A flexible carbon nanotube film modified with gradient lithiophilic Cu2O/ Cu heterojunction for dendrite-free lithium metal anodes

Lithium (Li) metal batteries have been extensively studied for their high energy density, but uncontrolled Li dendrites and severe volume fluctuation significantly limit their commercial applications. To address this issue in Li metal anodes, a flexible self-supporting film was developed by integrating Cu2O/Cu heterojunction with a gradient distribution and a three-dimensional (3D) single-walled carbon nanotube (SWCNT) network. The topdown gradient distribution of Cu2O/Cu effectively reduces the Li+ concentration polarization and conductivity polarization in the vertical direction within the 3D framework, achieving bottom-up deposition of Li inside the framework. Moreover, Mott-Schottky junction between lithiophilic Cu2O and Cu can trigger the built-in electric field (BIEF) at their heterointerfaces, thereby accelerating electron transfer and Li+ migration. Benefiting from the physicochemical bidirectional regulation, the Cu2O/Cu@SWCNT/Li realizes an ultralow voltage polarization of 13 mV and a prolonged cycling stability over 1800 h in a symmetric cell (1 mA cm-2 and 1 mAh cm-2). Additionally, the film shows excellent cycle stability in the Cu2O/Cu@SWCNT-Li//LiFePO4 full cell, providing practical ideas for the subsequent design of lithium metal anodes.

Automated summary

A flexible self-supporting film consisting of Cu2O/Cu heterojunction with a gradient distribution and a three-dimensional carbon nanotube network was developed to address the issues of Li dendrites and volume fluctuation in Li metal anodes. The film achieves bottom-up deposition of Li and accelerates electron transfer and Li+ migration through the physicochemical bidirectional regulation. The research provides practical ideas for the subsequent design of lithium metal anodes.