Cw

Ja

b

a

ARRAA

KGILLL

1

itdaushtodgeisprewcB

h0

Electrochimica Acta 132 (2014) 1–6

Contents lists available at ScienceDirect

Electrochimica Acta

j ourna l ho me page: www.elsev ier .com/ locate /e lec tac ta

ycling characteristics of lithium powder polymer cells assembledith cross-linked gel polymer electrolyte

i-Ae Choia, Ji-Hyun Yooa, Woo Young Yoonb, Dong-Won Kima,∗

Department of Chemical Engineering, Hanyang University, Seungdong-Gu, Seoul 133-791, South KoreaDepartment of Materials Science and Engineering, Korea University, Seongbuk-Gu, Seoul 136-701, South Korea

r t i c l e i n f o

rticle history:eceived 13 January 2014eceived in revised form 8 March 2014ccepted 17 March 2014vailable online 31 March 2014

a b s t r a c t

Lithium polymer cells composed of lithium powder anode and LiV3O8 cathode were assembled with an in-situ cross-linked gel polymer electrolyte, and their cycling performance was evaluated. The Li/LiV3O8 cellsexhibited better capacity retention and greater rate performance than the liquid electrolyte-based cell.The stable cycling characteristics of the lithium powder polymer cells resulted from the strong interfacialadhesion between the electrodes and the electrolyte as well as the suppression of the dendritic growth

eywords:el polymer electrolyte

n-situ cross-linkingithium powderithium polymer cell

of lithium powder electrode during repeated cycling.© 2014 Elsevier Ltd. All rights reserved.

ithium dendrite

. Introduction

In recent years, the demand for rechargeable lithium batter-es with high energy density and enhanced safety has increasedo meet growing needs for smaller, lighter portable electronicevices and to accommodate growing interest in electric vehiclesnd energy storage systems [1–4]. As a result, lithium batteriessing lithium metal as a negative electrode are the focus of sub-tantial research interest because the lithium electrode offers a veryigh specific capacity (3,860 mAh g−1) [5], which is more than tenimes that of the currently used carbon electrode. However, the usef lithium metal electrodes has been limited by the occurrence ofendrite growth during repeated charge and discharge cycles, as itives rise to safety problems and gradual degradation of the cyclingfficiency [6,7]. Therefore, the control of dendrite growth is verymportant for developing lithium metal batteries with enhancedafety and good capacity retention. In our previous studies, lithiumowder instead of lithium foil was suggested as a new anode mate-ial to suppress dendritic growth, and distinct improvement in thelectrochemical properties and safety of lithium powder electrodes

as demonstrated [8,9]. Lithium vanadate (LiV3O8) is a promising

athode active material for use in lithium metal batteries [10–15].ased on theoretical calculations, lithium vanadate can deliver a

∗ Corresponding author.E-mail address: dongwonkim@hanyang.ac.kr (D.-W. Kim).

ttp://dx.doi.org/10.1016/j.electacta.2014.03.119013-4686/© 2014 Elsevier Ltd. All rights reserved.

high specific capacity (280 mAh g−1 for 3Li+ insertion/deinsertion)that is nearly double that of LiCoO2. Additionally, lithium vanadateworks in a potential range in which no side reactions due to elec-trolyte oxidation are expected. For the successful development oflithium metal batteries, there is also a pressing need for safer, morereliable electrolyte systems. Currently, gel polymer electrolytes areconsidered a promising alternative to the liquid electrolytes usedin lithium batteries [16–20]. As a type of gel polymer electrolyte,chemically cross-linked gel polymer electrolytes can be synthe-sized by an in-situ cross-linking reaction of a liquid electrolyte withcross-linking agents [20–25], a technique which has been appliedto the manufacture of commercialized lithium-ion polymer batter-ies. In this process, an electrolyte solution containing cross-linkingagents is injected into the cell and gelation is performed by heat-ing the cell, which resolves the leakage problem while maintaininggood thermal and dimensional stability as well as high ionic con-ductivity.

With the goal of developing high energy density lithium metalpolymer cells with good capacity retention and enhanced safety,the lithium powder polymer cells composed of a lithium pow-der anode, a cross-linked gel polymer electrolyte and a LiV3O8cathode were assembled and their cycling performance was eval-uated. The cross-linked gel polymer electrolytes were synthesized

by in-situ chemical cross-linking in the cells, and the amount ofthe cross-linking agent necessary to achieve good cycling perfor-mance was suggested. The morphological analysis of the lithiumpowder electrode after repeated cycling demonstrated that the

2 J.-A. Choi et al. / Electrochimica Acta 132 (2014) 1–6

assem

dic

2

2

piabapwcvatcdeps

2

nstdwt8awcbbcpfcccpi

Fig. 1. Schematic presentation of lithium powder polymer cell

endritic growth of lithium metal could be effectively suppressedn cross-linked gel polymer electrolytes, resulting in stable cyclingharacteristics.

. Experimental

.1. Synthesis of gel polymer electrolytes

Poly(ethylene glycol) dimethacrylate (PEGDMA, Mn = 550) wasurchased from Aldrich and used as a cross-linking agent after dry-

ng under a vacuum at 60 ◦C for 24 hr. The water content in PEGDMAfter vacuum drying was determined by Karl Fisher titration toe 18 ppm. PEGDMA and t-amyl peroxypivalate (Seki Arkema) as

thermal radical initiator were added to a liquid electrolyte torepare the precursor electrolyte solution. The liquid electrolyte,hich consisted of 1.0 M LiPF6 in ethylene carbonate (EC)/diethyl

arbonate (DEC) (1:1 by volume, battery grade) containing 1 wt.%inylene carbonate (VC), was kindly supplied by Soulbrain Co. Ltd.,nd used without further treatment. VC was added as a solid elec-rolyte interphase (SEI) forming agent. In order to optimize theontent of the cross-linking agent, PEGDMA was dissolved withifferent concentrations (0, 2.0, 4.0, 6.0 and 8.0 wt.%) in the liquidlectrolyte. The cross-linked gel polymer electrolyte was then pre-ared by a radical-initiated reaction of the precursor electrolyteolution at 90 ◦C for 20 min.

.2. Electrode preparation and cell assembly

Lithium powders were prepared by the droplet emulsion tech-ique [8,9,26]. A mixture of molten lithium and silicone oil washeared at approximately 25,000 rpm to produce an emulsion. Ashe emulsion was cooled to room temperature, the liquid lithiumroplets solidified to form solid powders. The lithium powdersere compacted by pressing to form an electrode. The LiV3O8 elec-

rode was prepared by coating a water-based slurry containing0 wt.% lithium vanadate (GfE, Germany), 15 wt.% Ketchen blacknd 5 wt.% carboxymethyl cellulose (CMC) on Al foil. The electrodeas roll pressed to enhance particulate contact and adhesion to the

urrent collector. The lithium powder polymer cell was assembledy sandwiching the polypropylene (PP) separator (Celgard 2400)etween the lithium powder anode and the LiV3O8 cathode. Theell was enclosed in a pouch bag, injected with the gel electrolyterecursor and then vacuum-sealed. The cell assembly was per-ormed in a dry box filled with argon gas. After cell assembly, theells were maintained at 90 ◦C for 20 min to induce in-situ thermal

uring of the gel electrolyte precursor within the cell. The in-situross-linking enabled bonding of the separator firmly to the lithiumowder anode and LiV3O8 cathode together in the cell, as illustrated

n Fig. 1.

bled by in-situ cross-linking of a precursor electrolyte solution.

2.3. Measurements

The morphologies of the electrodes were examined using a scan-ning electron microscope (SEM, JEOL JSM-6300). Fourier transforminfrared (FT-IR) spectra were recorded on JASCO 460 IR spectrom-eter in the range of 400-4000 cm−1. The ionic conductivity of theliquid electrolyte was measured by a Cond 3210 conductivity meter(WTW GmbH, Germany), and the ionic conductivity of the cross-linked gel polymer electrolyte after thermal curing was determinedfrom AC impedance measurements. AC impedance measurementswere performed using a Zahner Electrik IM6 impedance analyzerover a frequency range of 100 Hz to 100 kHz with an amplitude of10 mV. Charge and discharge cycling tests of the lithium powderpolymer cells were conducted at a constant current over a volt-age range of 2.0–3.6 V with battery test equipment (WBCS 3000,Wonatech) at room temperature. To observe the morphologicalchanges of the lithium powder electrodes, the cells were disassem-bled after 100 cycles in a glove box and the electrodes were washedwith dimethyl carbonate to remove the residual electrolyte. Afterdrying in an argon-filled glove box, the morphology of the lithiumpowder electrodes was characterized using a field emission scan-ning electron microscope.

3. Results and discussion

The cross-linked gel polymer electrolytes were synthesizedby thermal curing of the liquid electrolyte with different cross-linking agent contents at 90 ◦C for 20 min. Fig. 2-(a) shows thephoto images of the cross-linked gel polymer electrolytes curedwith different amounts of PEGDMA. As the content of PEGDMAincreased at intervals of 2.0 wt.%, the electrolyte solution becamehighly viscous and finally non-fluidic, indicating that PEGDMA withmultiple oligo(ethylene oxide) acrylate functional groups effec-tively induced the thermal cross-linking reaction. Gel polymerelectrolytes without liquid flow were obtained at PEGDMA contentsgreater than 6 wt.%, as shown in Fig. 2-(a). Ionic conductivities ofthe gel polymer electrolytes after thermal curing were measuredas a function of the PEGDMA content, and the results are shownin Fig. 2-(b). The ionic conductivity of the base liquid electrolytewas 7.0×10−3 S cm−1. The ionic conductivities of the gel poly-mer electrolytes decreased with increasing PEGDMA content, sincethe thermal curing with cross-linking agent increased the viscosityof the resulting electrolytes and produced the three-dimensionalelectrolyte polymer networks. The large decrease in the ionic con-ductivity with increasing PEGDMA content from 4.0 to 6.0 wt.%can be ascribed to the abrupt reduction of ionic mobility dueto the formation of cross-linked polymer electrolytes with highcross-linking density. Because the complete gelation of the liquid

electrolyte failed at PEGDMA contents less than 6 wt.%, a gel elec-trolyte precursor containing 6.0 or 8.0 wt.% PEGDMA was applied tothe lithium powder polymer cells. In order to confirm the chemicalcross-linking reaction of PEGDMA, FT-IR analysis was carried out

J.-A. Choi et al. / Electrochimica Acta 132 (2014) 1–6 3

Fig. 2. (a) Photographs of gel polymer electrolytes cured with different amounts ofPf

bsgtPte

Fc

EGDMA, and (b) ionic conductivities of cross-linked gel polymer electrolytes as aunction of the PEGDMA content.

efore and after thermal curing, and the resulting FT-IR spectra arehown in Fig. 3. The characteristic peak of C = C for the methacrylateroup observed at 1637 cm−1 [27,28] was found to disappear afterhermal curing at 90 ◦C for 20 min, indicating full cross-linking ofEGDMA. This result reveals that the curing condition is sufficient

o complete the thermal cross-linking of PEGDMA in the precursorlectrolyte solution.

600800100012001400160018002000

(a)

Tran

smitt

ance

Wavenumber (cm-1)

(b)

ig. 3. FT-IR spectra of (a) PEGDMA and (b) cross-linked gel polymer electrolyteured by 6 wt.% PEGDMA.

Fig. 4. SEM images of (a) the compacted lithium powder electrode and (b) thepositive electrode prepared with LiV3O8 powders.

The morphology of a compacted lithium powder electrodeis shown in Fig. 4-(a). The lithium powders were spherical inshape, and porous characteristics of the lithium electrode couldbe observed. The porous structure of the lithium powder electrodewith a large surface area is expected to enhance the charge trans-fer reaction at the electrode surface. The larger reactive surfacearea can also reduce the apparent current density on the lithiumelectrode surface, which may suppress dendrite formation dur-ing charge and discharge cycling of the cells. Fig. 4-(b) shows aSEM image of the positive electrode prepared with LiV3O8 powder,binder and a conducting agent. Ketchen blacks as the conductivematerial were homogeneously dispersed with active LiV3O8 pow-ders with lath-like structures in the electrode.

The Li/LiV3O8 cells were cycled in the voltage range of 2.0–3.6 Vat a constant current rate of 0.2 C and room temperature. Fig. 5 (a)and (b) show the voltage profiles of the cell assembled with liquidelectrolyte and cross-linked gel polymer electrolyte, respectively.The discharge plateau around 2.8 V corresponds to the single-phaseinsertion process and the 2.6 V plateau is ascribed to the two-phasetransformation between Li1+xV3O8 (1≤x≤2) and Li4V3O8, as previ-ously reported [29,30]. The Li/LiV O cell with liquid electrolyte

3 8delivered an initial discharge capacity of 240.5 mAh g−1 based onthe LiV3O8 active material in the positive electrode, and its dis-charge capacity declined to 150.3 mAh g−1 at the 100th cycle. For

4 J.-A. Choi et al. / Electrochimica Acta 132 (2014) 1–6

2502001501005001.5

2.0

2.5

3.0

3.5

4.0Vo

ltage

(V)

Specifi c ca pacit y (mAh g-1)

1st cycle 10th cycle 20th cycle 50th cycle 100 th cycle

(a)

2502001501005001.5

2.0

2.5

3.0

3.5

4.0

Volta

ge (V

)

Specifi c ca pacit y (mAh g-1)

1st cycle 10 th cycle 20 th cycle 50 th cycle 100 th cycle

(b)

Fig. 5. Charge and discharge curves of the lithium powder polymer cell (Li/LiV O )ac

ttrc

tuiPiticcccabiFtactedg

1008060402000

50

100

150

200

250

300

Dis

char

ge c

apac

ity(m

Ah

g-1)

Cycle nu mber

liquid ele ctrolyte GPE with 6 wt.% PEGDMA GPE wi th 8 wt.% PE GDMA

(a)

10080604020092

94

96

98

100

102

Cou

lom

bic

effic

ienc

y (%

)

Cycle nu mber

liquid el ectro lyte GPE wi th 6 wt.% PE GDMA GPE wi th 8 wt.% PE GDMA

(b)

negative electrode.To understand the interfacial behavior of Li/LiV3O8 cells with

different electrolytes, we obtained ac impedance spectra of thecells after 100 cycles. Fig. 7 shows the ac impedance spectra of

60504030201000

10

20

30

40

50

60liquid electrolyte GPE with 6 wt.% PEGDMA GPE with 8 wt.% PE GDMA

-ZIm

(Ω)

ZRe(Ω)

3 8

ssembled with (a) liquid electrolyte and (b) cross-linked gel polymer electrolyteured by 6.0 wt.% PEGDMA (0.2 C rate, cut-off: 2.0–3.6 V, 25 ◦C).

he Li/LiV3O8 cell assembled with cross-linked gel polymer elec-rolyte cured by 6.0 wt.% PEGDMA, an initial discharge capacity waseduced to 220.3 mAh g−1, however, it delivered higher dischargeapacity than liquid electrolyte-based cell at the 100th cycle.

Fig. 6-(a) presents the discharge capacities as a function ofhe cycle number in the Li/LiV3O8 cells assembled with the liq-id electrolyte or the cross-linked gel polymer electrolytes. The

nitial discharge capacity of the cell decreased with increasingEGDMA content, due to the increased resistance for ion migrationn both electrolyte and electrodes. Note that the capacity reten-ion was improved using the cross-linked gel polymer electrolyte,rrespective of the PEGDMA content. By thermal curing with theross-linking agent, the liquid electrolyte becomes a chemicallyross-linked gel polymer electrolyte within the cell. Additionally,uring allows effective encapsulation of the liquid electrolyte in theell and promotes good interfacial adhesion between the separatornd electrodes, which results in good capacity retention. Coulom-ic efficiencies of the cells with cross-linked gel polymer electrolyte

nitially increased and stabilized with cycle number, as shown inig. 6-(b). On the other hand, in case of the cell with liquid elec-rolyte, the coulombic efficiency initially increased but decreasedgain with cycling. High and stable coulombic efficiencies in theells with cross-linked gel polymer electrolytes can be ascribed to

he presence of ionic conductive cross-linked polymer layer cov-ring the lithium powder electrode, which reduces the reductiveecomposition of electrolyte on lithium electrode and suppressrowth of lithium dendrite during cycling. Based on these results,

Fig. 6. (a) Discharge capacities and (b) coulombic efficiencies of the Li/LiV3O8 cellsassembled with liquid electrolyte or cross-linked gel polymer electrolytes (0.2 C rate,cut-off: 2.0–3.6 V, 25 ◦C).

we believe that an in-situ cross-linking is very effective for enhanc-ing cycling stability of the cell with lithium powder electrode as a

Fig. 7. AC impedance spectra of the Li/LiV3O8 cells assembled with liquid electrolyteand cross-linked gel polymer electrolytes, which are measured after the repeated100 cycles.

J.-A. Choi et al. / Electrochimica Acta 132 (2014) 1–6 5

Fia

tms[fm

22520017515012510075502501.5

2.0

2.5

3.0

3.5

4.0

Volta

ge (V

)

Specific ca pac ity (mAh g-1)

0.2C 0.5C 1.0C 2.0C

(a)

2.01.51.00.50.070

75

80

85

90

95

100

105

110

Rel

ativ

e ca

paci

ty (%

)

C rate

liquid elec trolyte GPE with 6 wt.% PEGDM A GPE with 8 wt.% PEGDM A

(b)

Fig. 9. (a) Discharge profiles of the lithium polymer cell cured by 6 wt.% PEGDMAat different current rates, and (b) relative capacities of the Li/LiV3O8 cells assem-

ig. 8. SEM images of the surface of the lithium powder electrodes after 100 cyclesn (a) the liquid electrolyte, (b) gel polymer electrolyte cured by 6 wt.% PEGDMA,nd (c) gel polymer electrolyte cured by 8 wt.% PEGDMA.

he Li/LiV3O8 cells with liquid electrolyte or cross-linked gel poly-er electrolytes. After charge and discharge cycles, ac impedance

pectra showed a poorly separated semicircle. By previous works31,32], the overlapped semicircle observed from high to lowrequency regions corresponds to the resistance due to Li+ ion

igration through the surface film on the electrode (Rf) and charge

bled with liquid electrolyte or cross-linked gel polymer electrolytes, as a functionof the current rate. The cells were charged to 3.6 V at a constant current of 0.2 C anddischarged at different current rates, from 0.2 to 2.0 C.

transfer resistance between the electrode and electrolyte (Rct). Ofparticular our interest in the depressed semicircles is the totalinterfacial resistance, which is sum of Rf and Rct. When compar-ing the interfacial resistances, the cell cured by 6 wt.% PEGDMAexhibited the lowest value. It is plausible that the interfacial contactbetween electrodes and electrolyte is improved by in-situ chemicalcross-linking, which is essential for efficient charge transport dur-ing charge-discharge cycling. However, an increase the PEGDMAcontent to 8 wt.% may suppress the ionic migration and the chargetransfer reaction, though it can promote strong interfacial adhesion.These results imply that the proper control of cross-linking densityin the cell is important to achieve good cycling performances.

SEM analysis of the lithium powder electrodes was performedafter 100 cycles of cells. Fig. 8 compares the SEM images of thesurface of lithium powder electrodes after cycling in different elec-trolytes. For the lithium powder electrode cycled in the liquidelectrolyte, the individual lithium powders did not retain their orig-inal spherical shapes, likely due to the repeated deposition andstripping of lithium on the powder surface during cycling. Somescattered and unevenly deposited lithium was observed on thepowder surface, which may grow to dendrites with further cycling.Alternatively, the lithium powder electrode in the cell assembled

by in-situ chemical cross-linking was covered by the gel polymerelectrolyte layer. In these electrodes, dendritic morphology washardly observed in the lithium powders, likely due to the forma-tion of the protective cross-linked gel polymer electrolyte layer on

6 chimic

tccllrbmt

ecfcPaAwrptdtatdiGaiPcic

4

cacdcgresa

A

aNCE

R

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

J.-A. Choi et al. / Electro

he electrode surface. Thus, stable cycling characteristics of theells with cross-linked gel polymer electrolytes shown in Fig. 6an be ascribed to the presence of the ionic conductive polymerayer covering the lithium powders, which suppresses growth ofithium dendrites during cycling, as explained earlier. Choi et al. alsoeported that the cell assembled with a lithium electrode protectedy a gel polymer electrolyte based on a semi-interpenetrating poly-er network exhibited better cycling characteristics compared to

he cell with an unprotected lithium electrode [33,34].The rate capability of the Li/LiV3O8 cells assembled with differ-

nt electrolytes was evaluated. The cells were charged to 3.6 V at aonstant current of 0.2 C and discharged at different current rates,rom 0.2 to 2.0 C. Voltage profiles of the lithium powder polymerell prepared with the gel polymer electrolyte cured by 6.0 wt.%EGDMA are presented in Fig. 9-(a). Both the discharge voltagend discharge capacity were nearly the same up to a 1.0 C rate.t a 2.0 C rate, the discharge capacity decreased to 188.4 mAh g−1,hich corresponds to 85% of the capacity as delivered at the 0.2 C

ate. Fig. 9-(b) compares the relative capacities of the Li/LiV3O8 cellsrepared with liquid electrolyte or cross-linked gel polymer elec-rolytes as a function of the current rate. The relative capacity isefined as the ratio of the discharge capacity at a specific C rateo the discharge capacity delivered at a 0.2 C rate. Notably, the rel-tive capacity of the cell cured with 6 wt.% PEGDMA was greaterhan that of the cell assembled with a liquid electrolyte. This resultemonstrates that the ionic conductivity of the electrolyte system

s not the only factor in determining the high rate performance.ood interfacial contact between electrodes (the Li powder anodend LiV3O8 cathode) and electrolyte is also important for improv-ng the rate capability at high current rates. However, increasing theEGDMA content to 8 wt.% decreased the relative capacity at a highurrent rate, which occurred from a reduction in the ionic mobil-ty in both the electrolyte and electrodes as a result of excessiveross-linking, as explained earlier.

. Conclusions

Lithium polymer cells assembled with lithium powder anode,ross-linked gel polymer electrolyte and LiV3O8 cathode delivered

relatively high discharge capacity and exhibited stable cyclingharacteristics. The morphological analysis of the lithium pow-er electrode demonstrated that the dendritic growth of lithiumould be effectively suppressed by the protective cross-linkedel polymer electrolyte layer on the lithium powder surface. Ouresults revealed that the lithium powder polymer cell with highnergy density and good capacity retention can be produced by in-itu chemical cross-linking of the electrolyte with an appropriatemount of cross-linking agent.

cknowledgements

This work was supported by Pohang Steel Corporation (POSCO)nd the Research Institute of Industrial Science & Technology (RIST,o. 2011K128) and a grant from the Fundamental R&D Program forore Technology of Materials, funded by the Ministry of Knowledgeconomy, Korea.

eferences

[1] A.S. Arico, P. Bruce, B. Scrosati, J.-M. Tarascon, W.V. Schalkwijk, Nanostruc-tured materials for advanced energy conversion and storage devices, NatureMaterials 4 (2005) 366.

[2] B. Dunn, H. Kamath, J.-M. Tarascon, Electrical energy storage for the grid: Abattery of choices, Science 928 (2011) 334.

[3] V. Etacheri, R. Marom, R. Elazari, G. Salitra, D. Aurbach, Challenges in the devel-opment of advanced Li-ion batteries: a review, Energy and EnvironmentalScience 4 (2011) 3243.

[

a Acta 132 (2014) 1–6

[4] N.S. Choi, Z. Chen, S.A. Freunberger, X. Ji, Y.K. Sun, K. Amine, G. Yushin, L.F. Nazar,J. Cho, P.G. Bruce, Challenges facing lithium batteries and electrical double-layercapacitors, Angewandte Chemie International Edition 51 (2012) 9994.

[5] J.M. Tarascon, M. Armand, Issues and challenges facing rechargeable lithiumbatteries, Nature 414 (2001) 359.

[6] D. Aurbach, E. Zinigard, Y. Cohen, H. Teller, A short review of failure mechanismsof lithium metal and lithiated graphite anodes in liquid electrolyte solutions,Solid State Ionics 148 (2002) 405.

[7] M. Rosso, C. Brissot, A. Teyssot, M. Dolle, L. Sannier, J.-M. Tarascon, R. Bouchet,S. Lascaud, Dendrite short-circuit and fuse effect on Li/polymer/Li cells, Elec-trochimica Acta 51 (2006) 5334.

[8] W.S. Kim, W.Y. Yoon, Observation of dendritic growth on Li powder anode usingoptical cell, Electrochimica Acta 50 (2004) 541.

[9] Y.S. Lee, J.H. Lee, J.A. Choi, W.Y. Yoon, D.W. Kim, Cycling characteristics oflithium powder polymer batteries assembled with composite gel polymer elec-trolytes and lithium powder anode, Advanced Functional Materials 23 (2013)1019.

10] K. West, Z. Bachau-C, S. Skaarup, Y. Saidi, J. Barker, I.I. Olsen, R. Pynenburg,R. Koksbang, Comparison of LiV3 O8 cathode materials prepared by differentmethods, Journal of the Electrochemical Society 143 (1996) 820.

11] G.Q. Liu, C.L. Zeng, K. Yang, Study on the synthesis and properties of LiV3O8

rechargeable lithium batteries cathode, Electrochimica Acta 47 (2002) 3239.12] S. Jouanneau, A.L. La Salle, A. Verbaere, D. Guyomard, The origin of capacity

fading upon lithium cycling in Li1.1V3O8, Journal of the Electrochemical SocietyA1660 (2005) 152.

13] N. Tran, K.G. Bramnik, H. Hibst, J. Prolb, N. Mronga, M. Holzapfel, W. Scheifele,P. Novak, Spray-drying synthesis and electrochemical performance of lithiumvanadates as positive electrode materials for lithium batteries, Journal of theElectrochemical Society 155 (2008) A384.

14] S.H. Ju, Y.C. Kang, Morphological and electrochemical properties of LiV3O8 cath-ode powders prepared by spray pyrolysis, Electrochimica Acta 55 (2010) 6088.

15] Y.Q. Qiao, X.L. Wang, J.P. Zhou, J. Zhang, C.D. Gu, J.P. Tu, Synthesis and electro-chemical performance of rod-like LiV3O8 cathode materials for rechargeablelithium batteries, Journal of Power Sources 198 (2012) 287.

16] K.M. Abraham, H.S. Choe, D.M. Pasquariello, Polyacrylonitrile electrolyte-basedLi ion batteries, Electrochimica Acta 43 (1998) 2399.

17] J.Y. Song, Y.Y. Wang, C.C. Wan, Review of gel-type polymer electrolytes forlithium-ion Batteries, Journal of Power Sources 77 (1999) 183.

18] K. Zaghib, P. Charest, A. Guerfi, J. Shim, M. Perrier, K. Striebel, Safe Li-ion polymerbatteries for HEV applications, Journal of Power Sources 134 (2004) 124.

19] V.D. Noto, S. Lavina, G.A. Giffin, E. Negro, B. Scrosati, Polymer electrolytes:Present, past and future, Electrochimica Acta (2011) 4.

20] J.A. Choi, Y. Kang, D.W. Kim, Lithium polymer cell assembled by in-situ chemicalcross-linking of ionic liquid electrolyte with phosphazene-based cross-linkingagent, Electrochimica Acta 89 (2013) 359.

21] W. Kim, J.J. Cho, Y. Kang, D.W. Kim, Study on cycling performances of lithium-ion polymer cells assembled by in situ chemical cross-linking with star-shapedsiloxane acrylate, Journal of Power Sources 178 (2008) 837.

22] J.R. Nair, C. Gerbaldi, G. Meligrana, R. Bongiovanni, S. Bodoardo, N. Penazzi,P. Reale, V. Gentili, UV-cured methacrylic membranes as novel gel–polymerelectrolyte for Li-ion batteries, Journal of Power Sources 178 (2008) 751.

23] J. Reiter, R. Dominko, M. Nadherna, I. Jakubec, Ion-conducting lithium bis(oxalato) boratebased polymer electrolytes, Journal of Power Sources 189(2009) 133.

24] J.A. Choi, Y.K. Kang, H.J. Shim, D.W. Kim, E.H. Cha, D.W. Kim, Cyclingperformance of a lithium-ion polymer cell assembled by in-situ chemical cross-linking with fluorinated phosphorous-based cross-linking, Journal of PowerSources 195 (2010) 6177.

25] Y.W. Lee, W.K. Shin, D.W. Kim, Cycling performance of lithium-ion polymerbatteries assembled using in-situ chemical cross-linking without a free radicalinitiator, Solid State Ionics 255 (2014) 6.

26] H.E. Park, I.W. Seong, W.Y. Yoon, Electrochemical behaviors of wax-coated Lipowder/Li4Ti5O12 cells, Journal of Power Sources 189 (2009) 499.

27] A.C. Karmaker, A.T. Dibenedetto, A.J. Goldberg, Extent of conversion and itseffect on the mechanical performance of Bis-GMA/PEGDMA-based resins andtheir composites with continuous glass fibres, Journal of Materials Science:Materials in Medicine 8 (1997) 369.

28] Z. Tang, L. Qi, G. Gao, Polymer electrolytes based on copolymer of poly(ethyleneglycol) dimethacrylate and imidazolium ionic liquid, Solid State Ionics 180(2009) 226.

29] H. Liu, Y. Wang, W. Yang, H. Zhou, Large capacity of LiV3O8 cathode materialfor rechargeable lithium-based batteries, Electrochimica Acta 56 (2011) 1392.

30] J. Kawakita, T. Miura, T. Kishi, Lithium insertion and extraction kinetics ofLi1+xV3O8, Journal of Power Sources 83 (1999) 79.

31] Y.C. Chang, J.H. Jong, T.G. Fey, Kinetic characterization of the electrochemicalintercalation of lithium ions into graphite electrodes, Journal of the Electro-chemical Society 147 (2000) 2033.

32] S.S. Zhang, K. Xu, J.L. Allen, T.R. Jow, Effect of propylene carbonate on the lowtemperature performance of Li-ion cells, Journal of Power Sources 110 (2002)216.

33] N.S. Choi, Y.M. Lee, J.H. Park, J.K. Park, Interfacial enhancement between lithium

electrode and polymer electrolytes, Journal of Power Sources 119–121 (2003)610.

34] N.S. Choi, Y.M. Lee, W. Seol, J.A. Lee, J.K. Park, Protective coating of lithium metalelectrode for interfacial enhancement with gel polymer electrolyte, Solid StateIonics 172 (2004) 19.