ZrO_2/堇青石微滤膜表面荷电性能及其对膜通量的影响(英文)

采用挤压成型和流铸法制备了ZrO2/堇青石微滤膜,并通过错流方式下的流动电势测量对所制备微滤膜的表面荷电性能进行了表征.研究了过滤介质溶液的pH值、电解质种类和浓度等对膜的表面荷电性能和渗透通量的影响.结果表明:膜流动电势大小取决于过滤溶液的pH值、电解质种类和浓度.溶液浓度为10-3 mol/L时,膜等电点随着电解质种类改变而在4.2和5.4之间变化.膜的流动电势随NaCl溶液浓度提高而逐渐减小,但等电点不变;而CaCl2和Na2SO4溶液中的Ca2+和SO42-/在膜孔表面存在特定吸附,导致膜的等电点和表面净电荷符号改变.制备的ZrO2/堇青石微滤膜在等电点附近出现最大离子溶液过滤通量.     

Electrokinetic characterization of the Al2O3 ceramic MF membrane by streaming potential measurements

The alumina microfiltration(MF) membrane was modified with nanocrystalline TiO₂ in the pore wall. The electrokinetic properties of unmodified and modified alumina membranes were characterized by streaming potential measurements during tangential filtration at various conditions of pH, ionic concentration and ionic species in solutions. The modified membrane reveals a more acidic characteristic. The influence of pH value on the streaming potential of both membranes is explained by the shifting of the proton equilibrium that occurs at the surface of the membrane. The modification of the alumina membrane with TiO₂ leads to the decrease of its isoelectric point (IEP) from 6.1 to 4.0 when filtered with NaCl solution. The ionic concentration and electrolyte species also have influence on the streaming potential of both membranes. The reversal of the streaming potential sign and the change of the isoelectric point of the membrane when filtered with CaCl₂ and Na₂SO₄ solutions show specific adsorption of Ca²⁺ and SO₄^2- ions onto the surface.     

Streaming effect of single electrolyte mass transfer in nanofiltration: potential application for the selective defluorination of brackish drinking waters

This work deals with electrical properties of nanosurfaces in contact with electrolyte solutions. Single halide ion solutions were studied by streaming potential (SP) measurements and observed retention (R_obs) of the F⁻, Cl⁻, and Br⁻ ions across nanofiltration (NF) membranes. The detailed understanding of an electrolyte solution mass transfer requires an intimate knowledge of the physicochemical interactions occurring between nanoporous materials and electrolyte solutions across the first-generation composite membranes called NF55, NF70 and NF90. These membranes are composed of a polysulfone mesoporous sublayer and a microporous skin layer in polyamide. In order to get a better understanding of these effects, it seems attractive to compare the mass transfer permeation of the monovalent ions F⁻, Cl⁻, and Br⁻ with the electrokinetic characterizations deduced from a properly developed SP apparatus. SP measurements is a very simple method to show the intrinsinc charges on membrane pore walls. The membrane's electrical properties are studied with SP design modeling pH, ionic strength and kind of electrolyte solutions. We have observed that the isoelectric point (IEP) of the membrane materials is both dependent on the ionic strength and on the kind of electrolyte solution. The IEP in the presence of KCl is 4.4 at 0.0001 mol/L and 5.8 at 0.001 mol/L, showing an increasing adsorption of the cation K⁺ by increasing its solution concentration. For a fixed concentration, the effect of the electrolyte solution has shown that a higher adsorption of Ca⁺⁺ occurs in comparison to K⁺ and Na⁺. But the adsorption of these electrolyte solutions is essentially reversible as observed under dilution conditions. Furthermore SP measurements were used for the first time to characterize the transmembrane pressure ranges where a convective and/or a diffusional mass transfer occurs. Such an approach was developed to correlate the R_obs of the halide ions F⁻, Cl⁻ and Br⁻ with the kind of mass transfer (diffusional and/or convective) occurring predominantly under transmembrane pressure variations. Thus the NF70 membrane shows at low pressure (under 3 bar) the order of R_obs following the hydrated ionic radius: R_obs.(F⁻)>R_obs.(Cl⁻)>R_obs.(Br⁻). For a higher pressure (> 3 bar) an inversion occurs between Cl⁻ and Br⁻, but F⁻ was not affected. These results open a new prospective area for selective defluorination of brackish drinking waters using NF membranes under low transmembrane pressure.     

Electrochemical behavior of LiCoO2 in a saturated aqueous Li2SO4 solution

The electrochemical behavior of a commercial LiCoO₂ with spherical shape in a saturated Li₂SO₄ aqueous solution was investigated with cyclic voltammetry and electrochemical impedance spectroscopy. Three redox couples at E_SCE = 0.87/0.71, 0.95/0.90 and 1.06/1.01 V corresponding to those found at ELi/Li⁺=4.08/3.83, 4.13/4.03 and 4.21/4.14 V in organic electrolyte solutions were observed. The diffusion coefficient of lithium ions is 1.649 × 10⁻¹⁰ cm² s⁻¹, close to the value in organic electrolyte solutions. The results indicate that the intercalation and deintercalation behavior of lithium ions in the Li₂SO₄ solution is similar to that in the organic electrolyte solutions. However, due to the higher ionic conductivity of the aqueous solution, current response and reversibility of redox behavior in the aqueous solution are better than in the organic electrolyte solutions, suggesting that the aqueous solution is favorable for high rate capability. The charge transfer resistance, the exchange current and the capacitance of the double layer vary with the charge voltage during the deintercalation process. At the peak of the oxidation (0.87 V), the charge transfer resistance is the lowest. These fundamental results provide a good base for exploring new safe power sources for large scale energy storage.     

Preparation of binary washcoat deposited on cordierite substrate for catalytic applications

The deposition of binary M–ZrO₂ (M = Al₂O₃, SiO₂ or TiO₂) as secondary support on cordierite substrate by dip-coating was investigated and the as-prepared M–ZrO₂/cordierite was characterized by means of XRD and SEM techniques. After two successive dip-coating processes, the highest washcoat loading of 25.1% was achieved in Al₂O₃–ZrO₂/cordierite, followed by 18.7% in TiO₂–ZrO₂/cordierite and then 17.4% in SiO₂–ZrO₂/cordierite. The optimal parameters to prepare Al₂O₃–ZrO₂ washcoat on cordierite were investigated in detail. After introduction of noble metal active components (Rh and Pd) to the secondary support, the obtained Rh/M–ZrO₂/cordierite and Pd/M–ZrO₂/cordierite were further tested as monolithic catalysts for the decomposition of nitrous oxide and the deep oxidation of benzene, respectively.     

Electrospun hydrophilic fumed silica/polyacrylonitrile nanofiber-based composite electrolyte membranes

Hydrophilic fumed silica (SiO₂)/polyacrylonitrile (PAN) composite electrolyte membranes were prepared by electrospinning composite solutions of SiO₂ and PAN in N,N-dimethylformamide (DMF). Among electrospinning solutions with various SiO₂ contents, the 12 wt% SiO₂ in PAN solution has highest zeta potential (−40.82 mV), and exhibits the best dispersibility of SiO₂ particles. The resultant 12 wt% SiO₂/PAN nanofiber membrane has the smallest average fiber diameter, highest porosity, and largest specific surface area. In addition, this membrane has a three-dimensional network structure, which is fully interconnected with combined mesopores and macropores because of a good SiO₂ dispersion. Composite electrolyte membranes were prepared by soaking these porous nanofiber membranes in 1 M lithium hexafluorophosphate (LiPF₆) in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1 vol%). It is found that 12 wt% SiO₂/PAN electrolyte membrane has the highest conductivity (1.1 × 10⁻² S cm⁻¹) due to the large liquid electrolyte uptake (about 490%). In addition, the electrochemical performance of composite electrolyte membranes is also improved after the introduction of SiO₂. For initial cycle, 12 wt% SiO₂/PAN composite electrolyte membrane delivers the discharge capacity of 139 mAh g⁻¹ as 98% of theoretical value, and still retains a high value of 127 mAh g⁻¹ as 89% at 150th cycle, which is significantly higher that of pure PAN nanofiber-based electrolyte membranes.     

New mechanism of gas transport at the interface solid/liquid

It was recently shown that an abnormally fast transport of CO molecules takes place at the electrode/electrolyte interface of Pt and PtRu electrodes in H₂SO₄ and HClO₄ solutions. In the present paper, this phenomenon is tested for other gases, such as hydrogen and oxygen. The fast transport is also observed at the solid/electrolyte solution interface of other electrode materials and at the glass/electrolyte interface. Several experiments are shown, demonstrating that mass transfer takes place at a velocity, which is more than one order of magnitude higher than expected for usual diffusion conditions.Assuming radial mass transfer at the interface of a Pt disc, the activation energy, E_a = 23 kJ mol⁻¹, was calculated from Arrhenius plots. The same value was measured in H₂SO₄ and HClO₄ as supporting electrolytes. The mass transport parameter, Y, at 298 K was 4.8 × 10⁻³ cm² s⁻¹ and 2.9 × 10⁻³ cm² s⁻¹ in 0.5 M H₂SO₄ and 1 M HClO₄ respectively.     

Study of the preasphaltenes of coal liquefaction and its hydro-conversion kinetics catalyzed by SO4/ZrO2

The investigation of hydro-conversion behavior of the heavy intermediate products derived from coal direct liquefaction is advantageous to optimize the technological conditions of direct coal liquefaction and improve the oil yield. In this paper, the hydro-conversion of preasphaltenes catalyzed by SO₄²⁻/ZrO₂ solid acid was investigated based on the structural characterization of preasphaltenes and its hydro-conversion products, and the determination of products distribution and the kinetics of preasphaltenes hydro-conversion. The results indicated that the content of condensed aromatic rings increased, and the contents of hydrogen, oxygen and aliphatic side chains of preasphaltenes decreased with the increase of coal liquefaction temperature. The preasphaltenes showed higher hydro-conversion reactivity while SO₄²⁻/ZrO₂ solid acid was used as catalyst. Higher temperature and longer time were in favor of increasing the conversion and the oil + gas yield. The conversion of preasphaltenes hydro-conversion under 425 °C, for 40 min reached 81.3% with 51.2% oil + gas yield. SO₄²⁻/ZrO₂ solid acid was in favor of the catalytic cracking rather than the catalytic hydrogenation in the hydro-conversion of preasphaltenes. The activation energy of preasphaltenes conversion into asphaltenes was 72 kJ/mol. The regressive reactions were only observed at a higher temperature.     

流动电位法研究聚烯烃微孔膜在电解质溶液中的动电现象

对NaCl、KCl、MgCl2、Na2SO4、MgSO4等5种电解质溶液中2种不同微孔膜(管式聚乙烯微滤膜和管式聚丙烯腈超滤膜)的流动电位进行了实验研究。考察了电解质浓度、离子种类和价态对膜的流动电位的影响。根据Helmholtz-Smoluchowski方程和Gouy-Chapmann理论算出2种膜的微孔表面zeta电位和电荷密度。结果表明，两种微孔膜均由于离子的吸附而带有负电荷，电解质浓度、离子种类及价态对膜的流动电位、表面zeta电位和电荷密度均具有重要的影响。     

Characterization and control of foulants occurring from RO disc-tube-type, membrane treating, fluorine manufacturing, process wastewater

This study was carried out to find a way to limit fouling of disc-tube-type reverse osmosis membranes in the treatment of acid rinse wastewater from the fluorine manufacturing process as well as to pretreat the wastewater before it entered the membrane process. Experiments showed that the scale consisted of Ca²⁺, SO₄⁻² and F⁻. Complex scales were removed in a subsequent procedure where the membrane was rinsed with NaOH followed by citric acid which could consequently recover its flux up to 86%. Cleaning chemicals had to be used regularly for efficient recovery of permeate flux. Ultrasonic cleaning could also improve the recovery of permeate flux up to 83%. Calcium salts were used to remove fluoride ions. CaCl₂ removed fluoride ions up to 11% more than Ca(OH)₂ at 0.5 [Ca²⁺]/[F⁻]. At acidic pH 4-7 or alkaline pH 7 and above, residual fluoride ions increased as Ca²⁺ reacted more efficiently with Cl⁻, OH⁻ and SO₄⁻² rather than F⁻. On the other hand, fluoride ions were best removed at pH 7. Adding Ca²⁺ salt above pH 7 caused an increase of residual Ca²⁺ salt in the effluent, even if fluoride ions can be ideally removed in the form of CaF₂ at a pH over 11.     

Inactivation of Escherichia coli in Na2SO4 electrolyte using boron-doped diamond anode

Electrochemical disinfection in chloride-free electrolyte has attracted more and more attention due to advantages of no production of disinfection byproducts (DBPs), and boron-doped diamond (BDD) anode with several unique properties has shown great potential in this field. In this study, inactivation of Escherichia coli (E. coli) was investigated in Na₂SO₄ electrolyte using BDD anode. Firstly, disinfection tests were carried on at different current density. The inactivation rate of E. coli and also the concentration of hydroxyl radical (OH) increased with the current density, which indicated the major role of OH in the disinfection process. At 20 mA cm⁻² the energy consumption was the lowest to reach an equal inactivation. Moreover, it was found that inactivation rate of E. coli rose with the increasing Na₂SO₄ concentration and they were inactivated more faster in Na₂SO₄ than in NaH₂PO₄ or NaNO₃ electrolyte even in the presence of OH scavenger, which could be attributed to the oxidants produced in the electrolysis of SO₄²⁻, such as peroxodisulfate (S₂O₈²⁻). And the role of S₂O₈²⁻ was proved in the disinfection experiments. These results demonstrated that, besides hydroxyl radical and its consecutive products, oxidants produced in SO₄²⁻ electrolysis at BDD anode played a role in electrochemical disinfection in Na₂SO₄ electrolyte.     

Electrochemical studies of electrospun organic/inorganic hybrid nanocomposite fibrous polymer electrolyte for lithium battery

Poly(vinylidene fluoride-co-hexafluoropropylene) P(VdF-co-HFP)/magnesium aluminate (MgAl₂O₄) hybrid fibrous nanocomposite polymer electrolyte membranes were newly prepared by electrospinning method. The as-prepared electrospun pure and nanocomposite fibrous polymer membranes with various MgAl₂O₄ filler contents were characterized by X ray diffraction, differential scanning calorimetry and scanning electron microscopy techniques. The fibrous nanocomposite polymer electrolytes were prepared by soaking the electrospun membranes in 1 M LiPF₆ in EC:DEC (1:1, v/v). The fibrous nanocomposite polymer electrolyte membrane with 5 wt.% of MgAl₂O₄ show high electrolyte uptake, enhanced ionic conductivity is found to be 2.80 × 10⁻³ S cm⁻¹ at room temperature and good electrochemical stability window higher than 4.5 V. Electrochemical performance of commercial celgard 2320, fibrous pure and nanocomposite polymer electrolyte (PE, NCPE) membranes with different MgAl₂O₄ filler content is evaluated in Li/celgard 2320, PE, NCPE/LiCoO₂ CR 2032 coin cells at current density 0.1 C-rate. The NCPE with 5 wt.% of MgAl₂O₄ delivers an initial discharge capacity of 158 mAhg⁻¹ and stable cycle performance compared with the other cells containing celgard 2320 separator and pure membrane.     

Enhanced electrokinetic remediation of polluted kaolinite with an azo dye

In this work, the feasibility of the combination of electrokinetic remediation and electrochemical oxidation for the remediation of polluted soil with organic compounds had been development and evaluated in kaolinite spiked with Reactive Black 5 (RB5) an azo dye. The process consists in the use of two combined phenomena to achieve a full remediation of RB5 spiked kaolinite and the degradation of the organic pollutant. Those phenomena were soil electrokinetic treatment combined to liquid electrochemical oxidation. Reactive Black 5 (0.39 g dye kg⁻¹) could be effectively removed from the kaolinite matrix by electrokinetics, however the removal results largely depended on the operating conditions. Complete removal of RB5 was achieved using K₂SO₄ as processing fluid (which enhanced the desorption of RB5 from the kaolinite matrix) and operating with pH control at 7 on the anode. This favoured the alkalinization of the system and, at high pH values, RB5 was ionized and migrated towards the anode chamber where it was collected and could be oxidized electrochemically. Also, it must be pointed out that in these optimized conditions the electric power consumption (56 kW/mg of removed dye) was ten times lower compared to the unenhanced electrokinetic process (with no pH-control in the electrode solutions). Separate electrochemical decolourization tests of RB5 showed the effectiveness of K₂SO₄ in the efficiency of the process. A linear relationship between K₂SO₄ concentration and the decolourization rate was found. Thus, nearly complete decolourization was achieved after 2 and 3 h of electrochemical treatment when the electrolyte concentration was 0.1 and 0.01 M of K₂SO₄, respectively.     

Exceptional ion-exchange selectivity for perchlorate based on polyaniline films

Polyaniline (PANI) films were electrochemically synthesized on graphite electrode and their ion-exchange selectivities for ClO₄⁻ were investigated. Cyclic voltammetry (CV) results showed that PANI-H₂SO₄ film represented higher selectivity for ClO₄⁻ than PANI–HCl and PANI–HClO₄. Furthermore, the CV records of PANI–H₂SO₄ film in different acidic solutions demonstrated that ClO₄⁻ exchange was performed in a lower potential range (from −0.025 V to 0.097 V), which is distinguished from SO₄²⁻ and Cl⁻. Additionally, chronoamperomertry (CA) studies of PANI–H₂SO₄ film in 0.1 M various acidic solutions (H₂SO₄, HCl and HClO₄) confirmed that the diffusion coefficient values in HClO₄ (13.319/18.184 × 10⁻⁶ cm² s⁻¹) were the biggest during doping/de-doping process. The exceptional ion-exchange selectivity for ClO₄⁻ was explained by the process of dominant accumulation, quick insertion of anions, and the sluggish mobility of ClO₄⁻ inside the membrane. Results of present work demonstrated that PANI may serve as a promising membrane for ClO₄⁻ removal by ion-exchange process.     

Supercapacitive properties of a nanowire-structured MnO2 electrode in the gel electrolyte containing silica

Nanowire-structured MnO₂ active materials were prepared by a chemical precipitation method and their supercapacitive properties for use in the electrodes of supercapacitors were investigated by means of cyclic voltammetry in an aqueous gel electrolytes consisting of 1 M Na₂SO₄ and fumed silica (SiO₂). The MnO₂ electrode showed a maximum specific capacitance of 151 F g⁻¹ after 1000 cycles at 100 mV s⁻¹ when using the gel electrolyte containing 3 wt.% of SiO₂, which is higher than 121 F g⁻¹ obtained when using the 1 M Na₂SO₄ liquid electrolyte alone.     

Thermodynamic modeling of CO2 solubility in aqueous solutions of NaCl and Na2SO4

A thermodynamic model based on the electrolyte NRTL activity coefficient equation and PC-SAFT equation-of-state is developed for CO₂ solubility in aqueous solutions of NaCl and Na₂SO₄ with temperature up to 473.15 K, pressure up to 150 MPa, and salt concentrations up to saturation. The Henry's constant parameters of CO₂ in H₂O and the characteristic volume parameters for CO₂ required for pressure correction of Henry's constant are identified from fitting the experimental gas solubility of CO₂ in pure water with temperature up to 473.15 K and pressure up to 150 MPa. The NRTL binary parameters for the CO₂-(Na⁺, Cl⁻) pair and the CO₂-(Na⁺, SO₄²⁻) pair are regressed against the experimental VLE data for the CO₂-NaCl-H₂O ternary system up to 373.15 K and 20 MPa and the CO₂-Na₂SO₄-H₂O ternary system up to 433.15 K and 13 MPa, respectively. Model calculations on solubility and heat of solution of CO₂ in pure water and aqueous solutions of NaCl and Na₂SO₄ are compared to the available experimental data of the CO₂-H₂O binary, CO₂-NaCl-H₂O ternary and CO₂-Na₂SO₄-H₂O ternary systems with excellent results.     

Electrochemical behaviour of titanium in H2SO4-MnSO4 electrolytes

The corrosion of titanium in H₂SO₄ electrolytes (0.001-1.0 M) at temperatures from ambient to 98 °C has been investigated using steady-state polarization measurements. Four distinct regions of behaviour were identified, namely active corrosion, the active-passive transition, passive region and the dielectric breakdown region. The active corrosion and active-passive transition were characterized by anodic peak current (i_m) and voltage (E_m), which in turn were found to vary with the experimental conditions, i.e., d(log?(im))/dpH=−0.8±0.1 and dE_m/dpH which was −71 mV at 98 °C, −58 mV at 80 °C and −28 mV at 60 °C. The activation energy for titanium corrosion, determined from temperature studies, was found to be 67.7 kJ mol⁻¹ in 0.1 M H₂SO₄ and 56.7 kJ mol⁻¹ in 1.0 M H₂SO₄. The dielectric breakdown voltage (E_d) of the passive TiO₂ film was found to vary depending on how much TiO₂ was present. The inclusion of Mn²⁺ into the H₂SO₄ electrolyte, as is done during the commercial electrodeposition of manganese dioxide, resulted in a decrease in titanium corrosion current, possibly due to Mn²⁺ adsorption limiting electrolyte access to the substrate.     

Extended UNIQUAC model for correlation and prediction of vapor-liquid-liquid-solid equilibria in aqueous salt systems containing non-electrolytes. Part B. Alcohol (ethanol, propanols, butanols)-water-salt systems

The Extended UNIQUAC model for electrolyte solutions is an excess Gibbs energy function consisting of a Debye-Hückel term and a term corresponding to the UNIQUAC equation. For vapor-liquid equilibrium calculations, the fugacities of gas-phase components are calculated with the Soave-Redlich-Kwong equation of state. The model only requires binary, temperature-dependent interaction parameters. It has previously been used to describe the excess Gibbs energy for aqueous electrolyte mixtures and aqueous electrolyte systems containing methanol. It has been found to be an adequate model for representing solid-liquid-vapor equilibrium and thermal property data for strongly non-ideal systems. In this work, the model is extended to aqueous salt systems containing higher alcohols. The calculations are based on an extensive database consisting of salt solubility data, vapor liquid equilibrium data, and liquid-liquid equilibrium data for solvent mixtures and for mixed solvent-electrolyte systems.The application of this model to represent the vapor-liquid-liquid-solid equilibria in aqueous systems containing various non-electrolytes (ethanol, 1-propanol, 2-propanol, 1-butanol, 2- butanol, 2-methyl 1-propanol, 2-methyl 2-propanol) and various ions (Na⁺, K⁺, NH₄⁺, Cl⁻, NO₃⁻, SO₄²⁻, SO₃²⁻, HSO₃⁻, CO₃²⁻, and HCO₃⁻) shows the capability of the model to accurately represent the phase behavior of these kinds of systems.     

A macaroni-like Li1.2V3O8 nanomaterial with high capacity for aqueous rechargeable lithium batteries

A macaroni-like Li_1.2V₃O₈ nanomaterial was directly prepared through a facile solution route using β-cyclodextrin (β-CD) as a template reagent. Its crystal structure was determined by the X-ray diffraction (XRD) pattern. From the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs, we observed that the as-prepared Li_1.2V₃O₈ material consisted of the aggregated macaroni-like nanoparticles and showed a porous structure. The electrochemical properties of the as-prepared Li_1.2V₃O₈ in 1.0 M Li₂SO₄ aqueous electrolyte were studied through cyclic voltammograms and charge-discharge measurements. The results revealed that the as-prepared Li_1.2V₃O₈ could deliver the initial specific capacities of 189, 140, and 101 mAh g⁻¹ at 0.1, 0.5, and 1.0 C, respectively. It suggests that the as-prepared Li_1.2V₃O₈ should have an attractive future to be applied in aqueous rechargeable lithium battery (ARLB).     

The effect of quaternary ammonium on discharge characteristic of a non-aqueous electrolyte Li/O2 battery

The effect of quaternary ammonium on discharge characteristic of Li/O₂ cells was studied by using Super-P carbon as air cathode, a 0.2 mol kg⁻¹ LiSO₃CF₃ 1:3 (wt.) PC/DME solution as baseline electrolyte, and tetrabutylammonium triflate (NBu₄SO₃CF₃) as an electrolyte additive or a co-salt. Results show that Li/O₂ cells can run normally in an electrolyte with NBu₄SO₃CF₃ as the sole conductive salt. However, such cells suffer lower voltage and capacity as compared with those using the lithium ionic baseline electrolyte. This is due to the larger molar volume of quaternary ammonium cation, which results in less deposition of oxygen reduction products on the surface of carbon. When used as an electrolyte additive or a co-salt, the ammonium is shown to increase capacity of Li/O₂ cells. The plot of differential capacity versus cell voltage shows that the Li/O₂ cell with ammonium added has broad and scatted differential capacity peaks between the voltages of two reactions of “2Li + O₂ → Li₂O₂” and “2Li + Li₂O₂ → 2Li₂O”. This phenomenon can be attributed to the phase transfer catalysis (PTC) property of quaternary ammonium on the second reaction. Due to inverse effects of the cation geometric volume and the PTC property of ammonium ions on the discharge capacity, there is an optimum range for the concentration of ammonium. It is shown that the addition of NBu₄SO₃CF₃ increases discharge capacity of Li/O₂ cell only when its concentration is in a range from 5 mol% to 50 mol% vs. the total of Li/ammonium mixed salt, and that the optimum concentration is about 5 mol%. In this work we show that the addition of 5 mol% NBu₄SO₃CF₃ into the baseline electrolyte can increase discharge capacity of a Li/O₂ cell from 732 mAh g⁻¹ to 1068 mAh g⁻¹ (in reference to the weight of Super-P carbon) when the cell is discharged at 0.2 mA cm⁻².