of 12 mg cm −2 , outperforming the state‐of‐art PVH‐based inorganic/organic composite electrolytes in Li||LiFePO 4 battery. The work demonstrates an efficient strategy for achieving fast Li + diffusion dynamics across polymeric matrices of classic solid‐state electrolytes.