Multiple intermolecular engineering of polymer electrolyte interphase by polyoxometalate-modified polydopamine filler for all-solid-state batteries

Polyethylene oxide (PEO)-based composite solid electrolytes (CPEs) are viewed as one class of the most promising candidates for all-solid-state batteries (ASSBs). Vast efforts have been made to address the ionic conductivity mainly by extending its amorphous phase, but the mobility of cations is strictly limited by the strong coordination with PEO. Herein, the design of polyoxometalate-modified polydopamine (PMo12@PDA) as composite filler is first proposed to simultaneously increase the ionic migration of PEO segments and intrinsic mobility of cations. PDA serves as versatile mediator and collaborates with PMo12 clusters to construct multiple Lewis acid-base interactions with the undissociated salts as well as the coordinated ether oxygen units. Raman spectra, solid-state nuclear magnetic resonance and the first principles calculations results confirm that more mobile cations are generated. The constructed CPEs exhibit wide utilization in all-solid-state Li/Na batteries by assembly with cathodes of LiFePO4, LiNi0.5Co0.2Mn0.3O2 or Na3V2(PO4)3@C, achieving long cycling stability and excellent rate performance. This work offers a viable route towards intermolecular engineering of CPE intrerphases at sub-nanometer scale and fast cationic movement in ASSBs applications.