- Email: [email protected]
Imidazolium ionic liquids as electrolytes for manganese dioxide free Leclanché batteries
Applied Energy 86 (2009) 1512–1516
Contents lists available at ScienceDirect
Applied Energy journal homepage: www.elsevier.com/locate/apenergy
Imidazolium ionic liquids as electrolytes for manganese dioxide free Leclanché batteries M.P. Stracke a, M.V. Migliorini b, E. Lissner a, H.S. Schrekker b, J. Dupont a, R.S. Gonçalves c,* a
Laboratory of Molecular Catalysis, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, P.O. Box 15003, CEP 91501-970, Porto Alegre – RS, Brazil b Laboratory of Technological Processes and Catalysis, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, P.O. Box 15003, CEP 91501-970, Porto Alegre – RS, Brazil c Laboratory of Electrochemistry, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, P.O. Box 15003, CEP 91501-970, Porto Alegre – RS, Brazil
a r t i c l e
i n f o
Article history: Received 7 July 2008 Received in revised form 12 November 2008 Accepted 14 November 2008 Available online 13 January 2009 Keywords: Energy storage Environmental impact Energy technology Leclanché battery Imidazolium ionic liquid electrolytes Benzoquinone reduction
a b s t r a c t A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic solid was screened for its potential as electrolytes in manganese dioxide free Leclanché batteries, equipped with a zinc anode and graphite cathode. Electrical impedance spectroscopy allowed to determine the room-temperature ionic solids (RTISs) ionic conductivities, which was the highest for carboxylic acid functionalized RTIS 3 [C2O2MIm][Cl]. The toxic manganese dioxide was substituted by benzoquinone. A systematic ionic conductivity optimization of RTIS 3–benzoquinone–ZnSO4–H2O mixtures at room temperature resulted in the identification of the following conditions for the Leclanché battery studies: 50 mg of a 50:50 RTIS:benzoquinone mixture and 96 mg of water. The chronopotentiometric experiments with a constant current of 5 lA showed a remarkable performance for the RTIS 3 based battery. The potential (1.47 V) and stability is comparable to that of the commercial RayovacÒ battery filling (model AA). Furthermore, linear potentiodynamic voltammetry (0.01 V/s) and chronoamperometric analysis at short-circuit conditions (0.0 V) validated the RTIS 3–benzoquinone–water battery as a promising alternative for manganese dioxide free Leclanché batteries. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction The discovery of air and water stable imidazolium room-temperature ionic liquids (RTILs) by the proper choice of the anion initiated intensive research efforts towards their application [1]. Further attractive physical and chemical properties of the imidazolium RTILs include [2–5]; a neglectable vapor pressure; low inflammability; display wide electrochemical windows; high inherent conductivities; thermal stability; liquidity over a wide temperature range; easy recycling; and being a good solvent for a wide variety of organic and inorganic chemical compounds. The physicochemical properties of an ionic liquid vary greatly depending on the molecular structure, e.g., miscibility with water and organic solvents [6,7], melting point, and viscosity [2]. Besides, imidazolium RTILs are ‘‘designable” as structural modifications in both the cation (especially the 1 and 3 positions of the imidazolium ring) and anion permit the possibility to design task-specific applications when the ionic liquid contain a specific functionality covalently incorporated in either the cation or anion [8–13]. As a result, appli* Corresponding author. Tel.: +55 51 3308 7236; fax: +55 51 3308 7304. E-mail address: [email protected] (R.S. Gonçalves). 0306-2619/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.apenergy.2008.11.014
cations of imidazolium RTILs are numerous and found in the fields of, for instance, extraction and separation processes [3,14,15], synthetic chemistry [3,5], catalysis (organometallic [4,5,16,17], transition-metal nanoparticle [16–21], bio [22]) and materials science [3,23]. The RTILs possess a number of unique properties that make them ideal in the field of electrochemistry, which is due to their chemical and electrochemical stability, wide electrochemical windows, and high electrical conductivities and ionic mobilities [2– 5,24–26]. Electrochemical applications of imidazolium RTILs as electrolytes are found in, e.g., fuel cells [27], electrodeposition [28], capacitors [29–31], solar cells [32,33], batteries [34], and water electrolysis for hydrogen generation [35]. However, the use of imidazolium RTILs could suffer from sealing problems due to leakage issues. Possible alternatives are, e.g., imidazolium RTIL polymer homologues as gel [36] or solid [37] polyelectrolytes, and imidazolium RTILs confined in silica-derived networks (ionogels) [38] and polymers [29]. Without doubt, the direct application of imidazolium ionic liquids that are solid at room temperature and imidazolium ionic solids would be another attractive option for batteries and capacitors. Previously we have studied the electrochemical properties of imidazolium RTISs by electrical impedance
M.P. Stracke et al. / Applied Energy 86 (2009) 1512–1516
spectroscopy [39]. Herein, we report about the application of imidazolium RTISs as electrolytes in Leclanché batteries. Besides, the toxic manganese dioxide [40] was substituted with benzoquinone, which is recyclable [41–42]. Optimization of this RTIS–benzoquinone based Leclanché battery resulted in performances comparable to that of the commercial RayovacÒ battery electrolyte (model AA). 2. Experimental
1513
removed. Its interior was washed with ethanol and water, and dried under vacuum. A paper separator was impregnated with hydrophilic RTIS 1 and used as bridge salt. The teflon film in the battery interior was necessary to isolate the Zn/Zn2+ and benzoquinone/hydroquinone semi-cells. The total weight of the RTIS– benzoquinone–ZnSO4 battery mixture was kept constant at 500 mg. A computer-controlled potentiostat Autolab PGSTAT 30 was connected to the home-made battery. The humidity and the temperature were kept constant.
2.1. Materials 3. Results and discussion Benzoquinone and ZnSO4 were used as purchased from Sigma– Aldrich. Deionized water was used from Easy pure LF. Ethanol 96% (v/v) was purchased from VETEC Química Fina LTDA and used without further purification. 2.2. Preparation of imidazolium room-temperature ionic solids The deaerated imidazolium RTISs 1 [43], 2a–c [43–46], and 3 [47] were prepared according to known procedures, and the NMR spectral data were in agreement with the literature data. 2.3. Electrical impedance spectroscopy The ionic conductivities (r) of the RTISs 1–3 and the RTIS 3 based battery fillings were determined by electrical impedance spectroscopy as described previously [39]. 2.4. Leclanché battery
The RTISs applied in this work are presented in Fig. 2, and can be divided in three classes: (1) RTIS 1: hydrophilic; (2) RTISs 2a–c: hydrophobic; and (3) RTIS 3: hydrophilic and functionalized with a carboxylic acid group. Fig. 3 shows the ionic conductivity of RTIS 3 [C2O2MIm][Cl] at different temperatures. The same ionic conductivity-temperature correlation was observed for the RTISs 1 and 2a–c [39]. As such, the transport of the species involved in the charge transfer reaction is temperature dependent. Furthermore, the ionic conductivity was characterized by two distinct temperature dependencies: (1) small conductivity increases in the lower temperature range and (2) large conductivity increases in the higher temperature range. The ionic conductivities of the RTISs 1–3 at room temperature are presented in Table 1. Ionic conductivities of 1.4–12 lS m 1 were determined for the RTISs 1–2. In strong contrast, carboxylic acid functionalized RTIS 3 showed a much higher ionic conductivity of 500 lS m 1.
A home-made device (Fig. 1), equipped with a zinc anode and graphite cathode, was used to perform the Leclanché battery tests. A commercial alkaline RayovacÒ Leclanché battery (model AA) was reduced to 1/3 of its initial size, and the battery filling was
Fig. 1. Illustration of the home-made Leclanché battery.
Fig. 3. Ionic conductivity of RTIS 3 [C2O2MIm][Cl] at different temperatures.
Fig. 2. Imidazolium room-temperature ionic solids applied in this work.
1514
M.P. Stracke et al. / Applied Energy 86 (2009) 1512–1516
Table 1 Conductivities of the imidazolium RTISs 1–3 at room temperature. Entry
RTISa
r (lS m 1)b
1 2 3 4 5
1 [PhC3MIm][SO3CH3] 2a [Ph2C2MIm][NTf2] 2b [PhC3MIm][NTf2] 2c [PhC2MIm][NTf2] 3 [C2O2MIm][Cl]
12 1.4 3.6 6.7 500
a b
RTIS = room-temperature ionic solid. Ionic conductivity determined by electrical impedance spectroscopy.
RTIS 3 was chosen as electrolyte for the optimization of the room-temperature ionic conductivity of the battery filling (Table 2). The RTIS 3–benzoquinone–ZnSO4 ratio and the water content were varied. Addition of 12 mg of water to a 50:50 mixture of RTIS 3:benzoquinone resulted in a strongly increased ionic conductivity (Table 2, entries 1 and 2), which is desired for its application in Leclanché batteries. This increased ionic conductivity is probably due to the solubilization of the RTIS 3 in water. All other modifications of the battery filling composition resulted in reduced ionic conductivities, including: (1) a decreased ratio of RTIS 3:benzoquinone (Table 2, entries 5 and 6) and (2) addition of ZnSO4 (Table 2, entries 3, 4, and 7). As a consequence, the performance of the RTISs 1–3 as electrolytes in Leclanché batteries was studied with the 50:50 ratio of 500 mg RTIS:benzoquinone and the addition of 96 mg of water. A home-made Leclanché battery (Fig. 1) was used to validate the RTIS–benzoquinone based battery fillings. The chronopotentiometric performance of these RTIS–benzoquinone systems was com-
pared with the manganese dioxide based filling of a commercial RayovacÒ Leclanché battery (model AA), utilizing a constant current of 5 lA. All potential x time curves are shown in Fig. 4. A higher ionic conductivity (Table 1) of the RTIS seems to correlate to a higher potential of the RTIS–benzoquinone battery. The hydrophobic RTISs 2a–c showed the lowest potentials. Besides, the potential dropped with time when the RTISs 2a–b was used as electrolyte. The chronoamperometric performance of the system employing RTIS 3 [C2O2MIm][Cl] showed a high potential (1.47 V) quite close to that observed with the commercial RayovacÒ battery filling (1.56 V). Furthermore, this RTIS 3 based battery demonstrated an excellent stability as the potential did not decay after at least 8 h. Potentiodynamic linear voltammetric studies provided further support for the excellent performance of the RTIS 3 based Leclanché battery (Fig. 5). A potentiodynamic potential perturbation was applied on the battery, and the current x potential curves were recorded at a sweep rate of 0.01 V s 1. The current values for the batteries with the RTISs 2a–c were insignificant. Interestingly, a 20% higher current value was observed at the end of the scan with
Table 2 Ionic conductivity optimization of the RTIS 3 based battery filling. Entry
RTIS 3:benzoquinone:ZnSO4a,b
H2O (mg)
r (lS m 1)c
1 2 3 4 5 6 7
50:50:0 50:50:0 10:80:10 10:80:10 10:90:0 10:90:0 45:45:10
0 12 0 12 0 12 0
88 34,000 0.44 2.5 40 1000 100
a b c
RTIS = room-temperature ionic solid. The total weight of RTIS 3, benzoquinone, and ZnSO4 was 50 mg. Ionic conductivity determined by electrical impedance spectroscopy.
Fig. 4. Chronopotentiometric analyses of the Leclanché batteries at a current of 5 lA and room temperature: RTIS 2a [Ph2C2MIm][NTf2] (a); RTIS 2b [PhC3MIm][NTf2] (b); RTIS 2c [PhC2MIm][NTf2] (c); RTIS 3 [C2O2MIm][Cl] (d), and commercial RayovacÒ battery (e).
Fig. 5. Potentiodynamic linear voltammetry recorded at room temperature (0.01 V/s): RTIS 2a Ph2C2MIm][NTf2] (a); RTIS 2b [PhC3MIm][NTf2] (b); RTIS 2c [PhC2MIm][NTf2] (c); RTIS 3 [C2O2MIm][Cl] (d), and commercial RayovacÒ battery (e).
Fig. 6. Chronoamperometric analyses at short-circuit (0.0 V): RTIS 2a Ph2C2MIm][NTf2] (a); RTIS 2b [PhC3MIm][NTf2] (b); RTIS 2c [PhC2MIm][NTf2] (c); RTIS 3 [C2O2MIm][Cl] (d), and commercial RayovacÒ battery (e).
M.P. Stracke et al. / Applied Energy 86 (2009) 1512–1516
Scheme 1. Charge transfer reactions involved in the Zn–benzoquinone Leclanché battery.
RTIS 3 when compared to that of the commercial RayovacÒ battery filling. Chronoamperometric analyses were carried out by applying a potential of 0.0 V (short-circuit) in order to compare the current x time curves (Fig. 6). Both the RTIS 3–benzoquinone based battery and the commercial RayovacÒ battery filling showed a similar discharge curve, which further demonstrates the high potential of this manganese dioxide free Leclanché battery. The charge transfer processes observed in Fig. 6 with this Zn– benzoquinone based Leclanché battery are most likely due to the reactions presented in Scheme 1. The anodic reaction should be associated with zinc oxidation (Zn/Zn2+) and the cathodic reaction should be the result of benzoquinone reduction (Benzoquinone/ Hydroquinone). 4. Conclusions In conclusion, the high ionic conductivity of RTIS 3 appeared to be decisive for its successful application as electrolyte in a Leclanché battery with benzoquinone as manganese dioxide substitute. The addition of a small amount of water to a 50:50 mixture of RTIS 3:benzoquinone resulted in a battery filling with an excellent ionic conductivity. Higher ionic conductivities are related to higher Leclanché battery potentials. Chronopotentiometric, potentiodynamic linear voltammetric, and chronoamperometric studies showed an excellent performance of the RTIS 3–benzoquinone battery, which was similar to that of the commercial RayovacÒ battery filling. As such, the RTIS–benzoquinone battery filling is a promising option for the development of manganese dioxide free Leclanché batteries, which is important to diminish the amount of toxic manganese dioxide that ends up as trash in the ambient. Acknowledgement The authors thank the CNPq for financial support. References [1] Suarez PAZ, Dullius JEL, Einloft S, de Souza RF, Dupont J. The use of new ionic liquids in two-phase catalytic hydrogenation reaction by rhodium complexes. Polyhedron 1996;15:1217–9. [2] Wasserscheid P, Welton T. Ionic liquids in synthesis. 1st ed. Weinheim: VCH; 2002. [3] Dupont J, Consorti CS, Spencer J. Room temperature molten salts: neoteric ‘‘green” solvents for chemical reactions and processes. J Braz Chem Soc 2000;11:337–44. [4] Dupont J, de Souza RF, Suarez PAZ. Ionic liquid (molten salt) phase organometallic catalysis. Chem Rev 2002;102:3667–92. [5] Welton T. Room-temperature ionic liquids. Solvents for synthesis and catalysis. Chem Rev 1999;99:2071–83. [6] Schrekker HS, Stracke MP, Schrekker CML, Dupont J. Ether-functionalized imidazolium hexafluorophosphate ionic liquids for improved water miscibilities. Ind Eng Chem Res 2007;46:7389–92.
1515
[7] Dupont J, Silva SM, de Souza RF. Mobile phase effects in Rh/sulfonated phosphine/molten salts catalysed the biphasic hydroformylation of heavy olefins. Catal Lett 2001;77:131–3. [8] Lee SG. Functionalized imidazolium salts for task-specific ionic liquids and their applications. Chem Commun 2006;10:1049–63. [9] Davis JH. Task-specific ionic liquids. Chem Lett 2004;33:1072–7. [10] Fei ZF, Geldbach TJ, Zhao DB, Dyson PJ. From dysfunction to bis-function: on the design and applications of functionalised ionic liquids. Chem Eur J 2006;12:2122–30. [11] Schrekker HS, Gelesky MA, Stracke MP, Schrekker CML, Machado G, Teixeira SR, et al. Disclosure of the imidazolium cation coordination and stabilization mode in ionic liquid stabilized gold(0) nanoparticles. J Colloids Interf Sci 2007;316:189–95. [12] Cassol CC, Ebeling G, Ferrera B, Dupont J. A simple and practical method for the preparation and purity determination of halide-free imidazolium ionic liquids. Adv Synth Catal 2006;348:243–8. [13] Schrekker HS, Silva DO, Gelesky MA, Stracke MP, Schrekker CML, Gonçalves RS, et al. Preparation, cation–anion interactions and physicochemical properties of ether-functionalized imidazolium ionic liquids. J Braz Chem Soc 2008;19: 426–33. [14] Huddleston JG, Willauer HD, Swatloski RP, Visser AE, Rogers RD. Room temperature ionic liquids as novel media for ‘clean’ liquid–liquid extraction. Chem Commun 1998:1765–6. [15] Abraham MH, Zissimos AM, Huddleston JG, Willauer HD, Rogers RD, Acree Jr WE. Some novel liquid partitioning systems: water-ionic liquids and aqueous biphasic systems. Ind Eng Chem Res 2003;42:413–8. [16] Welton T. Ionic liquids in catalysis. Coord Chem Rev 2004;248:2459–77. [17] Pârvulescu VI, Hardacre C. Catalysis in ionic liquids. Chem Rev 2007;107: 2615–65. [18] Astruc D, Lu F, Aranzaes JR. Nanoparticles as recyclable catalysts: the frontier between homogeneous and heterogeneous catalysis. Angew Chem Int Ed 2005;44:7852–72; Angew Chem 2005;117:8062–82. [19] Migowski P, Dupont J. Catalytic applications of metal nanoparticles in imidazolium ionic liquids. Chem Eur J 2007;13:32–9. [20] Roucoux A, Schulz J, Patin H. Reduced transition metal colloids: a novel family of reusable catalysts? Chem Rev 2002;102:3757–78. [21] Ott LS, Finke RG. Transition-metal nanocluster stabilization for catalysis: a critical review of ranking methods and putative stabilizers. Coord Chem Rev 2007;251:1075–100. [22] Yang Z, Pan W. Ionic liquids: green solvents for nonaqueous biocatalysis. Enzyme Microb Technol 2005;37:19–28. [23] Klingshirn MA, Spear SK, Holbrey JD, Rogers RD. Ionic liquids as solvent and solvent additives for the synthesis of sol–gel materials. J Mater Chem 2005;15:5174–80. [24] Suarez PAZ, Selbach VM, Dullius JEL, Einloft S, Piatnicki CMS, Azambuja DS, et al. Enlarged electrochemical window in dialkyl-imidazolium cation based room-temperature air and molten salts. Electrochim Acta 1997;42:2533–5. [25] Donato RK, Migliorini MV, Benvegnú MA, Dupont J, Gonçalves RS, Schrekker HS. The electrochemical properties of a platinum electrode in functionalized room temperature imidazolium ionic liquids. J Solid State Electrochem 2007;11:1481–7. [26] Migliorini MV, Donato RK, Benvegnú MA, Dupont J, Gonçalves RS, Schrekker HS. Imidazolium ionic liquid–water mixtures: the formation of a new species that inhibits the electrocatalytical charge transfer processes on a platinum surface. Catal Commun 2008;9:971–5. [27] de Souza RF, Padilha JC, Gonçalves RS, Dupont J. Room temperature dialkylimidazolium ionic liquid-based fuel cells. Electrochem Commun 2003;5:728–31. [28] Abedin SZE, Endres F. Electrodeposition of metals and semiconductors in airand water-stable ionic liquids. Chem Phys Chem 2006;7:58–61. [29] Lewandowski A, S´widerska A. Solvent-free double-layer capacitors with polymer electrolytes based on 1-ethyl-3-methylimidazolium triflate ionic liquid. Appl Phys A 2006;82:579–84. [30] Zhu Q, Song Y, Zhu X, Wang X. Ionic liquid-based electrolytes for capacitor applications. J Electroanal Chem 2007;601:229–36. [31] McEwen AB, Ngo HL, LeCompte K, Goldman JL. Electrochemical properties of imidazolium salt electrolytes for electrochemical capacitor applications. J Electrochem Soc 1999;146:1687–95. [32] Stathatos E, Lianos P, Jovanovski V, Orel B. Dye-sensitized photoelectrochemical solar cells based on nanocomposite organic–inorganic materials. J Photochem Photobiol A – Chem 2005;169:57–61. [33] Papageorgiou N, Athanassov Y, Armand M, Bonhôte P, Pettersson H, Azam A, et al. The performance and stability of ambient temperature molten salts for solar cell applications. J Electrochem Soc 1996;143:3099–108. [34] Markevich E, Baranchugov V, Aurbach D. On the possibility of using ionic liquids as electrolyte solutions for rechargeable 5 V Li ion batteries. Electrochem Commun 2006;8:1331–4. [35] de Souza RF, Padilha JC, Gonçalves RS, de Souza MO, Rault-Berthelot J. Electrochemical hydrogen production from water electrolysis using ionic liquid as electrolytes: towards the best device. J Power Sources 2007;164: 792–8. [36] Yang F, Jiao L, Shen Y, Xu X, Zhang Y, Niu L. Enhanced response induced by polyelectrolyte-functionalized ionic liquid in glucose biosensor based on sol– gel organic–inorganic hybrid material. J Electroanal Chem 2007;608:78–83.
1516
M.P. Stracke et al. / Applied Energy 86 (2009) 1512–1516
[37] Matsumi N, Sugai K, Miyake M, Ohno H. Polymerized ionic liquids via hydroboration polymerization as single ion conductive polymer electrolytes. Macromolecules 2006;39:6924–7. [38] Néouze M-A, Bideau JL, Gaveau P, Bellayer S, Vioux A. Ionogels, new materials arising from the confinement of ionic liquids within silica-derived networks. Chem Mater 2006;18:3931–6. [39] Stracke MP, Migliorini MV, Lissner E, Schrekker HS, Back D, Lang ES et al. Electrochemical methodology for determination of imidazolium ionic liquids (solids at room temperature) properties: influence of the temperature. New J Chem. doi:10.1039/b812258j. [40] Archuleta MM. Toxicity of materials used in the manufacture of lithium batteries. J Power Sources 1995;54:138–42. [41] Alt H, Binder H, Köhling A, Sandstede G. Investigation into the use of quinone compounds for battery cathodes. Electrochim Acta 1972;17:873–87. [42] Gall TL, Reiman KH, Grossel MC, Owen JR. Poly(2,5-dihydroxy-1,4-benzoquinone-3,6-methylene): a new organic polymer as positive electrode material for rechargeable lithium batteries. J Power Sources 2003;119–121:316–20.
[43] Stracke MP, Ebeling G, Cataluña R, Dupont J. Hydrogen-storage materials based on imidazolium ionic liquids. Energy Fuels 2007;21:1695–8. [44] Dzyuba SV, Bartsch RA. Influence of structural variations in 1-alkyl(aralkyl)-3methylimidazolium hexafluorophosphates and bis(trifluoromethylsulfonyl)imides on physical properties of the ionic liquids. Chem Phys Chem 2002;3: 161–6. [45] Lee JK, Kim MJ. Ionic liquid coated enzyme for biocatalysis in organic solvents. J Org Chem 2002;67:6845–7. [46] Moret ME, Chaplin AB, Lawrence AK, Scopelliti R, Dyson PJ. Synthesis and characterization of organometallic ionic liquids and a heterometallic carbene complex containing the chromium tricarbonyl fragment. Organometallics 2005;24:4039–48. [47] Fei Z, Zhao D, Geldbach TJ, Scopelitti R, Dyson PJ. Brønsted acidic ionic liquids and their zwitterions: synthesis, characterization and pKa determination. Chem Eur J 2004;10:4886–93.
Contents lists available at ScienceDirect
Applied Energy journal homepage: www.elsevier.com/locate/apenergy
Imidazolium ionic liquids as electrolytes for manganese dioxide free Leclanché batteries M.P. Stracke a, M.V. Migliorini b, E. Lissner a, H.S. Schrekker b, J. Dupont a, R.S. Gonçalves c,* a
Laboratory of Molecular Catalysis, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, P.O. Box 15003, CEP 91501-970, Porto Alegre – RS, Brazil b Laboratory of Technological Processes and Catalysis, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, P.O. Box 15003, CEP 91501-970, Porto Alegre – RS, Brazil c Laboratory of Electrochemistry, Institute of Chemistry, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, P.O. Box 15003, CEP 91501-970, Porto Alegre – RS, Brazil
a r t i c l e
i n f o
Article history: Received 7 July 2008 Received in revised form 12 November 2008 Accepted 14 November 2008 Available online 13 January 2009 Keywords: Energy storage Environmental impact Energy technology Leclanché battery Imidazolium ionic liquid electrolytes Benzoquinone reduction
a b s t r a c t A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic solid was screened for its potential as electrolytes in manganese dioxide free Leclanché batteries, equipped with a zinc anode and graphite cathode. Electrical impedance spectroscopy allowed to determine the room-temperature ionic solids (RTISs) ionic conductivities, which was the highest for carboxylic acid functionalized RTIS 3 [C2O2MIm][Cl]. The toxic manganese dioxide was substituted by benzoquinone. A systematic ionic conductivity optimization of RTIS 3–benzoquinone–ZnSO4–H2O mixtures at room temperature resulted in the identification of the following conditions for the Leclanché battery studies: 50 mg of a 50:50 RTIS:benzoquinone mixture and 96 mg of water. The chronopotentiometric experiments with a constant current of 5 lA showed a remarkable performance for the RTIS 3 based battery. The potential (1.47 V) and stability is comparable to that of the commercial RayovacÒ battery filling (model AA). Furthermore, linear potentiodynamic voltammetry (0.01 V/s) and chronoamperometric analysis at short-circuit conditions (0.0 V) validated the RTIS 3–benzoquinone–water battery as a promising alternative for manganese dioxide free Leclanché batteries. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction The discovery of air and water stable imidazolium room-temperature ionic liquids (RTILs) by the proper choice of the anion initiated intensive research efforts towards their application [1]. Further attractive physical and chemical properties of the imidazolium RTILs include [2–5]; a neglectable vapor pressure; low inflammability; display wide electrochemical windows; high inherent conductivities; thermal stability; liquidity over a wide temperature range; easy recycling; and being a good solvent for a wide variety of organic and inorganic chemical compounds. The physicochemical properties of an ionic liquid vary greatly depending on the molecular structure, e.g., miscibility with water and organic solvents [6,7], melting point, and viscosity [2]. Besides, imidazolium RTILs are ‘‘designable” as structural modifications in both the cation (especially the 1 and 3 positions of the imidazolium ring) and anion permit the possibility to design task-specific applications when the ionic liquid contain a specific functionality covalently incorporated in either the cation or anion [8–13]. As a result, appli* Corresponding author. Tel.: +55 51 3308 7236; fax: +55 51 3308 7304. E-mail address: [email protected] (R.S. Gonçalves). 0306-2619/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.apenergy.2008.11.014
cations of imidazolium RTILs are numerous and found in the fields of, for instance, extraction and separation processes [3,14,15], synthetic chemistry [3,5], catalysis (organometallic [4,5,16,17], transition-metal nanoparticle [16–21], bio [22]) and materials science [3,23]. The RTILs possess a number of unique properties that make them ideal in the field of electrochemistry, which is due to their chemical and electrochemical stability, wide electrochemical windows, and high electrical conductivities and ionic mobilities [2– 5,24–26]. Electrochemical applications of imidazolium RTILs as electrolytes are found in, e.g., fuel cells [27], electrodeposition [28], capacitors [29–31], solar cells [32,33], batteries [34], and water electrolysis for hydrogen generation [35]. However, the use of imidazolium RTILs could suffer from sealing problems due to leakage issues. Possible alternatives are, e.g., imidazolium RTIL polymer homologues as gel [36] or solid [37] polyelectrolytes, and imidazolium RTILs confined in silica-derived networks (ionogels) [38] and polymers [29]. Without doubt, the direct application of imidazolium ionic liquids that are solid at room temperature and imidazolium ionic solids would be another attractive option for batteries and capacitors. Previously we have studied the electrochemical properties of imidazolium RTISs by electrical impedance
M.P. Stracke et al. / Applied Energy 86 (2009) 1512–1516
spectroscopy [39]. Herein, we report about the application of imidazolium RTISs as electrolytes in Leclanché batteries. Besides, the toxic manganese dioxide [40] was substituted with benzoquinone, which is recyclable [41–42]. Optimization of this RTIS–benzoquinone based Leclanché battery resulted in performances comparable to that of the commercial RayovacÒ battery electrolyte (model AA). 2. Experimental
1513
removed. Its interior was washed with ethanol and water, and dried under vacuum. A paper separator was impregnated with hydrophilic RTIS 1 and used as bridge salt. The teflon film in the battery interior was necessary to isolate the Zn/Zn2+ and benzoquinone/hydroquinone semi-cells. The total weight of the RTIS– benzoquinone–ZnSO4 battery mixture was kept constant at 500 mg. A computer-controlled potentiostat Autolab PGSTAT 30 was connected to the home-made battery. The humidity and the temperature were kept constant.
2.1. Materials 3. Results and discussion Benzoquinone and ZnSO4 were used as purchased from Sigma– Aldrich. Deionized water was used from Easy pure LF. Ethanol 96% (v/v) was purchased from VETEC Química Fina LTDA and used without further purification. 2.2. Preparation of imidazolium room-temperature ionic solids The deaerated imidazolium RTISs 1 [43], 2a–c [43–46], and 3 [47] were prepared according to known procedures, and the NMR spectral data were in agreement with the literature data. 2.3. Electrical impedance spectroscopy The ionic conductivities (r) of the RTISs 1–3 and the RTIS 3 based battery fillings were determined by electrical impedance spectroscopy as described previously [39]. 2.4. Leclanché battery
The RTISs applied in this work are presented in Fig. 2, and can be divided in three classes: (1) RTIS 1: hydrophilic; (2) RTISs 2a–c: hydrophobic; and (3) RTIS 3: hydrophilic and functionalized with a carboxylic acid group. Fig. 3 shows the ionic conductivity of RTIS 3 [C2O2MIm][Cl] at different temperatures. The same ionic conductivity-temperature correlation was observed for the RTISs 1 and 2a–c [39]. As such, the transport of the species involved in the charge transfer reaction is temperature dependent. Furthermore, the ionic conductivity was characterized by two distinct temperature dependencies: (1) small conductivity increases in the lower temperature range and (2) large conductivity increases in the higher temperature range. The ionic conductivities of the RTISs 1–3 at room temperature are presented in Table 1. Ionic conductivities of 1.4–12 lS m 1 were determined for the RTISs 1–2. In strong contrast, carboxylic acid functionalized RTIS 3 showed a much higher ionic conductivity of 500 lS m 1.
A home-made device (Fig. 1), equipped with a zinc anode and graphite cathode, was used to perform the Leclanché battery tests. A commercial alkaline RayovacÒ Leclanché battery (model AA) was reduced to 1/3 of its initial size, and the battery filling was
Fig. 1. Illustration of the home-made Leclanché battery.
Fig. 3. Ionic conductivity of RTIS 3 [C2O2MIm][Cl] at different temperatures.
Fig. 2. Imidazolium room-temperature ionic solids applied in this work.
1514
M.P. Stracke et al. / Applied Energy 86 (2009) 1512–1516
Table 1 Conductivities of the imidazolium RTISs 1–3 at room temperature. Entry
RTISa
r (lS m 1)b
1 2 3 4 5
1 [PhC3MIm][SO3CH3] 2a [Ph2C2MIm][NTf2] 2b [PhC3MIm][NTf2] 2c [PhC2MIm][NTf2] 3 [C2O2MIm][Cl]
12 1.4 3.6 6.7 500
a b
RTIS = room-temperature ionic solid. Ionic conductivity determined by electrical impedance spectroscopy.
RTIS 3 was chosen as electrolyte for the optimization of the room-temperature ionic conductivity of the battery filling (Table 2). The RTIS 3–benzoquinone–ZnSO4 ratio and the water content were varied. Addition of 12 mg of water to a 50:50 mixture of RTIS 3:benzoquinone resulted in a strongly increased ionic conductivity (Table 2, entries 1 and 2), which is desired for its application in Leclanché batteries. This increased ionic conductivity is probably due to the solubilization of the RTIS 3 in water. All other modifications of the battery filling composition resulted in reduced ionic conductivities, including: (1) a decreased ratio of RTIS 3:benzoquinone (Table 2, entries 5 and 6) and (2) addition of ZnSO4 (Table 2, entries 3, 4, and 7). As a consequence, the performance of the RTISs 1–3 as electrolytes in Leclanché batteries was studied with the 50:50 ratio of 500 mg RTIS:benzoquinone and the addition of 96 mg of water. A home-made Leclanché battery (Fig. 1) was used to validate the RTIS–benzoquinone based battery fillings. The chronopotentiometric performance of these RTIS–benzoquinone systems was com-
pared with the manganese dioxide based filling of a commercial RayovacÒ Leclanché battery (model AA), utilizing a constant current of 5 lA. All potential x time curves are shown in Fig. 4. A higher ionic conductivity (Table 1) of the RTIS seems to correlate to a higher potential of the RTIS–benzoquinone battery. The hydrophobic RTISs 2a–c showed the lowest potentials. Besides, the potential dropped with time when the RTISs 2a–b was used as electrolyte. The chronoamperometric performance of the system employing RTIS 3 [C2O2MIm][Cl] showed a high potential (1.47 V) quite close to that observed with the commercial RayovacÒ battery filling (1.56 V). Furthermore, this RTIS 3 based battery demonstrated an excellent stability as the potential did not decay after at least 8 h. Potentiodynamic linear voltammetric studies provided further support for the excellent performance of the RTIS 3 based Leclanché battery (Fig. 5). A potentiodynamic potential perturbation was applied on the battery, and the current x potential curves were recorded at a sweep rate of 0.01 V s 1. The current values for the batteries with the RTISs 2a–c were insignificant. Interestingly, a 20% higher current value was observed at the end of the scan with
Table 2 Ionic conductivity optimization of the RTIS 3 based battery filling. Entry
RTIS 3:benzoquinone:ZnSO4a,b
H2O (mg)
r (lS m 1)c
1 2 3 4 5 6 7
50:50:0 50:50:0 10:80:10 10:80:10 10:90:0 10:90:0 45:45:10
0 12 0 12 0 12 0
88 34,000 0.44 2.5 40 1000 100
a b c
RTIS = room-temperature ionic solid. The total weight of RTIS 3, benzoquinone, and ZnSO4 was 50 mg. Ionic conductivity determined by electrical impedance spectroscopy.
Fig. 4. Chronopotentiometric analyses of the Leclanché batteries at a current of 5 lA and room temperature: RTIS 2a [Ph2C2MIm][NTf2] (a); RTIS 2b [PhC3MIm][NTf2] (b); RTIS 2c [PhC2MIm][NTf2] (c); RTIS 3 [C2O2MIm][Cl] (d), and commercial RayovacÒ battery (e).
Fig. 5. Potentiodynamic linear voltammetry recorded at room temperature (0.01 V/s): RTIS 2a Ph2C2MIm][NTf2] (a); RTIS 2b [PhC3MIm][NTf2] (b); RTIS 2c [PhC2MIm][NTf2] (c); RTIS 3 [C2O2MIm][Cl] (d), and commercial RayovacÒ battery (e).
Fig. 6. Chronoamperometric analyses at short-circuit (0.0 V): RTIS 2a Ph2C2MIm][NTf2] (a); RTIS 2b [PhC3MIm][NTf2] (b); RTIS 2c [PhC2MIm][NTf2] (c); RTIS 3 [C2O2MIm][Cl] (d), and commercial RayovacÒ battery (e).
M.P. Stracke et al. / Applied Energy 86 (2009) 1512–1516
Scheme 1. Charge transfer reactions involved in the Zn–benzoquinone Leclanché battery.
RTIS 3 when compared to that of the commercial RayovacÒ battery filling. Chronoamperometric analyses were carried out by applying a potential of 0.0 V (short-circuit) in order to compare the current x time curves (Fig. 6). Both the RTIS 3–benzoquinone based battery and the commercial RayovacÒ battery filling showed a similar discharge curve, which further demonstrates the high potential of this manganese dioxide free Leclanché battery. The charge transfer processes observed in Fig. 6 with this Zn– benzoquinone based Leclanché battery are most likely due to the reactions presented in Scheme 1. The anodic reaction should be associated with zinc oxidation (Zn/Zn2+) and the cathodic reaction should be the result of benzoquinone reduction (Benzoquinone/ Hydroquinone). 4. Conclusions In conclusion, the high ionic conductivity of RTIS 3 appeared to be decisive for its successful application as electrolyte in a Leclanché battery with benzoquinone as manganese dioxide substitute. The addition of a small amount of water to a 50:50 mixture of RTIS 3:benzoquinone resulted in a battery filling with an excellent ionic conductivity. Higher ionic conductivities are related to higher Leclanché battery potentials. Chronopotentiometric, potentiodynamic linear voltammetric, and chronoamperometric studies showed an excellent performance of the RTIS 3–benzoquinone battery, which was similar to that of the commercial RayovacÒ battery filling. As such, the RTIS–benzoquinone battery filling is a promising option for the development of manganese dioxide free Leclanché batteries, which is important to diminish the amount of toxic manganese dioxide that ends up as trash in the ambient. Acknowledgement The authors thank the CNPq for financial support. References [1] Suarez PAZ, Dullius JEL, Einloft S, de Souza RF, Dupont J. The use of new ionic liquids in two-phase catalytic hydrogenation reaction by rhodium complexes. Polyhedron 1996;15:1217–9. [2] Wasserscheid P, Welton T. Ionic liquids in synthesis. 1st ed. Weinheim: VCH; 2002. [3] Dupont J, Consorti CS, Spencer J. Room temperature molten salts: neoteric ‘‘green” solvents for chemical reactions and processes. J Braz Chem Soc 2000;11:337–44. [4] Dupont J, de Souza RF, Suarez PAZ. Ionic liquid (molten salt) phase organometallic catalysis. Chem Rev 2002;102:3667–92. [5] Welton T. Room-temperature ionic liquids. Solvents for synthesis and catalysis. Chem Rev 1999;99:2071–83. [6] Schrekker HS, Stracke MP, Schrekker CML, Dupont J. Ether-functionalized imidazolium hexafluorophosphate ionic liquids for improved water miscibilities. Ind Eng Chem Res 2007;46:7389–92.
1515
[7] Dupont J, Silva SM, de Souza RF. Mobile phase effects in Rh/sulfonated phosphine/molten salts catalysed the biphasic hydroformylation of heavy olefins. Catal Lett 2001;77:131–3. [8] Lee SG. Functionalized imidazolium salts for task-specific ionic liquids and their applications. Chem Commun 2006;10:1049–63. [9] Davis JH. Task-specific ionic liquids. Chem Lett 2004;33:1072–7. [10] Fei ZF, Geldbach TJ, Zhao DB, Dyson PJ. From dysfunction to bis-function: on the design and applications of functionalised ionic liquids. Chem Eur J 2006;12:2122–30. [11] Schrekker HS, Gelesky MA, Stracke MP, Schrekker CML, Machado G, Teixeira SR, et al. Disclosure of the imidazolium cation coordination and stabilization mode in ionic liquid stabilized gold(0) nanoparticles. J Colloids Interf Sci 2007;316:189–95. [12] Cassol CC, Ebeling G, Ferrera B, Dupont J. A simple and practical method for the preparation and purity determination of halide-free imidazolium ionic liquids. Adv Synth Catal 2006;348:243–8. [13] Schrekker HS, Silva DO, Gelesky MA, Stracke MP, Schrekker CML, Gonçalves RS, et al. Preparation, cation–anion interactions and physicochemical properties of ether-functionalized imidazolium ionic liquids. J Braz Chem Soc 2008;19: 426–33. [14] Huddleston JG, Willauer HD, Swatloski RP, Visser AE, Rogers RD. Room temperature ionic liquids as novel media for ‘clean’ liquid–liquid extraction. Chem Commun 1998:1765–6. [15] Abraham MH, Zissimos AM, Huddleston JG, Willauer HD, Rogers RD, Acree Jr WE. Some novel liquid partitioning systems: water-ionic liquids and aqueous biphasic systems. Ind Eng Chem Res 2003;42:413–8. [16] Welton T. Ionic liquids in catalysis. Coord Chem Rev 2004;248:2459–77. [17] Pârvulescu VI, Hardacre C. Catalysis in ionic liquids. Chem Rev 2007;107: 2615–65. [18] Astruc D, Lu F, Aranzaes JR. Nanoparticles as recyclable catalysts: the frontier between homogeneous and heterogeneous catalysis. Angew Chem Int Ed 2005;44:7852–72; Angew Chem 2005;117:8062–82. [19] Migowski P, Dupont J. Catalytic applications of metal nanoparticles in imidazolium ionic liquids. Chem Eur J 2007;13:32–9. [20] Roucoux A, Schulz J, Patin H. Reduced transition metal colloids: a novel family of reusable catalysts? Chem Rev 2002;102:3757–78. [21] Ott LS, Finke RG. Transition-metal nanocluster stabilization for catalysis: a critical review of ranking methods and putative stabilizers. Coord Chem Rev 2007;251:1075–100. [22] Yang Z, Pan W. Ionic liquids: green solvents for nonaqueous biocatalysis. Enzyme Microb Technol 2005;37:19–28. [23] Klingshirn MA, Spear SK, Holbrey JD, Rogers RD. Ionic liquids as solvent and solvent additives for the synthesis of sol–gel materials. J Mater Chem 2005;15:5174–80. [24] Suarez PAZ, Selbach VM, Dullius JEL, Einloft S, Piatnicki CMS, Azambuja DS, et al. Enlarged electrochemical window in dialkyl-imidazolium cation based room-temperature air and molten salts. Electrochim Acta 1997;42:2533–5. [25] Donato RK, Migliorini MV, Benvegnú MA, Dupont J, Gonçalves RS, Schrekker HS. The electrochemical properties of a platinum electrode in functionalized room temperature imidazolium ionic liquids. J Solid State Electrochem 2007;11:1481–7. [26] Migliorini MV, Donato RK, Benvegnú MA, Dupont J, Gonçalves RS, Schrekker HS. Imidazolium ionic liquid–water mixtures: the formation of a new species that inhibits the electrocatalytical charge transfer processes on a platinum surface. Catal Commun 2008;9:971–5. [27] de Souza RF, Padilha JC, Gonçalves RS, Dupont J. Room temperature dialkylimidazolium ionic liquid-based fuel cells. Electrochem Commun 2003;5:728–31. [28] Abedin SZE, Endres F. Electrodeposition of metals and semiconductors in airand water-stable ionic liquids. Chem Phys Chem 2006;7:58–61. [29] Lewandowski A, S´widerska A. Solvent-free double-layer capacitors with polymer electrolytes based on 1-ethyl-3-methylimidazolium triflate ionic liquid. Appl Phys A 2006;82:579–84. [30] Zhu Q, Song Y, Zhu X, Wang X. Ionic liquid-based electrolytes for capacitor applications. J Electroanal Chem 2007;601:229–36. [31] McEwen AB, Ngo HL, LeCompte K, Goldman JL. Electrochemical properties of imidazolium salt electrolytes for electrochemical capacitor applications. J Electrochem Soc 1999;146:1687–95. [32] Stathatos E, Lianos P, Jovanovski V, Orel B. Dye-sensitized photoelectrochemical solar cells based on nanocomposite organic–inorganic materials. J Photochem Photobiol A – Chem 2005;169:57–61. [33] Papageorgiou N, Athanassov Y, Armand M, Bonhôte P, Pettersson H, Azam A, et al. The performance and stability of ambient temperature molten salts for solar cell applications. J Electrochem Soc 1996;143:3099–108. [34] Markevich E, Baranchugov V, Aurbach D. On the possibility of using ionic liquids as electrolyte solutions for rechargeable 5 V Li ion batteries. Electrochem Commun 2006;8:1331–4. [35] de Souza RF, Padilha JC, Gonçalves RS, de Souza MO, Rault-Berthelot J. Electrochemical hydrogen production from water electrolysis using ionic liquid as electrolytes: towards the best device. J Power Sources 2007;164: 792–8. [36] Yang F, Jiao L, Shen Y, Xu X, Zhang Y, Niu L. Enhanced response induced by polyelectrolyte-functionalized ionic liquid in glucose biosensor based on sol– gel organic–inorganic hybrid material. J Electroanal Chem 2007;608:78–83.
1516
M.P. Stracke et al. / Applied Energy 86 (2009) 1512–1516
[37] Matsumi N, Sugai K, Miyake M, Ohno H. Polymerized ionic liquids via hydroboration polymerization as single ion conductive polymer electrolytes. Macromolecules 2006;39:6924–7. [38] Néouze M-A, Bideau JL, Gaveau P, Bellayer S, Vioux A. Ionogels, new materials arising from the confinement of ionic liquids within silica-derived networks. Chem Mater 2006;18:3931–6. [39] Stracke MP, Migliorini MV, Lissner E, Schrekker HS, Back D, Lang ES et al. Electrochemical methodology for determination of imidazolium ionic liquids (solids at room temperature) properties: influence of the temperature. New J Chem. doi:10.1039/b812258j. [40] Archuleta MM. Toxicity of materials used in the manufacture of lithium batteries. J Power Sources 1995;54:138–42. [41] Alt H, Binder H, Köhling A, Sandstede G. Investigation into the use of quinone compounds for battery cathodes. Electrochim Acta 1972;17:873–87. [42] Gall TL, Reiman KH, Grossel MC, Owen JR. Poly(2,5-dihydroxy-1,4-benzoquinone-3,6-methylene): a new organic polymer as positive electrode material for rechargeable lithium batteries. J Power Sources 2003;119–121:316–20.
[43] Stracke MP, Ebeling G, Cataluña R, Dupont J. Hydrogen-storage materials based on imidazolium ionic liquids. Energy Fuels 2007;21:1695–8. [44] Dzyuba SV, Bartsch RA. Influence of structural variations in 1-alkyl(aralkyl)-3methylimidazolium hexafluorophosphates and bis(trifluoromethylsulfonyl)imides on physical properties of the ionic liquids. Chem Phys Chem 2002;3: 161–6. [45] Lee JK, Kim MJ. Ionic liquid coated enzyme for biocatalysis in organic solvents. J Org Chem 2002;67:6845–7. [46] Moret ME, Chaplin AB, Lawrence AK, Scopelliti R, Dyson PJ. Synthesis and characterization of organometallic ionic liquids and a heterometallic carbene complex containing the chromium tricarbonyl fragment. Organometallics 2005;24:4039–48. [47] Fei Z, Zhao D, Geldbach TJ, Scopelitti R, Dyson PJ. Brønsted acidic ionic liquids and their zwitterions: synthesis, characterization and pKa determination. Chem Eur J 2004;10:4886–93.