Manipulating dielectric property of polymer coatings toward high-retention-rate lithium metal full batteries under harsh critical conditions

Lithium (Li) metal batteries (LMBs) can potentially deliver much higher energy density but remain plagued by uncontrollable Li plating with dendrite growth, unstable interfaces, and highly abundant excess Li (> 50 mAh∙cm⁻²). Herein, different from the artificial layer or three-dimensional (3D) matrix host constructions, various dielectric polymers are initially well-comprehensively investigated from experimental characterizations to theoretical simulation to evaluate their functions in modulating Li ion distribution. As a proof of concept, a 3D interwoven high dielectric functional polymer (HDFP) nanofiber network with polar C–F dipole moments electrospun on copper (Cu) foil is designed, realizing uniform and controllable Li deposition capacity up to 5.0 mAh∙cm⁻², thereby enabling stable Li plating/stripping cycling over 1400 h at 1.0 mA∙cm⁻². More importantly, under the high-cathode loading (~ 3.1 mAh∙cm⁻²) and only 0.6 × excess Li (N/P ratio of 1.6), the full cells retain capacity retention of 97.4% after 200 cycles at 3.36 mA∙cm⁻² and achieve high energy density (297.7 Wh∙kg⁻¹ at cell-level) under lean electrolyte conditions (15 μL), much better than ever-reported literatures. Our work provides a new direction for designing high dielectric polymer coating toward high-retention-rate practical Li full batteries.