advanced instrumentation to study electrode and...

Advanced Instrumentation to Study Electrode and Electrochemistry Processes at Different Scales and Frequencies

Manuel Kasper & Ferry Kienberger

Keysight Labs Linz, Feb 2017

correspondence:[email protected][email protected]

mailto:[email protected]

mailto:[email protected]

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Agenda:

Part One: Source Measure Unit (SMU) Works as Potentiostat for Lithium Ion Cells

Part Two: Electrochemical Atomic Force Microscopy (AFM) at Nanoscale

Part Three: Fast Current and Impedance Measurements for Batteries

Summary and Outlook

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Why 3 electrodes? Becausethe flowing current causes avoltage drop in the electrolyte.The reference electrode helpsto compensate for that bysensing the potential in closeproximity to the workingelectrode.

Part One: Source Measure Unit (SMU) Works as Potentiostat for Li-Ion CellsElectrochemistry & electroanalytical methods: 3-electrode voltammetry measurements

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USB PC

Keysight Quick IV measurement software

B2900 SMU Electrochemical cells typically are equipped withthree electrodes. Voltage betweenelectrodes are few Volts for most applications and currentis in the range from 1µA – 100 mA.

Electrochemical cell

PotentiostatThe potentiostat enforces aconstant potential between thereference electrode (RE) andthe working electrode (WE)by adjusting the currentthrough the counterelectrode (CE) accordingly.

Low sense and force can becombined effectively forminga three terminal connectionsimilar to a potentistat.

Part One: Source Measure Unit (SMU) Works as Potentiostat for Li-Ion CellsElectrochemistry & electroanalytical methods: 3-electrode voltammetry measurements

Potentiostat setup

WE

CE

RE

SMU setup

SMU connection

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Part One: Source Measure Unit (SMU) Works as Potentiostat for Li-Ion Cells

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Electrochemistry & electroanalytical methods: cyclic voltammetry

Inpu

t Vol

tage

(V

)

Time (s)

Mea

sure

d C

urre

nt (A

)

Time (s)M

easu

red

Cur

rent

(A)

Voltage (V)

Schematic for CV with feedback loop Waveforms for CV Principle measures of C-V

V M = Measured Potential

A M

= Me

asur

ed C

urre

nt Epa

ipa

ipc

anodic (oxidation)positive current

cathodic (reduction)negative current Epc

WE

CE

RE

VM

AdjustableVoltage Source

AM

Feedback Waveform

E = Input waveform

Part One: Source Measure Unit (SMU) Works as Potentiostat for Li-Ion CellsLi-ion intercalation into TiO2: cyclic voltammetry

Liquid Cell

SMUKeysight Quick IV software

Experimental setupSketch of the experiment

Electrochemical reaction

Resulting CV curves

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Agenda:

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Summary and Outlook

AFM

Electrochemistry Cell

15mM CuSO4 in 0.1M H2SO4

Source: DLR Germany, Comp. Electrochemistry Prof Latz

Scales: from nano-surface to battery stacksAFM EC liquid cell

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Part Two: Electrochemical Atomic Force Microscopy (AFM) at NanoscaleNano Imaging and Cyclic Voltammetry

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Metal film lithiation and de-lithiation

Electrochemistry option available in AFM and STM mode

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Part Two: Electrochemical Atomic Force Microscopy (AFM) at NanoscaleApplication to Lithium Ion Cells

ECAFM Images of lithium foil in proprietary non-aqueouselectrolyte after (a) zero and (b) forty potential scans

Taken with AFM sitting on a Glovebox

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Agenda:

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Summary and Outlook

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Electrochemicalexperiment

• Three or two electrode setup• Optional DC bias (SMU)• Signal excitation with external function generator• Harmonic signals, pulses or AWG• Fast current sampling with CX3300

+ sensor head up to MHz range

• Applications:• fast current / impedace measurements for batteries• medium sized and small electrodes for electrochemistry• nonlinear processes, • corrosion processes

CX3300 result

current vs. time

CX3300 key specs

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Part Three: Fast Current and Impedance Measurements for BatteriesCX3300 Current Waveform Analyzer for Capturing Fast Transient Processes

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Dielectric processes at molecular levelElectrochemical Impedance Spectroscopy (EIS) in frequency domain:• High frequency measurements allow to estimate parasitic

circuit elements and to model the equivalent circuit of a cell • Mid frequency measures the electrode reactions• Low frequency measures migration & diffusion• Built in bias function or external bias with SMU to establish

defined DC conditions or to perform charge / discharge cycles

Alligator clampKelvin connection

Impedance probe kit

Battery / cellunder test

R1 internal cell resistanceR2 charge transferC1 double layer capacitor

E4990A complex impedance Z(ω)Built in circuit models

E4990A impedance analyzer

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Part Three: Fast Current and Impedance Measurements for BatteriesImpedance Analyzer for Broad Frequency Electrode and Battery Testing

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Agenda:

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Summary and Outlook

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Summary and Outlook

The B2900 SMU replaces conventional potentiostats in three electrode electrochemistry measurements with 10 femto Ampere resolution (0.01 femto Ampere with Pico Ampere Meter B2980)

Electrochemical AFM allows to study electrodes at the nanoscale (nanometer lateral resolution) while cycling the potential

The CX3300 current waveform analyzer captures fast transient processes (up to 200 MHz) at very low (100 pA) and medium (10 A) currents

Calibrated Impedance analysis (mΩ − ΜΩ) allows to study material and electrode properties of batteries in a broad frequency range (20 Hz – 120 MHz) under defined bias conditions (+/- 40 V)

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Thank you

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