A ketone-containing all-solid-state polymer electrolyte with rapid Li-ion conduction for lithium metal batteries

Solid-state polymer electrolytes (SPEs) have gained considerable attention in the application of all-solid-state lithium batteries (ASSLBs), but the low ionic conductivity at room temperature and inferior interfacial compatibility largely drag the practical development of SPEs. Herein, a ketone-containing poly(allyl acetoacetate) (PAAA) based polymer electrolyte is designed and prepared for the first time. The structure of ester and ketone groups provides PAAA polymers with not only strong dissociation of lithium salts but also weak coordination interactions with Li+ ions. Thus the prepared PAAA polymer electrolytes show excellent ion conductive behavior with ionic conductivity as high as 1.1 × 10-4 S cm−1 at 30 °C. Moreover, the PAAA polymer electrolytes still maintain superior viscoelasticity without compromising mechanical integrity. When assembling cells, the reduction-tolerant poly(ethylene oxide) (PEO) polymer electrolytes are employed as interlayers between the PAAA SPEs and lithium electrodes in order to improve interfacial stability. As a result, the hierarchical polymer electrolytes possess wide electrochemical window above 4.8 V, thus matching well with LiFePO4 or Li1.2Ni0.2Mn0.6O2 high-voltage cathode. The hierarchical structure does not affect interfacial contact, and the Li/PEO-PAAA-PEO/Li cells show low interfacial resistance and stable striping/plating behavior for at least 500 h at 0.2 mA cm−2 and 60 °C. This study enriches carbonyl-based polymer electrolytes by allying ketone with ester groups, and provides guidance for designing novel high-performance polymer electrolytes for practical application.