Energy impact of cathode drying and solvent recovery during lithium-ion battery manufacturing

• Energy for NMP vaporization is a small fraction of that needed for cathode drying.
• Large air flow is required to operate at low fraction of NMP flammability limits.
• Energy demand for cathode drying and NMP recovery because of large air flow.
• It requires ∼10 kWh to evaporate and recover a kg of NMP.
• It requires ∼420 kWh to evaporate and recover NMP for a 10 kWh LIB pack.

Successful deployment of electric vehicles requires maturity of the manufacturing process to reduce the cost of the lithium ion battery (LIB) pack. Drying the coated cathode layer and subsequent recovery of the solvent for recycle is a vital step in the lithium ion battery manufacturing plant and offers significant potential for cost reduction. A spreadsheet model of the drying and recovery of the solvent, is used to study the energy demand of this step and its contribution towards the cost of the battery pack. The base case scenario indicates that the drying and recovery process imposes an energy demand of ∼10 kWh per kg of the solvent n-methyl pyrrolidone (NMP), and is almost 45 times the heat needed to vaporize the NMP. For a plant producing 100 K battery packs per year for 10 kWh plug-in hybrid vehicles (PHEV), the energy demand is ∼5900 kW and the process contributes $107 or 3.4% to the cost of the battery pack. The cost of drying and recovery is equivalent to $1.12 per kg of NMP recovered, saving $2.08 per kg in replacement purchase.