Selecting inactive materials with low electrolyte reactivity for lithium-ion cells

Electrolyte reactivity on Cu, Ni, 304 stainless steel, Ti, TiN, Mo, and Fe, was investigated at the negative electrode in VC and non-VC containing electrolytes. TiN and Ti were found to have the lowest cathodic electrolyte reactivity in both VC and non-VC containing electrolytes, with a reactivity less than graphite. In contrast, inactive materials commonly used in Li-ion batteries at the negative electrodes, Cu (current collector) and Ni (tabs), have high irreversible capacities, high electrolyte reaction rates (2-3.5 times graphite) and high impedance growth. These studies show that the current materials widely in use today at the negative electrode could be contributing to fade and impedance growth in Li-ion batteries. The use of more inert materials, such as Ti or TiN, may result in an increase of Li-ion battery cycle life.