Bifunctional 3D Graphite@Ni-Fe foam negative current collector toward stable liquid metal battery

Negative current collectors play vital roles in the electrochemical performance of liquid metal batteries (LMBs). Employing a three-dimensional (3D) current collector is an effective approach to host molten lithium and reduce the effective current density. The Ni-Fe foam is a frequently used 3D current collector for the negative electrode. However, the corrosion of molten lithium towards the Ni-Fe foam skeleton devastates the 3D structure of the current collector and so deteriorates seriously the electrochemical performance of LMB. To enhance the corrosion resistivity, herein, the graphite layer coated Ni-Fe foam (Graphite@ Ni-Fe) is prepared by the chemical vapor deposition method. The prepared scaly-like graphite layer plays a bifunctional role in chemistry, preventing corrosion as an effective barrier and improving remarkably the surface lithiophilicity of Ni-Fe foam. The assembled Li parallel to Bi batteries with Graphite@Ni-Fe foam as negative current collector exhibit stable cycling performance with capacity retention of 98.10% and high Coulombic efficiencies over 98.3% at 0.4 A cm(-2) over 100 cycles at 500 degrees C. More importantly, outstanding rate capability is achieved and almost no capacity degradation is observed upon current density change from 0.2 to 2.0 A cm(-2). This work highlights the importance of the lithiophilicity and the corrosion resistance ability of the negative current collectors for LMBs. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the influence of negative current collectors on the performance of liquid metal batteries and develops a graphite-coated Ni-Fe foam as an effective negative current collector. The prepared collector exhibits improved cycling performance, high Coulombic efficiencies, and outstanding rate capability, highlighting the importance of lithiophilicity and corrosion resistance ability of negative current collectors for LMBs.