Performance Evaluation of Commercial CFx Materials in 

Lithium Batteries 

by Jeffrey Read, Michelle Marx, Jeffrey Wolfenstine, Sheng Zhang, 

and Don Foster 

ARL-TR-5001 October 2009 

Approved for public release; distribution unlimited. 
NOTICES 

Disclaimers 

The findings in this report are not to be construed as an official Department of the Army position 

unless so designated by other authorized documents. 

Citation of manufacturer’s or trade names does not constitute an official endorsement or 

approval of the use thereof. 

Destroy this report when it is no longer needed. Do not return it to the originator. 
Army Research Laboratory 

Adelphi, MD 20783-1197 

ARL-TR-5001 October 2009 

Performance Evaluation of Commercial CFx Materials in 

Lithium Batteries 

Jeffrey Read, Michelle Marx, Jeffrey Wolfenstine, Sheng Zhang, 

and Don Foster 

Sensors and Electron Devices Directorate, ARL 

Approved for public release; distribution unlimited. 
ii 

REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the 

data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the 

burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. 

Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently 

valid OMB control number. 

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 

1. REPORT DATE (DD-MM-YYYY)

October 2009 

2. REPORT TYPE 

Summary 

3. DATES COVERED (From - To) 

May 2008 to July 2009 

4. TITLE AND SUBTITLE 

Performance Evaluation of Commercial CFx Materials in Lithium Batteries 

5a. CONTRACT NUMBER 

5b. GRANT NUMBER 

5c. PROGRAM ELEMENT NUMBER 

6. AUTHOR(S) 

Jeffrey Read, Michelle Marx, Jeffrey Wolfenstine, Sheng Zhang, and Don 

Foster 

5d. PROJECT NUMBER 

5e. TASK NUMBER 

5f. WORK UNIT NUMBER 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 

U.S. Army Research Laboratory 

ATTN: RDRL-SED-C 

2800 Powder Mill Road 

Adelphi, MD 20783-1197

8. PERFORMING ORGANIZATION 

 REPORT NUMBER 

ARL-TR-5001

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) 

11. SPONSOR/MONITOR'S REPORT 

 NUMBER(S) 

12. DISTRIBUTION/AVAILABILITY STATEMENT 

Approved for public release; distribution unlimited. 

13. SUPPLEMENTARY NOTES 

14. ABSTRACT 

The performance of six different commercially available carbon monofluoride (CFx) materials were evaluated at four different 

discharge rates. The physical and chemical properties of the CFx materials were correlated to cell performance in lithium coin 

cells. This study was undertaken to determine if there are specific physical or chemical properties that can be tied to 

performance and if modification of these properties could lead to an improved carbon monofluoride material. 

15. SUBJECT TERMS

CFx, lithium batteries, physical properties, electrochemical properties 

16. SECURITY CLASSIFICATION OF:

17. LIMITATION 

OF ABSTRACT 

UU 

18. NUMBER 

OF PAGES 

16 

19a. NAME OF RESPONSIBLE PERSON

Jeffrey Read 

a. REPORT 

Unclassified 

b. ABSTRACT 

Unclassified 

c. THIS PAGE 

Unclassified 

19b. TELEPHONE NUMBER (Include area code) 

(301) 394-0313 

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18
iii 

Contents 

List of Figures iv

List of Tables iv

1. Introduction 1

2. Experiment 1

3. Results and Discussion 2

4. Summary and Conclusions 8

5. References 9

Distribution List 10 
iv 

List of Figures 

Figure 1. Optical microscope images of CFx powders. ..................................................................5

Figure 2. Voltage profiles at 5 mA/g. .............................................................................................6

Figure 3. Voltage profiles at 40 mA/g. ...........................................................................................6

Figure 4. Specific capacity versus rate. ..........................................................................................7

Figure 5. Peak voltage versus rate. .................................................................................................7

List of Tables 

Table 1. Chemical and physical data on CFx powders....................................................................3
1 

1. Introduction 

Li-CFx batteries are proposed for use in Soldier applications where a high specific energy 

primary power source is needed. Li-CFx D-cells have been shown to have the rate capability 

necessary for Soldier applications (1–4). Voltage delay at low temperature and heat generation at 

higher discharge rates (2, 3) are existing problems that need to be mitigated. 

The overall discharge reaction that takes place in a Li-CFx cell is shown in equation 1. 

 Li + CFx  C + LiF Eo = 4.55V (1) 

The E° value is that given by Wood et al. (5) for a CF1.12 material. The open circuit voltage 

(OCV) of a Li-CFx cell is normally 3.1–3.6 V, significantly lower than the theoretical value 

above. This difference between theoretical and actual potential can be explained in several 

different ways. The first and currently accepted explanation states that there is formation of 

ternary phases (6, 7) such as CLixF or CFLix:Sy where S is a solvent molecule that is 

co-intercalated with the lithium ion upon discharge. The potential for the formation of this 

intercalated phase, it is proposed, would be lower than that for direct reaction of lithium with 

CFx. The heat generated by a Li-CFx cell is normally assigned to the heat generated when this 

proposed ternary phase decomposes to LiF and carbon in a chemical reaction. One alternate 

explanation for the low OCV is that there is a large activation energy and therefore large 

overpotential associated with breaking any C-F bond, especially the covalent C-F bonds found in 

commercial CFx battery materials. This large activation energy would also lead to poor kinetics 

during discharge and significant heat. 

The purpose of this work was to investigate how the physical and chemical properties of 

commercial CFx materials affect discharge capacity, discharge voltage, rate capability, and 

voltage delay in Li-CFx cells. A variety of commercially available CFx materials were evaluated 

in this work. The chemical compositions of the various materials are similar with total fluoride 

contents in the range 60–65 wt% (CF0.95–CF1.15). These CFx materials are prepared from 

different starting materials such as cokes, graphites, carbon fibers, and carbon blacks, and have 

different physical properties such as particle size, surface area, and decomposition temperature. 

2. Experiment 

CFx powders from Advanced Research Chemical (Catoosa, OK) and Lodestar (Howell, NJ) were 

used as received. The decomposition temperature for each material was measured on a Perkin 

Elmer TGA 7 at a heating rate of 5 °C/min under N2 atmosphere. Surface area measurements 
2 

using N2 absorption were carried out on a Micromeritics ASAP 2010 after degassing samples at 

250 °C. Particle morphology was characterized using optical microscopy. 

Cathodes were prepared by mixing CFx, PVDF, carbon black, dibutylphthalate (DBP), and 

acetone in a stainless steel blender cup. The slurry was cast on glass and dried in air. The 

plasticized films were laminated to treated aluminum grids and extracted in methanol to remove 

the DBP. The cathode composition after extraction was 75 wt% CFx, 10 wt% carbon black, and 

15 wt% PVDF. Cathodes were dried under vacuum at 105 °C for 2 hrs before use. Cells were 

constructed from 2035 coin cell hardware using 0.020 inch thick lithium foil, 2 layers of Celgard 

separator, and 1M LiBF4 propylene carbonate:1,2-dimethoxyethane (1:1 wt/wt) electrolyte. Cell 

impedance and OCV was measured for each cell before being placed on test. 

The cells were allowed to equilibrate for 3 hrs at 20 °C before being discharged at rates of 5, 10, 

20, and 40 mAh/g. The discharge was tailored to the cathode weight of each cell to insure that 

any differences in cathode density or thickness were minimized. Cells were discharged until all 

of the capacity was removed or the voltage dropped below 2.0 V. 

3. Results and Discussion 

The CFx materials commonly used in batteries are prepared from either coke or carbon fiber 

which is then fluorinated at high temperature. ARC 1000 and Fluorstar PC/10 are produced from 

coke while ARC 4000 and Fluorstar F are prepared from carbon fiber. Several CFx materials 

typically used for lubrication purposes were also evaluated in this study, one prepared from 

graphite (ARC 3000) and one from carbon black (ARC 2065). Table 1 shows the properties of 

each of the materials tested. Carbon source, total fluoride %, and median particle size are 

reproduced in the table from the suppliers data sheets while the remaining properties were 

measured here. One can see that the total fluoride % is typically 60–65% for these materials. 

This corresponds to a carbon to fluorine ratio of around 1.0. The color of the various CFx

materials reflects the total fluoride % with ARC 3000, the material with the lowest fluoride 

content, being dark grey and ARC 2065 with the highest fluoride content, being pure white. 
3 

Table 1. Chemical and physical data on CFx powders. 

 

ARC 1000 ARC 2065 

Product 

ARC 3000 ARC 4000 FluorStar PC/10 FluorStar F 

Carbon Source Petroleum Coke Carbon Black Graphite Carbon Fiber Coke Carbon Fiber 

Total Fluoride % 62.6 64–65 60.4 63.5 61–62 61–63 

Color Light Gray White Dark Gray Light Gray Light Gray Light Gray 

Median Particle 

Size, μm 

8 <1 2 6 8 8 

BET Surface Area, 

m2

/g 

139 350 109 323 170 340 

Micropore Surface 

Area, m2

/g 

78 82 52 92 102 96 

External Surface 

Area, m2

/g 

61 268 57 230 68 244 

Decomposition 

Temp., °C 

672 660 640 659 672 700 

Sources: 

ARC (Advanced Research Chemical) 

FluorStar (Lodestar) 

The BET surface areas measured here and given in table 1 correspond well with those from the 

data sheets provided by the manufacturers. In addition to the total BET surface area, our 

measurements also give values for the surface area due to micropores. Table 1 shows that for all 

of these materials, there is a significant contribution to the surface area (50–100 m2/g) from these 

micropores. According to the BET data, these micropores have an average diameter of 25–50 

angstroms. The micropores are formed during the fluorination process as some of the carbon 

material is converted to CF4 gas or other volatile CFn compound. 

The decomposition temperature we measured using TGA is typically higher than that given by 

the manufacturer, if a number was given. We assume that this is due to the fact that we are using 

a different atmosphere (N2 vs. air) and to the analytical method used to extract the onset 

temperature. We were consistent in our determination method such that a comparative analysis 

could be made even if the absolute value can be in dispute. 

Figure 1 shows the optical microscope images for the various powders, confirming the particle 

size and morphology for the materials. The ARC 2065 powder is extremely small, certainly 

smaller than 1 m. The ARC 1000 material appears to have particles up to 10 m in size while 

the ARC 3000 material has a maximum particle size of about 4m. The ARC 4000 material has 

particles that are possibly up to 12m in width but with lengths up to 100 m. The particle size 

as seen in the optical images correlates well with the values given by the manufacturers. 

Figures 2 and 3 show the discharge curves of the various CFx materials at both 5 mA/g and 40 

mA/g. With the exception of the ARC 3000 material, all have very similar discharge profiles and 

specific capacities. The curves demonstrate the two phase nature of the discharge with a very flat 

voltage profile. From figures 2 and 3, one can see that the ARC 3000 material has 20% lower 

capacity than any of the other materials and a more sloping discharge curve. From table 1, the 

two obvious differences between this material and the others are that the total fluoride % and the 
4 

decomposition temperature is the lowest of any of the materials tested. This lower fluoride 

content can account for only about half of the capacity decrease, while both the lower fluoride 

content and the lower decomposition temperature points to a material that has some ionic CF 

bonds, that is it is subfluorinated and could account for the sloping discharge profile seen in this 

material. 

Figures 4 and 5 show how the specific capacity and peak voltage vary with rate for the different 

materials. From the data in table 1, it appears that particle size has a significant affect on actual 

running voltage. The smallest particle size materials have the highest running potential. The 

particle size of the ARC 2065 material is in fact less than 1 m. Given that the discharge reaction 

can be characterized as a two phase reaction, small particle size should lead to lower electrode 

polarization since the electrochemical interface becomes significantly larger as the particles 

become smaller. 

The voltage and rate performance does not appear to correlate with BET, external, or micropore 

surface area. Table 1 shows that both ARC 1000 and Fluorstar PC/10 have higher micropore 

area and higher external surface area when compared to ARC 3000, yet this material has a 

significantly higher running potential. In addition, ARC 2065, ARC 4000, and Fluorstar F have 

almost identical BET surface areas, yet their running potentials are significantly different, as 

shown in figure 2. It would appear that the small size of the micropores and the surface 

roughness that leads to the high surface area does not result in either higher running voltage or 

better rate capability in these materials. It could be that these micropores and surface features are 

too small to be part of the electrochemical interface during discharge. 
5 

 ARC 1000 (Coke) ARC 4000 (Carbon Fiber) 

 ARC 2065 (Carbon Black) Fluorstar Type F (Carbon Fiber) 

 ARC 3000 (Graphite) Fluorstar PC/10 (Coke) 

Figure 1. Optical microscope images of CFx powders. 
6 

Figure 2. Voltage profiles at 5 mA/g. 

Figure 3. Voltage profiles at 40 mA/g. 
7 

Figure 4. Specific capacity versus rate. 

Figure 5. Peak voltage versus rate. 
8 

4. Summary and Conclusions 

The performance of six different commercially available carbon monofluoride (CFx) materials 

were evaluated and it was found that most give a discharge profile that can be interpreted as a 2 

phase discharge. The materials have similar specific capacities, except for ARC 3000 which has 

a discharge capacity that is 20% lower. This lower capacity can be accounted for at least 

partially by the lower fluoride content. The main physical property that can be tied to 

performance is the particle size, with smaller particle sizes giving less overpotential and higher 

running voltage. The ability to produce a nanosized CFx might be one approach to increase the 

running potential of Li/CFx cells. ARC 2065 performs as well as the battery grade materials in 

terms of specific capacity and might be considered as an additive to commercial batteries to 

increase rate or voltage performance. 
9 

5. References 

1. Tan, T.; Tsukamoto, H. 200% capacity improvement of ARMY BA5590 pack with using 

newly developed D-size Li/CFx batteries. Workshop on Carbon Fluorides for Lithium 

Batteries, Pasadena, CA, Feb. 2006. 

2. Suszko, A.; Thompson, R.; Stevens, Diane. Performance of Lithium Carbon Monofluoride 

for Soldier Portable Power Sources. Workshop on Carbon Fluorides for Lithium Batteries, 

Pasadena, CA, Feb. 2006. 

3. Sazhin, S. V.; Ramaswami, K.; Gurrie, T. J.; Niendorf, C. R.; Suszko, A. Development of 

Lithium Fluorinated Carbon System for Military Battery Packs. Proc. of the 42nd Power 

Sources Conf., Philadelphia, PA, p.61, June 2006. 

4. Tan, T.; Lam, P.; Tsukamoto, H.; Hendrickson, M.; Plichta, E. Li/(CF)n Battery for Low 

Temperature and High Power Application. Proc. of the 42nd Power Sources Conf., 

Philadelphia, PA, p.73, June 2006. 

5. Wood, J. L.; Valerga, A. J.; Badachhape, R. B.; Margrave, J. L. Thermodynamic, 

Electrochemical and Synthetic Studies of the Graphite-Fluorine Compounds CF and C4F. 

TR-ECOM-0105-F (1972); J. L. Wood, R. B. Badachhape, R. J. Lagow, J. L Margrave, Heat 

of Formation of Poly (Carbon Monofluoride). Journal of Physical Chemistry 1969, 73 (9), 

3139. 

6. Whittingham, M. S. J. Electrochem. Soc. 1975, 122 (4), 526. 

7. Watanabe, N.; Hagiwara, R.; Nakajima, T.; Touhara, H.; Ueno, K. Electrochemica Acta 

1982, 27 (11), 1615. 
10 

NO. OF 

COPIES ORGANIZATION 

 1 ADMNSTR 

 ELEC DEFNS TECHL INFO CTR 

 ATTN DTIC OCP 

 8725 JOHN J KINGMAN RD STE 0944 

 FT BELVOIR VA 22060-6218 

 1 DARPA 

 ATTN IXO S WELBY 

 3701 N FAIRFAX DR 

 ARLINGTON VA 22203-1714 

 1 CD OFC OF THE SECY OF DEFNS 

 ATTN ODDRE (R&AT) 

 THE PENTAGON 

 WASHINGTON DC 20301-3080 

 1 US ARMY RSRCH DEV AND 

 ENGRG CMND 

 ARMAMENT RSRCH DEV AND 

 ENGRG CTR 

 ARMAMENT ENGRG AND 

 TECHNLGY CTR 

 ATTN AMSRD AAR AEF T J MATTS 

 BLDG 305 

 ABERDEEN PROVING GROUND MD 

 21005-5001 

 1 PM TIMS, PROFILER (MMS-P) 

 AN/TMQ-52 

 ATTN B GRIFFIES 

 BUILDING 563 

 FT MONMOUTH NJ 07703 

 1 US ARMY INFO SYS ENGRG CMND 

 ATTN AMSEL IE TD A RIVERA 

 FT HUACHUCA AZ 85613-5300 

 1 COMMANDER 

 US ARMY RDECOM 

 ATTN AMSRD AMR 

 W C MCCORKLE 

 5400 FOWLER RD 

 REDSTONE ARSENAL AL 

 35898-5000 

 1 US GOVERNMENT PRINT OFF 

 DEPOSITORY RECEIVING SECTION 

 ATTN MAIL STOP IDAD J TATE 

 732 NORTH CAPITOL ST NW 

 WASHINGTON DC 20402 

NO. OF 

COPIES ORGANIZATION 

 1 US ARMY RSRCH LAB 

 ATTN RDRL CIM G T LANDFRIED 

 BLDG 4600 

 ABERDEEN PROVING GROUND MD 

 21005-5066 

 8 US ARMY RSRCH LAB 

 ATTN IMNE ALC HRR 

 MAIL & RECORDS MGMT 

 ATTN RDRL CIM L TECHL LIB 

 ATTN RDRL CIM P TECHL PUB 

 ATTN RDRL SED C D FOSTER 

 ATTN RDRL SED C J READ 

 ATTN RDRL SED C 

 J WOLFENSTINE 

 ATTN RDRL SED C M MARX 

 ATTN RDRL SED C S ZHANG

 ADELPHI MD 20783-1197 

TOTAL: 17 (1 ELEC, 1 CD, 15 HCS)