Electrical properties of GdBaCo2O5+x for ITSOFC applications

In order to develop a cathode that can be used in intermediate temperature solid oxide fuel cells (ITSOFC), the double perovskite material GdBaCo₂O_5+x has been prepared and its electrode performance investigated at temperatures below 700 °C by AC impedance spectroscopy. Preliminary results show that the ASRs of GdBaCo₂O_5+x cathode materials are as low as 0.53 Ω cm² at 645 °C. This encouraging data identifies GdBaCo₂O_5+x as a potential cathode material for ITSOFCs.     

Evaluation of a cobalt-free Ba0.5Sr0.5Fe0.9Nb0.1O3?δ cathode material for intermediate-temperature solid oxide fuel cells

A cobalt-free Ba_0.5Sr_0.5Fe_0.9Nb_0.1O_3??? (BSFNb) perovskite-type oxide was investigated as the cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs) with Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte. XRD results showed that BSFNb cathode was chemically compatible with the electrolyte SDC up to 1,000?°C. The maximum output of anode-supported thin-film SOFC reached 503?mW?cm^?2 at 650?°C when employing humidified H₂ as fuel and static air as oxidizer. The electrode polarization resistance was low as 0.078????cm² at 650?°C, and the activation energy of the electrode polarization resistance was 129.72?kJ?mol^?1. The experimental results indicated that the cobalt-free BSFNb was a promising cathode candidate for IT-SOFCs.     

Synthesis and electric properties of perovskite Pr0.6Ca0.4Fe0.8Co0.2O3 for SOFC applications

In this study, polycrystalline powder Pr_0.6Ca_0.4Fe_0.8Co_0.2O₃ (PCFC) was synthesized by a sol–gel process. This oxide was analyzed by X-ray powder diffraction. Synthesized Pr_0.6Ca_0.4Fe_0.8Co_0.2O₃ showed up to be single phase and belongs to the orthorhombic crystalline system with a Pbnm space group. The microstructural features of the synthesized products display particles having an irregular morphology and a size in the range of 50–100 nm. X-ray diffraction (XRD) analysis shows the chemical compatibility between the PCFC cathode and the electrolyte Sm-doped ceria since no reaction products were honored when the material was mixed and co-fired at 1,000 °C for 168 h. The thermal expansion coefficient of PCFC 16.9?×?10^?6 °C^?1 is slightly higher than that of Ce_0.8Sm_0.2O_1.9 (SDC) over the studied temperature range. The greater contribution to the total resistance of the electrode is the electrochemical resistance associated with oxygen exchange in the cathode surface (0.96 Ωcm²). The dc four-probe measurement indicated that PCFC exhibits fairly high electrical conductivity, over 100 S cm^?1 at T?≥?500 °C, making this material promising as a cathode material for intermediate temperature solid oxide fuel cells.     

Electrical and electrochemical properties of SrBiMTiO<Subscript>6</Subscript> (M = Fe,Mn, Cr) as potential cathodes for solid oxide fuel cells

A series of perovskite oxides SrBiMTiO₆ (M = Fe, Mn, Cr) have been synthesized and characterized towards application as cathode materials for solid oxide fuel cells (SOFCs). X-ray diffraction (XRD) patterns reveal that all samples are stabilized in \( \mathrm{Pm}\ \overline{3}\mathrm{m} \) space group. Electrical conductivity, AC impedance characteristics, and thermal and chemical stability have been studied in order to assess their possible use as SOFC cathode materials. In comparison with other low electrical conductivity cathodes of SOFC, our results suggest that SrBiMnTiO₆, which has the highest electrical conductivity (4.02 S cm^?1) and moderate polarization resistance (0.104 Ω cm²) at 850 °C, is the most promising candidate among the three perovskite oxides for further study and optimization as a SOFC cathode material.     

Investigation of Ce0.9Sr0.1Cr0.5Co0.5O3−δ as the anode material for solid oxide fuel cells fueled with H2S

Ce_0.9Sr_0.1Cr_0.5Co_0.5O_3?δ (CSCrCo) as an anode catalyst was studied in a solid oxide fuel cell (SOFC), where hydrogen sulfide (H₂S) was used as fuel. The conductivities were evaluated with a four-probe DC technique in 3 % H₂-N₂ and 5 % H₂S-N₂ at 570–800 °C, respectively. X-ray diffraction (XRD) patterns show that CSCrCo powders are fluorite structure which is similar to that of CeO₂ parent (JCPDS card no. 34-0394). Meanwhile, CSCrCo anode material has good chemical compatibility with electrolyte (Ce_0.8Sm_0.2O_1.9 (SDC)) in N₂. Through the analysis of XRD and Fourier transform infrared patterns, no other new phase is detected after treatment in 5 % H₂S-N₂ at 800 °C for 5 h, which indicate that the material has a good sulfur tolerance. H₂ temperature-programmed reduction and Tafel curves indicate that the temperature of the best catalytic activity is 600 °C. The electrochemical properties of the cell comprising CSCrCo-SDC/SDC/Ag are measured in 5 % H₂S-N₂ at low temperatures (500 and 600 °C). The maximal open circuit voltage is 1.04 V, the maximal power density is 12.55 mW cm^?2, and the maximal current density is 40 mA cm^?2 at 500 °C. While at 600 °C, the corresponding values are 0.95 V, 14.21 mW cm^?2, and 90.01 mA cm^?2, respectively. After SOFC operating in 5 % H₂S, X-ray photoelectron spectroscopy is used to compare the fresh sample with the H₂S-treated one.     

RF-sputtered LiCoO2 thick films: microstructure and electrochemical performance as cathodes in aqueous and nonaqueous microbatteries

Films of LiCoO₂ are prepared on metallized silicon substrates using RF-magnetron sputtering technique. The microstructural properties of the films are investigated by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The films deposited at a substrate temperature of 250 °C with subsequent annealing at 650 °C exhibited hexagonal layered structure with R $ \overline 3 $ m symmetry. The kinetics of lithium ions in LiCoO₂ film cathode host matrix and its cycleability are studied in aqueous Pt//LiCoO₂ and nonaqueous Li//LiCoO₂ cell. Both the electrochemical cells at same current density of 50 μA cm^?2 delivered the same initial discharge capacity of about 60 μA h?cm^?2 μm^?1 with a chemical diffusion coefficient of ca. 10^?11 cm² s^?1 for Li⁺ ions. The capacity fade rates for the Pt//LiCoO₂ and Li//LiCoO₂ cells, in average are 3.0 and 0.15 % per cycle, respectively, for the first 20 cycles. The Pt//LiCoO₂ cell is found to be advantageous for small number of cycles and is cost effective than the Li//LiCoO₂ cell.     

Li+ transportation kinetics of FeF3 · 0.33H2O/C nanocomposite synthesized by one-step solid state method

A new cathode material for lithium ion battery FeF₃?·?0.33H₂O/C was synthesized successfully by a simple one-step chemico-mechanical method. It showed a noticeable initial discharge capacity of 233.9 mAh g^?1 and corresponding charge capacity of 186.4 mAh g^?1. A reversible capacity of ca.157.4 mAh g^?1 at 20 mA g^?1 can be obtained after 50 charge/discharge cycles. To elucidate the lithium ion transportation in the cathode material, the methods of electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) were applied to obtain the lithium diffusion coefficients of the material. Within the voltage level of 2.05–3.18 V, the method of EIS showed that \( {D}_{{\mathrm{Li}}^{+}} \) varied in the range of 1.2?×?10^?13?~?3.6?×?10^?14 cm² s^?1 with a maximum of 1.2?×?10^?13 cm² s^?1 at 2.5 V. The method of GITT gave a result of 8.1?×?10^?14?~?1.2?×?10^?15 cm² s^?1. The way and the range of the variation for lithium ion diffusion coefficients measured by the GITT method show close similarity with those obtained by the EIS method. Besides, they both reached their maximum at a voltage level of 2.5 V.     

Characterization of doped La0.7A0.3Cr0.5Mn0.5O3 − δ (A = Ca,Sr, Ba) electrodes for solid oxide fuel cells

Doped lanthanum manganese chromite based perovskite, La_0.7A_0.3Cr_0.5Mn_0.5O_3 ? δ (LACM, A = Ca, Sr, Ba), on yttria-stabilized zirconia (YSZ) electrolyte is investigated as potential electrode materials for solid oxide fuel cells (SOFCs). The electrical conductivity and electrochemical activity of LACM depend on the A-site dopant. The best electrochemical activity is obtained on the La_0.7Ca_0.3Cr_0.5Mn_0.5O_3 ? δ/YSZ (LCCM/YSZ) composite electrodes. The conductivity of LCCM is 29.9 S cm^? 1 at 800 °C in air, and the electrode polarization resistance (R_E) of the LCCM/YSZ composite cathode for the O₂ reduction reaction is 0.5 Ω cm² at 900 °C. The effect of Gd-doped ceria (GDC) impregnation on the LCCM cathode polarization resistances is also studied. GDC impregnation significantly enhances the electrochemical activity of the LCCM cathode. In the case of the 6.02 mg cm^? 2 GDC-impregnated LCCM cathode, R_E is 0.4 Ω cm² at 800 °C, ~ 60 times smaller than 24.4 Ω cm² measured on a LCCM cathode without the GDC impregnation. Finally the electrochemical activities of the doped lanthanum manganese chromites for the H₂ oxidation reaction are also investigated.     

PVA-assisted synthesis and characterization of nano-crystalline La3+ and Mg2+ co-doped CeO2 electrolyte for intermediate-temperature solid oxide fuel cells

A series of nano-crystalline ceria-based solid solution electrolyte, Ce_0.8La_0.2?x Mg_xO_2?δ (x?=?0.0, 0.05, 0.10, 0.15, and 0.2), were synthesized via the polyvinyl alcohol (PVA) assisted combustion method, and then characterized to the crystalline structure, powder morphology, sintering micro-structure, and electrical properties. Present study showed that Ce_0.8La_0.2?x Mg _x O_2?δ was exceedingly stable as a cubic phase in all temperature range and exhibited fine crystals ranging from 15 to 20 nm. After sintering at 1,400 °C, the as-prepared pellets exhibited a dense micro-structure with 96 % of theoretical density. The electrical conductivity was studied using AC impedance spectroscopy and it was observed that the composition Ce_0.8La_0.1?Mg_0.1O_2?δ showed higher electrical conductivity of 0.020 S?cm^?1 at 700 °C. The thermal expansion was measured using dilatometer technique in the temperature range 30–1,000 °C. The average thermal expansion coefficient of Ce_0.8La_0.1?Mg_0.1O_2?δ was 12.37?×?10^?6 K^?1, which was higher than that of the commonly used SOFC electrolyte YSZ (~10.8?×?10^?6 K^?1).     

Electrochemical characterization of ionic liquid based gel polymer electrolyte for lithium battery application

High molecular weight polymer poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP), ionic liquid 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIMFSI), and salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-based free-standing and conducting ionic liquid-based gel polymer electrolytes (ILGPE) have been prepared by solution cast method. Thermal, electrical, and electrochemical properties of 80 wt% IL containing gel polymer electrolyte (GPE) are investigated by thermogravimetric (TGA), impedance spectroscopy, linear sweep voltammetry (LSV), and cyclic voltammetry (CV). The 80 wt% IL containing GPE shows good thermal stability (~?200 °C), ionic conductivity (6.42?×?10^?4 S cm^?1), lithium ion conductivity (1.40?×?10^?4 S cm^?1 at 30 °C), and wide electrochemical stability window (~?4.10 V versus Li/Li⁺ at 30 °C). Furthermore, the surface of LiFePO₄ cathode material was modified by graphene oxide, with smooth and uniform coating layer, as confirmed by scanning electron microscopy (SEM), and with element content, as confirmed by energy dispersive X-ray (EDX) spectrum. The graphene oxide-coated LiFePO₄ cathode shows improved electrochemical performance with a good charge-discharge capacity and cyclic stability up to 50 cycles at 1C rate, as compared with the without coated LiFePO₄. At 30 °C, the discharge capacity reaches a maximum value of 104.50 and 95.0 mAh g^?1 for graphene oxide-coated LiFePO₄ and without coated LiFePO₄ at 1C rate respectively. These results indicated improved electrochemical performance of pristine LiFePO₄ cathode after coating with graphene oxide.     

Robust doped BaCeO<Subscript>3-δ</Subscript> electrolyte for IT-SOFCs

Single phase polycrystalline BaZr_0.3Ce_0.5Y_0.1Yb_0.1O_{3 - δ} electrolyte material was prepared by solid state reaction route. Rietveld analysis of the XRD data confirms the tetragonal symmetry in the I4/mcm space group with unit cell parameters of a = b = 6.0567(3) Å and c = 8.5831(5) Å. The addition of ZnO as a sintering additive was found to reduce the sintering temperature and enhance both overall sinterability and grain growth. Sintering temperature was reduced by 200–300 °C, and a very high relative density of about 98% was achieved at 1400 °C. Impedance spectroscopy in humidified 5% H₂/Ar atmosphere shows that the protonic conductivity at 600 °C was 8.60 × 10^?3 S cm^?1. Thermal analysis performed in pure CO₂ atmosphere shows very good chemical stability up to 1200 °C. Good biaxial flexure strength of 100–200 MPa was reported which makes this material a promising electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs).     

CeO<Subscript>2</Subscript> and Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> modified Ni-YSZ anode for solid oxide fuel cell

Ni sintering at high temperature (～ 800 °C) operation drastically degrades the performance of Ni-yttria-stabilized zirconia (YSZ) anode in solid oxide fuel cell (SOFC). Mixed ionic and electronic conductive oxides such as CeO₂ and Nb₂O₅ enhance the dispersion of Ni, CeO₂ enhances the redox behavior and promotes charge transfer reactions, and Nb₂O₅ increases the triple phase boundary. In the present work, anode-supported SOFC is fabricated and tested in H₂ fuel at 800 °C. YSZ and lanthanum strontium manganite (LSM)-YSZ are used as the electrolyte and composite cathode with NiO-YSZ, CeO₂-NiO-YSZ, and Nb₂O₅-NiO-YSZ as an anode. The peak power density obtained for the cell with 10% CeO₂–30% NiO-YSZ anode at the 5 and 25 h of operation is 330 and 290 mW cm^?2 which is higher than that for 40% NiO-YSZ anode (275 mW cm^?2 at 5 h). The peak power density obtained for the cell with 10% Nb₂O₅–30% NiO-YSZ anode at the 5 and 25 h of operation is 301 and 285 mW cm^?2 which is higher than that for 40% NiO-YSZ anode (275 mW cm^?2 at 5 h). Physical characterization has been carried to study morphology, elemental analysis, particle size, and phase formation of the fabricated anode before and after cell operation to correlate the cell performance.     

Fabrication and electrochemical performance of La<Subscript>0.5</Subscript>Sr<Subscript>0.5</Subscript>CoO<Subscript>3</Subscript> impregnated porous YSZ cathode

La_0.5Sr_0.5CoO₃-yttria-stabilized zirconia (LSCO-YSZ) composite cathode for solid oxide fuel cell (SOFC) has been fabricated by wet impregnation method. Nitrate precursors of La, Sr, and Co have been impregnated into the pre-sintered porous YSZ matrix, which is converted into LSCO phase after calcination at 850 °C in the presence of glycine as confirmed from X-ray diffraction. LSCO of 5, 7, and 10 wt% impregnated porous YSZ have been electrochemically characterized using 2-probe AC conductivity method. Maximum ionic conductivity of 0.27 S/cm at 800 °C and activation energy of 0.15 eV between 600 and 800 °C have been observed for 10 wt% LSCO-YSZ cathode. Area-specific resistance of 1.01 Ω cm² at 800 °C is estimated for the electrolyte-supported half-cell (10 wt% LSCO-YSZ/YSZ). After testing the LSCO-YSZ cathode matrix, the electrolyte-supported full cell (10 wt% LSCO-YSZ/YSZ/NiO-YSZ) has been tested and produced maximum power density 51.12 mW/cm² (109.38 mA/cm²) at 800 °C. The electrolyte-supported full cell exhibited 6 Ω cm² electrode polarization at 800 °C in H₂, which is in higher side leading to low performance. LSCO-YSZ/YSZ/NiO-YSZ SOFC found to give stable performance up to 2 h and scanning electron microscopy analysis has been carried out before and after cell testing to assess the morphological changes.     

Evaluation and optimization of SrCo0.9Ta0.1O3−δ perovskite as cathode for solid oxide fuel cells

The SrCo_0.9Ta_0.1O_3-δ (SCT) perovskite-type oxide is synthesized by the conventional solid state reaction method and examined as an alternative cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). The electrical conductivity of SCT sample reaches 250–152 S cm^?1 in the temperature range 600–800 °C. SCT exhibits good chemical compatibility with the intermediate-temperature electrolyte material Sm_0.2Ce_0.8O_1.9 (SDC). The average thermal expansion coefficient of SCT is 21.4 × 10^?6 K^?1. The cathode area specific resistance (ASR) of SCT is only 0.095 Ω cm² at 750 °C and it decreases to 0.068 Ω cm² when SDC is added to form a SCT-SDC composite cathode. The results indicate that the SCT can be a promising alternative cathode material for IT-SOFCs.     

Synthesis and evaluation of thermal, electrical, and electrochemical properties of Ba0.5Sr0.5Co0.04Zn0.16Fe0.8O3�C�� as a novel cathode material for IT-SOFC applications

Ba_0.5Sr_0.5[Co_xZn_0.2-x]Fe_0.8O_3?C??, (x?=?0, 0.04, 0.08, 0.12) cathode formulations were successfully synthesized by solid state reactions and the effect of cobalt doping at Zn site of Ba_0.5Sr_0.5Zn_0.2Fe_0.8O_3?C?? (BSZF0.2) on the electrical conductivity, the polarization resistance and electrochemical behavior was evaluated. X-ray diffraction patterns indicate that a single cubic perovskite phase of Ba_0.5Sr_0.4Co_0.8Fe_0.2O_3?C?? oxide is successfully obtained. Ba_0.5Sr_0.5Co_0.04Zn_0.16Fe_0.8O_3?C?? (BSCZF0.16) exhibited a high electrical conductivity of 10 S/cm at 400 °C in comparison to the BSZF0.2 showing 5.5 S/cm. Further, BSCZF0.16 also possess a low polarization resistance as low as 0.22, 0.38, 0.87, and 1.55 ?? cm² at 750, 700, 650, and 600 °C in air, respectively. Accordingly, a low activation energy value of 149.8 kJ/mol for BSCZF0.16 in comparison to 159.4 kJ/mol for BSZF0.2 indicates high catalytic efficiency. Enhancement of desirable properties such as electrical conductivity in combination with low-polarization resistance and low-activation energy values can be attributed to the coexistence of Co and Zn in the B-site of BSCZF0.16 leading to the multivalent states which contributes to the enhanced electron transport properties demonstrating BSCZF0.16 as a better cathode for intermediate temperature solid oxide fuel cells applications.     

Ferroelectric (Na1/2Bi1/2)TiO3 thin films showing photoluminescence properties

Polycrystalline lead-free (Na_1/2Bi_1/2)TiO₃ (NBT) ferroelectric thin films doped with 1 mol% of rare earth (RE) elements are processed on Pt-terminated silicon substrates using a solution deposition method. The thin films that exhibit single-phase perovskite structure show photoluminescence properties with highest intensities in the wavelength range between 700 and 850 nm, depending on RE element. The ferroelectric properties of the pure NBT film (P _r: 20.5 µC cm^?2, E _c: 150 kV cm^?1) are somewhat decreased for the doped films, which is ascribed to decreasing of the number of Bi lone pairs through the substitution of Bi with RE elements in the perovskite lattice.     

The intercalation/deintercalation kinetic studies on the structure-integrated cathode material 0.5Li2MnO3 0.5LiNi0.5Mn0.5O2

A cathode material, 0.5Li₂MnO₃ 0.5LiNi_0.5Mn_0.5O₂, was prepared by citric acid-assisted sol–gel method and its electrochemical performance was investigated. It delivered a charge capacity of 270 mAh g^?1 and a discharge capacity of 189 mAh g^?1 in the first cycle. With the increase of current density from 14 to 28 mA g^?1, the discharge capacity dropped severely to 130 mA g^?1. Obviously, the rate capability of the material was inferior to most of the oxide cathode materials. The diffusion coefficient of this material was calculated to be 6.04?×?10^?12 cm² s^?1 from the results of cyclic voltammetry measurements. Moreover, diffusion coefficients between 3.13?×?10^?12 and 1.22?×?10^?10 cm² s^?1 in the voltage range of 3.8–4.7 V were obtained by capacity intermittent titration technique. This, together with the localized Li₂MnO₃ domains in the crystal structure, may validate the poor rate capability.     

Promising performances for a La<Subscript>0.6</Subscript>Sr<Subscript>0.4</Subscript>Co<Subscript>0.8</Subscript>Fe<Subscript>0.2</Subscript>O<Subscript>3-δ</Subscript> cathode with a dense interfacial layer at the electrode-electrolyte interface

As for the commonly studied La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (6428), here, a very low area-specific resistance (ASR) was measured for La_0.6Sr_0.4Co_0.8Fe_0.2O_3-δ (6482) cathode deposited on a Ce_0.9Gd_0.1O_2-δ (GDC) electrolyte with addition of a thin (1 μm) dense LSCF film deposited by spin coating at the interface between the GDC electrolyte and a 40-μm-thick screen-printed electrode. The ASR ranged from 1 Ω.cm² at 500 °C, 0.11 Ω.cm² at 625 °C and value as low as 0.03 Ω.cm² at 700 °C. Impedance spectra collected in between 500 and 700 °C were carefully studied. They could all be modelled with two R//CPE in series which are likely associated to the oxygen reduction reaction itself (dissociation/adsorption/ionization) at low frequency and to the oxide ion transfer at the electrode/electrolyte interface at high frequency.     

Di-urethanesil hybrid electrolytes doped with Mg(CF3SO3)2

Two siloxane-based di-urethanesil frameworks incorporating poly(oxyethylene) (POE) chains have been synthesized by the sol–gel process and doped with magnesium triflate (Mg(CF₃SO₃)₂) with the goal of developing electrolytes for the fabrication of solid-state rechargeable magnesium batteries. In these matrices, short POE chains are covalently bonded to the siloxane network via urethane linkages. The xerogels have been represented by the notation d-Ut(Y) _n Mg(CF₃SO₃)₂, where Y?=?300 and 600 represents the average molecular weight of the POE chains and n stands for salt composition (molar ratio of OCH₂CH₂ units per Mg²⁺). Xerogels with compositions ranging from 2?≤?n?<?∞ were prepared. A crystalline POE/Mg(CF₃SO₃)₂ complex of unknown stoichiometry is formed in the d-Ut(300) _n Mg(CF₃SO₃)₂ materials with n?≤?6 and in the d-Ut(600) _n Mg(CF₃SO₃)₂ materials with n?≤?5. The organically modified silicate electrolytes with the highest conductivity of the d-Ut(300) _n Mg(CF₃SO₃)₂ and d-Ut(600) _n Mg(CF₃SO₃)₂ series are the samples with n?=?6 (3.9?×?10^?8 S cm^?1 at 26 °C and 8.7?×?10^?5 S cm^?1 at 97 °C) and n?=?100 (2.63?×?10^?7 S cm^?1 at 20 °C and 1.4?×?10^?5 S cm^?1 at 85 °C), respectively. Since the electrolytes for Mg batteries that have been proposed up to now have many intrinsic problems and although the room temperature conductivity values exhibited by the systems developed in the present study are still low in view of practical application, this work opens new directions for the development of solid-state Mg ion electrolytes.     

Flexible paper-based borohydride-vanadium fuel cell for powering micro-nanosystems

This work deals about the development of paper-based fuel cells with high open-circuit voltages for application in powering the micro-nanosystems such as bio-sensors. The developed fuel cell employs Whatman paper as the ion conductor placed between the anode and the cathode to replace expensive ion-conducting membranes such as Nafion. A maximum open-circuit voltage of ～2.1 V per single cell and a power output of ～4.5 mW cm^?2 at ～6 mA cm^?2 are obtained when employing 1 M NaBH₄ in 20 wt% NaOH solution and 1 M VO₂ ⁺ in 2.5 M H₂SO₄ solution. Chronoamperometric measurement performed at 1 V indicates that the output power density varies from 6 to 1 mW cm^?2 in about 100 min. The power delivered at the end of even 100 min is comparable to that of the peak power delivered by many of the micro-fuel cell systems reported in the literature.