X-ray photoelectron spectroscopy (XPS) was used to analyze a 70% Si/C-carbon black/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping Facility (CAMP), Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). An initial survey spectrum together with O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor copper, nitrogen, calcium, and lithium signals and show the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure as well contributions related to the binder material.

  • Accession#: 01624

  • Technique: XPS

  • Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid electrode

  • Instrument: Kratos Axis Ultra

  • Major Elements in Spectra: O, C, and Si

  • Minor Elements in Spectra: Cu, N, Ca, and Li

  • Published Spectra: 5

  • Spectra in Electronic Record: 5

  • Spectral Category: Comparison

Commercial lithium-ion batteries (LIBs) typically contain graphite as the electrochemically active material in the negative electrode (anode). Silicon is being considered as the intercalation material to partially or fully replace graphite in next-generation, high energy density, LIBs because the theoretical lithium storage capacity of silicon is about ten times greater than that of graphite (Ref. 1). However, the commercialization of silicon-based electrodes has been hindered by the large volume changes (320% increase) that result from the insertion/extraction of lithium-ions into the silicon particles; graphite, in comparison, displays an ∼10% volume change. Additionally, electrochemical alloying/dealloying with lithium fractures the silicon particles and increases their surface area, which, in turn, increases parasitic side-reactions that trap lithium-ions and degrades battery performance.

Various strategies are being pursued to improve the performance and longevity of silicon-containing lithium-ion batteries. Modifying the silicon particle surfaces to increase electronic conductivity and minimize reactivity with the electrolyte ranks high among these approaches. In this study, we report x-ray photoelectron spectroscopy (XPS) data from an electrode prepared with silicon powders obtained from a commercial vendor (Paraclete Energy, Inc.). All silicon particles have an oxide surface layer that forms during material synthesis. Coating these particles with carbon can prevent H2 evolution reactions that occur during water-based electrode fabrication processes. Here, data are presented from an electrode containing 70% Si/C (carbon-coated silicon), carbon black, and lithiated polyacrylic acid binder. The spectra indicate the expected silicon-carbon species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure as well as contributions related to the binder material.

XPS measurements of the powder and anode samples were made using a Kratos Axis Ultra x-ray photoelectron spectrometer (Kratos Analytical, Inc., Manchester, UK) using monochromatic Al Kα radiation (1486.6 eV). High-resolution spectra were collected from a single spot at an emission angle of 0° at a pass energy of 40 eV from a 0.7 × 0.3 mm2 area using the hybrid (electrostatic and magnetic immersion) lens mode.

Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid electrode

CAS Registry #: Unknown

Host Material Characteristics: Homogeneous; solid; polycrystalline; conductor; composite; coating

Chemical Name: Silicon/carbon, carbon black, and lithiated polyacrylic acid

Source: Si particles coated with 2.5 wt. % carbon were obtained from Paraclete Energy, Inc. The electrode was fabricated at the Cell Analysis, Modeling and Prototyping Facility, Argonne National Laboratory.

Host Composition: 70% Si/C, 15 wt. % carbon black, and 10 wt. % lithiated polyacrylic acid

Form: Composite coating on the copper substrate

Structure: Silicon has a diamond cubic structure, carbon black has a paracrystalline structure, and lithiated polyacrylic acid is amorphous.

History and Significance: The electrode was fabricated by coating a mixture of 70% Si/C (2.5% wt. %) powder, 15 wt. % Timcal C45 conductive carbon black, and 10 wt. % lithiated polyacrylic acid (LiOH titrate) onto a 10 μm-thick Cu current collector. The coating was 11 μm thick and not calendered. The electrode had a coating loading density of 0.85 mg/cm2 and 61% porosity.

As Received Condition: As-fabricated electrode

Analyzed Region: Same as the host material

Ex Situ Preparation/Mounting: Specimen was mounted onto a sample holder with an insulating double-sided office tape (3M 665) (Ref. 2). The sample holder was then loaded onto a grounded sample stage.

In Situ Preparation: None

Charge Control: Low energy flood gun/magnetic immersion lens combination with filament current = 1.8 A, charge balance = 3.5 V, and filament bias = 1 V (Ref. 3).

Temp. During Analysis: 300 K

Pressure During Analysis: <3 × 10−7 Pa

Preanalysis Beam Exposure: First survey 10 s, high-resolution spectra 1279 s, and second survey 10 664 s.

Manufacturer and Model: Kratos Axis Ultra

Analyzer Type: Spherical sector

Detector: Channeltron

Number of Detector Elements: 8

Analyzer Mode: Constant pass energy

Throughput (T = EN): N = 0

Excitation Source Window: None

Excitation Source: Al Kα monochromatic

Source Energy: 1486.6 eV

Source Strength: 210 W

Source Beam Size: 2000 × 2000 μm2

Signal Mode: Multichannel direct

Incident Angle: 60°

Source-to-Analyzer Angle: 60°

Emission Angle:

Specimen Azimuthal Angle: N/A

Acceptance Angle from Analyzer Axis:

Analyzer Angular Acceptance Width: 40° × 40°

Manufacturer and Model: Kratos Minibeam I

Energy: 4000 eV

Current: 0.001 mA

Current Measurement Method: Biased stage

Sputtering Species: Ar+

Spot Size (unrastered): 1000 μm

Raster Size: 2000 × 2000 μm2

Incident Angle: 90°

Polar Angle: 45°

Azimuthal Angle: 90°

Comment: Sputtering was performed with a differentially pumped ion gun for the calibration spectra only.

Energy Scale Correction: The binding energy scale of the instrument was calibrated using the Cu 2p (932.6 eV) and Au 4f (84.0 eV) photoelectron lines (Ref. 4). The data for the two survey spectra were referenced to Si 2p = 99 eV (Ref. 3). The data for the high-resolution spectra were referenced to Si 2p = 99.3 eV, as determined by peak fitting [GL(10)].

Recommended Energy Scale Shift: First survey 2 eV, high-resolution spectra 3.0 eV, and second survey 2 eV

Peak Shape and Background Method: Peak shape: See the supplementary material (Ref. 2). Background: A noniterative Shirley background was used for all remaining regions (Ref. 5).

Quantitation Method: Quantification was done using region definitions for the survey and peak fitting component definitions for the high-resolution spectra (Refs. 6 and 7) with casaxps version 2.3.18. Sensitivity factors supplied by Kratos Analytical.

SPECTRAL FEATURES TABLE

Spectrum ID #Element/TransitionPeak Energy
(eV)
Peak Width FWHM
(eV)
Peak Area
(eV × counts/s)a
Sensitivity FactorbConcentration
(at. %)
Peak Assignment
01624-01c Cu 2p 934 4.03 4 336.2 58.740 0.1 Cu 
01624-01c O 1s 532 3.18 195 125.0 7.496 27.7 
01624-01c N 1s 408 2.19 1 217.3 4.282 0.3 
01624-01c Ca 2p 347 3.17 1 989.8 15.926 0.1 Ca 
01624-01c C 1s 284 3.31 113 800.0 2.333 52.0 
01624-01c Si 2p 99 3.20 42 013.3 2.492 18.0 Si 
01624-01c Li 1s 56 2.37 306.6 0.182 1.8 Li 
01624-02d O 1s 532.5 1.87 18 877.2 0.745 25.7 —C=O, O—C=O, SiOy 
01624-03d C 1s 284.0 1.21 4 687.7 0.237 20.0 Ce, SiCx 
01624-03d C 1s 285.5 1.52 6 425.8 0.238 27.4 —CC—, —CH 
01624-03d C 1s 287.4 1.50 271.8 0.238 1.2 —C—O 
01624-03d C 1s 289.3 1.48 881.7 0.238 3.8 O—C=O 
01624-04d Si 2p 99.3 1.14 2 964.7 0.260 11.5 Si 
01624-04d Si 2p 100.2 1.40 853.2 0.260 3.3 SiCx, SiOy 
01624-04d Si 2p 102.3 1.64 570.5 0.261 2.2 SiCxOy 
01624-04d Si 2p 103.4 1.62 1 277.0 0.261 5.0 SiO2 
01624-05c Cu 2p 933 2.20 1 676.3 58.736 0.0 Cu 
01624-05c O 1s 532 3.22 198 002.0 7.496 25.1 
01624-05c N 1s 399 3.00 1 846.6 4.261 0.4 
01624-05c C 1s 284 3.64 124 010.0 2.333 50.5 
01624-05c Si 2p 99 3.44 58 591.4 2.492 22.3 Si 
01624-05c Li 1s 55 2.34 314.1 0.182 1.6 Li 
Spectrum ID #Element/TransitionPeak Energy
(eV)
Peak Width FWHM
(eV)
Peak Area
(eV × counts/s)a
Sensitivity FactorbConcentration
(at. %)
Peak Assignment
01624-01c Cu 2p 934 4.03 4 336.2 58.740 0.1 Cu 
01624-01c O 1s 532 3.18 195 125.0 7.496 27.7 
01624-01c N 1s 408 2.19 1 217.3 4.282 0.3 
01624-01c Ca 2p 347 3.17 1 989.8 15.926 0.1 Ca 
01624-01c C 1s 284 3.31 113 800.0 2.333 52.0 
01624-01c Si 2p 99 3.20 42 013.3 2.492 18.0 Si 
01624-01c Li 1s 56 2.37 306.6 0.182 1.8 Li 
01624-02d O 1s 532.5 1.87 18 877.2 0.745 25.7 —C=O, O—C=O, SiOy 
01624-03d C 1s 284.0 1.21 4 687.7 0.237 20.0 Ce, SiCx 
01624-03d C 1s 285.5 1.52 6 425.8 0.238 27.4 —CC—, —CH 
01624-03d C 1s 287.4 1.50 271.8 0.238 1.2 —C—O 
01624-03d C 1s 289.3 1.48 881.7 0.238 3.8 O—C=O 
01624-04d Si 2p 99.3 1.14 2 964.7 0.260 11.5 Si 
01624-04d Si 2p 100.2 1.40 853.2 0.260 3.3 SiCx, SiOy 
01624-04d Si 2p 102.3 1.64 570.5 0.261 2.2 SiCxOy 
01624-04d Si 2p 103.4 1.62 1 277.0 0.261 5.0 SiO2 
01624-05c Cu 2p 933 2.20 1 676.3 58.736 0.0 Cu 
01624-05c O 1s 532 3.22 198 002.0 7.496 25.1 
01624-05c N 1s 399 3.00 1 846.6 4.261 0.4 
01624-05c C 1s 284 3.64 124 010.0 2.333 50.5 
01624-05c Si 2p 99 3.44 58 591.4 2.492 22.3 Si 
01624-05c Li 1s 55 2.34 314.1 0.182 1.6 Li 
a

Reported as raw area.

b

Reported as RSF × T × MFP. RSF, relative sensitivity factor; T, transmission; and MFP, mean-free path.

c

Quantification based on region definition.

d

Quantification based on component definition.

e

Carbon black.

ANALYZER CALIBRATION TABLE

Spectrum ID #Element/TransitionPeak Energy
(eV)
Peak Width FWHM
(eV)
Peak Area
(eV × counts/s)
Sensitivity FactorConcentration
(at. %)
Peak Assignment
… Au 4f7/2 84.0 0.95 63 959.3 … … … 
… Cu 2p3/2 932.6 1.25 94 273.9 … … … 
Spectrum ID #Element/TransitionPeak Energy
(eV)
Peak Width FWHM
(eV)
Peak Area
(eV × counts/s)
Sensitivity FactorConcentration
(at. %)
Peak Assignment
… Au 4f7/2 84.0 0.95 63 959.3 … … … 
… Cu 2p3/2 932.6 1.25 94 273.9 … … … 

GUIDE TO FIGURES

Spectrum (Accession) #Spectral RegionVoltage ShiftaMultiplierBaselineComment #
01624-01 Survey −2 b 
01624-02 O 1s −3.0 c 
01624-03 C 1s −3.0 c 
01624-04 Si 2p −3.0 c 
01624-05 Survey −2 d 
Spectrum (Accession) #Spectral RegionVoltage ShiftaMultiplierBaselineComment #
01624-01 Survey −2 b 
01624-02 O 1s −3.0 c 
01624-03 C 1s −3.0 c 
01624-04 Si 2p −3.0 c 
01624-05 Survey −2 d 
a

Voltage shift of the archived (as-measured) spectrum relative to the printed figure. The figure reflects the recommended energy scale correction due to a calibration correction, sample charging, flood gun, or other phenomenon.

b

After 10 s of beam exposure.

c

After 1279 s of beam exposure.

d

After 10 664 s of beam exposure.

Accession #01624-01
Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid anode 
Technique: XPS 
Spectral Region: Survey 
Instrument: Kratos Axis Ultra 
Excitation Source: Al Kα monochromatic 
Source Energy: 1486.6 eV 
Source Strength: 210 W 
Source Size2000 × 2000 mm2 
Analyzer Type: Spherical sector analyzer 
Incident Angle: 60° 
Emission Angle: 0° 
Analyzer Pass Energy160 eV 
Analyzer Resolution2.4 eV 
Total Signal Accumulation Time600 s 
Total Elapsed Time1200 s 
Number of Scans
Effective Detector Width33.6 eV 
Accession #01624-01
Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid anode 
Technique: XPS 
Spectral Region: Survey 
Instrument: Kratos Axis Ultra 
Excitation Source: Al Kα monochromatic 
Source Energy: 1486.6 eV 
Source Strength: 210 W 
Source Size2000 × 2000 mm2 
Analyzer Type: Spherical sector analyzer 
Incident Angle: 60° 
Emission Angle: 0° 
Analyzer Pass Energy160 eV 
Analyzer Resolution2.4 eV 
Total Signal Accumulation Time600 s 
Total Elapsed Time1200 s 
Number of Scans
Effective Detector Width33.6 eV 

Accession #01624-01
Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid anode 
Technique: XPS 
Spectral Region: Survey 
Instrument: Kratos Axis Ultra 
Excitation Source: Al Kα monochromatic 
Source Energy: 1486.6 eV 
Source Strength: 210 W 
Source Size2000 × 2000 mm2 
Analyzer Type: Spherical sector analyzer 
Incident Angle: 60° 
Emission Angle: 0° 
Analyzer Pass Energy160 eV 
Analyzer Resolution2.4 eV 
Total Signal Accumulation Time600 s 
Total Elapsed Time1200 s 
Number of Scans
Effective Detector Width33.6 eV 
Accession #01624-01
Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid anode 
Technique: XPS 
Spectral Region: Survey 
Instrument: Kratos Axis Ultra 
Excitation Source: Al Kα monochromatic 
Source Energy: 1486.6 eV 
Source Strength: 210 W 
Source Size2000 × 2000 mm2 
Analyzer Type: Spherical sector analyzer 
Incident Angle: 60° 
Emission Angle: 0° 
Analyzer Pass Energy160 eV 
Analyzer Resolution2.4 eV 
Total Signal Accumulation Time600 s 
Total Elapsed Time1200 s 
Number of Scans
Effective Detector Width33.6 eV 

Close modal

  • Accession #:01624-02

  • Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid electrode

  • Technique: XPS

  • Spectral Region: O 1s

  • Instrument: Kratos Axis Ultra

  • Excitation Source: Al Kα monochromatic

  • Source Energy: 1486.6 eV

  • Source Strength: 210 W

  • Source Size: 2000 × 2000 mm2

  • Analyzer Type: Spherical sector

  • Incident Angle: 60°

  • Emission Angle: 0°

  • Analyzer Pass Energy: 40 eV

  • Analyzer Resolution: 0.6 eV

  • Total Signal Accumulation Time: 1206 s

  • Total Elapsed Time: 3317 s

  • Number of Scans: 20

  • Effective Detector Width: 8.4 eV

  • Accession #:01624-02

  • Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid electrode

  • Technique: XPS

  • Spectral Region: O 1s

  • Instrument: Kratos Axis Ultra

  • Excitation Source: Al Kα monochromatic

  • Source Energy: 1486.6 eV

  • Source Strength: 210 W

  • Source Size: 2000 × 2000 mm2

  • Analyzer Type: Spherical sector

  • Incident Angle: 60°

  • Emission Angle: 0°

  • Analyzer Pass Energy: 40 eV

  • Analyzer Resolution: 0.6 eV

  • Total Signal Accumulation Time: 1206 s

  • Total Elapsed Time: 3317 s

  • Number of Scans: 20

  • Effective Detector Width: 8.4 eV

Close modal

  • Accession #:01624-03

  • Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid electrode

  • Technique: XPS

  • Spectral Region: C 1s

  • Instrument: Kratos Axis Ultra

  • Excitation Source: Al Kα monochromatic

  • Source Energy: 1486.6 eV

  • Source Strength: 210 W

  • Source Size: 2000 × 2000 mm2

  • Analyzer Type: Spherical sector

  • Incident Angle: 60°

  • Emission Angle: 0°

  • Analyzer Pass Energy: 40 eV

  • Analyzer Resolution: 0.6 eV

  • Total Signal Accumulation Time: 1206 s

  • Total Elapsed Time: 3317 s

  • Number of Scans: 20

  • Effective Detector Width: 8.4 eV

  • Accession #:01624-03

  • Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid electrode

  • Technique: XPS

  • Spectral Region: C 1s

  • Instrument: Kratos Axis Ultra

  • Excitation Source: Al Kα monochromatic

  • Source Energy: 1486.6 eV

  • Source Strength: 210 W

  • Source Size: 2000 × 2000 mm2

  • Analyzer Type: Spherical sector

  • Incident Angle: 60°

  • Emission Angle: 0°

  • Analyzer Pass Energy: 40 eV

  • Analyzer Resolution: 0.6 eV

  • Total Signal Accumulation Time: 1206 s

  • Total Elapsed Time: 3317 s

  • Number of Scans: 20

  • Effective Detector Width: 8.4 eV

Close modal

  • Accession #:01624-04

  • Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid electrode

  • Technique: XPS

  • Spectral Region: Si 2p

  • Instrument: Kratos Axis Ultra

  • Excitation Source: Al Kα monochromatic

  • Source Energy: 1486.6 eV

  • Source Strength: 210 W

  • Source Size: 2000 × 2000 mm2

  • Analyzer Type: Spherical sector

  • Incident Angle: 60°

  • Emission Angle: 0°

  • Analyzer Pass Energy: 40 eV

  • Analyzer Resolution: 0.6 eV

  • Total Signal Accumulation Time: 1206 s

  • Total Elapsed Time: 3317 s

  • Number of Scans: 20

  • Effective Detector Width: 8.4 eV

  • Accession #:01624-04

  • Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid electrode

  • Technique: XPS

  • Spectral Region: Si 2p

  • Instrument: Kratos Axis Ultra

  • Excitation Source: Al Kα monochromatic

  • Source Energy: 1486.6 eV

  • Source Strength: 210 W

  • Source Size: 2000 × 2000 mm2

  • Analyzer Type: Spherical sector

  • Incident Angle: 60°

  • Emission Angle: 0°

  • Analyzer Pass Energy: 40 eV

  • Analyzer Resolution: 0.6 eV

  • Total Signal Accumulation Time: 1206 s

  • Total Elapsed Time: 3317 s

  • Number of Scans: 20

  • Effective Detector Width: 8.4 eV

Close modal

Accession #01624-05
Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid anode 
Technique: XPS 
Spectral Region: Survey 
Instrument: Kratos Axis Ultra 
Excitation Source: Al Kα monochromatic 
Source Energy: 1486.6 eV 
Source Strength: 210 W 
Source Size: 2000 × 2000 mm2 
Analyzer Type: Spherical sector analyzer 
Incident Angle: 60° 
Emission Angle: 0° 
Analyzer Pass Energy: 160 eV 
Analyzer Resolution: 2.4 eV 
Total Signal Accumulation Time: 600 s 
Total Elapsed Time: 1200 s 
Number of Scans: 
Effective Detector Width: 33.6 eV 
Accession #01624-05
Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid anode 
Technique: XPS 
Spectral Region: Survey 
Instrument: Kratos Axis Ultra 
Excitation Source: Al Kα monochromatic 
Source Energy: 1486.6 eV 
Source Strength: 210 W 
Source Size: 2000 × 2000 mm2 
Analyzer Type: Spherical sector analyzer 
Incident Angle: 60° 
Emission Angle: 0° 
Analyzer Pass Energy: 160 eV 
Analyzer Resolution: 2.4 eV 
Total Signal Accumulation Time: 600 s 
Total Elapsed Time: 1200 s 
Number of Scans: 
Effective Detector Width: 33.6 eV 

Accession #01624-05
Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid anode 
Technique: XPS 
Spectral Region: Survey 
Instrument: Kratos Axis Ultra 
Excitation Source: Al Kα monochromatic 
Source Energy: 1486.6 eV 
Source Strength: 210 W 
Source Size: 2000 × 2000 mm2 
Analyzer Type: Spherical sector analyzer 
Incident Angle: 60° 
Emission Angle: 0° 
Analyzer Pass Energy: 160 eV 
Analyzer Resolution: 2.4 eV 
Total Signal Accumulation Time: 600 s 
Total Elapsed Time: 1200 s 
Number of Scans: 
Effective Detector Width: 33.6 eV 
Accession #01624-05
Host Material: 70% Si/C-carbon black/lithiated polyacrylic acid anode 
Technique: XPS 
Spectral Region: Survey 
Instrument: Kratos Axis Ultra 
Excitation Source: Al Kα monochromatic 
Source Energy: 1486.6 eV 
Source Strength: 210 W 
Source Size: 2000 × 2000 mm2 
Analyzer Type: Spherical sector analyzer 
Incident Angle: 60° 
Emission Angle: 0° 
Analyzer Pass Energy: 160 eV 
Analyzer Resolution: 2.4 eV 
Total Signal Accumulation Time: 600 s 
Total Elapsed Time: 1200 s 
Number of Scans: 
Effective Detector Width: 33.6 eV 

Close modal

This work was carried out in part in the Frederick Seitz Materials Research Laboratory Central Research Facilities, University of Illinois. The CAMP facility is supported within the core funding of the Applied Battery Research (ABR) for Transportation Program. This manuscript has been cocreated by UChicago Argonne, LLC, Operator of Argonne National Laboratory. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

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Supplementary Material