New battery index pinpoints when sodium-ion cells can replace lithium-ion

Southwest Research Institute developed the Electrical Interchangeability Index (EII), a numerical method showing when sodium-ion cells can replace lithium-ion in the same device. Tests on the 18650 format identified zones of high and low interchangeability by temperature, capacity and power.

• EII assesses whether two batteries can perform the same duty cycle
• Tests used sodium-ion and lithium-ion cells in the 18650 format
• High and low interchangeability zones identified by heat and power
• Method does not guarantee replacement in all scenarios or full service life