Solid Proton Electrolytes Research Articles

Acidified Nitrogen Self-Doped Porous Carbon with Superprotonic Conduction for Applications in Solid-State Proton Battery.

Solid proton electrolytes play a crucial role in various electrochemical energy storage and conversion devices. However, the development of fast proton conducting solid proton electrolytes at ambient conditions remains a significant challenge. In this study, a novel acidified nitrogen self-doped porous carbon material is presented that demonstrates exceptional superprotonic conduction for applications in solid-state proton battery. The material, designated as MSA@ZIF-8-C, is synthesized through the acidification of nitrogen-doped porous carbon, specifically by integrating methanesulfonic acid (MSA) into zeolitic imidazolate framework-derived nitrogen self-doped porous carbons (ZIF-8-C). This study reveals that MSA@ZIF-8-C achieves a record-high proton conductivity beyond 10-2 Scm-1 at ambient condition, along with good long-term stability, positioning it as a cutting-edge alternative solid proton electrolyte to the default aqueous H2 SO4 electrolyte in proton batteries.

Study of proton conductivity of composite metal-ceramic materials based on neodimium tugstates using a four-electrode technique with ionic probes

Ceramic solid proton electrolytes La0.99Ca0.01NbO4, Nd5.5WO11.25- Nd5.5W0.5Mo0.5O11.25-δ were synthesized and their proton conductivity was measured in the temperature range of 300–650 °С in an atmosphere of dry and humid air. It is shown that solid electrolytes have a high proton conductivity ∼10−4 S/cm at 500 °С. Dense metal-ceramic composites containing phases of metal Ni0.5Cu0.5 and oxides Nd5.5WO11.25 or Nd5.5W0.5Mo0.5O11.25-δ with the total conductivity typical of metals were obtained using hot pressing technique an argon atmosphere. An experimental determination of the contribution of the ionic (in this case proton) conductivity to the overall conductivity of the material comprises is an actual problem in investigation of the properties of metal-ceramic materials. The values of proton conductivity can be estimated from the results of studying the hydrogen permeability of membranes and the diffusion of hydrogen, but these methods are rather complicated in instrumentation. Therefore the use of relatively simple and accessible electrical measurement methods to solve this problem is very relevant. In this paper, the partial proton conductivity of the composite materials mentioned above was first measured using a 4-electrode cell with ion probes made of a ceramic proton conductor La0.99Ca0.01NbO4 in an atmosphere of moist hydrogen and at the temperature range of 300–650 °C. In the low-temperature region, the values of the partial proton conductivity measured in the 4-electrode cell are in good agreement with those obtained by standard complex impedance analysis for the pure ceramics not containing metal. At high temperatures, the values obtained by two independent techniques differ. This can be explained by the contribution of the electrochemical reaction proceeding at the interface between the ion probe and the metal phases and accompanied by the dissolution of atomic hydrogen in the metal. In general, the measured value of the ionic conductivity can be either underestimated or overestimated in comparison with the real one, depending on the rate of chemical reactions occurring at the electrodes. Nevertheless, in a limited temperature range, the use of four-electrode measurements with ionic (proton) probes allows one to obtain correct results.

Functional group engineering of graphene oxide

Graphene oxide (GO) has many functions, because it has many kinds of functional groups and defects. However, a detailed analysis of the functions and the relationships between the functions and functional groups, has never been made. Here, a detailed analysis of these functions and relationships is given based on our results. The epoxide of GO is unique, and shows a reversible reaction with changing pH. The high proton conductivity of GO is attributed to the presence of epoxide in the interlayers of GO. New types of electrochemical devices such as fuel cells and lead acid batteries where GO is used as a solid proton electrolyte, are proposed. CH defects are also important for the electrode with a high capacitance in supercapacitor and magnetism. GO is also very useful as electrocatalyst substrates because there are both hydrophilic and hydrophobic nano-level areas on the surface. [TANSO 2015 (No. 266) 31–34.]

High-voltage electrical conductivity and its postactivation relaxation in the binary NaHSO4-CsHSO4 system

The effect of high-voltage pulses on the electrical conductivity of the binary NaHSO4-CsHSO4 system of a solid proton electrolyte and its melt with 25, 50, and 75 mol % CsHSO4 is studied. The relaxation processes that occur in this electrolyte and its melt after high-voltage pulsed discharges are investigated. The relaxation times of nonequilibrium charge carriers are calculated (they are on the order of 104 s). The resistance of the melt is calculated as a function of time from the current and voltage oscillograms recorded during a high-voltage discharge.

Ceramic membrane fuel cells based on solid proton electrolytes

The development of solid oxide fuel cells (SOFCs) has reached its new stage characterized with thin electrolytes on porous electrode support, and the most important fabrication techniques developed in which almost all are concerned with inorganic membranes, and so can be named as ceramic membrane fuel cells (CMFCs). CMFCs based on proton electrolytes (CMFC-H) may exhibit more advantages than CMFCs based on oxygen-ion electrolytes (CMFC-O) in many respects, such as energy efficiency and avoiding carbon deposit. Ammonia fuelled CMFC with proton-conducting BaCe 0.8Gd 0.2O 2.9 (BCGO) electrolyte (50 μm in thickness) is reported in this works, which showed the open current voltage (OCV) values close to theoretical ones and rather high power density. And also, we have found that the well known super oxide ion conductor, La 0.9Sr 0.1Ga 0.8Mg 0.2O 3− α (LSGM), is a pure proton conductor in H 2 and mixed proton and oxide ion conductor in wet air, while it is a pure oxide ion conductor in oxygen or dry air. To demonstrate the CMFC-H concept to get high performance fuel cells the techniques for thin membranes, chemical vapor deposition (CVD), particularly novel CVD techniques, should be given more attention because of their many advantages.

Behavior of manganese dioxide electrodes in a system containing a solid protonic electrolyte

The behavior of manganese dioxide electrodes containing powders of graphite and titanium as electroconducting additives is studied in a system with a solid protonic hydrated electrolyte (SPHE). The MnO2 reduction is accompanied by ion exchange between formed Mn2+ ions and structural protons of SPHE. The open-circuit potentials drift in the anodic direction and stabilize when the MnO2 composition at a boundary with SPHE is close to stoichiometric. The drift is due to conjugated reactions of the MnO2 reduction and the graphite oxidation process that decays with time. With increasing cathodic current density, the solid-phase reduction of MnO2 via an electronic-protonic mechanism becomes predominant. At low polarizing-current densities, the open-circuit and steady-state potentials remain passably stable until the exchange capacity of SPHE by protons is exhausted or MnO2 near the interface with SPHE is spent. The feasibility of using MnO2-SPHE-based amperometric sensors for assaying components whose oxidation in a gas medium yields protons is considered

On the nature of transition processes in ammetric gas sensors based on solid proton electrolytes

Transition processes have been studied in gas sensor models based on catalytically active electrodes ( cae) and hydrogenated solid proton electrolyte in reaching current-free potentials and the current of chlorine and ozone reduction. A reversible chlorine adsorption and irreversible ozone adsorption and decomposition have been shown to proceed at a cae of Pt, RuO 2 and their compositions with TiO 2. It has been established that in the conditions of real humidity of the air caes possess the properties of porous electrodes with poorly pronounced ionic conductivity. The rate of cathodic reactions at the cae is limited by the external diffusion regime of mass transfer in gas phase and by the internal diffusion-ohmic regime of mass transfer of chlorine, ozone and products of their reduction. It has been shown that the time of transition processes in the systems under consideration is determined from the time of reaching an adsorption equilibrium in those sections of the cae where the reduction of chlorine and ozone does not occur.

Impedance of nonuniform distributed solid protonic electrolyte - polymer systems

The conductivity of mixtures of the solid electrolytes H3[PMo12O40]·13H2O and Cs2H[PW12O40] · 13H2O follows the predictions of the percolation theory, whereas the electrode impedance in the high frequency range fits well the model of double layer adsorption relaxation. It is concluded that both the adsorption relaxation and the reversibility of the electrodes are related to oxygen transfer, the oxygen ions being the minority charge carriers. Fast oxygen dispersion may occur at the polymer-solid electrolyte interface.

Solid Protonic Electrolyte Based on Antimony Pentoxide and Hydrogen Gas Sensor

Solid Protonic Electrolyte Based on Antimony Pentoxide and Hydrogen Gas Sensor

Tritium gettering from air with hydrogen uranyl phosphate

Hydrogen uranyl phosphate (HUP), a solid proton electrolyte, getters tritium gas and water vapor from air by dc electrical action. We have reduced the formation of residual tritiated water to less than 2% and demonstrated that HUP can clean a 5.5 m3 working glove box. Data are presented to illustrate the parameters of the gettering and a model is derived. Two other tritium gettering electrolytes have been discovered.

Electrolytic gettering of tritium from air

We have achieved the first direct gettering of tritium gas from moist air using the dc electrical action of the solid proton electrolyte, hydrogen uranyl phosphate (HUP). The HUP action is imperfect as 90% of the original 1 ppm is gettered by the HUP while the remaining 10% forms tritiated water. Modifications to the HUP unit may be possible to reduce this HTO background.

Relation between proton and hole conduction in SrCeO 3-based solid electrolytes under water-containing atmospheres at high temperatures

Electrical conduction in the solid proton electrolyte based on SrCeO 3 was studied under water-containing atmospheres at high temperatures. The change of conductivity was measured systematically as a function of the concentration of the dopant or of the partial pressures of water vapor and oxygen. Since the conduction in the oxides was not purely protonic but partially electronic, these conductivities were determined separately using a steam concentration cell. It was observed that the proton conductivity increased in proportion to P 1 2 H 2O and was independent of P O 2 . It was also recognized that the electronic conduction present in the oxides was due to holes and the hole conductivity followed the P 1 4 O 2 law. A possible model for the proton formation in the oxides is discussed and it is proposed that the protons might be produced from water vapor at the expense of holes.

Three-electrode solid-state fuel cell for evaluating working electrodes

Development of a commercial solid-state fuel cell depends on identification of suitable catalytic electrodes to replace platinum. A three-electrode test cell for electrode evaluation is reported. The solid protonic electrolyte used was dodecamolybdophosphoric acid, H 3Mo 12PO 40·29H 2O, and a thin platinum wire inserted into the electrolyte served as the third electrode. Reproducibility and insensitivity to third-electrode position were demonstrated. The third electrode measures separately the anode and cathode interfacial resistances, thus providing a direct measure of the relative catalytic activity of a given test electrode. Application of the technique is illustrated.