Journal of The Electrochemical Society, *** * A***-A493 2008

A488

****-****/****/*** * /A488/6/$23.00 The Electrochemical Society

Electrochemical Characterization of Vanadium Oxide

Nanostructured Electrode

Elsa A. Olivetti, Kenneth C. Avery, Ikuo Taniguchi, Donald R. Sadoway,* and

Anne M. Mayesz

Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge,

Massachusetts 02139-4307, USA

Films consisting of a vanadium pentoxide i.e., V2O5 phase formed within a rubbery block copolymer were developed for their

potential use as nanocomposite cathodes in lithium rechargeable batteries. Films were prepared by sol-gel synthesis from vanadyl

triisopropoxide precursor in poly oligooxyethylene methacrylate -block-poly butyl methacrylate, incorporating LiCF3SO3 and

carbon black as conductivity additives. The morphology of the lms was examined using electron microscopy, and their electro-

chemical performance was assessed by galvanostatic cycling. An all-solid-state battery comprising a polymer-based cathode and

a block copolymer electrolyte was cycled repeatedly. The capacity was measured to be 40 mAh /g and found to be limited by the

conductivity of the polymer electrolyte. A comparison between a nanocomposite cathode and a control cathode with the same

carbon:vanadium oxide ratio demonstrated higher rate capability for the nanocomposite sample when paired with a liquid elec-

trolyte. This study demonstrates the potential utility of block copolymers in the fabrication of high-surface-area cathodes for

lithium batteries.

2008 The Electrochemical Society. DOI: 10.1149/1.2909560 All rights reserved.

Manuscript submitted December 19, 2007; revised manuscript received March 25, 2008. Available electronically May 2, 2008.

Vanadium oxide has been studied extensively as an insertion access high surface area-to-volume ratios using microphase-

separating block copolymers to structure direct the sol-gel synthesis

cathode material for lithium-ion batteries due to its stability, relative

safety, low cost, ease of synthesis, and high energy density.1 Vana- of vanadium oxide. Our previous research employed the block co-

polymer electrolyte poly oligooxyethylene methacrylate -block-

dium oxides synthesized via sol-gel chemistry from vanadic acid or

vanadyl alkoxides result in amorphous xerogels.2 One method em- poly n-butyl methacrylate, POEM-b-PBMA, as a matrix to grow

vanadium oxide within the lithium ion-conducting POEM

ployed to improve the capacity of sol-gel vanadium oxides in

domains.19 The present study extends this work by incorporating

lithium batteries has been altering the way the solvent phase is re-

moved through techniques including supercritical drying,3 carbon black CB into the nanocomposite lms as a conductivity

additive, essential for the construction of batteries. The morphology

freeze-drying,4 or solvent exchange.5,6 The resulting microstructures

of the lms was examined by electron microscopy, and their elec-

called aerogels in the case of supercritical or freeze-drying and

trochemical performance was assessed by galvanostatic cycling. The

ambigels in the case of solvent exchange methods lead to a higher

nanocomposite cycled reversibly as a cathode vs lithium using a

capacity and rate capability than vanadium oxide xerogels due to

solid polymer electrolyte and showed improved rate capability over

200 to 400 m2 /g compared to 20 m2 /g

increased surface area

the composite cathode control.

and reduced diffusion distances for intercalated ions.7 When cycled

between 4.0 and 1.5 V, vanadium oxide aerogels achieved capaci-

Experimental

ties of 410 mAh /g at C/40.6 Baudrin et al. have used the vanadium

The block copolymer POEM-b-PBMA was synthesized by atom

oxide aerogel structure to access a metastable phase with capacities

transfer radical polymerization as described previously.19,20 The

in excess of 500 mAh /g.8 Recently, vanadium oxide sol coated onto

chemical structure of the nal POEM-b-PBMA block copolymer is

colloidal-crystal-templated porous carbon resulted in cathodes with

shown in Fig. 1. The resulting material comprised 70:30 wt:wt

capacities as high as 90 mAh per gram of V2O5/carbon composite at

speci c currents as high as 5 A /g.9

Other nanoscale microstructures of vanadium oxide investigated

for battery applications include nanoparticles, -tubes, -rolls, -rods,

and -ribbons.10-18 Singhal et al. observed increased capacity for elec-

trodes incorporating partially crystalline nanoparticles vs coarse-

grained particles of vanadium oxide produced using a combustion-

process.10

ame/chemical-vapor-condensation Patrissi and

11,12

Sides et al., and Sides and Martin16 synthesized vana-

13

Martin,

dium oxide nanorods using track-etched polycarbonate or anodic

alumina membranes as templates and demonstrated their increased

rate capability and capacity compared to that of thin- lm controls.

In one study, nanorod arrays exhibited three times the capacity of

thin lms at discharge rates of 200 C.11 More recently, Cui et al.

demonstrated fully reversible cycling of nanoribbons between

Li3V2O5 and V2O5 phases, which they attributed to rapid phase

transformation kinetics in these nanoscale materials.15 Vanadium ox-

ide nanotubes for battery applications have also been synthesized

through hydrothermal methods employing V2O5 precursors and

structure-directing amphiphiles,17 and through template-based elec-

trodeposition techniques.14,18

In the present work, an alternate synthesis approach is taken to

Figure 1. Chemical structure of POEM-b-PBMA block copolymer x

* Electrochemical Society Active Member.

z

= 150, y = 350 .

E-mail: abqq6e@r.postjobfree.com

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Journal of The Electrochemical Society, 155 7 A488-A493 2008 A489

A489

Figure 2. Color online Schematic illus-

trations of test cells. SPE: solid polymer

electrolyte, LP50: liquid electrolyte, CCC:

conventional composite cathode.

POEM:PBMA and had a molecular weight of 70 kg /mol based on a diamond knife, placing the sections on copper grids and coating

gel permeation chromatography analysis with polystyrene standards. them with 15 nm of carbon through thermal evaporation. Wide-

To obtain samples for pyrolysis and scanning electron microscopy angle X-ray scattering WAXS experiments were carried out on a

SEM analysis, coassembled nanocomposite lms of Rigaku Rota ex 18 kW rotating anode X-ray generator with Cu K

POEM-b-PBMA incorporating 34 wt % vanadium oxide, termed radiation operated at 60 kV and 300 mA. The 2 range was from 5

herein POEM-b-PBMA /VOx, were prepared as previously to 60 with a scanning speed of 2 /min and sample-to-detector dis-

reported.19,20 Brie y, POEM-b-PBMA 5 wt % was dissolved in tance of 185 mm.

acetone followed by the addition of 50 wt % vanadyl triisopro- Coin cells, of several con gurations shown in Fig. 2a-c, were

poxide, VO OC3H7 3 VO OiPr 3,Gelest, and the resulting solu- prepared in an argon- lled glove box to assess the electrochemical

behavior of the composite lms. Figure 2a depicts cells containing

tion stirred for 30 min. Deionized DI water was then added in a

POEM-b-PBMA /VOx /CB lms as cathodes and a POEM-b-PBMA

molar ratio of 40:1 H2O:V to initiate gelation. After 1 h stirring,

solid polymer electrolyte SPE 20 to enable a seamless interface. For

solutions were solvent cast into Te on dishes VWR Scienti c and

dried in air under glass Petri dishes for 48 h, then heated under these cells, polymer lms 30 m doped with LiCF3SO3 at a

vacuum at 80 C overnight to remove residual solvent. Some lms Li:EO ratio of 1:20 acting as the solid electrolyte were cast from

were subsequently heated to 400 C under argon ramped at anhydrous tetrahydrofuran on a lithium metal disk VWR Scienti c

3 K /min; held 1.5 h at temperature to pyrolyze the polymer phase, used as the anode. After casting the electrolyte, the coated disk was

followed by a heating phase in air ramped to 400 C at 2 K /min and vacuum dried for 40 min to remove residual solvent. Then a porous

removed immediately upon reaching temperature to ensure the for- polypropylene washer Celgard 2300, Celgard, Inc., Charlotte, NC

mation of V2O5. SEM was performed on lms after pyrolysis to was placed on the Li disk to prevent edge shorting, and the

visualize the morphology of the oxide component. Samples were POEM-b-PBMA /VOx /CB cathode was placed on top. Stainless

coated with Au /Pd and mounted with carbon tape onto aluminum steel current collectors were used on both sides of the cells. Cells

posts and the microscopy was performed on a JEOL 6320FV eld- were also made with the POEM-b-PBMA /VOx /CB cathode

emission high-resolution SEM at 1 kV. The surface area of the lms using liquid electrolyte containing 1 M LiPF6 in ethylene

samples was also determined using the Brunauer, Emmet, and Teller carbonate:dimethyl carbonate Merck kGaA 1:1 by mass with a

BET technique on a Micrometrics ASAP2020 instrument. Prior to Celgard 2300 disk as a separator to prevent shorting shown in Fig.

the measurement, the samples underwent degassing for 2 h under 2b .

owing nitrogen at 100 C. Control lms of sol-gel derived VOx Cells for controls were prepared using conventional composite

synthesized in the absence of POEM-b-PBMA were also character- cathodes made of sol-gel vanadium oxide, CB and poly vinylidene

ized. uoride PVDF, Kynar as a binder as shown in Fig. 2c. Conven-

In order to obtain lms that could be cycled as cathodes in Li tional composite cathodes were made by mixing the active battery

batteries, modi cations were made to the previously described pro- material vanadium oxide with 10 wt % PVDF, and 5 wt % Super

cedure. Lithium tri uoromethanesulfate, LiCF3SO3 VWR Scien- P CB. N-methylpyrrolidone NMP Sigma Aldrich was added in

ti c, was added to 0.1 g of POEM-b-PBMA in the ratio 20:1 EO:Li the mixture and was cast onto aluminum foil VWR Scienti c and

in the glove box under inert conditions. The polymer/salt mixture allowed to dry. Lower current rates were explored using a poten-

was then dissolved in 5 g acetone outside the glove box. After stir- tiostat Solartron 1287, Solartron Analytical, Oak Ridge, TN con-

ring, 0.1 g VO OiPr 3 was added to this solution. Films also con- trolled by a PC running CorrWare Scribner Associates, Inc., South-

tained 5 wt % acidi ed CB Super P, Cabot Corp. acting as a con- ern Pines, NC . Cycle testing was conducted galvanostatically at

ductivity additive. To modify the surface chemistry of the CB, the 25 C with a Maccor series 4000 automated test system. Voltage

powder was re uxed with fuming sulfuric acid VWR Scienti c for limits were set at 3.5 and 2.5 V with varying discharge and charge

1 h at 80 C.21 After rinsing with DI water, the CB was dried under rates.

vacuum overnight at 100 C, cryoground in liquid nitrogen to break In addition, the conductivity of POEM-b-PBMA /VOx /CB nano-

up aggregates, and sonicated in acetone 5 mL for 1 h. This mix- composite lms was measured by impedance spectroscopy using a

ture was added to the precursor/polymer solution. frequency response analyzer Solartron 1255, Solartron Analytical,

The mixture containing POEM-b-PBMA, VO OiPr 3, and CB Oak Ridge, TN, coupled to a potentiostat Solartron 1287, Solartron

was allowed to stir for 15 minutes. DI water was subsequently added Analytical, Oak Ridge, TN and controlled by a PC running com-

and the solution cast into a Te on dish and dried overnight as mercially available software Zplot, Scribner Associates, Inc.,

described above. The resulting 100 m thick lms, termed herein Southern Pines, NC . The test xture consisted of two blocking

POEM-b-PBMA /VOx /CB, were vacuum dried at 80 C overnight. electrodes made of stainless steel and a Te on washer of known

diameter xed the specimen area. The thickness of the sample was

Thermogravimetric analysis TGA, model Q50, TA Instruments,

Inc. was performed on the product lm under a nitrogen atmo- measured using a micrometer before and after the conductivity mea-

sphere using a heating rate of 20 C /min and a temperature range of surement to verify its consistency throughout the experiment.

30 600 C. TGA revealed the vanadium oxide content of the nal Control lms containing POEM-b-PBMA block copolymer and

salt with addition of vanadium oxide only or CB only were also

lm to be 34 wt % accounting for the presence of the CB

component.19 fabricated and dried under similar conditions. The redox behavior of

Microstructural characterization of the POEM-b-PBMA /VOx / the POEM-b-PBMA /VOx /CB lms was compared to these control

CB lms was carried out using a JEOL 2010 CX transmission elec- lms using cyclic voltammetry CV in a three-electrode cell. Films

were cast on indium tin oxide-coated glass substrates for three-

tron microscope TEM in bright eld mode at 200 keV. The

samples were prepared by cryomicrotoming 50 nm sections using electrode cell measurements. The electrolyte consisted of 1 M

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Journal of The Electrochemical Society, 155 7 A488-A493 2008

A490

A490

Figure 4. Color online WAXS pattern for sol-gel derived, block

copolymer-templated vanadium oxide heated to 400 C.

structure of vanadium oxide is formed on heating to 400 C. The

observed diffraction peaks match those of V2O5 PDF no. 41-1426,

shown below the experimental data.

Templated and control nontemplated vanadium oxide samples

were mixed with PVDF, CB, and NMP, and cast on aluminum foil to

create conventional composite cathodes. Cells were cycled with

liquid electrolyte to assess the effects of the nanoporous oxide struc-

ture on cathode performance. Results of rst discharge curves at

C/10 and 10 C, where C/1 is de ned as the current rate to discharge

the theoretical capacity of V2O5 147 mAh /g in 1 h, from 2.5 to

3.5 V are shown in Fig. 5. The plateaus evident in the discharge

Figure 3. a SEM image of control lm of vanadium oxide produced via

pro les of both lms are consistent with orthorhombic vanadium

sol-gel synthesis without polymer matrix and heated to 400 C. b SEM

pentoxide.4,14 At a rate of C/10, the capacities of the two cells are

image of sol-gel vanadium oxide templated by POEM-b-PBMA, with poly-

comparable, 150 mAh /g for the templated V2O5 vs 147 mAh /g for

mer removed on heating to 400 C.

the control. Signi cantly, the rst discharge capacity at 10 C for the

templated cathode is 70% of the capacity at C/10, while the control

at 10 C was only 27% of the C/10 capacity. The cycling data which

was reproduced in six different cells for each current rate indicates

LiClO4 in propylene carbonate. The reference electrode was a glass

a 2.5 improvement in capacity at 10 C for the templated cathodes.

tube sealed at one end and containing a silver wire immersed in a

It is also noted that the capacities at 3 C for the templated and

solution of acetonitrile saturated with AgNO3. A frit at the bottom of

control samples were 96 and 58% of the C/10 capacity, respectively.

the tube enabled electrical contact with the electrolyte in the main

Cathodes were also prepared preserving the POEM-b-PBMA

chamber. A platinum foil served as the counter electrode. The po-

component to act as an electrolyte in all-solid-state cells. For these

tential was swept from 1.0 to 1.5 V vs Ag /Ag+ at 50 mV /s using a

cells, lms containing POEM-b-PBMA and V2O5 were cast with

potentiostat Solartron 1287, Solartron Analytical, Oak Ridge, TN

5 wt % CB to wire the active material electronically. Prior to cast-

controlled by a PC running CorrWare Scribner Associates, Inc.,

Southern Pines, NC .

Results

19

As shown previously, the microphase-separated morphology of

POEM-b-PBMA serves to structure direct the growth of nanophase

vanadium oxide within the ion-conducting POEM domains. On re-

moving the polymer through pyrolysis, SEM could be used to better

visualize the resulting oxide microstructure. Figure 3 shows the

microstructure of the POEM-b-PBMA /VOx lms after pyrolysis at

400 C under argon followed by a heating phase in air along with

that of a VOx control nontemplated lm heated under the same

conditions. Elemental analysis performed on the templated lm re-

vealed that after the argon step of the pyrolysis 12 wt % carbon

remained from the partial conversion of the copolymer and after the

full heat-treatment 0.13 wt % carbon remained. The microstruc-

ture of the control lm Fig. 3a shows large featureless micron-

sized plates. By contrast, the block copolymer-templated vanadium

oxide Fig. 3b exhibits a high degree of porosity, with pore size and

spacing that are consistent with the template morphology.19 The sur-

face area of the templated oxide was measured to be 200 m2 /g Figure 5. Color online Discharge pro les from crystalline composite cath-

using BET techniques, while the control had a surface area odes made from templated and nontemplated sol-gel vanadium oxide. First

20 m2 /g. discharge pro les are shown at C/10 b and 3C . The templated cath-

The WAXS data shown in Fig. 4 verify that the orthorhombic odes are shown in gray and the nontemplated are in black.

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Journal of The Electrochemical Society, 155 7 A488-A493 2008 A491

A491

Figure 7. Color online Cycling data for solid-state batteries incorporating

cathode lms with untreated or acid-treated CB and with POEM-b-PBMA

solid electrolyte.

electroactive phase in the cathode, the V2O5, was used to determine

the capacity. The reversible capacity of the cell was 40 mAh /g,

and it cycled reversibly for over 20 cycles. The acid-treated CB

sample shows an improved capacity compared to that of the un-

treated sample on the rst and second cycles, but the capacity rap-

idly decays by the seventh cycle to around the same plateau value as

that of the untreated sample. The increase in capacity with cycling

seen for the untreated CB sample is similar to results reported pre-

viously for all-solid-state batteries incorporating microphase-

separating electrolytes employing thin- lm vanadium oxide

cathodes.20,22 In those studies, the improvement with cycling was

hypothesized to be linked to the reorientation of the polymer elec-

trolyte morphology under the applied potential.

To verify that the origin of the observed capacity was the inter-

calation of Li+ into vanadium oxide, control lms were tested

Figure 6. TEM micrographs of a POEM-b-PBMA containing 34 wt %

by CV in a three-electrode con guration. Three voltammograms

V2O5 and 5 wt % CB and b POEM-b-PBMA /VOx lm without CB.

are depicted in Fig. 8a for lms containing POEM-b-PBMA

with VOx, CB, or both. Blowups of the CV curves for the

POEM-b-PBMA /VOx and POEM-b-PBMA/CB composite lms are

ing, the CB was treated with fuming sulfuric acid and a series of shown in Fig. 8b. The vanadium oxide lm alone is characterized by

sonicating and cryogrinding steps to facilitate interaction with one set of corresponding redox peaks re ecting intercalation/

POEM chains and reduce particle aggregation. A TEM dark- eld deintercalation of Li+ into/from the VOx structure, while the

image depicting a cross section of the nal POEM-b-PBMA / POEM-b-PBMA/CB lm mainly exhibits capacitive behavior. The

VOx /CB nanocomposite lm is shown in Fig. 6a. CB particles acid- POEM-b-PBMA /VOx /CB lm exhibits the same peaks, but the cur-

treated are visible as light spherical regions 40 nm diam . Also rent obtained from this lm is a factor of 20 higher.

seen on careful inspection is the lamentous network structure of Even though lms cycled reversibly in solid-state batteries, their

VOx previously reported for POEM-b-PBMA /VOx lms;19 dark capacity was a great deal lower than that of the theoretical capacity

portions of the image correspond to the PBMA domains. A TEM for vanadium oxide of 147 mAh /g. To discover the origin of this

image of a POEM-b-PBMA /VOx lm without CB is shown in Fig. disparity in capacity, cathodes were cycled with solid electrolyte of

6b for comparison. The lamentous structure of VOx seen in Fig. 6b three different thicknesses, using cathode lms incorporating acid-

appears largely preserved in lms containing CB, as exempli ed in treated CB. In recognition of the decrease in capacity upon cycling,

Fig. 6a. TEM revealed CB particles distributed throughout the lms, data are plotted from the second cycle. The test was repeated three

although some aggregation of particles was observed. times for each thickness to verify reproducibility. Representative

Conductivity measurements on the lms using impedance spec- curves for the second discharge step for these lms, shown in Fig. 9,

troscopy with blocking electrodes indicate a substantial improve- indicate no plateaus in voltage, as would be expected for an amor-

ment in conductivity in lms with CB over those without. The con- phous material. The total capacity for these lms varied by

ductivity of POEM-b-PBMA /VOx lms alone was 10 10 S /cm, 5 to 10 mAh /g for each electrolyte thickness investigated; how-

while lms with 5 wt % CB had values close to 10 5 S /cm. The ever, the trend of decreasing capacity with increasing solid electro-

conductivity was suf cient to allow use of the cathode lms in an lyte thickness was always observed. The second discharge capacities

for 30, 60, and 90 m SPE lms were 97, 63, and 22 mAh /g,

all-solid-state battery con guration.

POEM-b-PBMA /VOx /CB lms 100 m thick containing ei- respectively. These data indicate that one limit of the cell s capacity

ther acid-treated or untreated CB were used as cathodes in solid- is the low ionic conductivity of the electrolyte. Reducing the thick-

state cells tted with SPE POEM-b-PBMA doped with LiCF3SO3 ness of the electrolyte, or employing an electrolyte of higher

conductivity,22 should result in a closer alignment of measured and

at 20:1 EO:Li and lithium foil anodes. Representative cycling data

at a C/10 rate for batteries employing cathodes prepared with acid- theoretical values of capacity.

treated and untreated CB are shown in Fig. 7. The mass of the To investigate improvements in rate capability afforded by

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Journal of The Electrochemical Society, 155 7 A488-A493 2008

A492

A492

Figure 10. Cycling data for cells made with liquid electrolyte and using

either nanostructured POEM-b-PBMA /VOx /CB lm cathode open shapes

or control cathode lled shapes .

for each of the cathodes cycled. The open shapes correspond to the

nanocomposite cathode lm while the lled shapes are for the con-

trol. The capacities of batteries employing liquid electrolyte

90 mAh /g at C/10 was improved over those using the SPE

40 mAh /g for the same rate . Although the conventional cathode

begins with a higher capacity at the low charge/discharge rate of

C/10, the nanocomposite lm shows less capacity loss and higher

capacity at the higher rate of C/1.3. At current rates of C/1.3, the

nanostructured cathode maintains 85% of the capacity obtained at

C/10, while the control maintains 55% of that capacity. The cy-

cling data indicate the ability to cycle these materials as cathodes in

rechargeable lithium batteries and demonstrate a rate capability im-

provement for the nanocomposite cathode. The capacity/rate en-

hancements observed in this work are consistent with ndings re-

ported elsewhere on other active electrode materials coassembled

into nanocomposite electrodes using structure-directing agents.23-25

Figure 8. Color online Cyclic voltammograms for POEM-b-PBMA lms

containing a VOx and/or CB on ITO in LiClO4/propylene carbonate elec- Conclusion

trolyte and b only VOx or CB. Swept from 1.0 to 1.5 V at 50 mV /s vs

Cathode lms containing a nanoscale vanadium oxide phase

Ag /Ag+.

were fabricated using POEM-b-PBMA as a structure-directing ma-

trix and CB as a conductivity additive. The lms were cycled in

all-solid-state batteries using POEM-b-PBMA as the electrolyte to

the coassembly of vanadium oxide with POEM-b-PBMA,

provide a seamless interface between cathode and electrolyte. The

POEM-b-PBMA /VOx /CB nanocomposite lms were cycled with

cell performance was found to be limited, however, by the low ionic

LP50 liquid electrolyte and compared to conventional composite

conductivity of the electrolyte,20 as demonstrated by the dependence

cathode lms. Data from these cycling experiments are shown in

of the capacity on polymer electrolyte thickness, and by the higher

Fig. 10. The area and weight of active material were held constant

observed capacities in lms cycled in the presence of a liquid elec-

trolyte. The nanostructured morphology of the vanadium oxide gave

improved rate performance over that of conventional cathode geom-

etries.

A potential alternative to improving the electronic conductivity

of the vanadium oxide would be the partial conversion of the poly-

mer to graphitic carbon through heating after the sol-gel processing

of vanadium oxide, resulting in carbon coating on the oxide sur-

faces. Odani et al. have produced carbon-coated vanadium oxide

through their RAPET method which stands for reaction under au-

togenic pressure at elevated temperatures using a vanadyl alkoxide

precursor.26 Sides et al. have used similar carbonization strategies to

improve the conductivity of LiFePO4 by pyrolizing a polycarbonate

template.12 With vanadium oxide chemistries, unlike iron phosphate,

there is a balance between preserving the graphitized carbon from

pyrolyzed hydrocarbons in the system and avoiding reduction of the

Li+ insertion material V2O5 to less desirable oxides, such as VO2

and V2O3. Investigating this approach to improve electronic conduc-

tivity could be the topic of future study.

Acknowledgments

This work was sponsored by the Of ce of Naval Research under

Figure 9. Color online Discharge pro les for the second cycle of three

contract no. N00014-05-1-0056 and, in part, by the MIT MRSEC

solid-state batteries using three different thicknesses of POEM-b-PBMA

Program of the National Science Foundation under award grant no.

electrolyte as indicated.

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Journal of The Electrochemical Society, 155 7 A488-A493 2008 A493

A493

11. C. J. Patrissi and C. R. Martin, J. Electrochem. Soc., 146, 3176 1999 .

DMR-0213282. This work made use of Shared Experimental Facili-

12. C. J. Patrissi and C. R. Martin, J. Electrochem. Soc., 148, A1247 2001 .

ties under the MRSEC Program of the National Science Foundation

13. C. R. Sides, F. Croce, V. Y. Young, C. R. Martin, and B. Scrosati, Electrochem.

under award grant no. DMR-0213282. The authors gratefully ac- Solid-State Lett., 8, A484 2005 .

knowledge Dr. Steve Kooi for his assistance with the BET work. 14. Y. Wang and G. Z. Cao, Chem. Mater., 18, 2787 2006 .

15. C. K. Chan, H. L. Peng, R. D. Twesten, K. Jarausch, X. F. Zhang, and Y. Cui, Nano

Massachusetts Institute of Technology assisted in meeting the publication Lett., 7, 490 2007 .

costs of this article. 16. C. R. Sides and C. R. Martin, Adv. Mater. (Weinheim, Ger.), 17, 125 2005 .

17. M. E. Spahr, P. Stoschitzki-Bitterli, R. Nesper, O. Haas, and P. Novak, J. Electro-

References chem. Soc., 146, 2780 1999 .

1. M. S. Whittingham, Y. Song, S. Lutta, P. Y. Zavalij, and N. A. Chernova, J. Mater. 18. K. Takahashi, Y. Wang, and G. Cao, Appl. Phys. Lett., 86, 053***-**** .

Chem., 15, 3362 2005 . 19. E. A. Olivetti, J. H. Kim, D. R. Sadoway, A. Asetakin, and A. M. Mayes, Chem.

2. J. Livage, Solid State Ionics, 50, 307 1992 . Mater., 18, 2828 2006 .

3. F. Chaput, B. Dunn, P. Fuqua, and K. Salloux, J. Non-Cryst. Solids, 188, 11 20. P. E. Trapa, B. Huang, Y.-Y. Won, D. R. Sadoway, and A. M. Mayes, Electrochem.

1995 . Solid-State Lett., 5, A85 2002 .

4. G. Sudant, E. Baudrin, B. Dunn, and J. M. Tarascon, J. Electrochem. Soc., 151, 21. H. Huang and L. F. Nazar, Angew. Chem., Int. Ed., 40, 3880 2001 .

A666 2004 .

22. P. E. Trapa, Y.-Y. Won, S. C. Mui, E. A. Olivetti, B. Huang, D. R. Sadoway, A. M.

5. J. H. Harreld, W. Dong, and B. Dunn, MRS Bull., 33, 561 1998 .

Mayes, and S. Dallek, J. Electrochem. Soc., 152, A1 2005 .

6. F. Coustier, J.-M. Lee, S. Passerini, and W. H. Smyrl, Solid State Ionics, 116, 279

23. S. C. Mui, P. E. Trapa, B. Huang, P. P. Soo, M. I. Lozow, T. C. Wang, R. E. Cohen,

1999 .

A. N. Mansour, S. Mukerjee, A. M. Mayes, and D. R. Sadoway, J. Electrochem.

7. F. Coustier, S. Passerini, and W. H. Smyrl, J. Electrochem. Soc., 145, L73 1998 .

Soc., 149, A1610 2002 .

8. E. Baudrin, G. Sudant, D. Larcher, B. Dunn, and J. M. Tarascon, Chem. Mater., 18,

24. S. Bullock and P. J. Ko nas, J. Power Sources, 132, 256 2004 .

4369 2006 .

25. K. T. Nam, D. W. Kim, P. Yoo, C. Y. Chiang, N. Meethong, P. T. Hammond, Y. M.

9. H. Yamada, K. Tagawa, M. Komatsu, I. Moriguchi, and T. Kudo, J. Phys. Chem. C,

Chiang, and A. M. Belcher, Science, 312, 885 2006 .

111, 8397 2007 .

26. A. Odani, V. G. Pol, S. V. Pol, M. Koltypin, A. Gedanken, and D. Aurbach, Adv.

10. A. Singhal, G. Skandan, G. Amatucci, F. Badway, N. Ye, A. Manthiram, H. Ye, and

Mater. (Weinheim, Ger.), 18, 1431 2006 .

J. J. Xu, J. Power Sources, 129, 38 2004 .

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