As the energy storage industry continues to evolve, it is important for electric company utility planners to be aware of the battery energy storage system (BESS) landscape. This report serves as a companion report to the 2021 TAGWeb® lithium ion energy storage updates. It includes discussion of the current energy storage landscape and potential use cases as well as capital costs (CAPEX), ongoing costs, and performance estimates for 66 potential lithium ion energy storage configurations based on ongoing EPRI research. The cost data provided in the report are broken down to a major component level providing bottom-up estimates of CAPEX and ongoing costs. The cases presented in the study include capacities ranging from 1 MW to 100 MW and 1- to 8-hour storage durations. The study also compares the capital and ongoing cost tradeoffs for an initial capacity overbuild ratio of 1.3 to account for energy capacity degradation throughout the life, and no overbuild scenarios (with energy capacity additions periodically throughout the life).