摘要
Solid polymer electrolytes (SPEs) are urgently required for achieving practical all-solid-state lithium metal batteries (ASSLMBs) but remain plagued by low ionic conductivity.Herein,we propose a strategy of salt polarization to fabricate a highly ion-conductive SPE by employing a high-dielectric polymer that can interact strongly with lithium salts.Such a polymer with large dipole moments can guide lithium cations (Li^(+)) to be arranged along the chain,forming a continuous pathway for Li^(+) hopping within the SPE.The as-fabricated SPE,poly(vinylidene difluoride)(PVDF)-LiN(SO_(2)F)_(2)(LiFSI),has an extraordinarily high dielectric constant (up to 10^(8)) and ultrahigh ionic conductivity (0.77×10^(-3)S cm^(-1)).Based on the PVDF–LiFSI SPE,the assembled Li metal symmetrical cell shows excellent Li plating/stripping reversibility at 0.1 m A cm^(-2),0.1 m Ah cm^(-2)over 1500 h^(-1) the ASS LiFePO_(4) batteries deliver long-term cycling stability at 1 C over 350 cycles (2.74 mg cm^(-2)) and an ultralong cycling lifespan of over 2600 h(100 cycles) with high loading (11.5 mg cm^(-2)) at 28°C.First-principles calculations further reveal the ion-dipole interactions-controlled conduction of Li^(+) in PVDF–LiFSI SPE along the PVDF chain.This work highlights the critical role of dielectric permittivity in SPE,and provides a promising path towards high-energy,long-cycling lifespan ASSLMBs.
基金
supported by the National Natural Science Foundation of China (No. 51877132)
the Program of Shanghai Academic Research Leader (No. 21XD1401600)
the Beijing Natural Science Foundation (No. 2214061)。
