assignment

Question 1

If the spontaneous polarization of a ferroelectric material decreases continuously as the temperature increases from below to above Curie temperature, the material is undergoing a first-order phase transition. (T/F)

Answer 1

False

Question 2

The orientational polarization due to a permanent dipole will not contribute to the dielectric constant of a material under a high frequency in the visible range. (T/F)

Answer 2

TRUE

Question 3

BaTiO3 is a perovskite material. It possesses a cubic unit cell above the Curie temperature, with the Ti atom located at ___ of the cubic unit cell.
a. body center
b. face center
c. corner
d. random position

Answer 3

a. body center

Question 4

A parallel plate capacitor is originally empty between the two metal electrodes. A dielectric material is then inserted into the empty space between the two electrode. The capacitance is then ____?
a. increased
b. unable to determine
c. unchanged
d. decreased

Answer 4

a. increased

Question 5

A dielectric material normally has a dielectric constant greater than 1. (T/F)

Answer 5

True

Question 6

When the temperature of ferroelectric PZT material is above the Curie temperature, the PZT is in a ____ phase.
a. antiferroelectric
b. paraelectric
c. ferroelectric
d. dielectric

Answer 6

b. paraelectric

Question 7

The direction of a dipole moment is pointing from the positive charge to the negative charge of the dipole. (T/F)

Answer 7

False

Question 8

The volumetric energy density of a parallel plate dielectric capacitor will be increased if the thickness of the capacitor is decreased. Assume the electric field applied to the capacitor remains unchanged. (T/F)

Answer 8

False

Question 9

Increasing the surface area of a supercapacitor can result in a higher capacitance. (T/F)

Answer 9

True

Question 10

The cyclic voltammetry (CV) curve of an ideal electric double layer capacitor should be in a(n) _____ shape.
a. triangular
b. circular
c. rectangular
d. irregular

Answer 10

c. rectangular

Question 11

The iR voltage drop in a GCD curve is related to the equivalent series resistance of a supercapacitor. (T/F)

Answer 11

True

Question 12

The electrochemical performance of an electrode material can be evaluated by a three-electrode system. (T/F)

Answer 12

True

Question 13

Merely decreasing the distance between the positive and negative electrodes of an electrochemical supercapacitor can increase its capacitance. (T/F)

Answer 13

False

Question 14

The Galvanostatic charge discharge (GCD) curve of an ideal electric double layer capacitor should be in a(n) _____ shape.
a. triangular
b. rectangular
c. irregular
d. circular

Answer 14

a.trianglar

Question 15

If the charge storage mechanism of a supercapacitor is the solid-state diffusion of ions, the voltammetry current in the CV curve is proportional to v^n. Here v is the voltage scan rate and n is _____.

Answer 15

1/2

Question 16

Which of the following electrolytes can be used in lieu of a separator in a supercapacitor?
a. Solid-state electrolyte
b. Organic electrolyte
c. Ionic liquid electrolyte
d. Aqueous electrolyte

Answer 16

a. Solid-state electrolyte

Question 17

In a cyclic voltammetry measurement, which of the following quantity is kept constant?

Answer 17

Voltage Scan Rate (dV/dT)

Question 18

In general, which of the following types of electrolyte has the highest ionic conductivity?

Answer 18

Aqueous electrolyte

Question 19

A Galvanostatic charge discharge (GCD) curve is measured under a constant _________.

Answer 19

current density

Question 20

An electrochemical supercapacitor normally has a higher energy density than a lithium-ion battery. (T/F)

Answer 20

False

Question 21

A separator is indispensable for a solid-state lithium battery. (T/F)

Answer 21

False

Question 22

Which of the following component in a lithium-ion battery uses Aluminum foil?
a. Current collector on the anode side.
b. Anode.
c. Current collector on the cathode side.
d. Cathode.

Answer 22

c. Current collector on the cathode side.

Question 23

Copper cannot be used as the current collector for anode of a lithium-ion battery. (T/F)

Answer 23

False

Question 24

LiCoO2 has a three-dimensional framework for the diffusion of Li ions. (T/F)

Answer 24

False

Question 25

In graphite material, theoretically, how many carbon atoms can accommodate the insertion of one Li ion? a. 5 b. 6 c. 4 d. 7

Answer 25

b.6

Question 26

During discharge, Li ions intercalate into the LiCoO2 cathode. (T/F)

Answer 26

True

Question 27

Lithium-ion capacitors embody both the advantages of lithium-ion batteries and electrochemical supercapacitors. (T/F)

Answer 27

True

Question 28

A lithium-ion battery is discharged at a rate of 2C. How long will it take for this battery to be fully discharged under this rate?

Answer 28

0.5 hours

Question 29

In a Li-S battery, the polysulfide intermediates Li2Sx (x=4-8) are insoluble in electrolyte. (T/F)

Answer 29

False

Question 30

Which of the following materials belongs to NCM cathode material for lithium-ion batteries? a. LiCoO2 b. LiMn2O4 c. LiNi0.8Co0.1Mn0.1O2 d. LiFePO4

Answer 30

c. LiNi0.8Co0.1Mn0.1O2

Question 31

The storage of Li in graphite belongs to the conversion reaction mechanism. (T/F)

Answer 31

False

Question 32

The Li ion diffusion in LiMn2O4 is ___. a. one dimensional b. two dimensional c. three dimensional d. unable to determine

Answer 32

c. three dimensional

Question 33

Which of the following ions are conducted through the electrolyte of a direct methanol fuel cell? a. H+ b. OH- c. O^2- d. CO3^2-

Answer 33

a. H+

Question 34

Which material below is the best for an SOFC electrolyte? a. La1-xSrxGa1-yMgyO3-d (LSGM) b. graphite c. H2 d. O2

Answer 34

a. La1-xSrxGa1-yMgyO3-d (LSGM)

Question 35

Y-doped zirconia (YSZ) is used as ____ in a solid oxide fuel cell.

Answer 35

electrolyte

Question 36

In an SOFC, the thermal expansion coefficients of cathode, anode and electrolyte should be matched. (T/F)

Answer 36

True

Question 37

ORR is a two-electron process. (T/F)

Answer 37

False

Question 38

Which of the following ions are conducted through the electrolyte of a molten carbonate fuel cell? a. OH- b. H+ c. O^2- d. CO3^2-

Answer 38

d. CO3^2-

Question 39

As an SOFC electrolyte, YSC should work at a lower temperature than GDC. (T/F)

Answer 39

False

Question 40

In the temperature range of 600-1000°C, the ionic conductivity of YSZ _______. a. increases with increasing temperature b. decreases with increasing temperature c. is independent of temperature d. first increases then decreases with temperature

Answer 40

a. increases with increasing temperature

Question 41

Alkaline fuel cells are sensitive to CO2. (T/F)

Answer 41

True

Question 42

In the Nernst equation, the activity of solute ions in an ideal solution is normally taken as _____. a. 0.5 b. the concentration ratio of that solute ions to the standard concentration c. 1 d. 0.1

Answer 42

b. the concentration ratio of that solute ions to the standard concentration

Question 43

Both of the cathodic and anodic polarizations will contribute to the voltage loss during the operation of a fuel cell. (T/F)

Answer 43

True

Question 44

The electronic conductivity of an SOFC electrolyte should be kept high, while the ionic conductivity should be kept low under working condition. (T/F)

Answer 44

False

Question 45

Under a forced oscillation, a material will have the largest deformation when the frequency of applied force equals the resonance frequency of the material. (T/F)

Answer 45

True

Question 46

The working principle of a quartz crystal microbalance is based on the mass-dependent resonance frequency.

Answer 46

True

Question 47

We use piezoelectric constant to evaluate the polarization developed on the surface of a ceramic sample due to the application of an electric field. If the electric field is along z-direction and we are interested in the polarization developed in this direction, which of the following piezoelectric constant should be used? A. d15 B. d33 C. d13 D. d12

Answer 47

B. d33

Question 48

PZT is a piezoelectric material whose Curie temperature depends on the ratio of PbZrO3 and PbTiO3 (T/F)

Answer 48

True

Question 49

Triboelectric nanogenerator (TENG) outperforms a conventional electromagnetic generator particularly in the high frequency range. (T/F)

Answer 49

False