Two-dimensional nanofluidic suppressing anion mobility toward dendrite-free lithium metal anode

Modification of separator with lithium-ion redistributor has been considered to be an effective strategy to evade lithium dendrite by evening lithium-ion concentration on electrode surface. According to the Sand equation, the mobility of anion is also critical to realizing smooth lithium deposition. Herein, a fast cation conductor layer was constructed by assembling exfoliated vermiculite sheets on commercial separator to form vermiculite composite separator (VCS). The negative surface charged 2D nanofluidic channels in VCS repel anions, blocking the shuttle of anions between electrodes. Nevertheless, lithium ions are attracted, and mobility is dramatically enhanced, which increases the lithium-ion transference numbers (tLi+) and intrinsically improves the electrochemical performance. Resultantly, the Coulombic efficiency of Cu//Li battery with VCS is more than 96%, and the voltage polarization of symmetric battery is only a quarter of the commercial separator even at a high current density of 5 mA/cm2. Furthermore, the inorganic nature of the vermiculite sheet endows the VCS with excellent thermal stability. The superior electrochemical performance of VCS highlights the importance of constructing 2D nanofluidic channels and provides new avenues for the development of high-performance and long-lifespan lithium metal batteries. (C) 2022 Published by Elsevier Ltd.

Automated summary

Constructing a fast cation conductor layer on a commercial separator to form a vermiculite composite separator (VCS) can improve the electrochemical performance and thermal stability of lithium metal batteries, enhancing the Coulombic efficiency and reducing voltage polarization.