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J. Zhu et al.
used to form low-temperature eutectic alloys, such as Ga, In, Sn, Bi, Tl, etc. The lowtemperature comelt is liquid on the aluminum surface within the working temperature
range of the battery, destroying the combination of the passivation film and the metal
substrate, thus improving the electrochemical activity of the aluminum cathode. (3)
metals used to activate aluminum, reduce self-corrosion rate and increase hydrogen
evolution overpotential, such as Pb, Sn, Hg, Zn, etc.
Adding Sn element can play the above three roles. Sn can cause pores in the passivation film on the aluminum surface to accelerate ion transport, and holes formed after
Al
+3 element in the passivation film is replaced by trace Sn
+4 can reduce the resistance of the passivation film. Sn has high hydrogen evolution overpotential, which can
effectively inhibit hydrogen evolution corrosion of Sn-containing aluminum alloy.
Sn can also form a low cosoluble mixture with Ga, In and the like, which damages
the combination of the aluminum surface passivation film and the aluminum alloy
substrate and produces the effect of activating the negative electrode. The addition
of Ga element can also improve the electrochemical performance of aluminum alloy
cathode. Ga, Bi, Pb and other elements form a low-temperature cosoluble mixture
within the working temperature range of the electrode (60–100 °C) to prevent the
formation of a passivation film on the aluminum surface; The existence of Ga can
also change the anisotropy of pure grains in the dissolution process, thus making
the corrosion of aluminum cathode uniform. In and Ga are more active metals than
aluminum. Adding aluminum can greatly negative shift the potential of the alloy
anode and reduce the polarization of the cathode. Zn, Sn, Pb, Hg, Bi and other
elements in the alloy have high hydrogen evolution overpotential, which can inhibit
hydrogen evolution corrosion of aluminum alloy cathode and improve its current
efficiency and utilization rate of aluminum alloy electrode.
Heat treatment is mainly achieved by affecting the distribution of trace elements
and the microstructure of aluminum alloy. The distribution of a small amount of
added elements and impurity elements contained in aluminum is affected by heat
treatment, especially for elements with small solid solubility in aluminum, the effect
of heat treatment is more significant, such as Pb, Bi and other elements have very
small solid solubility in aluminum, Pb and Bi will diffuse to the surface during
heat treatment, thus activating and enhancing aluminum alloy. However, the solid
solubility of In, Sn, Ga and other elements is slightly higher, and the effect of heat
treatment is very small. For aluminum alloy with high Fe content, heat treatment can
affect the distribution of Fe, thus affecting the overall properties of aluminum alloy.
Among the four heat treatment methods (normalizing, annealing, quenching and
tempering), normalizing treatment has the most negative potential and small polarization. After annealing, the potential slightly moves forward and the polarization
is also very small. Quenching treatment increases polarization and uneven dissolution of surface anode. Normalized and annealed anodes have the highest efficiency
(94–98%), because they avoid grain boundary corrosion and the surface corrosion is
uniform, while quenched and tempered anodes have an efficiency of only about 69%,
because quenched and tempered anodes contain microscopic defects and produce
local dissolution corrosion.
J. Zhu et al.
used to form low-temperature eutectic alloys, such as Ga, In, Sn, Bi, Tl, etc. The lowtemperature comelt is liquid on the aluminum surface within the working temperature
range of the battery, destroying the combination of the passivation film and the metal
substrate, thus improving the electrochemical activity of the aluminum cathode. (3)
metals used to activate aluminum, reduce self-corrosion rate and increase hydrogen
evolution overpotential, such as Pb, Sn, Hg, Zn, etc.
Adding Sn element can play the above three roles. Sn can cause pores in the passivation film on the aluminum surface to accelerate ion transport, and holes formed after
Al
+3 element in the passivation film is replaced by trace Sn
+4 can reduce the resistance of the passivation film. Sn has high hydrogen evolution overpotential, which can
effectively inhibit hydrogen evolution corrosion of Sn-containing aluminum alloy.
Sn can also form a low cosoluble mixture with Ga, In and the like, which damages
the combination of the aluminum surface passivation film and the aluminum alloy
substrate and produces the effect of activating the negative electrode. The addition
of Ga element can also improve the electrochemical performance of aluminum alloy
cathode. Ga, Bi, Pb and other elements form a low-temperature cosoluble mixture
within the working temperature range of the electrode (60–100 °C) to prevent the
formation of a passivation film on the aluminum surface; The existence of Ga can
also change the anisotropy of pure grains in the dissolution process, thus making
the corrosion of aluminum cathode uniform. In and Ga are more active metals than
aluminum. Adding aluminum can greatly negative shift the potential of the alloy
anode and reduce the polarization of the cathode. Zn, Sn, Pb, Hg, Bi and other
elements in the alloy have high hydrogen evolution overpotential, which can inhibit
hydrogen evolution corrosion of aluminum alloy cathode and improve its current
efficiency and utilization rate of aluminum alloy electrode.
Heat treatment is mainly achieved by affecting the distribution of trace elements
and the microstructure of aluminum alloy. The distribution of a small amount of
added elements and impurity elements contained in aluminum is affected by heat
treatment, especially for elements with small solid solubility in aluminum, the effect
of heat treatment is more significant, such as Pb, Bi and other elements have very
small solid solubility in aluminum, Pb and Bi will diffuse to the surface during
heat treatment, thus activating and enhancing aluminum alloy. However, the solid
solubility of In, Sn, Ga and other elements is slightly higher, and the effect of heat
treatment is very small. For aluminum alloy with high Fe content, heat treatment can
affect the distribution of Fe, thus affecting the overall properties of aluminum alloy.
Among the four heat treatment methods (normalizing, annealing, quenching and
tempering), normalizing treatment has the most negative potential and small polarization. After annealing, the potential slightly moves forward and the polarization
is also very small. Quenching treatment increases polarization and uneven dissolution of surface anode. Normalized and annealed anodes have the highest efficiency
(94–98%), because they avoid grain boundary corrosion and the surface corrosion is
uniform, while quenched and tempered anodes have an efficiency of only about 69%,
because quenched and tempered anodes contain microscopic defects and produce
local dissolution corrosion.