Effect of Si Addition on Mechanical and Electrochemical Properties of Al-Fe-Cu-La Alloy for Current Collector of Lithium Battery

Xu Xu,Huang Huang,Ding Ding,Chen Chen,Tang Tang,Gao Gao,Wu Wu,Yang Yang,Zhang Zhang

doi:10.3390/met9101072

Abstract

The increasing demand for high-performance current collectors of lithium ion secondary batteries requires that the employed aluminum alloys have better mechanical properties and superior electrochemical performance. The effect of Si addition on the microstructure, tensile and electrochemical performance of Al-Fe-Cu-La alloy was investigated by optical microscopy, X-ray diffraction, scanning electron microscopy, a tensile test, conductivity test and Tafel polarization curve test. Experimental results indicated that Si addition to the Al-Fe-Cu-La alloy helped to refine the longitudinal grain size of the alloy. The Si-containing phase (AlFeSi) nucleated and grew along the surface of the AlFeLa phase. The Si addition to the Al-Fe-Cu-La alloy could greatly increase the tensile strength in the temperature range of −20 °C to 50 °C and improve high temperature stability of the alloy. Also, the addition of Si promoted the formation of the AlFeSi ternary phase, which helped to improve the corrosion resistance of the alloy.

Highlights

The electrical conductivity of aluminum is lower than that of copper, the weight of aluminum is half that of copper required to deliver the same amount of electricity
We could observe that the Si-containing alloys had uniform grain size distribution and finer grain size compared to the matrix alloy without Si element, and the average grain size obtained by using Image Pro Plus (IPP6.0, Media Cybernetics, Washington D.C., USA) software are
As the grain size decreased the number of grain boundaries increased, which caused an increase of electron scattering, which adversely affected the electrical conductivity of the alloy

Summary

Introduction

The electrical conductivity of aluminum is lower than that of copper, the weight of aluminum is half that of copper required to deliver the same amount of electricity. The use of aluminum current collectors helps to increase the energy density of lithium ion batteries. Since aluminum is a relatively active metal, a dense oxide film is formed on the surface. During the charge/discharge cycle of the lithium ion battery, the oxide film on the surface of the aluminum current collector improves the corrosion resistance. Aluminum foil is often used as the current collector for positive active material (LiCoO2, LiCo1/3Ni1/3O1/3, LiMnO2) of the lithium ion battery [1]. It is worth noting that the drying temperature after coating the positive active material should be selected appropriately

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