Dr. Natalia StryzhakovaDr. Yurii MaletinDr. Sergiy Zelinskiy Methodology for supercapacitor performance measurements

ReferencesFreedomCAR Ultracapacitor Test Manual. Idaho National Laboratory Report DOE/NE-ID-11173, September 21, 2004. IEC 62391-2 . Fixed electric double layer capacitors for use in electronic equipment. Part 2. Sectional specification Electric double layer capacitors for power application.IEC 62576. Electric double layer capacitors for use in hybrid electric vehicles Test methods for electrical characteristics.A. Burke, M. Miller. Testing of Electrochemical Capacitors: Capacitance, Resistance, Energy Density, and Power Capability. ISEECap09 Conference, Nantes, 2009.A. Burke, M. Miller. Testing of Electrochemical Capacitors: Capacitance, Resistance, Energy Density, and Power Capability. Idaho National Engineering Laboratory Report DOE/ID-10491, October 1994.S. Zhao, F. Wu, L. Yang, L. Gao, A. Burke. A measurement method for determination of dc internal resistance of batteries and supercapacitors. Electrochemistry Communications, 2010, v.12, p.242-245. A. Burke. Testing Large Format Electrochemical Capacitors. Tutorial of ISEECap2011, Poznan, Poland, June 12, 2011.Methodology for supercapacitor performance measurement*

Main characteristics of a supercapacitor unit cellRated voltage, Ur (V)Capacitance, C (F)Internal resistance, R (Ohm)Specific energy, E (Wh/kg)Specific power, P (W/kg)Specific energy vs. Specific power (Ragone plot)Resistance and capacitance vs. temperature (-40+70 C) Cycle lifeSelf dischargeCalendar life (hours) at rated voltage and high temperature (60 C)*Methodology for supercapacitor performance measurement

Test proceduresConstant current charge/discharge Capacitance and resistanceCycle lifePulse tests to determine resistance Constant power charge/dischargeRagone Plot for power densities between 100 and at least 1000 W/kg for the voltage between Ur and Ur.Test at increasing W/kg until discharge time is less than 5 sec. The charging is often done at constant current with a charge time of at least 30 sec.Voltage maintenance Self discharge testContinuous application of rated voltage at high temperature Endurance test (calendar life estimation) *Methodology for supercapacitor performance measurement

CapacitanceTest procedure: Constant current charge/dischargeUSABC test procedure

*Current of 5C corresponds to 12 min dischargeIMAX can be chosen as the lowest of: (a) the current required to cause an immediate (

*Test procedure: Constant current charge/dischargeIEC procedure (# 62576) Single test to determine the capacitor performance at a single current so that the efficiency in charge and discharge to be of 95%.CapacitanceMethodology for supercapacitor performance measurement

*Test procedure: Constant current charge/dischargeUC Davis procedure (ITS, Dr.A.Burke) 1) The nominal charge/discharge current In corresponding to nominal power density (200 or 400 W/kg)2) A set of current values: 0.25, 0.5, 1.0, 2.0, 4.0, 8.0InCapacitanceMethodology for supercapacitor performance measurement

*Test procedure: Constant current charge/dischargeYunasko procedure 1) A set of current values from 0.2Itest to Itest.; Itest 200 A2) From = f(I) plot the 0 max capacitance value (extrapolation to zero current) and -dC/dI value (the slope) can be found.

NOTE: The -dC/dI slope characterizes the system behavior at high power loads and depends on electrode material and system design.CapacitanceMethodology for supercapacitor performance measurement

CapacitanceConclusions:Capacitance value depends on test conditions, though, not dramatically.Testing current conditions differ significantly:Methodology for supercapacitor performance measurement9

Yunasko supercapacitor cell: 1200F, 0.15 mOhm, 0.12 kg ProcedureItest, range, AUSABCfrom 2.5 A (5C) to 800 A (Imax)IEC450 AITSfrom 35 A to 280 AYunaskofrom 40 A to 200 A

Internal resistanceEquivalent Series Resistance (ESR) - the resistance due to all the resistive components within the supercapacitor.

Equivalent Distributed Resistance (EDR) includes ESR and an additional contribution from the charge redistribution process in the electrode pore matrix due to non-homogeneous electrode structure, the process adding significantly to Joule heating: I2Rt.Methodology for supercapacitor performance measurement10

Internal resistanceTest procedure: Constant current method, sampling rate of 10 msMethodology for supercapacitor performance measurement11

Internal resistanceESR is independent of current value. EDR value depends on testing currentMethodology for supercapacitor performance measurement12

Internal resistanceMeasurements using the voltage recovery after current interruption (Maxwell procedure)Methodology for supercapacitor performance measurement13

Internal resistanceYunasko procedureMethodology for supercapacitor performance measurement14

Internal resistancePulse procedure (Arbin)Methodology for supercapacitor performance measurementRpulse = Average (Voltage at P2 Voltage at P3) / (2 I). 15

Internal resistanceComparison of different procedures:Methodology for supercapacitor performance measurementConclusions:Internal resistance measurements involve different time intervals to fix the voltage drop/jump.Resistance values depend on test conditions, in particular, on time interval and testing current chosen.16

Yunasko cellsC, FResistance, mOhmpulseESRinterruptionE-type15000.2420.2250.265P-type12000.0910.1010.104

*Test procedure: Constant power tests 1) Power values between 200 and at least 1000 W/kg2) For each constant power test, the energy is calculated as E = UIt during charge and discharge.The usable specific energy Em (Wh/kg)Specific energy and powerThe efficiency :Ragone plot: a plot illustrating Em (or Ev) vs Pm (or Pv)Methodology for supercapacitor performance measurement

*Test procedure: Constant power tests, Ragone plot Specific energy and powerMethodology for supercapacitor performance measurement

*Maximum energy stored - the energy that can be obtained at discharge from the rated voltage to zero:Specific energy and powerAvailable energy - at discharge from the rated voltage Ur to Ur/2 Methodology for supercapacitor performance measurement

*Maximum power (matched impedance power) - the power that can be delivered to the load of the same resistance as a supercapacitor. Specific energy and powerThe power at efficiency and at discharge from the rated voltage Ur to Ur/2:NOTE: YUNASKO normally uses the value of 0.95Power density according to IEC 62391-2:where U6=0.2U (20%)Ue=0.4U (40%)Methodology for supercapacitor performance measurement

*The time dependence of the capacitor self-dissipation, i.e., the rate of internal processes that cause the capacitor discharge when not connected to a load. Self-discharge testwhere B is the voltage maintenance rate (%)Methodology for supercapacitor performance measurement

*Self-discharge test - examplewhere B is the voltage maintenance rate (%)Methodology for supercapacitor performance measurement

*Stable performance over more than 100,000 charge/discharge cycles is desired. Constant-current charge and discharge are used. Typical procedure: Condition the capacitor at 25 3C. Charge the device by a current I chosen so that the voltage reaches Ur in 30 s. Maintain voltage Ur of the device for 15 s. Then discharge the capacitor to Umin with current I. Hold the capacitor at Umin for 50 s. Repeat cycling. Devices shall be characterized initially and after 1000; 4000; 10,000; 40,000; 100,000 cycles.Characterization tests to be performed at each measurement cycle include: 1. Constant-Current Charge/Discharge (In) 2. ESR (from constant-current test data) 3. Constant Power Discharge (200 W/kg, 1000 W/kg) Cycle-life testMethodology for supercapacitor performance measurement

*Cycle-life test SC exampleMethodology for supercapacitor performance measurementCycling a 1200F device between 2.0 and 3.2 V at 60 C

*Cycle-life test hybrid capacitor exampleMethodology for supercapacitor performance measurement

*Temperature influences the energy that can be stored in a device as well as the power it can deliver. Typical procedure: Step 1 - Condition the device at 253C and perform the followed tests: 1. Constant-Current Charge/Discharge (In) 2. ESR (from constant-current test data) 3. Constant Power Discharge (200 W/kg, 1000 W/kg) . Step 2 - Condition the capacitor at 60 3C until thermal equilibrium is achieved. Perform the above mentioned tests at this temperature.Step 3 - Condition the capacitor at -30 3C until thermal equilibrium is achieved. Perform the above mentioned tests at this temperature .Step 4 - Condition the capacitor at 25 3C and repeat the tests listed above. This test data will provide information about the stability of the capacitor under thermal cycling conditions. Step 5 - Perform a visual inspection of the capacitors to identify any damage or electrolyte leakage caused by the thermal cycle Temperature PerformanceMethodology for supercapacitor performance measurement

*Temperature performanceMethodology for supercapacitor performance measurementEDLCHybrid

*This procedure characterizes device life properties and performance using an accelerated aging condition. Typical procedure: Device properties and performance are measured initially and then periodically throughout the aging period. Age the capacitors in a suitable oven or environmental chamber maintained at 60 3C with an applied voltage equal to Ur. Characterization tests of the devices should be performed at the start of the test sequence and after 250 10, 500 25, 1000 50, and 2000 100 hours. Measurements are made at 25 3C. 1. Constant-Current Charge/Discharge (In) 2. ESR (from constant-current test data) 3. Constant Power Discharge (200 W/kg, 1000 W/kg)Endurance test Methodology for supercapacitor performance measurement

*Endurance test Methodology for supercapacitor performance measurement

*ConclusionsMethodology for supercapacitor performance measurement There is a need to further standardization of test procedures. The largest uncertainty is related with the resistance measurements. The effective capacitance of carbon/carbon devices is well-defined from constant current tests, but varies with the voltage range used; it is recommended the voltage range of Vr and Vr/2 to be used. Further work is needed to define the effective capacitance and resistance of hybrid capacitors. The energy density should be measured at the constant power discharge; this is especially the case for hybrid capacitors Definition and determination of maximum power capability of both supercapacitors and lithium batteries remains a very confused issue (A.F. Burke)

Acknowledgements

Special thanks to my R&D and Design Bureau colleagues: S.Podmogilny, S.Chernukhin, S.Tychina, D. Gromadsky, O.Gozhenko, A.Maletin, D.Drobny, and A.SlezinOur Pilot Plant and Administrative Department: For the great support, diligence and dedication to workYUNASKO investment, technical, scientific and industrial partners: For the great collaboration and support during the projectsMany thanks to Dr. Andrew F. Burke (ITS) and Dr. John R. Miller (JME) for their measurements and stimulating discussions Financial support from FP7 Project no. 286210 (Energy Caps) is very much acknowledged *Methodology for supercapacitor performance measurement

THANKS FOR YOUR ATTENTION! Please visit us at: www.yunasko.com*

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