Effect of catalysts on dc corona discharge poisoning

The processes of ozone generation in non-thermal plasma produced by an electrical discharge in air at atmospheric pressure are burdened by the presence of nitrogen oxides, which on the one hand contribute to ozone generation and on the other hand are responsible for unpleasant discharge poisoning. The term discharge poisoning refers to the situation when the discharge ozone formation completely breaks down. Discharge poisoning can be affected by placing a catalyst in the discharge chamber. For the dc hollow needle to mesh corona discharge enhanced by the flow of air through the needle electrode we studied the effect of titanium dioxide TiO₂, ZSM-5 zeolite or Cu⁺⁺ZSM-5 zeolite on discharge poisoning by monitoring the ozone, nitrogen monoxide and nitrogen dioxide discharge production. We found that placing globules of any of these catalysts on the mesh decreases the energy density of the onset of discharge poisoning, and this energy density is smallest for a discharge with globules of a TiO₂ on the mesh.     

Decomposition of NO2 in Oxygen-free NO2: N2 Gas Mixture by Back-Corona Generated Plasma

The back-corona discharge has been successfully applied as a plasma source for decomposition of NO₂ in the oxygen-free gas mixture of N₂:NO₂. The paper reports a first attempt to use back-corona discharge for noxious gas conversion. The preliminary results of laboratory experiments in a needle-to-plate reactor show that the De-NO_x processes in back-corona discharge are similar to the dc streamer corona discharges generated in the same geometry. Both types of discharges convert NO₂ to nitrogen, oxygen and also to N₂O and NO. However, back-corona discharge produces less NO, and is more efficient energetically in NO_x decomposition than the dc streamer corona discharge.     

Measurement of atomic hydrogen density in non-thermal H<Subscript>2</Subscript> plasmas via threshold ionisation-molecular beam mass spectrometry

Determinations of radical density are essential to investigate the physical-chemical processes in plasmas and setup the related theoretical models. This paper presents the experimental measurement of atomic hydrogen near grounded electrode in dielectric barrier discharge medium-pressure hydrogen plasma via threshold ionisation-molecular beam mass spectrometry. After investigating the possible influences from parent molecules in excited states, background component and space-charge, evolution of atomic hydrogen density as functions of discharge parameters are investigated utilising the signal of H₂ molecule beam as the reference. At fixed gas pressure of 6.0 torr and a discharge voltage of 24 kV, atomic hydrogen density increases monotonously from 1.1×10¹⁴ to 2.0×10¹⁵ cm^-3 as the discharge frequency increases from 9 to 26 kHz. Similarly the rising discharge voltage also lead to enhancement of atomic hydrogen density.     

Nitrogen fixed into HNO3 by pulsed high voltage discharge

By applying pulsed high voltage discharge to a needle-mesh reactor that using seven acupuncture needles as discharge electrode and stainless steel wire mesh as ground electrode, nitrogen from bubbling gas could be fixed into NO₂^? and NO₃^? with equivalent mol H⁺ produced in the liquid phase and a small amount of NO and NO₂ yielded in the gas phase. The HNO₂ was originally formed and then converted into HNO₃. The ·OH and H₂O₂ stimulated the conversion reaction from HNO₂ to HNO₃, which caused HNO₂ concentration increased in the first 12 min and then decreased until lower than its detection limit. The concentration of HNO₃ still increased with discharge time. After 36 min, HNO₃ was the only and ultimate product in the liquid. The total yield of HNO₂ and HNO₃ could be affected by processing parameters such as electric factors of peak voltage and frequency, mesh size of ground electrode and content of nitrogen in N₂/O₂ bubbling. Increasing peak voltage or frequency, the total yield of HNO₂ and HNO₃ increased. Gas composition had a heavy impact on the fixation efficiency that obtained its maximum value at an oxygen content of 66.7% with bubbling O₂/N₂ gas. At the end of the 36 min discharge, the HNO₃ concentration with bubbling air was 2.215 mmol L^?1 at an applied voltage of 25 kV, pulse repetition frequency of 140 Hz and ground electrode mesh of 20 × 20. The energy yield was about 1.22 g (HNO₃)/kWh.     

A multi-wire-to-cylindrical type packed-bed plasma reactor for the inactivation of M. aeruginosa

Eutrophication in drinking water supplies brings about serious impact on the drinking water safety. In this study, a new multi-wire-to-cylindrical type packed-bed plasma reactor has been proposed and experimentally investigated its ability to control excessive growth of Microcystis aeruginosa (M. aeruginosa). Experimental results show the removal efficiency of M. aeruginosa and the inactivation constant were increased with the increased electrode number and air flow rate. More than 93% of optical density was removed at an air flow rate of 0.75 m³/h with treatment for 40 min at the end of the fifth day and the inactivation constant 16.20 was obtained in the multi-wire-to-cylindrical type packed-bed plasma reactor with 3 mm diameter 6-wire high-voltage electrodes; the difference in the electrode material on the removal efficiency of M. aeruginosa was unobvious, but the effects of pulse repetitive rate and applied peak pulse voltage on the inactivation of M. aeruginosa were significant. The changes in the visible spectra of M. aeruginosa solution demonstrated that photosynthetic pigments, such as chlorophyll-a, phycocyanins, carotenoids have been damaged, indicating the inhibitive behaviors of discharge on the algal growth. These results implicate that M. aeruginosa cells were inactivated by a multi-wire-to-cylindrical type packed-bed plasma reactor, demonstrating the considerable potential of such an alternative process for efficient water purification.     

Combination of spontaneous polarization plasma and photocatalyst for toluene oxidation

In this paper, we report toluene destruction using a spontaneous polarization plasma and photocatalyst reactor in air at atmospheric pressure and room temperature. A spontaneous polarization material (BaTiO₃) and photocatalyst (TiO₂) were added to the plasma system simultaneously. Three types of catalyst, i.e., TiO₂, BaTiO₃, or TiO₂/BaTiO₃, were used for toluene removal. The catalyst carrier, type, and amount were important factors in the toluene removal efficiency. The specific energy density and energy yield during the discharge process were investigated. The toluene removal efficiency increased when a spontaneous polarization plasma was combined with the photocatalyst. In terms of toluene removal efficiency, the activity order was TiO₂/BaTiO₃ > BaTiO₃ > TiO₂ > none. Large amounts of BaTiO₃ in the TiO₂/BaTiO₃ catalyst gave slightly better conversion. The TiO₂/BaTiO₃ catalyst not only enhanced the toluene removal efficiency, but also saved energy, making it useful for industrial applications.     

Self-Supported Graphite/Graphene/NiFe-LDH Electrodes for High Performance Oxygen Evolution Reaction

Reducing energy consumption and improving energy utilization efficiency has become the focus of research in the 21^st century. Electrocatalytic water splitting is one of the promising strategies for producing hydrogen energy. In this study, the non-noble nickel-iron layered double hydroxide (NiFe-LDH) catalyst is deposited on the electrochemically intercalated graphite/graphene (G/GE) substrate and directly used as the self-supported and binder-free electrode for electrocatalytic water oxidation. The Ni₂Fe₁-LDH@G/GE catalyst shows a low overpotential of 194 mV at a current density of 10 mA cm^–2, which is better than the noble metal catalyst IrO₂ (314 mV) and RuO₂ (330 mV) and many other related works. This research provides a facile way to directly prepare the catalyst electrode with high performance and low cost.     

Pseudo-capacitive properties of LiCoO<Subscript>2</Subscript>/AC electrochemical capacitor in various aqueous electrolytes

LiCoO₂ particles were synthesized by a sol-gel process. X-ray diffraction analysis reveals that the prepared sample is a single phase with layered structure. A hybrid electrochemical capacitor was fabricated with LiCoO₂ as a positive electrode and activated carbon (AC) as a negative electrode in various aqueous electrolytes. Pseudo-capacitive properties of the LiCoO₂/AC electrochemical capacitor were determined by cyclic voltammetry, charge–discharge test, and electrochemical impedance measurement. The charge storage mechanism of the LiCoO₂-positive electrode in aqueous electrolyte was discussed, too. The results showed that the potential range, scan rate, species of aqueous electrolyte, and current density had great effect on capacitive properties of the hybrid capacitor. In the potential range of 0–1.4 V, it delivered a discharge specific capacitance of 45.9 Fg^–1 (based on the active mass of the two electrodes) at a current density of 100 mAg^–1 in 1 molL^–1 Li₂SO₄ aqueous electrolyte. The specific capacitance remained 41.7 Fg^–1 after 600 cycles.     

Characteristic study of cold atmospheric argon plasma jets with rod-tube/tube high voltage electrode

Atmospheric argon plasma jets are generated with the rod-tube/tube high voltage electrode and a ring ground electrode at 8 kHz sinusoidal excitation voltage. It is found that the vibrational temperature, electronic excitation temperature, atomic oxygen density and spectral intensity with the rod-tube high voltage electrode are enhanced significantly than that with the tube high voltage electrode. The atomic oxygen density, molecular nitrogen density, and average electronic density are about magnitude of 10¹⁶ cm^?3, 10¹⁵ cm^?3, and 10¹² cm^?3 respectively, and the excited Ar, N₂, OH and O are presented in the plasma plume with the rod-tube/tube high voltage electrode.     

Electrochemical characterization on layered lithium ruthenate for electrochemical supercapacitors

Electrochemical characteristics of lithium ruthenate (Li_xRuO_2+0.5x·nH₂O) for electrochemical capacitors' electrode material were first examined in this paper by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge tests. Results show that Li_xRuO_2+0.5x·nH₂O has electrochemical capacitive characteristic within the potential range of − 0.2–0.9 V (vs. SCE) in 1 M Li₂SO₄ solution. The capacitance mainly arises from pseudo-capacitance caused by lithium ions' insertion/extraction into/out of the Li_xRuO_2+0.5x·nH₂O electrode. The specific capacitance of 391 F g^− 1 can be delivered at 1 mA charge–discharge current for Li_xRuO_2+0.5x·nH₂O electrode with an energy density of 65.7 W h kg^− 1. This material also exhibits an excellent cycling performance and there is no attenuation of capacitance over 600 cycles.     

Investigation of liquid plasma catalysis on Ti electrodes for the decolorization of a brilliant red B solution

This investigation is intended to determine the catalytic effect of liquid plasma on TiO₂, generated in situ on Ti anodes submerged in Na₂SO₄ electrolyte solution by observing the efficiency of the reaction in decolorizing a brilliant red B solution under voltage-stabilized DC power. The orthogonal test was performed in order to obtain the optimal reaction conditions for the test device. When placed under a constant voltage of 550 V, and with an electrode depth of 2 mm, Na₂SO₄ concentration of 5 g/L, pH of 2, the maximum decolorization ratio of 100 mL brilliant red B solution with the concentration of 20 mg/L was 97.8% after 40 min. The reaction rate constant was about 0.102 min^?1, conforming to the first-order reaction kinetic model. Comparative tests were conducted with: Al electrode under 450 V; Mo electrode under 550 V; and a mixture of the electrolyte and TiO₂ powder. The results showed that liquid plasma – TiO₂ on the electrode of the catalytic system naturally integrated on the discharge electrode, with an increase in reaction rate by 26.8% while utilizing the same energy consumption.     

Preparation of MnO<Subscript>2</Subscript>/WMNT composite and MnO<Subscript>2</Subscript>/AB composite by redox deposition method and its comparative study as supercapacitive materials

The manganese oxide/multi-walled carbon nanotube (MnO₂/MWNT) composite and the manganese oxide/acetylene black (MnO₂/AB) composite were prepared by translating potassium permanganate into MnO₂ which formed the above composite with residual carbon material using the redox deposition method and carbon as a reducer. The products were characterized by X-ray diffraction, Fourier transform infrared, and scanning electron microscope. Electrochemical properties of both the MnO₂/MWNT and MnO₂/AB electrodes were studied by using cyclic voltammetry, electrochemical impedance measurement, and galvanostatic charge/discharge tests. The results show that the MnO₂/MWNT electrode has better electrochemical capacitance performance than the MnO₂/AB electrode. The charge–discharge test showed the specific capacitance of 182.3 F·g⁻¹ for the MnO₂/MWNT electrode, and the specific capacitance of 127.2 F·g⁻¹ for the MnO₂/AB electrode had obtained, within potential range of 0–1 V at a charge/discharge current density of 200 mA·g⁻¹ in 0.5 mol·L⁻¹ potassium sulfate electrolyte solution in the first cycle. The specific capacitance of both the MnO₂/MWNT and MnO₂/AB electrodes were 141.2 F·g⁻¹ and 78.5 F·g⁻¹ after 1,200 cycles, respectively. The MnO₂/MWNT electrode has better cycling performance. The effect of different morphologies was investigated for both MnO₂/MWNT and MnO₂/AB composites.     

Rechargeability improvement of δ-type chemical manganese dioxide with the co-doping of Bi and Ni in alkaline electrolyte

δ-MnO₂ with the doping of Ni and Bi was prepared through a simple chemical precipitation/oxidation method. Its structure was confirmed by the X-ray diffraction tests. The results of cyclic voltammetry and galvanostatic charge–discharge tests showed that both the doping of Bi and Ni benefited the electrochemical activity of the MnO₂ electrode. Compared to the un-doped electrode, the Bi-doped one showed larger discharge capacity and the Ni-doped one showed higher discharge potential and better cycleability. With the co-doping of 5 wt% Bi and 10 wt% Ni, the discharge capacity of the MnO₂ electrode reached 252 mA h g^?1 at a 0.2C rate and 116 mA h g^?1 at a 1C rate, respectively. Its capacity remained in 105 mA h g^?1 after 50 cycles at a 1C rate, but the capacity of a commercial electrolytic MnO₂ electrode was only 37 mA h g^?1.     

Absolute density measurement of hydrogen atom in inductively coupled Ar/H2 plasmas using vacuum ultraviolet absorption spectroscopy

The absolute density measurement of atomic species such as hydrogen is crucial for plasma processing because of their strong chemical reactivity. In this work, to measure the hydrogen atom density in Ar/H₂ inductively coupled plasmas (ICP), the self-absorption-applied vacuum ultraviolet absorption spectroscopy (VUVAS) is studied with a micro-hollow cathode H₂/He discharge lamp (MHCL) emitting VUV light (Lyman alpha line; L_α 121.56 nm). The absolute density of hydrogen atoms in the ICP is investigated for various powers (50 W–850 W) in the low pressure region (30 mTorr–50 mTorr). The hydrogen density in remote plasma region is shown to vary from 2.1 × 10¹¹ cm⁻³ to 1.25 × 10¹² cm⁻³ with respect to plasma power.     

Effect of neutral pressure on the He plasma flow measurement in a linear device

Axial and azimuthal flow velocities have been measured in a linear plasma device called NAGDIS-II (NAGoya DIvertor Simulator-II), along with plasma density and electron temperature, using a vector Mach probe composed of two Mach probes, one of which is for the axial flow, and the other is for the azimuthal flow. To study the effect of neutral pressure on the deduction of the Mach numbers, the ratio of upstream to downstream currents are measured by changing the neutral pressure for the deduction of flow velocities. Helium plasma was generated with pressure of 2–35 mTorr. Since the ion gyro-radius at the magnetic flux of 300 G is larger than the probe size, an unmagnetized collisionless Mach probe theory was used for the deduction of Mach numbers and their variations. In order to check the range of collisionality, plasma density (n_e = 10¹⁰–10¹¹ cm^?3) and electron temperature (T_e = 2–9 eV) are measured by a single electric probe using a conventional collisionless probe theory. Variations of Mach number, electron temperature and plasma density with collisionless models are to be compared with those using collisional models for different pressures where ionization and ion-neutral collision are included. Mach numbers by the collisionless model are found to be overestimated by 120% for the maximum difference even in weakly collisional plasmas. A clear flow reversal exists in the axial direction with higher pressure plasma, even in the linear machine. Azimuthal flows are also measured simultaneously along with axial flows, yet they seem to be very small in the present cold ion plasma (T_i/T_e << 1).     

High-efficiency degradation catalytic performance of a novel Angelica sinensis polysaccharide-silver nanomaterial for dyes by ultrasonic cavitation

Currently, the polluted wastewater discharged by industry accounts for the major part of polluted bodies of water. As one of the industrial wastewaters, dye wastewater is characterized by high toxicity, wide pollution, and difficulty in decolorization degradation. In this paper, a novel composite nanomaterial catalyst of silver was prepared by using Angelica sinensis polysaccharide (ASP) as a reducing and stabilizing agent. And the optimum reaction conditions explored are V_AgNO3 = 5 mL (300 mM) and v_ASP = 7% (w/v) for 6 h at 90 °C. In addition, the ASP-Ag nanocatalyst was characterized by several techniques. The results demonstrated that ASP-Ag nanoparticles were successfully synthesized. Degradation rate, which provides a numerical visualization of the percentage reduction in pollutant concentration. With the wrapping of ASP, the ultrasonic catalytic degradation rates of different organic dyes including rhodamine B (RB), methylene blue (MB), and methyl orange (MO) were from 88.2%, 88.7%, and 85.2% to 96.1%, 95.2% and 93.5% at room temperature, respectively. After the experiments, when c_dyes = 10 mg/L, the highest degradation rate can be observed under c_APS-AgNPs = 10 mg/L with the most powerful cavitation frequency f = 59 kHz. The effect of ultrasonic frequency on the acoustic pressure distribution in the reactor was investigated by using COMSOL Multiphysis^@ software to propose the mechanism of ultrasonic degradation and the mechanism was confirmed by OH radical trapping experiments. It indicates that OH produced by the ultrasonic cavitation effect plays a determinant role in the degradation. And then, the intermediate products of the dye degradation process were analyzed by gas chromatography and mass spectrometry (GC–MS), and the possible degradation processes of dyes were proposed. The resulting products of degradation are SO₄²⁻, NH₄⁺, NO₃⁻, N₂, CO₂ and H₂O. Finally, the recycling degradation experiments showed that catalyst maintains a high degradation rate within reusing 5 cycles. Thus, this catalyst is highly efficient and recyclable.     

Optimization of a heterogeneous catalytic hydrodynamic cavitation reactor performance in decolorization of Rhodamine B: Application of scrap iron sheets

A low pressure pilot scale hydrodynamic cavitation (HC) reactor with 30 L volume, using fixed scrap iron sheets, as the heterogeneous catalyst, with no external source of H₂O₂ was devised to investigate the effects of operating parameters of the HC reactor performance. In situ generation of Fenton reagents suggested an induced advanced Fenton process (IAFP) to explain the enhancing effect of the used catalyst in the HC process. The reactor optimization was done based upon the extent of decolorization (ED) of aqueous solution of Rhodamine B (RhB). To have a perfect study on the pertinent parameters of the heterogeneous catalyzed HC reactor, the following cases as, the effects of scrap iron sheets, inlet pressure (2.4–5.8 bar), the distance between orifice plates and catalyst sheets (submerged and inline located orifice plates), back-pressure (2–6 bar), orifice plates type (4 various orifice plates), pH (2–10) and initial RhB concentration (2–14 mg L^?1) have been investigated. The results showed that the highest cavitational yield can be obtained at pH 3 and initial dye concentration of 10 mg L^?1. Also, an increase in the inlet pressure would lead to an increase in the ED. In addition, it was found that using the deeper holes (thicker orifice plates) would lead to lower ED, and holes with larger diameter would lead to the higher ED in the same cross-sectional area, but in the same holes’ diameters, higher cross-sectional area leads to the lower ED. The submerged operation mode showed a greater cavitational effects rather than the inline mode. Also, for the inline mode, the optimum value of 3 bar was obtained for the back-pressure condition in the system. Moreover, according to the analysis of changes in the UV–Vis spectra of RhB, both degradation of RhB chromophore structure and N-deethylation were occurred during the catalyzed HC process.     

Preparation of magnetic nanoparticles by pulsed plasma chemical vapor synthesis

FePt nanoparticle is expected as a candidate for the magnetic material of the high density recording media. We attempted to synthesize FePt alloy nanoparticles using 13.56 MHz glow discharge plasma with the pulse operation of a square-wave on/off cycle of plasma discharge to control the size of nanoparticles. Vapors of metal organics, Biscyclopentadienyl iron (ferrocene) for Fe and (Methylcyclopentadienyl) trimethyl platinum for Pt, were introduced into the capacitively coupled flow-through plasma chamber, which consisted of shower head RF electrode and grounded mesh electrode. Synthesis experiments were conducted at room temperature under the conditions of pressure 0.27 Pa, source gas concentration 0.005 Pa, gas residence time 0.5 s and plasma powers 60 watts. Pulse width for plasma duration was chosen from 0.5 to 30 s and plasma off period was 4 s to each pulse operation. Visual observations during the particle growth showed plasma emission in the bulk region was increased with the particle growth. These were theoretically explained by using the model for both transient particle charging in the plasma and single particle behavior in the stationary plasma as well as assuming the similarity between the negative charged particle and negative gas containing plasma. Synthesized nanoparticles were directly collected onto TEM grid, which was placed just below the grounded mesh electrode in the plasma reactor downstream. TEM pictures showed two kinds of particles in size, one of which was nanometer size and isolated with crystal structures and the other appeared agglomerate of nanometer size particles. The size of agglomerated particle was controlled in the 10–120 nm range by varying the plasma-on time from 0.5 to 30 s, although the nanometer size particles did not change. The composition of FePt alloy particles could be altered by adjusting the source gas feed ratio. Also magnetization of FePt nanoparticles was measured by use of SQUID (superconducting quantum interference device) magnetometry measurements. As-synthesized FePt nanoparticles did not exhibit loop-shape characteristic, which indicated superpamagnetic property. Annealed nanoparticles with the composition of Fe₅₈Pt₄₂ at 650°C in atmospheric hydrogen showed clear hysterisis loop with the coercivity as large as 10 KOe.     

Numerical study on effects of hydrothermal aging to composite regeneration in CeO2-based catalyzed diesel particulate filter

The effects of hydrothermal aging on the performance of CeO₂-based catalyzed diesel particulate filter (CDPF) was numerically investigated in this study based on a zero-dimensional model using the plug flow reactor in which a chemical reaction kinetic mechanism was established and validated by the simulated gas environment experiment. The effects of regeneration temperature, O₂ concentration in the ultimate emission conditions, the ratio of NO₂ in NOx (α) and the ratio of NOx to soot (β) on catalyst deactivation temperature and soot oxidation rate were investigated with fresh and hydrothermal aging CeO₂-based CDPF. The results show that hydrothermal aging of CeO₂-based catalysts raises the regeneration temperature from 613 to 783 K and shifts the soot catalytic combustion reaction path from complete to incomplete oxidation. Soot oxidation rate of fresh catalyst first increases rapidly at 516 K and then starts to slow down gradually at 633 K, but for hydrothermal aging catalysts, are 601 K and 789 K, respectively. With O₂ concentration increased from 1.5 mol/m³ to 5.5 mol/m³, the catalyst deactivation of fresh and hydrothermal aging catalyst increased from 609 K to 602 K, 791 K to 818 K, respectively. The increase in α and β leads to an increase in soot oxidation rate and a decrease in regeneration temperature. The deactivation temperature of catalyst is increased in higher α (1.0) and lower β (0.1), which the highest is 821 K. Synergistic mechanisms of NOx, regeneration temperature, and hydrothermal aging effects on soot catalytic combustion in CeO₂-based CDPF are revealed deeply with the help of zero-dimensional model.     

Structural and electrochemical properties of LiNi0.5Mn0.5 − xAlxO2 (x = 0, 0.02, 0.05, 0.08, and 0.1) cathode materials for lithium-ion batteries

Layered LiNi_0.5Mn_0.5 ? xAl_xO₂ (x = 0, 0.02, 0.05, 0.08, and 0.1) series cathode materials for lithium-ion batteries were synthesized by a combination technique of co-precipitation and solid-state reaction, and the structural, morphological, and electrochemical properties were examined by XRD, FT-IR, XPS, SEM, CV, EIS, and charge–discharge tests. It is proven that the aliovalent substitution of Al for Mn promoted the formation of LiNi_0.5Mn_0.5 ? xAl_xO₂ structures and induced an increase in the average oxidation number of Ni, thereby leading to the shrinkage of the lattice volume. Among the LiNi_0.5Mn_0.5 ? xAl_xO₂ materials, the material with x = 0.05 shows the best cyclability and rate ability, with discharge capacities of 219, 169, 155, and 129 mAh g^? 1 at 10, 100, 200, and 400 mA g^? 1 current density respectively. Cycled under 40 mA g^? 1 in 2.8–4.6 V, LiNi_{0. 5}Mn_0.45Al_0.05O₂ shows the highest discharge capacity of about 199 mAh g^? 1 for the first cycle, and 179 mAh g^? 1 after 40 cycles, with a capacity retention of 90%. EIS analyses of the electrode materials at pristine state and state after first charge to 4.6 V indicate that the observed higher current rate capability of LiNi_{0. 5}Mn_0.45Al_0.05O₂ can be understood due to the better charge transfer kinetics.