The search for high cycle life, high capacity, self healing negative electrodes for lithium ion batteries and a potential solution based on lithiated gallium

Automotive components, for the most part, are designed to last for the life of the vehicle. This is especially true for more expensive subsystems. As we move towards electrified vehicles with large traction batteries, it becomes increasingly important to (a) reduce the cost of the batteries and (b) improve battery life. This life challenge for the traction battery is quite different from that of most consumer electronics applications, which often require no more than a few years of life and a few hundred cycles of full charge and discharge. In this paper, we provide context for the automotive battery landscape and subsequently introduce a potential solution pathway to the cycle life problem associated with high capacity negative electrodes for lithium ion batteries. The approach is based on a solid (in the substantially lithiated state) to liquid (in the absence of significant lithium) transition for the gallium electrode. Because of gallium's low melting point (29°C), heating the cell to just above ambient temperature transforms the electrode to a semi-liquid state, cracks vanish, to a large extent, and the electrode heals.