All solid-state lithium batteries (SSLBs) are poised to have higher energy density and better safety than current liquid-based Li-ion batteries, but a central requirement is effective ionic conduction pathways throughout the entire cell. Here we develop a catholyte based on an emerging class of porous materials, porous organic cages (POCs). A key feature of these Li+ conducting POCs is their solution-processibility. They can be dissolved in a cathode slurry, which allows the fabrication of solid-state cathodes using the conventional slurry coating method. These Li+ conducting cages recrystallize and grow on the surface of the cathode particles during the coating process and are therefore dispersed uniformly in the slurry-coated cathodes to form a highly effective ion-conducting network. This catholyte is shown to be compatible with cathode active materials such as LiFePO4, LiCoO2 and LiNi0.5Co0.2Mn0.3O2, and results in SSLBs with decent electrochemical performance at room temperature.

Solid polymer electrolytes (SPEs), which are favorable to form intimate interfacial contacts with electrodes, are promising electrolyte of choice for long-cycling lithium metal batteries (LMBs). However, typical SPEs with easily oxidized oxygen-bearing polar groups exhibit narrow electrochemical stability window (ESW), making it impractical to increase specific capacity and energy density of SPE based LMBs with charging cut-off voltage of 4.5 V or higher. Here, we apply a polyfluorinated crosslinker to enhance oxidation resistance of SPEs. The crosslinked network facilitates transmission of the inductive electron-withdrawing effect of polyfluorinated segments. As a result, polyfluorinated crosslinked SPE exhibits a wide ESW, and the Li|SPE|LiNi0.5Co0.2Mn0.3O2 cell with a cutoff voltage of 4.5 V delivers a high discharge specific capacity of ~164.19 mAh g−1 at 0.5 C and capacity retention of ~90% after 200 cycles. This work opens a direction in developing SPEs for long-cycling high-voltage LMBs by using polyfluorinated crosslinking strategy.