Patent Application
20240063370
This application claims priority to Taiwan Patent Application No. 111131180, filed on Aug. 18, 2022. The entire contents of the above-mentioned patent application are incorporated herein by reference for all purposes.
The present disclosure relates to a secondary battery, and more particularly to a dual-cation metal battery and a charging and discharging method thereof to reduce the cost of materials, maintain the long-term service life and provide multiple varied applications.
Lithium-ion battery (Lithium-ion battery) is a secondary battery that can be recharged and discharged repeatedly. With the lithium ions moved between the positive electrode and the negative electrode, the lithium-ion battery is capable of implementing the charging and discharging work. Therefore, the lithium-ion battery needs to use an intercalated lithium compound as the electrode material. The positive electrode materials used in the conventional lithium-ion batteries are mainly the lithium cobalt oxide (LiCoO2), the lithium manganate (LiMn2O4), the lithium nickelate (LiNiO2) and the lithium iron phosphate (LiFePO4). Particularly, since the lithium iron phosphate has the features of good safety, large specific capacity, long cycle life, high temperature resistance and low cost, the lithium iron phosphate batteries are widely used in an electric vehicle and energy storage equipment.
In recent years, with the extensive application of lithium-ion battery on the electric vehicle and the energy storage equipment, the prices of related raw materials have been caused to fluctuate drastically. Considering that the future demand will continue to increase, it is even more important to find alternatives to replace lithium ions. Furthermore, when looking for alternatives to replace lithium ions in lithium-ion battery, it is necessary to consider the impact of differences in voltage platforms on the convenience of use, the product life, and the battery stability.
Therefore, there is a need to provide a dual-cation metal battery and a charging and discharging method thereof to reduce the cost of materials, maintain the long-term service life, provide multiple varied applications and obviate the drawbacks encountered by the prior arts.
One object of the present disclosure is to provide a dual-cation metal battery and a charging and discharging method thereof to reduce the cost of materials, maintain the long-term service life and provide multiple varied applications. The lithium ions and the sodium ions are allowed to be intercalated or intercalated together in the olivine structure of lithium iron phosphate (LiFePO4) and heterosite (FePO4), so as to form dual-cation positive electrode material of LixNa1-xFePO4 with the olivine structure. Therefore, two different voltage platforms of LiFePO4 and NaFePO4 are provided in a metal battery. In the present disclosure, the sodium ions are used to replace part of the lithium ions to form the dual-cation positive electrode material LixNa1-xFePO4, so that it is different from the conventional lithium-ion positive electrode material and the conventional sodium-ion positive electrode material, which is a single-cation cathode material. The dual-cation metal battery of the present disclosure uses sodium ions, which are more abundant in the earth's crustal elements, to replace part of the lithium ions. In addition to making secondary battery materials more sustainable, the voltage platform and the capacity greater than the sodium iron phosphate cathode material are provided and the multiple varied applications are achieved.
Another object of the present disclosure is to provide a dual-cation metal battery and a charging and discharging method thereof. In a dual cation metal battery, the lithium metal and the sodium metal are mixed as a composite negative electrode. Since the lithium metal (theoretical capacitance of lithium metal is 3840 mAh/g) and the sodium metal (theoretical capacitance of sodium metal is 1166 mAh/g) both have high capacitance per gram, it is helpful of reducing the thickness of the negative electrode, so as to achieve the purpose of increasing the energy density of the battery.
A further object of the present disclosure is to provide a dual-cation metal battery and a charging and discharging method thereof. The dual-cation metal battery includes the positive electrode materials such as heterosite (FePO4), lithium iron phosphate (LiFePO4) or LixNa1-xFePO4 combined with a mixture of the lithium metal and the sodium metal. There are two different voltage platforms of LiFePO4 and NaFePO4 in the charging and discharging process. Preferably, different electrical properties are shown by using different charging and discharging modes in the case of the dual-cation positive electrode material of LixNa1-xFePO4 matched with the lithium-sodium metal negative electrode. When the dual-cation metal battery is discharged in a ramp voltage mode, it allows to control the ratio of the lithium-ion intercalation structure and the sodium-ion intercalation structure by controlling the rate of voltage drop. On the other hand, the dual-cation metal battery can be used in an energy storage battery application that does not require a large discharge current output. For example, the dual-cation metal battery is used in a solar power generation system. The solar power is generated during the day with full sunlight, and the current from the solar panel can slowly fill the battery. When discharging at night, if a higher power is needed, it can be discharged through the constant-current-constant-voltage discharging mode. That is, the dual-cation metal battery is discharged through the LiFePO4 voltage platform. On the contrary, if considering that the dual cation metal battery does not require high power output, it can be discharged using the ramp voltage discharging mode to make full use of the electricity released by the NaFePO4 voltage platform. Therefore, the ramp voltage mode or constant-current-constant-voltage can be selected according to the actual application conditions.
In accordance with an aspect of the present disclosure, a dual-cation metal battery is provided and includes a positive electrode, a negative electrode, an electrolyte solution and a separator. The positive electrode includes a positive electrode material selected from the group consisting of heterosite (FePO4), lithium iron phosphate (LiFePO4) and LixNa1-xFePO4, and 0<x<1. The negative electrode includes a metal mixture consisting of lithium metal and sodium metal, wherein a weight ratio of the lithium metal to the sodium metal is 1:3. The electrolyte solution is disposed between the positive electrode and the negative electrode. The separator is disposed in the electrolyte solution, wherein the positive electrode and the negative electrode are separated from each other by the separator.
In an embodiment, the dual-cation metal battery is charged and discharged through a constant-current-constant-voltage mode, wherein the constant-current-constant-voltage mode is a 0.1 C constant-current-constant-voltage mode.
In an embodiment, the dual-cation metal battery is charged and discharged through a constant-current-constant-voltage mode and a ramp voltage mode switched, wherein the constant-current-constant-voltage mode is a 0.1 C constant-current-constant-voltage mode, and the ramp voltage mode includes a charging-and-discharging interval ranged from 2.0 V to 4.0 V and a charging-and-discharging rate of ±0.2 mV/s
In an embodiment, the positive electrode material is LixNa1-xFePO4, the dual-cation metal battery is charged through a constant-current-constant-voltage mode, and discharged through a ramp voltage mode, wherein the constant-current-constant-voltage mode is 0.1 C constant-current-constant-voltage mode, and the ramp voltage mode includes a discharging interval ranged from 4.0 V to 2.0 V, and a discharging rate of −0.2 mV/s.
In an embodiment, the ramp voltage mode includes the discharge interval ranged from 2.8 V to a cut-off voltage of 2.0 V.
In accordance with an aspect of the present disclosure, a charging and discharging method of a dual-cation metal battery is provided and includes: (a) providing a dual-cation metal battery comprising a positive electrode, a negative electrode, an electrolyte solution and a separator, wherein the positive electrode comprises a positive electrode material selected from the group consisting of heterosite (FePO4), lithium iron phosphate (LiFePO4) and LixNa1-xFePO4, and 0<x<1, wherein the negative electrode comprises a metal mixture consisting of lithium metal and sodium metal, and a weight ratio of the lithium metal to the sodium metal is 1:3, wherein the electrolyte solution is disposed between the positive electrode and the negative electrode, wherein the separator is disposed in the electrolyte solution, and the positive electrode and the negative electrode are separated from each other by the separator; and (b) selecting a constant-current-constant-voltage mode or a ramp voltage mode for charging or discharging the dual-cation metal battery.
In an embodiment, the dual-cation metal battery is charged and discharged through the constant-current-constant-voltage mode in the step (b), wherein the constant-current-constant-voltage mode is a 0.1 C constant-current-constant-voltage mode.
In an embodiment, the dual-cation metal battery is charged and discharged through the constant-current-constant-voltage mode and the ramp voltage mode switched in the step (b), wherein the constant-current-constant-voltage mode is a 0.1 C constant-current-constant-voltage mode, and the ramp voltage mode includes a charging-and-discharging interval ranged from 2.0 V to 4.0 V and a charging-and-discharging rate of ±0.2 mV/s.
In an embodiment, the positive electrode material is LixNa1-xFePO4, the dual-cation metal battery is charged through the constant-current-constant-voltage mode, and discharged through the ramp voltage mode in the step (b), wherein the constant-current-constant-voltage mode is 0.1 C constant-current-constant-voltage mode, and the ramp voltage mode includes a discharging interval ranged from 4.0 V to 2.0 V, and a discharging rate of −0.2 mV/s.
In an embodiment, the ramp voltage mode includes the discharge interval ranged from 2.8 V to a cut-off voltage of 2.0 V.
The above contents of the present disclosure will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:
The present disclosure will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this disclosure are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Further, spatially relative terms, such as “inner,” “outer,” “high,” “low” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. When an element is referred to as being “connected,” or “coupled,” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Although the wide numerical ranges and parameters of the present disclosure are approximations, numerical values are set forth in the specific examples as precisely as possible. In addition, although the “first,” “second,” “third,” and the like terms in the claims be used to describe the various elements can be appreciated, these elements should not be limited by these terms, and these elements are described in the respective embodiments are used to express the different reference numerals, these terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. Besides, “and/or” and the like may be used herein for including any or all combinations of one or more of the associated listed items. Alternatively, the word “about” means within an acceptable standard error of ordinary skill in the art-recognized average. In addition to the operation/working examples, or unless otherwise specifically stated otherwise, in all cases, all of the numerical ranges, amounts, values and percentages, such as the number for the herein disclosed materials, time duration, temperature, operating conditions, the ratio of the amount, and the like, should be understood as the word “about” decorator. Accordingly, unless otherwise indicated, the numerical parameters of the present invention and scope of the appended patent proposed is to follow changes in the desired approximations. At least, the number of significant digits for each numerical parameter should at least be reported and explained by conventional rounding technique is applied. Herein, it can be expressed as a range between from one endpoint to the other or both endpoints. Unless otherwise specified, all ranges disclosed herein are inclusive.
Notably, in the embodiment, the dual-cation positive electrode material of LixNa1-xFePO4 included in the positive electrode material 11 refers to allowing Li+ ions and Na+ ions be intercalated or intercalated together in the structure of lithium iron phosphate (LiFePO4), so that two positive electrode materials, LiFePO4 and NaFePO4 with the olivine structure, are disposed on the same positive electrode 10. After the lithium ions are removed from the olivine structure of lithium iron phosphate (LiFePO4), the olivine structure of lithium iron phosphate (LiFePO4) will transform into the structure of heterosite (FePO4). The structure of heterosite (FePO4) can exist stably in the atmospheric environment. There is no structural damage due to the removal of cations. Preferably but not exclusively, in an embodiment, the heterosite (FePO4) is applied to the positive electrode material 11 of the metal battery 1, the cationic lithium or cationic sodium required for the subsequent charging and discharging is provided by the metal mixture 21 of the negative electrode 20. Certainly, the present disclosure is not limited thereto.
Preferably but not exclusively, in the embodiment, the positive electrode 10 is made into a positive electrode sheet in a manner that the proportioning is (the positive electrode material 11: the auxiliary carbon: the binder=8:1:1). The electrolyte 30 is 1.0 M lithium hexafluorophosphate (LiPF6)/sodium hexafluorophosphate (NaPF6) in propylene carbonate (PC) solution. The separator 40 is a glass-fiber filter paper. For preparing the negative electrode 20 that includes the lithium-sodium metal mixture 21, the lithium metal and the sodium metal with a weight ratio of 1:3 are mixed, and then the lithium-sodium metal mixture is rolled to a thickness of 200 μm. Thereafter, a circular lithium-sodium metal negative electrode sheet with a diameter of 12 mm is cut out and served as the negative electrode 20 for testing. Notably, in an embodiment, the positive electrode 10 includes Li0.25Na0.75FePO4 served as the positive electrode material 11. For preparing the positive electrode 10 including the positive electrode material of Li0.25Na0.75FePO4, a positive electrode sheet of LiFePO4, a lithium foil, a separator and 1.0 M LiPF6 ethylene carbonate (EC)/dimethyl carbonate (DMC) electrolyte solution are assembled in a Swagelok three-electrode battery. Then, a 0.1 C slow charging is performed and cooperated with charging time. After 75% of the lithium ions is removed, the Swagelok battery is dissembled, the positive electrode sheet containing 25% lithium ions is taken out. Dimethyl carbonate (DMC) solvent is used to rinse the positive electrode containing 25% lithium ions three times to remove excess electrolyte. In that, the Li0.25FePO4 material is be obtained, and the positive electrode 10 with the positive electrode material 11 is pretreated. Thereafter, the rinsed positive electrode 10, the electrolyte solution 30 of 1.0 M LiPF6/NaPF6 in propylene carbonate (PC) solution, the separator 40 of the glass-fiber filter paper and the negative electrode 20 of the lithium metal and the sodium metal are assembled in a button cell, so as to obtain the metal battery 1 for testing a dual-cation positive electrode material 11. In the embodiment, in order to ensure that sodium ions are intercalated in the structure of the positive electrode material 11, the aforementioned test half-cell is discharged in a ramp voltage (V-ramp) mode. That is, the discharging is performed from 2.8 V at a rate of −0.2 mV/sec to a cut-off voltage of 2.0 V to ensure that the sodium ions are intercalated in the structure of the positive electrode material 11 to form Li0.25Na0.75FePO4. Certainly, in other embodiments, the positive electrode material 11 is selected from the group consisting of heterosite (FePO4), lithium iron phosphate (LiFePO4) and LixNa1-xFePO4. The positive electrode material 11 is adjustable according to the practical requirements, and the present disclosure is not limited thereto.
In the embodiment, the dual-cation positive electrode material 11 in the metal battery 1 is further analyzed for electrochemical characteristics by cyclic voltammetry. Taking the aforementioned metal battery 1 with Li0.25Na0.75FePO4 as an example to test the dual-positive electrode material 11. After a slow scan is performed at a scan rate of 0.1 mV/s by cyclic voltammetry, the oxidation peak and the reduction peak of the obtained dual-cation positive electrode 11 are shown in
Table 2 lists the charging and discharging capacities of the dual-cation metal battery 1 with the positive electrode material 11 of Li0.25Na0.75FePO4 through the ramp voltage mode (V-ramp). The obtained data are shown in Table 2. The charging and discharging capacities and the voltage interval corresponding to the response current of the metal battery 1 are similar to the charging and discharging capacities and the charging and discharging voltage platform of LiFePO4. Therefore, it can be inferred that the main proportion of the charging and discharging capacity obtained by charging and discharging Li0.25Na0.75FePO4 through the ramp voltage mode is mostly the charging and discharging capacity provided by LiFePO4.
In addition, according to the testing results, it is observed that the lithium ions and the sodium ions are intercalated into the structure, when the aforementioned dual-cation metal battery with the positive electrode material 11 of Li0.25Na0.75FePO4 is charged and discharged through the ramp voltage mode.
Table 4 lists the charging and discharging capacities of the dual-cation metal battery 1 with the positive electrode material 11 of Li0.25Na0.75FePO4 through the constant-current-constant-voltage (CC-CV) mode and the ramp voltage (V-ramp) mode switched. As shown in Table 4, after comparing the charging capacity, the discharging capacity and the relationship of the circuit and the voltage, it can be inferred that the charging capacity and discharging capacity measured in testing is provided through the LiFePO4 voltage platform in LixNa1-xFePO4.
From the above, the sodium ions and the lithium ions are removed from the structure of the positive electrode material 11 in the charging process of the dual-cation metal battery 1 containing positive electrode material 11 of Li0.25Na0.75FePO4. Moreover, in the discharging process, the sodium ions or the lithium ions are moved from the negative electrode 20 to the positive electrode 10 and then intercalate into the structure of the positive electrode material 11. It can be understood from the foregoing descriptions that the voltage platforms for the intercalation of sodium ions or lithium ions into the structure of the positive electrode material 11 are different, and controlling the voltage in the process is regarded as an important factor, so as to allow the sodium ions or the lithium ions to be intercalated into the structure of the positive electrode material 11 sequentially to complete the discharging behavior. In an embodiment, the constant-current-constant-voltage mode is used for charging during the charging process, and the ramp voltage mode is used for discharging during the discharging process. The testing results are shown in
Table 5 lists the charging and discharging capacities of the dual-cation metal battery 1 with the positive electrode material 11 of Li0.25Na0.75FePO4 through the constant-current-constant-voltage (CC-CV) mode in the charging process and the ramp voltage (V-ramp) mode in the discharging process. As shown in Table 5 and the cyclic charge/discharge testing in
From the above, the lithium-sodium dual-cation positive electrode material 11 of the positive electrode 10 combined with the negative electrode 20 of the lithium-sodium metal mixture 21 is used in the metal battery 1 of the present disclosure. Moreover, in different usage situations, it allows to select different discharge modes to make the metal battery 1 exhibit different characteristics.
In an embodiment, the positive electrode 10 including the positive electrode material of the heterosite (FePO4) and the negative electrode 20 including the lithium-sodium metal mixture 21 are used to produce the metal battery 1 for carrying out the testing of the mixed charging and discharging mode. The testing results are shown in
In the embodiment, the rate of voltage drop is controlled in the ramp voltage discharge mode to achieve the purpose of discharging. It allows to control the ratio of the lithium-ion intercalation structure and the sodium-ion intercalation structure. The dual-cation metal battery 1 is suitable for an energy storage battery application that does not require a large discharge current output. Preferably but not exclusively, the dual-cation metal battery 1 is used in a solar power generation system. The solar power is generated during the day with full sunlight, and the current from the solar panel can slowly fill the battery. For discharging at night to meet the requirements of higher power, the metal battery 1 can be discharged through the constant-current-constant-voltage discharging mode. That is, the dual-cation metal battery is discharged through the LiFePO4 voltage platform. On the contrary, if considering that the dual cation metal battery 1 does not require high power output, it can be discharged through the ramp voltage discharging mode to make full use of the electricity released by the NaFePO4 voltage platform. Therefore, the ramp voltage mode or constant-current-constant-voltage can be selected according to the actual application conditions. The present disclosure is not limited thereto and not redundantly described hereafter.
In summary, the present disclosure provides a dual-cation metal battery and a charging and discharging method thereof to reduce the cost of materials, maintain the long-term service life and provide multiple varied applications. The lithium ions and the sodium ions are allowed to be intercalated or intercalated together in the olivine structure of lithium iron phosphate (LiFePO4) and heterosite (FePO4), so as to form dual-cation positive electrode material of LixNa1-xFePO4 with the olivine structure. Therefore, two different voltage platforms of LiFePO4 and NaFePO4 are provided in a metal battery. In the present disclosure, the sodium ions are used to replace part of the lithium ions to form the dual-cation positive electrode material LixNa1-xFePO4, so that it is different from the conventional lithium-ion positive electrode material and the conventional sodium-ion positive electrode material, which is a single-cation cathode material. The dual-cation metal battery of the present disclosure uses sodium ions, which are more abundant in the earth's crustal elements, to replace part of the lithium ions. In addition to making secondary battery materials more sustainable, the voltage platform and the capacity greater than the sodium iron phosphate cathode material are provided and the multiple varied applications are achieved. In a dual cation metal battery, the lithium metal and the sodium metal are mixed as a composite negative electrode. Since the lithium metal (theoretical capacitance of lithium metal is 3840 mAh/g) and the sodium metal (theoretical capacitance of sodium metal is 1166 mAh/g) both have high capacitance per gram, it is helpful of reducing the thickness of the negative electrode, so as to achieve the purpose of increasing the energy density of the battery. The dual-cation metal battery includes the positive electrode materials such as heterosite (FePO4), lithium iron phosphate (LiFePO4) or LixNa1-xFePO4 combined with a mixture of the lithium metal and the sodium metal. There are two different voltage platforms of LiFePO4 and NaFePO4 in the charging and discharging process. Preferably, different electrical properties are shown by using different charging and discharging modes in the case of the dual-cation positive electrode material of LixNa1-xFePO4 matched with the lithium-sodium metal negative electrode. When the dual-cation metal battery is discharged in a ramp voltage mode, it allows to control the ratio of the lithium-ion intercalation structure and the sodium-ion intercalation structure by controlling the rate of voltage drop. On the other hand, the dual-cation metal battery can be used in an energy storage battery application that does not require a large discharge current output. For example, the dual-cation metal battery is used in a solar power generation system. The solar power is generated during the day with full sunlight, and the current from the solar panel can slowly fill the battery. When discharging at night, if a higher power is needed, it can be discharged through the constant-current-constant-voltage discharging mode. That is, the dual-cation metal battery is discharged through the LiFePO4 voltage platform. On the contrary, if considering that the dual cation metal battery does not require high power output, it can be discharged using the ramp voltage discharging mode to make full use of the electricity released by the NaFePO4 voltage platform. Therefore, the ramp voltage mode or constant-current-constant-voltage can be selected according to the actual application conditions.
While the disclosure has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.
| Number | Date | Country | Kind |
|---|---|---|---|
| 111131180 | Aug 2022 | TW | national |
