Presentation on theme: "KTH ROYAL INSTITUTE OF TECHNOLOGY Electrochemical Characterization of Li-ion Batteries for Hybrid Application Ageing Study Abdilbari Shifa Mussa, Rakel."— Presentation transcript:
KTH ROYAL INSTITUTE OF TECHNOLOGY Electrochemical Characterization of Li-ion Batteries for Hybrid Application Ageing Study Abdilbari Shifa Mussa, Rakel Wreland Lindström, Mårten Behm, Göran Lindbergh
Li-ion Battery Works by shuttling lithium ions between the two electrodes Lithiated metal oxides: LCO, LFP, LMO, NMC etc... Shuttling doesn’t continue indefinitely without loosing performance Lithium ion battery during charging operation Adapted from department-of0.html - Graphite + Lithiated metal oxides Electrolyte
Ageing Capacity and power fade with time and use. Temperature, C-rate, DOD, SOC are the main factors of ageing Life time is a challenge for batteries in vehicles!! ( Klett et. al, Journal of power sources 257 (2014) ) c) Hybrid Electric Vehicle Cycle Constant Current Cycle
How the battery age? Jens Groot, Main ageing mechanisms in Li-ion battery, 2012 Complex set of ageing mechanisms due to multiple interactions Complementary charcterization techniques and models needed
Electrochemical Characterization Using electrochemical techniques to observe changes in parametres affecting the performance with ageing Charge/Discharge cycling - Discharge capacity vs cycle number - Coulombic efficiency (CE) - Differential voltage (dV/dQ vs Q plot) etc... Potentiostatic test
Charge/Discharge Cycling High precission battery cycler experimental set up
Charge/Discharge Cycling dV/dQ vs Q State analysis Quantitative determination of active electrode mass and lithium loss K.Honkura, ECS Transactions, 13 (19) (2008) V cell Cell voltage V c Cathode half cell voltage V a Anode half cell voltage Q c Cathode half cell capacity Q a Anode half cell capacity Cathode Slippage a Anode Slippage S= a - c ma anode active mass (cell) mc cathode active mass (cell)
Potentiostatic test The cathodic current is an indication of a continuous reduction at the graphite probably due to SEI layer development. Generally, lower state of charge gives lower side reaction rate. The growth of SEI deviates from a parabolic rate law for higher % SOC. How side reaction rate depends on state of charge (SOC)?
Summary and Future works Ageing of lithium ion battery is a challenge being very complex. Need for complementary models and characterization techniques to determine aging rates and mechanisms. Future additional works: Physics based models for performance prediction and ageing. Electrochemical Impedance Spectroscopy (Model and Experiment).