Patent Application
20170179557
1. Field
Embodiments of the inventive concepts relate to a lithium-air battery and a method for manufacturing the same and, more particularly, to a lithium-air battery using a non-aqueous electrolyte including lithium iodide (LiI) and a method for manufacturing the same.
2. Description of the Related Art
A lithium-air battery is a battery system that uses a metal (e.g., lithium) as a negative electrode and uses oxygen in air as an active material of a positive electrode under the presence of a carbon carrier. Since oxygen included in the air is used as a positive electrode material corresponding to an important component of the battery, a weight of the battery can be markedly reduced. In addition, since the metal such as lithium is used in the negative electrode, the capacity of the battery can be increased. Thus, the lithium-air battery is being spotlighted.
In particular, the lithium-air battery is more environmentally friendly than a lithium ion battery. Therefore, methods for improving stability and charge/discharge characteristics of the lithium-air battery have been actively studied to apply the lithium-air battery to various fields such as automobiles and energy storage devices.
For example, Korean Patent Publication No. KR20150079488A (Applicant: SK innovation, Application No. KR20147014264A) discloses a lithium-air battery system that includes a lithium-air battery, a gas inflow pipe into which a mixture of air and an electrolyte solvent evaporated from the lithium-air battery flows, a reaction part which includes an inner space part and which is connected to the gas inflow pipe to receive the mixture of the electrolyte solvent vapor and the air in the inner space part, an electrolyte solvent filtering part which is provided in the reaction part to separate the electrolyte solvent from the mixture of the electrolyte solvent vapor and the air, and an electrolyte solvent collecting device. The electrolyte solvent collecting device includes a collecting part which is connected to the inner space part of the reaction part and which is formed under the reaction part, a transfer pipe which transfers the electrolyte solvent collected in the collecting part to the lithium-air battery, and a check valve. According to Korean Patent Publication No. KR20150079488A, the lithium-air battery system includes the electrolyte solvent collecting device capable of collecting the electrolyte solvent evaporated in the lithium-air battery, and thus stability of the lithium-air battery can be improved.
To commercialize the lithium-air battery, there is a need for methods for improving charge/discharge efficiency and a lifetime of the battery and for reducing a manufacture cost of the battery.
Embodiments of the inventive concepts may provide a lithium-air battery with improved charge/discharge efficiency and a method for manufacturing the same.
Embodiments of the inventive concepts may also provide a lithium-air battery with an improved lifetime and a method for manufacturing the same.
Embodiments of the inventive concepts may further provide a lithium-air battery capable of reducing a manufacture cost and a method for manufacturing the same.
In an aspect, a lithium-air battery may include a negative electrode including a lithium metal, a positive electrode using oxygen as a positive electrode active material, a non-aqueous electrolyte disposed between the negative electrode and the positive electrode and including lithium iodide (LiI), and a separator disposed between the positive electrode and the negative electrode. Lithium hydroxide (LiOH) may be produced as a discharge product at the positive electrode by iodine (I) of LiI included in the non-aqueous electrolyte.
In some embodiments, the non-aqueous electrolyte may react with lithium ions (Li+) at the positive electrode in a discharging operation to produce an intermediate compound of lithium, hydrogen, and oxygen, and the intermediate compound may react with iodine ions (I−) and lithium ions (Li+) included in the non-aqueous electrolyte in the discharging operation to produce LiOH and a lithium iodine compound.
In some embodiments, the intermediate compound may be LiOOH and the lithium iodine compound may be Li0I. LiOOH may react with the iodine ions (I−) and the lithium ions (Li+) included in the non-aqueous electrolyte in the discharging operation to produce LiOH and LiOI, as represented by the following reaction formula 1.
LiOOH+I−+Li+→LiOI+LiOH [Reaction formula 1]
In some embodiments, LiOI produced by the reaction formula 1 may react as the following reaction formula 2 in a charging operation to produce LiI and O2.
LiOI+LiOI→2LiI+O2 [Reaction formula 2]
In some embodiments, the non-aqueous electrolyte may include an ether-based solvent.
In some embodiments, the non-aqueous electrolyte may include tetraethyleneglycol dimethylether (TEGDME, C10H22O5), and TEGDME may react as the following reaction formula 3 in the discharging operation to produce LiOOH.
C10H22O5+Li2O2→C9H18O4+CH3O−Li++LiOOH [Reaction Formula 3]
In some embodiments, the iodine ions (ID included in the non-aqueous electrolyte may be reduced as the following reaction formula 4 in the charging operation to produce I2, and I2 produced by the following reaction formula 4 may react as the following reaction formula 5 in the charging operation to produce I3−.
I−I−→I2+2e− [Reaction formula 4]
I−+I2→I3− [Reaction formula 5]
In some embodiments, I3− produced by the reaction formula 5 may be reduced to I− in the discharging operation, as represented by the following reaction formula 6, and I31 produced by the following reaction formula 6 may react with LiOOH and Li+ to produce LiOH and LiOI in the discharging operation, as the reaction formula 1.
I3−→I−+I2 [Reaction formula 6]
In some embodiments, oxygen (O2) supplied through the positive electrode may react with the iodine ions (I−) included in the non-aqueous electrolyte in the discharging operation, as represented by the following reaction formula 7.
2O2+2I−→2O2−+I2 [Reaction formula 7]
In some embodiments, 2O2− and I2 produced by the reaction formula 7 may react with each other as the following reaction formula 8 in a charging operation to produce O2 and I−, and I− produced by the following reaction formula 8 reacts with LiOOH and Li+ to produce LiOH and LiOI, as the reaction formula 1.
2O2−+I2→2O2+2I− [Reaction formula 8]
In some embodiments, the discharge product may further include Li2O2, and a production amount of LiOH may be more than a production amount of Li2O2.
In some embodiments, an oxygen evolution curve according to an increase in battery cycle number may substantially remain constant in a voltage curve according to a specific capacity of the lithium-air battery.
In some embodiments, a concentration of LiI included in the non-aqueous electrolyte may range from 0.1M to 1.5M.
In some embodiments, the positive electrode may include a transition metal oxide.
In another aspect, a method for manufacturing a lithium-air battery may include adding a lithium salt and lithium iodide (LiI) into a base electrolyte to manufacture a non-aqueous electrolyte, manufacturing a positive electrode including an oxygen (O2) movement path, and after stacking the positive electrode, a separator, and a negative electrode, injecting the non-aqueous electrolyte between the positive electrode and the negative electrode.
In some embodiments, a concentration of LiI in the non-aqueous electrolyte may range from 0.1M to 1.5M.
In some embodiments, the base electrolyte may be an ether-based solvent.
In some embodiments, the base electrolyte may include tetraethyleneglycol dimethylether (TEGDME), triethyleneglycol dimethylether (TriEGDME), diethyleneglycol dimethylether (DEGDME), or dimethoxy ethane (DME).
In still another aspect, a lithium-air battery may include a negative electrode including a lithium metal, a positive electrode using oxygen as a positive electrode active material, a non-aqueous electrolyte disposed between the negative electrode and the positive electrode and including lithium iodide (LiI) of 0.1M to 1.5M, and a separator disposed between the positive electrode and the negative electrode.
In some embodiments, lithium hydroxide (LiOH), which is more easily decomposed than Li2O2, is produced as a discharge product at the positive electrode.
The inventive concepts will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the inventive concepts are shown. It should be noted, however, that the inventive concepts are not limited to the following exemplary embodiments, and may be implemented in various forms. Accordingly, the exemplary embodiments are provided only to disclose the inventive concepts and let those skilled in the art know the category of the inventive concepts.
It will be understood that when an element such as a layer, region or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present. In addition, in the drawings, the thicknesses of layers and regions are exaggerated for clarity.
It will be also understood that although the terms first, second, third etc.
may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element in some embodiments could be termed a second element in other embodiments without departing from the teachings of the present invention. Exemplary embodiments of aspects of the present inventive concepts explained and illustrated herein include their complementary counterparts. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular terms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes”, “including”, “have”, “has” and/or “having” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Furthermore, it will be understood that when an element is referred to as being “connected” or “coupled” to another element, it may be directly connected or coupled to the other element or intervening elements may be present.
In addition, in explanation of the present invention, the descriptions to the elements and functions of related arts may be omitted if they obscure the subjects of the inventive concepts.
Referring to
A lithium salt and lithium iodide (LiI) may be added into a base electrolyte to manufacture the non-aqueous electrolyte 100 (S100). For example, the base electrolyte may include an ether-based solvent. For example, the base electrolyte may include tetraethyleneglycol dimethylether (TEGDME), triethyleneglycol dimethylether (TriEGDME), diethyleneglycol dimethylether (DEGDME), or dimethoxy ethane (DME). For example, the lithium salt may include at least one of LiN(CF3SO2)2, LiN(FSO2)2, LiN(C2F5SO2)2, LiC(CF2SO2)3, LiBF4, LiPF6, LiClO4, LiCF3SO3, or LiAsF6. In some embodiments, the lithium salt and LiI may be added into the base electrolyte of TEGDME to manufacture the non-aqueous electrolyte 100.
In some embodiments, when a concentration of LiI included in the non-aqueous electrolyte 100 ranges from 0.1M to 1.5M, an oxygen evolution curve according to an increase in a charge/discharge cycle number of the battery may remain constant. That the oxygen evolution curve according to the increase in the charge/discharge cycle number remains constant means that the charge/discharge efficiency remains constant even though the charge/discharge cycle number of the lithium-air battery increases. Thus, the charge/discharge efficiency of the lithium-air battery according to some embodiments of the inventive concepts may substantially remain constant even though the charge/discharge cycle number increases.
If the concentration of LiI included in the non-aqueous electrolyte 100 is less than 0.1M, a gradient of the oxygen evolution curve may increase as the charge/discharge cycle number of the lithium-air battery increases. That the gradient of the oxygen evolution curve according to the charge/discharge cycle number of the lithium-air battery increases means that the charge/discharge efficiency of the lithium-air battery is deteriorated according to the increase in the charge/discharge cycle number. If the concentration of LiI included in the non-aqueous electrolyte 100 is greater than 1.5M, the lithium-air battery may not normally operate.
The positive electrode 110 including an oxygen (O2) movement path may be manufactured (S200). The positive electrode 110 may use oxygen (O2) as a positive electrode active material. The positive electrode 110 may be formed of a conductive material providing the oxygen (O2) movement path. For example, the positive electrode 110 may include at least one of a carbon-based material (e.g., carbon black, carbon nanotube, graphene, or carbon fiber), a conductive inorganic material (e.g., molybdenum oxide, molybdenum carbide, or titanium carbide), a conductive polymer material, or a transition metal oxide (e.g., an oxide of at least one transition metal selected from a group consisting of Co, Fe, Mn, Ru, Jr, Ag, Au, Ti, V, Pt, Pd, Rh, Cu, Mo, W, Zr, Zn, Ce, and La).
The negative electrode 120 may include lithium (Li). The negative electrode 120 may be formed of lithium metal or an alloy of lithium and other metal. For example, the negative electrode 120 may include an alloy of lithium and at least one of silicon (Si), aluminum (Al), tin (Sn), magnesium (Mg), indium (In), or vanadium (V).
The separator 140 may be disposed between the positive electrode 110 and the negative electrode 120. For example, the separator 140 may be a porous glass filter. Alternatively, the separator 140 may include at least one of olefin-based resin, fluorine-based resin (e.g., polyvinylidene fluoride or polytetrafluoroethylene), ester-based resin (e.g., polyethylene terephthalate), or cellulose-based non-woven fabric. In certain embodiments, the separator 140 may be formed of at least one of other various kinds of materials except the examples described above.
After the positive electrode 110, the separator 140, and the negative electrode 120 are sequentially stacked, the non-aqueous electrolyte 100 may be injected between the positive electrode 110 and the negative electrode 120 to manufacture the lithium-air battery according to some embodiments of the inventive concepts (S300).
Charging and discharging operations of the lithium-air battery according to some embodiments of the inventive concepts will be described hereinafter.
When the discharging operation of the lithium-air battery according to the inventive concepts is performed, oxygen (O2) supplied through the positive electrode 110 may react with iodine ions (I−) of LiI included in the non-aqueous electrolyte 100, as represented by the following reaction formula 1.
2O2+2I−→2O2−+I2 [Reaction formula 1]
Oxygen ions (O2−) reduced at the positive electrode 110 by the reaction formula 1 may react with lithium ions (Li+) oxidized at the negative electrode 120 to produce Li2O2 as a discharge product, as represented by the following reaction formula 2. Li2O2 of the discharge product is not easily decomposed during the charging operation of the lithium-air battery because of a low electrical conductivity and a high decomposition polarization of Li2O2. Li2O2 may be precipitated on the positive electrode 110 to reduce or deteriorate the charge/discharge efficiency of the lithium-air battery.
2Li++O2−→Li2O2 [Reaction formula 2]
However, when the lithium-air battery uses the non-aqueous electrolyte 100 manufactured by adding the lithium salt and LiI into the base electrolyte as described above, Li2O2 may be easily decomposed. Thus, LiOH may be produced as the discharge product in addition to Li2O2 during the discharging operation of the lithium-air battery.
In more detail, when the non-aqueous electrolyte 100 includes tetraethyleneglycol dimethylether (TEGDME, C10H22O5) and the discharging operation of the lithium-air battery according to the inventive concepts is performed, the non-aqueous electrolyte 100 may react with lithium ions (Li+) and oxygen ions (O2−) at the positive electrode 110 to produce an intermediate compound of lithium, hydrogen, and oxygen, as represented by the following reaction formula 3. When the non-aqueous electrolyte 100 includes TEGDME as described above, the intermediate compound may be LiOOH.
Li2O2 participating in the following reaction formula 3 may be Li2O2 which corresponds to the discharge product produced by the reaction formula 2. Unlike the above, in the following reaction formula 3, C10H22O5 may react with lithium ions (2Li+) produced from the lithium salt and LiI of the non-aqueous electrolyte 100 and oxygen ions (O2−) produced by the reaction formula 1, thereby producing the intermediate compound.
C10H22O5+Li2O2→C9H18O4+CH3O−Li++LiOOH [Reaction formula 3]
The intermediate compound (LiOOH) produced by the reaction formula 3 may react with iodine ions (I−) and lithium ions (Li+) of the non-aqueous electrolyte 100 to produce other discharge products (LiOH and a lithium iodine compound) different from the discharge product of Li2O2, as represented by the following reaction formula 4. In some embodiments, the lithium iodine compound is LiOI. Iodine ions (I−) participating in the following reaction formula 4 may be produced from LiI included in the non-aqueous electrolyte 100. In addition, as described above, lithium ions (Li+) participating in the following reaction formula 4 may be produced from Li2O2 of the discharge product produced by the reaction formula 2 and the lithium salt and LiI included in the non-aqueous electrolyte 100.
LiOOH+I−+Li+→LiOI+LiOH [Reaction formula 4]
When the lithium-air battery according to some embodiments of the inventive concepts performs the charging operation, LiOI produced by the reaction formula 4 may react as the following reaction formula 5 to produce LiI and O2. LiI produced by the following reaction formula 5 may be reused to decompose Li2O2 of the discharge product produced by the reaction formula 3. O2 produced by the following reaction formula 5 may be exhausted outward through the oxygen (O2) movement path of the positive electrode 110.
LiOI+LiOI→2LiI+O2 [Reaction formula 5]
In addition, iodine ions (I−) included in the non-aqueous electrolyte 100 may be reduced as the following reaction formula 6 to produce I2 during the charging operation of the lithium-air battery. In addition, I2 produced by the following reaction formula 6 may react as the following reaction formula 7 to produce I3.
I−+I−→I2+2e− [Reaction formula 6]
I++I2→I3− [Reaction formula 7]
I3 produced by the reaction formulas 6 and 7 may be reduced as the following reaction formula 8 during the discharging operation of the lithium-air battery. I− produced by the following reaction formula 8 may react with LiOOH and Li+ as the reaction formula 4 to produce LiOH and LiOI.
I3−→I−+I2 [Reaction formula 8]
In addition, 2O2− and I2 produced by the reaction formula 1 may react with each other as the following reaction formula 9 to produce O2 and I−. I− produced by the following reaction formula 9 may react with LiOOH and Li+ as the reaction formula 4 to produce LiOH and LiOI. O2 produced by the following reaction formula 9 may be exhausted outward through the oxygen (O2) movement path of the positive electrode 110.
2O2−+I2→2O2+2I− [Reaction formula 9]
As described above, Li2O2 of the discharge product may be produced at the positive electrode 110 during the discharging operation of the lithium-air battery according to some embodiments of the inventive concepts. At least a portion of Li2O2 of the discharge product may be decomposed as the reaction formulas 3 and 4 to produce LiOH and LiOI which can be more easily decomposed than Li2O2. Thus, a production amount of Li2O2 may be reduced. In some embodiments, a production amount of LiOH may be more than the production amount of Li2O2 during the discharging operation of the lithium-air battery according to some embodiments of the inventive concepts. As a result, the charge/discharge efficiency of the lithium-air battery according to some embodiments of the inventive concepts may not be reduced or deteriorated but may be substantially uniformly maintained.
Unlike the aforementioned embodiments of the inventive concepts, Li2O2 may be produced as a discharge product at a positive electrode during a discharging operation of a conventional lithium-air battery. Li2O2 of the discharge product is not easily decomposed during a charging operation of the conventional lithium-air battery because of the low electrical conductivity and the high decomposition polarization of Li2O2. Thus, Li2O2 may be precipitated on the positive electrode to reduce or deteriorate a charge/discharge efficiency of the conventional lithium-air battery.
However, as described above, the lithium-air battery according to some embodiments of the inventive concepts may include the non-aqueous electrolyte 100 into which LiI is added. During the discharging operation of the lithium-air battery according to some embodiments of the inventive concepts, at least a portion of Li2O2 of the discharge product produced at the positive electrode 110 may be decomposed by iodine ions (I−) of LiI included in the non-aqueous electrolyte 100, thereby producing LiOH. Unlike Li2O2, LiOH may be easily decomposed in the non-aqueous electrolyte 100 but may not be precipitated on the positive electrode 110. Thus, it is possible to prevent or inhibit a problem that Li2O2 of the discharge product is precipitated on the positive electrode in the conventional lithium-air battery to reduce or deteriorate the charge/discharge efficiency of the conventional lithium-air battery.
Evaluation results of characteristics of the lithium-air battery according to the aforementioned embodiments of the inventive concepts will be described hereinafter.
Carbon black (super P) and polyvinylidene fluoride (PVDF) were mixed with each other at a weight ratio of 80:20 to form a mixture, and the mixture was dispersed in N-methyl-2-pyrrolidone to manufacture a positive electrode active material layer composition. A current collector of a carbon paper (TGP-H-030, Torray) was coated with the positive electrode active material layer composition, and then, a drying process was performed to manufacture a positive electrode. A lithium-air battery was manufactured using the manufactured positive electrode, a lithium metal foil used as a negative electrode, and a porous filter (Whatman) used as a separator. An oxygen (O2) movement path was formed at the positive electrode to provide oxygen (O2) to the positive electrode. A lithium salt (e.g., LiCF3SO3) and lithium iodide (LiI) were added to a base electrolyte of tetraethyleneglycol dimethylether (TEGDME) to manufacture an electrolyte solution. Here, a kind and a concentration of the lithium salt and a concentration of the lithium iodide (LiI) were changed to manufacture electrolyte solutions according to various embodiments. Each of the electrolyte solutions was injected between the positive electrode and the negative electrode. The kind and the concentration of the lithium salt and the concentration of the lithium iodide (LiI) are shown in the following table 1.
A lithium-air battery was manufactured by the same method as the lithium-air batteries according to the aforementioned embodiments except an electrolyte. In the comparative example, 1M of LiCF3SO3 was added into the base electrolyte of TEGDME to manufacture a non-aqueous electrolyte, and then, the non-aqueous electrolyte was injected between the positive electrode and the negative electrode to manufacture a lithium-air battery.
Lithium-air batteries were manufactured by the same method as the lithium-air batteries according to the aforementioned embodiments except an electrolyte. In the modified embodiments, 0.1M of I2 was added to manufacture non-aqueous electrolytes, and each of the non-aqueous electrolytes was injected between the positive electrode and negative electrode to manufacture a lithium-air battery.
After the lithium-air battery according to the comparative example was manufactured, a specific capacity value according to a voltage was measured under a constant current condition of 0.1 mA in a state in which a battery cycle time was limited to 1 hour and 10 hours. The specific capacity value was calculated based on a weight including a gas diffusion layer and a positive electrode material of the positive electrode.
Referring to the graphs (a) and (b) of
Through the oxygen reduction curve, it is recognized that the voltage of about 2.7V substantially remains constant regardless of the battery cycle number even though the specific capacity value of the positive electrode increases. An early part of the oxygen reduction curve corresponding to cycles after the first cycle shows voltages between about 2.7V and about 3.0V. This phenomenon may be caused by a reduction reaction of by-products produced by an unclear side reaction.
On the contrary, as shown in an oxygen evolution curve, the gradient of the oxygen evolution curve increases as the battery cycle number increases, and the voltage increases to about 4V as the specific capacity value increases. A variation in potential value required to oxidize and remove Li2O2 precipitated on the positive electrode may be derived through the oxygen evolution curve. Thus, it is recognized that the lithium-air battery according to the comparative example needs a high potential value (i.e., a high charging potential value) to remove Li2O2 which is precipitated on the positive electrode and which increases as the battery cycle number increases.
After the lithium-air battery according to the first embodiment was manufactured, a specific capacity value according to a voltage was measured in an oxygen atmosphere under a constant current condition of 0.1 mA in a state in which a battery cycle time was limited to 1 hour and 10 hours. The specific capacity value was calculated based on a weight including a gas diffusion layer and a positive electrode material of the positive electrode.
Referring to the graphs (a) and (b) of
Thus, it is recognized that a charging potential value required to remove Li2O2 precipitated on the positive electrode is substantially uniformly maintained in the lithium-air battery including LiI according to embodiments of the inventive concepts even though the battery cycle number increases.
As shown in the graph (b) of
As shown in the results of
After the lithium-air batteries according to the modified embodiments were manufactured, a specific capacity value according to a voltage of each of the lithium-air batteries was measured in an oxygen atmosphere under a constant current condition of 0.1mA in a state in which a battery cycle time was limited to 1 hour. The specific capacity value was calculated based on a weight including a gas diffusion layer and a positive electrode material of the positive electrode.
Referring to the graph (a) of
Referring to the graph (b) of
After the lithium-air batteries according to the first embodiment and the modified embodiments were manufactured, a specific capacity value according to a voltage of each of the lithium-air batteries was measured under a constant current condition of 0.1 mA in a state in which oxygen was not supplied and a battery cycle time was limited to 1 hour. The specific capacity value was calculated based on a weight including a gas diffusion layer and a positive electrode material of the positive electrode.
Referring to
A variation of a current when a potential was randomly changed was measured using a cyclic voltammetry (CV). In addition, a variation of a mass when the potential was randomly changed was measured.
Referring to
After the lithium-air battery according to the first embodiment was manufactured, a specific capacity value according to a voltage was measured in an oxygen atmosphere under a constant current condition of 0.1 mA in a state in which a battery cycle time was limited to 20 hours. The specific capacity value was calculated based on a weight including a gas diffusion layer and a positive electrode material of the positive electrode.
Referring to
A light-emitting intensity according to X-ray absorption was measured with respect to the positive electrode by an X-ray diffraction (XRD) apparatus after the lithium-air battery according to the first embodiment was discharged.
The graph of
A surface image of the positive electrode was measured using a SEM apparatus before the lithium-air battery according to the first embodiment or the comparative example was discharged. In addition, a surface image of the positive electrode was measured after each of the lithium-air batteries according to the first embodiment and the comparative example was discharged one time.
As shown in the SEM images (a) and (b) of
As shown in the SEM images (a) and (c) of
As shown in
After the lithium-air batteries according to the embodiments were manufactured, a specific capacity value according to a voltage of each of the lithium-air batteries was measured in an oxygen atmosphere under a constant current condition of 0.1 mA in a state in which a battery cycle time was limited to 1 hour. The specific capacity value was calculated based on a weight including a gas diffusion layer and a positive electrode material of the positive electrode.
Referring to
When the lithium-air batteries according to the eighth embodiment were manufactured, the conductive structures of the positive electrodes were formed of materials (i.e., the carbon black and the transition metal oxide) different from each other. A specific capacity value according to a voltage of each of the lithium-air batteries was measured in an oxygen atmosphere under a constant current condition of 0.1 mA in a state in which a battery cycle time was limited to 1 hour. The specific capacity value was calculated based on a weight including a gas diffusion layer and a positive electrode material of the positive electrode.
Referring to the graphs (a) and (b) of
Referring to
The motor 1010 may convert electric energy of the battery pack 1040 into kinetic energy. The motor 1010 may provide the converted kinetic energy to the axle 1030 through the transmission 1020. The motor 1010 may include a single motor or a plurality of motors. For example, when the motor 1010 includes the plurality of motors, the motor 1010 may include a front motor supplying the kinetic energy to a front axle and a rear motor supplying the kinetic energy to a rear axle.
The transmission 1020 may be located between the motor 1010 and the axle 1030. The transmission 1020 may change the kinetic energy provided from the motor 1010 to meet a driving environment desired by a driver and may provide the changed kinetic energy to the axle 1030.
The battery pack 1040 may store electric energy provided from the charger 1060 and may provide the stored electric energy to the motor 1010. The battery pack 1040 may directly provide the electric energy to the motor 1010 and/or may provide the electric energy to the motor 1010 through the power controller 1050.
At this time, the battery pack 1040 may include at least one battery cell. In addition, the battery cell may include the lithium-air battery according to the aforementioned embodiments of the inventive concepts. However, embodiments of the inventive concepts are not limited thereto. In certain embodiments, the battery cell may further include at least one of other various kinds of secondary batteries. Meanwhile, the battery cell may mean an individual battery, and/or the battery pack may mean a battery cell assembly in which battery cells are connected to each other to meet desired voltage and/or capacity.
The power controller 1050 may control the battery pack 1040. In other words, the power controller 1050 may control the batter pack 1040 to allow the power transmitted from the battery pack 1040 to the motor 1010 to have desired voltage, current and/or waveform. To achieve this, the power controller 1050 may include at least one of a passive power device or an active power device.
The charger 1060 may receive power from an external power source 1070 and may provide the power to the battery pack 1040. The charger 1060 may entirely control a charging state. For example, the charger 1060 may control on/off of charging and a charging rate.
As described above, the lithium-air battery according to embodiments of the inventive concepts may include the non-aqueous electrolyte into which LiI is added. During the discharging operation of the lithium-air battery according to embodiments of the inventive concepts, at least a portion of Li2O2 of the discharge product produced at the positive electrode may be decomposed by iodine ions (I−) of LiI included in the non-aqueous electrolyte, thereby producing LiOH corresponding to another discharge product. Unlike Li2O2, LiOH may be easily decomposed in the non-aqueous electrolyte and may not be precipitated on the positive electrode. The production amount of LiOH may be more than the amount of Li2O2 which is not decomposed by iodine ions of the non-aqueous electrolyte but remains, and thus it is possible to reduce or solve the problem that Li2O2 of the discharge product is precipitated on the positive electrode in the conventional lithium-air battery to reduce or deteriorate the charge/discharge efficiency of the conventional lithium-air battery.
The lithium-air battery according to embodiments of the inventive concepts may have the excellent charge/discharge efficiency and lifetime characteristics by the non-aqueous electrolyte including LiI, as compared with a conventional lithium-air battery. Thus, the lithium-air battery according to embodiments of the inventive concepts may be used in electric cars, middle and large-sized energy storage devices, and electronic devices requiring small, light and environment-friendly characteristics.
According to embodiments of the inventive concepts, the lithium-air battery may be manufactured using the non-aqueous electrolyte into which LiI is added. During the discharging operation of the lithium-air battery according to embodiments of the inventive concepts, at least a portion of Li2O2 of the discharge product produced at the positive electrode may be decomposed by iodine ions (I−) of LiI included in the non-aqueous electrolyte, thereby producing LiOH. Unlike Li2O2, LiOH may be easily decomposed and may not be precipitated on the positive electrode. Thus, it is possible to prevent or inhibit the problem that Li2O2 of the discharge product is precipitated on the positive electrode in the conventional lithium-air battery to reduce or deteriorate the charge/discharge efficiency of the conventional lithium-air battery.
While the inventive concepts have been described with reference to exemplary embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirits and scopes of the inventive concepts. Therefore, it should be understood that the above embodiments are not limiting, but illustrative. Thus, the scopes of the inventive concepts are to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing description.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2014-0117325 | Sep 2014 | KR | national |
This application is a continuation of pending International Application No. PCT/KR2015/009326, which was filed on Sep. 3, 2015 and claims priority to Korean Patent Application No. 10-2014-0117325, filed on Sep. 3, 2014, in the Korean Intellectual Property Office, the disclosures of which are hereby incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/KR2015/009326 | Sep 2015 | US |
| Child | 15448778 | US |
