Investigation of nitriding treated Ni-free stainless steel as current collector for 5 V-class Li-ion secondary cell

Abstract

Nitrided Ni-free stainless steel was prepared and evaluated electrochemically in a non-aqueous solution for use as a current collector for a positive electrode for 5 V-class Li-ion secondary battery. The nitrided stainless steel was characterized using a surface conductivity meter, X-ray diffraction, and glow discharge optical emission spectroscopy. The cyclic voltammogram was obtained in 1 mol dm−3 LiPF6/EC: DMC (1:1 vol%). As the results indicate, the electrical conductivity and crystal structure of α-Fe remained after the nitrogen heat treatment. However, the results also suggest that oxides, nitrides, or nitrogen oxides of Al and Cr are formed on the surface. The untreated stainless steel brought about slight anode dissolution in a non-aqueous solution. In contrast, it was found that the nitrided stainless steel hardly underwent anodic dissolution at 1.5–5.4 V vs. Li/Li+, and has a wide electrochemical window for use in a positive electrode of a 5 V-class Li-ion secondary battery.