Li-ion batteries (LIBs) have advantages such as high energy and power density, making them suitable for a wide range of applications in recent decades, such as electric vehicles, large-scale energy storage, and power grids. Deep renewables penetration will require long duration energy storage (LDES) that can discharge for upwards of eight hours in order to keep the grid balanced and power flowing. Conventional wisdom is that lithium-ion caps out at around four hours, and that it will be new technologies unlocking this. Lithium-ion batteries, historically limited to consumer electronics and electric vehicles, have now moved into the larger realm of projects that will ultimately stabilize power systems, optimize renewable energy sources to the power grid, and improve grid reliability.