Complementary hybrid design of solvated electrolyte membranes enabled by porous carbon reinforcement for high-performance lithium batteries

Solid polymer electrolytes are potential replacement of liquid electrolytes due to their much less flammability and leakage. Among them, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based electrolytes have several advantages including improved processability and electrochemical stability. Unfortunately, poor ionic conductivity and mechanical properties due to high plasticizer concentration hinder their practical applications. Herein, we address these issues by exploiting the solvation effect in the electrolyte through tuning the amount of residual N-methyl-2-pyrrolidone (NMP) and lithium salts. Moreover, by blending with porous carbon (PC) the mechanical integrity of the PVDF-HFP electrolytes is substantially enhanced due to improved interfacial bonding and specific surface area. The appropriate value of electrical conductivity and highly porous morphology of PC also meet the ionic transport and electronic insulation requirements. With the absorbed residual NMP as plasticizer and complexed with Li ions to formLi[NMP](3)(+) , ionic conductivity and amorphicity are improved. By elucidating the solvent and salt concentration interplay, Li-ion conductivity of up to 0.56 mS cm(-,) wide electrochemical window of 5 V versus Li/Li+ and 1000 h of cycling stability (versus Li, 0.2 mA/cm(2)) are obtained. These findings afford a novel electrolyte design guideline for enhancing interfacial compatibility and cycling through hybridization and ion solvation to develop practical lithium batteries.

Automated summary

This research improves the ionic conductivity and mechanical properties of PVDF-HFP electrolytes by adjusting the residual NMP and lithium salt content, as well as blending with porous carbon. Additionally, a novel electrolyte design guideline is established to enhance cycling stability and electrical conductivity.