Effect of Carbon Nanotubes on the Electrochemical Performance of Li Powder Composite Anodes

Abstract

To achieve the high energy density of lithium secondary batteries, the Li metal anode with a high theoretical capacity (3860 mAh g-1) and the lowest electrochemical potential (-3.04 vs. SHE) has attracted attention. However, Li metal is plagued with challenges such as irregular dendritic growth during cycling and low Coulombic efficiency (CE), which hinder its commercialization as an anode. Li metal powder (LMP) offers a solution to these problems by enlarging the surface area resulting in a lower effective current density. However, the commercial LMP passivated by Li2CO3 layer on the surface could hinder the electrical contact between individual LMPs as well as LMP and Cu current collector. Consequently, a series of LMP particle contact failures result in dead regions within the LMP electrode where the Li source cannot be fully activated.Herein, we report the effect of multiwalled CNTs on the electrochemical performance of Li metal powder-based anodes for Li metal batteries. The CNT-LMP anode exhibits a remarkable improvement in the electrochemical performance of coin cells compared to the bare LMP system. This improvement is attributed to the enhanced electrical connection between individual LMP particles, activation of full Li utilization, and the seeding effect of CNTs. Electrochemical properties were investigated using postmortem scanning electron microscopy and galvanostatic cycling techniques.