High-Zeta-Potential Accelerates Interface Charge Transfer in Lithium Anodes Via Mxene-Graphdiyne Heterojunction Layers

Abstract

Lithium (Li) metal anodes are a crucial part of lithium-based batteries and are highly regarded as a top contender for achieving high-energy-density lithium batteries. However, the development of dendrites and other related issues have significantly impeded their practical applications. Here, we fabricated a MXene (Ti3C2Tx)-graphdiyne heterostructure layer anode with high-zeta-potential (−90 mV) using an electrostatic self-assembly method. The high-zeta-potential can accelerate the interface charge transfer in the lithium deposition process, facilitating the uniform Li nucleation on the surface of anodes. Theoretical simulations further reveal that the high-zeta-potential can not only reduce the lithium ion concentration gradient but also homogenize the electric field in the anodes. Besides, based on first-principles computation, the adsorption energy of lithium atoms on MXene-graphdiyne heterostructure is −3.4 eV. As a result, a low overpotential of 12.4 mV has been achieved by MXene-graphdiyne layers at 0.05 mA cm−2. Additionally, MXene-graphdiyne-Li anodes display an ultralong cycle life upto 1400 hours and good rate capability upto 8 mA cm−2 in symmetric cells. Full cells consisting of MXene-graphdiyne-Li anodes and LiFeO4 cathodes also show stable cyclic properties (300 cycles at 5 C).

Keywords: MXene-graphdiyne, high-zeta-potential, interface charge transfer, dendrite-free, lithium anodes