Inspired by philosophizing of “point to area”: Ion pre-intercalation induces the reconstitution of interlayer environment of MXene for lithium storage

Abstract

2D extended interspacing confined by MXene determines its function as intercalation electrodes of alkali metal ions batteries. However, the space electric field distribution within the adjacent MXene layers sets a barrier to the transport behavior of alkali metal ions. The presence of surface functional groups induces the negatively charged MXene and further leads to a deteriorative ion storage. Herein, the polar Al3+ pre-intercalated Ti3C2Tx MXene electrodes were prepared by an electrochemical approach to understand and optimize the interlayer charge distribution. The interactional relationship among intercalating space, interlayered charge distribution, and insertion/desertion behavior of electrolyte ions were investigated. The pre-intercalated Al3+ can induce a shrinkage of the restricted interlayer spacings and lead to a compressive strain of MXene. Moreover, these Al3+ confined interlayer space of MXene also can decrease electrostatic potential and regulate the charge density of original Ti3C2Tx MXene to improve electron transfer and lithium ion diffusion rate. The Ti3C2Tx-Al3+ electrode increased by 113.7 % in ion storage capacity. This work unlocks a new insight into the rational design of MXene electrodes based on ion pre-intercalation modulates interlayer environment.