In this work, affordability is expressed in terms of three main criteria: 1. the energy supplied by the battery over its useful lifetime (such as until it reaches 80% of initial energy) divided by the cost and number of cycles, 2. the average energy supplied by the battery multiplied by the number of cycles (e.g. to 80% capacity) divided by the cost, and 3. The maximum continuous power supplied by the battery divided by cost, termed in this work to be energy affordability (Wh $ -1 ), lifetime energy affordability (Wh cycles $ -1 ), and power affordability (W $ -1 ), respectively. Energy affordability is a useful metric when comparing with other criteria such as specific power and specific energy to see the trade-off between different chemistries because it is on an absolute scale with increasing values being favorable. However, the more commonly reported metrics are energy cost (unit: $ kWh -1 ) and power cost ($ W -1 ) . A third metric is proposed here that acts as a counterpart to energy cost and power cost: energy cost per cycle (unit: $ kWh -1 cycles -1 ). Note that each of these three is the inverse of the corresponding affordability metric. Because affordability is a less common representation, both energy affordability and cost will be provided as appropriate, except in charts comparing multiple metrics from those focused on in this work.