The document discusses heat generation and transfer mechanisms in lithium-ion batteries and how they can lead to thermal runaway. It examines various safety methods used at the pack and cell level to prevent thermal runaway, including active cooling, passive cooling using phase change materials, cell design approaches, and cell chemistry options. The document also presents case studies on using phase change materials for cooling battery packs and simulations showing their ability to prevent the propagation of thermal runaway from a single cell.