A battery must meet minimum performance requirements (energy, time, safety, and environment) given inherent limitations (mass, volume, and cost) which result in several criteria commonly used in industry (Figure , Table ). Six of these metrics are chosen and discussed: Cell-level specific energy and materials/processing limitations (mass, volume, and cost) combine to form six important criteria for commercial battery needs (specific energy, specific power, cycle life, affordability, safety, and storage characteristics). Specific energy: energy per mass. Specific power: energy per time per mass. Cycle life: the supply and release of energy repeatedly over time as the energy performance decays. Affordability: energy, power (energy per time) or lifetime energy per cost. Safety inevitably has trade-offs with mass, volume, and cost; any battery could be made safe with sufficient housing and protection but at the expense of increased mass, volume, and/or cost. Storage characteristics: calendar life and timeenergy retention (opposite of self-discharge) only have useful meanings in the context of other metrics such as specific energy. Incredibly high energy retention means little if the specific energy is not adequate to the application. Thus, minimum performance requirements must balance against materials and processing limitations, the combination of which result in several useful reporting metrics in industry discussed in this paper. Additional metrics may arise based on the specific application (e.g. operating temperature and pressure).