Constructing Electronic and Ionic Dual Conductive Polymeric Interface in the Cathode for High-Energy-Density Solid-State Batteries

Solid–solid interfaces in the composite cathode for solid-state batteries face the thorny issues of poor physical contact, chemical side reaction, temporal separation, and sluggish Li + /e − transfer. Developing key material to achieve the composite cathode with efficient solid–solid interfaces is critical to improving the coulombic efficiency, cycling life, and energy density of solid-state batteries. Herein, electronic and ionic dual conductive polymer (DCP) is prepared for the composite cathode via intermolecular interaction on the base of lithiated polyvinyl formal-derived Li + single-ion conductor (LiPVFM), lithium difluoro(oxalato)borate (LiODFB), and electronic conducting polymer. Crosslinking, coordination, and hydrogen-bonding effect enable DCP with high electrical conductivity of 68.9 S cm −1 , Li + ionic conductivity (2.76 × 10 −4 S cm −1 ), large electrochemical window above 6 V and a high modulus of 6.8 GPa. Besides, DCP can form a coating layer on the active material powders to maintain structural integrity via buffering the internal stress during lithiation/delithiation, meanwhile, to construct long- and short-range electronic/ionic conductive channel together with a small amount of CNTs. Rigid and flexible DCP-based composite cathode enables the excellent cycling of solid-state batteries with a high loading up to 11.7 mg cm −2 and high content of active materials close to 90 wt% without current collector.