Robust Multiscale Electron/Ion Transport and Enhanced Structural Stability in SiOx Semi-Solid Anolytes Enabled by Trifunctional Artificial Interfaces for High-Performance Li-Ion Slurry Flow Batteries.

Abstract

SiOx suspension is regarded as an attractive anolyte for high-energy-density Li-ion slurry flow batteries. However, the poor electronic conductivity and non-negligible volume variation of SiOx greatly hinder its practical applications. Herein, these issues are successfully addressed by rationally designing a trifunctional interface with mixed electron/ion and hard/soft modulated properties on SiOx surface via H-bonding interactions. The interface comprises a lithiated polymer layer (LiPN) interfused with functionalized single-walled carbon nanotubes. Carbon nanotubes work as electrical tentacles to enhance the multiscale electron conduction. The LiPN layer with transferable Li-ions facilitates ion transport. In addition, the LiPN layer employs lithiated rigid polyacrylic acid as a framework to provide mechanical support and soft nafion as a buffer to accommodate volume change, which maintains the structural integrity of SiOx . Hence, SiOx @LiPN/S anolytes exhibit significantly improved rate and cycle performances. Specially, the interface enables the anolytes to load more active particles (30wt%) or less conductive additives (0.4wt%). The semi-solid pouch cells based on high-active-content anolytes with stable cyclability are first demonstrated and the flow cell using low-conductive-content anolytes displays a high volumetric capacity of 207 AhL-1 . This strategy paves a novel approach for optimizing semi-solid electrodes for high-performance Li-ion slurry flow batteries.