Functionalized fillers as “ions relay stations” enabling Li+ ordered transport in quasi-solid electrolytes for high-stability lithium metal batteries

Abstract

Quasi–solid–state lithium–metal batteries (QSLMBs) are promising candidates for next–generation battery systems due to their high energy density and enhanced safety. However, their practical application has been hindered by low ionic conductivity and the growth of lithium dendrites. To achieve ordered transport of Li+ ions in quasi–solid electrolytes (QSEs), improve ionic conductivity, and homogenize Li+ fluxes on the surface of the lithium metal anode (LMA), we propose a novel method. This method involves constructing “ion relay stations” in QSEs by introducing cyano–functionalized boron nitride nanosheets into pentaerythritol tetraacrylate (PETEA) –based polymer electrolytes. The functionalized boron nitride nanosheets promote the dissociation of lithium salts through ion–dipole interactions, optimizing the solvated structure to facilitate the orderly transport of Li+ ions, resulting in an ionic conductivity of 2.5 × 10−3 S cm−1 at 30 °C. Notably, this strategy regulates the Li+ distribution on the surface of the LMA, effectively inhibiting the growth of lithium dendrites. Li||Li symmetrical cells using this type of electrolyte maintain stability for over 2000 h at 2 mA cm−2 and 2 mAh cm−2. Additionally, with a high LiNi0.8Co0.1Mn0.1O2 (NCM811) loading of 8.5 mg cm−2, the cells exhibit excellent cycling performance, retaining a high capacity after 400 cycles. This innovative QSE design strategy represents a significant advancement towards the development of high–performance QSLMBs.