Role of micro-Ca/In alloying in tailoring the microstructural characteristics and discharge performance of dilute Mg-Bi-Sn-based alloys as anodes for Mg-air batteries

The influence of micro-Ca/In alloying on the microstructural charac teristics,electrochemical behaviors and discharge properties of extruded dilute Mg-0.5Bi-0.5Sn-based(wt.%)alloys as anodes for Mg-air batteries are evaluated.The grain size and texture intensity of the Mg-Bi-Sn-based alloys are significantly decreased after the Ca/In alloying,particularly for the In-containing alloy.Note that,in addition to nanoscale Mg_(3)Bi_(2)phase,a new microscale Mg_(2)Bi_(2)Ca phase forms in the Ca-containing alloy.The electrochemical test results demonstrate that Ca/In micro-alloying can enhance the electrochemical activity.Using In to alloy the Mg-Bi-Sn-based alloy is effective in restricting the cathodic hydrogen evolution(CHE)kinetics,leading to a low self-corrosion rate,while severe CHE occurred after Ca alloying.The micro-alloying of Ca/In to Mg-Bi-Sn-based alloy strongly deteriorates the compactness of discharge products film and mitigates the"chunk effect"(CE),hence the cell voltage,anodic efficiency as well as discharge capacity are greatly improved.The In-containing alloy exhibits outstanding discharge performance under the combined effect of the modified microstructure and discharge products,thus making it a potential anode material for primary Mg-air battery.

Discharge properties of Mg-Sn-Y alloys as anodes for Mg-air batteries

Mg-Sn-Y alloys with different Sn contents(wt%)were assessed as anode candidates for Mg-air batteries.The relationship between microstructure(including the second phase,grain size,and texture)and discharge properties of the Mg-Sn-Y alloys was examined using microstructure observation,electrochemical measurements,and galvanostatic discharge tests.The Mg-0.7Sn-1.4Y alloy had a high steady discharge voltage of 1.5225 V and a high anodic efficiency of 46.6% at 2.5 mA·cm^(-2).These good properties were related to its microstructure:small grain size of 3.8μm,uniform distribution of small second phase particles of 0.6μm,and a high content(vol%)of(1120)/(1010)orientated grains.The scanning Kelvin probe force microscopy(SKPFM)indicated that the Sn_(3)Y_(5) and MgSnY phases were effective cathodes causing micro-galvanic corrosion which promoted the dissolution of Mg matrix during the discharge process.

The regulation of memory effect and its influence on discharge properties of a dielectric barrier discharge driven by bipolar pulse at atmospheric-pressure nitrogen

The regulation of memory effect that the residual charges generated during and after discharge act on the initiation and development of subsequent discharge is explored by adjusting the pulse parameters,which have an influence on the discharge characteristics.The memory effect is quantified by the measurement of‘wall voltage’through a series of reference capacitors.The influences of memory effect on the discharge properties corresponding to rising/falling time50–500 ns,pulse width 0.5–1.5μs,and frequency 200–600 Hz are analyzed.It is found that the‘wall voltage’increases from 1.4 kV to 2.4 kV with rising/falling time from 50 ns to 500 ns,it varies in the range of 0.18 kV with frequency of 200–600 Hz,and 0.17 k V with pulse width of 0.5–1.5μs.The propagation velocity of wavelike ionization under the negative pulse slows down from 2184 km s-1to 1026 km s-1 as the rising/falling time increases from 50 ns to 500 ns due to the weakening of the electric field by the surface memory effect.More intense and uniform emission can be achieved through faster rising/falling time and higher frequency based on the volume memory effect,while pulse width has less influence on the emission uniformity.Furthermore,similar laws are obtained for spectral and discharge intensity.Therefore,the memory effect is most effectively regulated by rising/falling time,and the discharge properties are affected by the surface and volume memory effect.

Synthesis of nanosize MnO_2 and its performence

Sol sol gel method and solid phase redox reaction were respectively applied in preparation of Nanosize MnO 2 powders. The experiments showed that only Mn 2O 3 could be obtained from ignition of Mn(Ⅱ) in the muffle furnace in air, and Mn 2O 3 had to be disproportionated in acids to gain MnO 2. The analysis of XRD and TEM technique revealed that the diameters of nanosize MnO 2 obtained by sol gel method was 35～45 nm and the x in MnO x was 1 9; the particle size of MnO 2 produced from solid phase redox reaction was 10～20 nm and the x in MnO x equaled 1 94. The test results have proved that the discharge property of alkaline manganese battery could be improved by nanosize MnO 2.

Study on electrochemical property of La_(0.75)Mg_(0.25)Ni_(2.85)Co_(0.45–x)(AlSn)_x (x=0.0,0.1,0.2,0.3) alloys

La_（0.75）Mg_（0.25）Ni_（2.85）Co_（0.45–x）（AlSn）_x（AlSn）_x（x=0.0,0.1,0.2,0.3） alloys were prepared by magnetic induction melting method, and the phase composition and electrochemical properties were investigated systematically. The alloys were mainly composed of LaNi5, La2Ni7 and LaNi3 phase, and the cell volume of LaNi5 increased with the Al and Sn contents. For the alloy corresponding to x=0.0, the Cmax and C150 were 348.9 and 185 mA h/g, respectively, then for the alloy electrode with x=0.2, even though the Cmax was only 309.0 mA h/g less than 348.9 mA h/g, the C150 of 231 mA h/g was much higher than 185 mA h/g. And the values of the limit current density, anodic peak current density and hydrogen diffusion coefficient of the La0.75Mg0.25Ni2.85Co0.35（AlS n）0.1（x=0.1） alloy were 1079.5, 1023.8 mA /g and 5.71×10–10 cm2/s, respectively. Which were the highest than that of any other electrodes. These results suggested that the kinetic property of the La_（0.75）Mg_（0.25）Ni_（2.85）Co_（0.45–x）（AlSn）_x（AlSn）_x（x=0.0, 0.1, 0.2, 0.3） electrodes could be improved effectively by adding moderate contents of Al and Sn.

Mechanism of the enhancement of discharge rate property for Nd_(0.8)Mg_(0.2)(Ni_(0.8)Co_(0.2))_(3.8) hydrogen storage alloy by magnetic annealing

For further improving the rate properties of Nd0.8Mg0.2(Ni0.8Co0.2)3.8 hydrogen storage alloy,the alloy was annealed in high mag-netic fields(10 T).The results showed that the electrochemical properties and magnetic properties of Nd0.8Mg0.2(Ni0.8Co0.2)3.8 hydrogen storage alloy were considerably enhanced.And there was no change of the phase composition.The lattice constants of c and c/a ratio increased for the sample magnetically annealed,yielding uniaxial magnetic anisotropy along the c axis.The increase o...

Realizing simultaneously excellent energy storage and discharge properties in AgNbO_(3)based antiferroelectric ceramics via La^(3t)and Ta^(5+)co-substitution strategy

AgNbO_(3)based antiferroelectric(AFE)ceramics have large maximum polarization and low remanent polarization,and thus are important candidates for fabricating dielectric capacitors.However,their energy storage performances have been still large difference with those of lead-based AFEs because of their room-temperature ferrielectric(FIE)behavior.In this study,novel La^(3+)and Ta^(5+)co-substituted AgNbO_(3)ceramics are designed and developed.The introduction of La^(3+)and Ta^(5+)decreases the tolerance factor,reduces the polarizability of B-site cations and increases local structure heterogeneity of AgNbO_(3),which enhance AFE phase stability and refine polarization-electric field(PeE)loops.Besides,adding La^(3+)and Ta^(5+)into AgNbO_(3)ceramics causes the decrease of the grain sizes and the increase of the band gap,which contribute to increased Eb.As a consequence,a high recoverable energy density of 6.79 J/cm3 and large efficiency of 82.1%,which exceed those of many recently reported AgNbO_(3)based ceramics in terms of overall energy storage properties,are obtained in(Ag0.88La0.04)(Nb0.96Ta0.04)O_(3)ceramics.Furthermore,the discharge properties of the ceramic with discharge time of 16 ns and power density of 145.03 MW/cm3 outperform those of many lead-free dielectric ceramics.

Clarifying the roles of grain boundary and grain orientation on the corrosion and discharge processes of α-Mg based Mg-Li alloys for primary Mg-air batteries

The corrosion behavior at open circuit potential(OCP)and discharge properties under applied anodic currents of twoα-Mg based Mg-Li alloys,i.e.,LAZ131 and LAZ531,with different microstructural features for primary Mg-air batteries are investigated.The results show that the grain boundaries contribute equally to the corrosion and discharge processes,which are attacked preferentially than the grain interiors and accelerate the dissolution processes ofα-Mg based Mg-Li alloys.The(10-10)/(11-20)orientated grains are attacked preferentially than the(0002)orientated grains on the corrosion and discharge process.The increased corrosion rate and improved discharge properties are attributed to the refinement of grain size,decreased content of(0002)orientated grains and increased content of(10-10)/(11-20)orientated grains.Of those,the LAZ531 alloy possesses high and steady discharge voltage at small discharge current density for long time,with the values of 1.4801 V at 2.5 mA cm^(-2)and 1.3742 V at 10 mA cm^(-2).

Tailoring the microstructure and improving the discharge properties of dilute Mg-Sn-Mn-Ca alloy as anode for Mg-air battery through homogenization prior to extrusion

Mg-0.5Sn-0.5Mn-0.5Ca(wt.%) alloys with different microstructures are designed through casting and extrusion with and without homogenization treatment prior to extrusion(HPE).The influence of HPE treatment on the microstructural characteristics and resultant discharge properties of Mg-Sn-Mn-Ca alloy in extruded condition as anode for Mg-air battery was investigated.HPE treatment exerts a prominent effect on the grain structure and orientation,distribution of the second phase particles as well as the dislocation density of the extruded alloy.The HPE alloy exhibits a distinctly high cell voltage together with specific energy compared with that of Non-HPE one.Intermittent discharge tests confirm that the HPE alloy possesses a more excellent discharge activity and more stable discharge process than the NonHPE one.All results demonstrate that the HPE alloy is an attractive anode material for Mg-air battery with long-term storage and under intermittent discharge.

Effects of Ti content on dielectric and energy storage properties of(Pb_(0.94)La_(0.04))[(Zr_(0.70)Sn_(0.30))_(1-x)Ti_(x)]O_(3)ferroelectric/antiferroelectric ceramics

Ferroelectric/antiferroelectric(FE/AFE)ceramics with composition of(Pb_(0.94)La_(0.04))[(Zr_(0.70)Sn_(0.30))_(1-x)Ti_(x)]O_(3)were fabricated via solid state reaction and the effects of Ti content on dielectric and energy storage properties were studied.High releasable energy density of 1.03 J/cm^(3)was obtained when x=0:12 under 65.7 kV/cm.With increasing Ti content,both the forward and backward phase transition fields would decrease.When x=0.16,the dielectrics would be under FE state at room temperature(22℃)and the phase transition from FE to AFE and then to paraelectric(PE)was observed with temperature rise.The discharge properties were also studied and the results proved that the stored charge in AFE could be released much more completely than that in FE.