Presentation on theme: "Electrochemical Characterization of Li-ion Batteries for Hybrid Application Ageing Study Abdilbari Shifa Mussa, Rakel Wreland Lindström, Mårten Behm,"— Presentation transcript:
1 Electrochemical Characterization of Li-ion Batteries for Hybrid Application Ageing StudyAbdilbari Shifa Mussa, Rakel Wreland Lindström, Mårten Behm, Göran Lindbergh
2 + Lithiated metal oxides Li-ion BatteryWorks by shuttling lithium ions between the two electrodesLithiated metal oxides:LCO, LFP, LMO, NMC etc...Shuttling doesn’t continue indefinitely without loosing performance-Graphite+ Lithiated metal oxidesElectrolyteLithium ion battery during charging operationAdapted from
3 AgeingCapacity 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!!Hybrid Electric Vehicle CycleConstant Current Cyclec)( Klett et. al, Journal of power sources 257 (2014) )
4 How the battery age?Jens Groot, Main ageing mechanisms in Li-ion battery, 2012Complex set of ageing mechanisms due to multiple interactionsComplementary charcterization techniques and models needed
5 Electrochemical Characterization Using electrochemical techniques to observe changes in parametres affecting the performance with ageingCharge/Discharge cycling- Discharge capacity vs cycle number- Coulombic efficiency (CE)- Differential voltage (dV/dQ vs Qplot)etc...Potentiostatic test
6 Charge/Discharge Cycling Coulombic effciency CE= 𝐷𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝐶ℎ𝑎𝑟𝑔𝑒 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 For precise measurement of CE: the voltage limits, the current, time and temperature should be precise Cost of instrumentation and time are in perspective High precision battery cyclers custom set up in our labHigh precission battery cycler experimental set up
7 Charge/Discharge Cycling dV/dQ vs Q State analysis Quantitative determination of active electrode mass and lithium loss𝒅𝑽𝒄𝒆𝒍𝒍 (𝑸𝒄+ 𝜹𝒄) 𝒅𝑸𝒄 = 𝟏 𝒎𝒂 𝒅𝑽𝒄(𝑸𝒄/𝒎𝒄) 𝒅𝒒𝒄 − 𝟏 𝒎𝒂 𝒅𝑽𝒂 ((𝑸𝒄−𝑺)/𝒎𝒂) 𝒅𝒒𝒂Vcell Cell voltageVc Cathode half cell voltageVa Anode half cell voltageQc Cathode half cell capacityQa Anode half cell capacity𝜹𝒄 Cathode Slippage𝜹a Anode SlippageS= 𝜹a - 𝜹cma anode active mass (cell)mc cathode active mass (cell)K.Honkura, ECS Transactions, 13 (19) (2008)
8 Potentiostatic testHow side reaction rate depends on state of charge (SOC)?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.
9 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).