EV Battery Parameters Dr. Marnix Wagemaker, Delft University of - - PowerPoint PPT Presentation

EV Battery Parameters

• Dr. Marnix Wagemaker, Delft University of Technology

Working principle

• Three main components
• Anode (-)
• Cathode (+)
• Electrolyte
• Electrochemical driving force
• Battery voltage

Working principle

• Only ions cross electrolyte
• Electrical current
• Ions in (+) electrode

→ Fully discharged

Battery performance parameters

Important parameters:

• Capacity
• State of charge (SOC)
• Coulombic efficiency
• Energy Content
• Energy Density
• Cycle life
• C-rate

Voltage at discharge

• Low discharge current
• Slow decrease in voltage
• Weakly bonded ions first

Capacity

• Amount of charge stored
• Unit of charge is Coulomb
• 1 electron charge = 1.6E-19 C
• Ampere = Coulomb/seconds
• 1 Ampere hour = 3600 C

Charging after discharge

• Voltage increase until fully charged
• Similar shape as discharge
• State of charge (SOC)

Battery efficiency

• Coulombic efficiency
• Indication for side reactions
• Energy efficiency

Energy content

• Voltage times capacity
• Area under curve
• 1 Watt hour = 3600 Joules

Energy Density

• Per weight or per volume
• Gravimetric (Wh/kg)
• Volumetric (Wh/L)

Cycle life

• Capacity fading
• 80% of initial capacity
• End of life time

C-Rate

• C/X rate in hours
• Higher C-rates, higher currents
• Lower efficiency

C-Rate

• Internal resistance
• Lower effective capacity
• More capacity fading

Ragone plot

• Higher specific power
• Lower specific energy
• Trade-off
• Energy vs. power

Thanks for your attention