Electrochemical energy storage device

Abstract

This invention provides an electrochemical energy storage device comprising: a cathode that generates a first metal ion substantially participating in the electrochemical reaction during an electrochemical reaction; an electrolyte that generates at least one second metal ion substantially participating in the electrochemical reaction during an electrochemical reaction, the second metal ion being different from the first metal ion, and the reduction potential / nucleation potential of the second metal ion being higher than that of the first metal ion; and an anode comprising at least one electrode foil. This invention proposes combining two or more dissimilar metal ions with differences in reduction potential / nucleation potential in the same electrochemical device, using the lowest reduction potential / nucleation potential to control the reaction window, thereby realizing a novel electrochemical energy storage device with dual or even multiple ion participation.

Description

[Technical Field]

[0001] This invention relates to electrochemical energy storage devices, particularly an electrochemical energy storage device that uses bimetallic or multimetallic ions to participate in redox reactions, and is applied in secondary reversible electrochemical devices using metal ions such as lithium, sodium, calcium, magnesium, and aluminum. [Previous Technology]

[0002] Traditional metal or metal-ion batteries typically utilize a single metal ion (such as lithium ion) to carry out redox reactions between the positive and negative electrodes. For example, in the common charge and discharge cycle of lithium metal or lithium-ion batteries, lithium ions shuttle between the positive and negative electrodes to achieve the charging and discharging performance.

[0003] In current commercial electrochemical devices, lithium metal and lithium ions have long been regarded as the most ideal energy storage ions due to their smallest radius and extremely low reduction potential / nucleation potential (-3.04 V). Lithium ions are the smallest metal ions that shuttle between the two electrodes, making them ideal ions for electrochemical devices.

[0004] However, the uneven distribution and high cost of lithium resources limit its large-scale application. Lithium batteries are currently considered too expensive for commercial use because lithium is not an abundant element on Earth, and over-mining would lead to shortages. Developing other metals or metal-ion batteries is one way to solve the current difficulties. Research has been conducted on alternative metal ions such as sodium, potassium, and calcium, but challenges remain in battery stability, reaction reversibility, and energy density. [Summary of the Invention]

[0005] To address the current problems of uneven distribution and high cost of lithium resources, as well as the poor stability and energy performance of alternative metal-ion batteries such as sodium, potassium, and calcium, this invention provides an electrochemical energy storage device, comprising: a cathode that can generate a first metal ion that substantially participates in the electrochemical reaction during the electrochemical reaction process; an electrolyte that can generate at least one second metal ion that substantially participates in the electrochemical reaction during the electrochemical reaction process, the second metal ion being different from the first metal ion, and the reduction potential / nucleation potential of the second metal ion being higher than that of the first metal ion; and an anode that includes at least one electrode foil.

[0006] In the process of electrochemical reaction, the electrolyte also generates the first metal ion that can substantially participate in the electrochemical reaction.

[0007] Wherein, the first metal ion or the second metal ion comprises lithium (Li), sodium (Na), calcium (Ca), potassium (K), magnesium (Mg), barium (Ba), strontium (Sr), aluminum (Al), zinc (Zn), nickel (Ni) or iron (Fe).

[0008] Wherein, in addition to the second metal ion, the electrolyte further contains one or more foreign metal ions, and the reduction potential / nucleation potential of these foreign metal ions is higher than that of the first metal ion.

[0009] Wherein, the electrode foil of the negative electrode includes copper foil, aluminum foil or stainless steel foil.

[0010] Wherein, the charge / discharge voltage / potential of the electrochemical energy storage device is lower than the first metal ion reduction potential and higher than the second metal ion reduction potential; or equal to the first metal ion reduction potential.

[0011] The cathode includes a positive electrode material, which includes ternary materials such as lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt oxide, and lithium cobalt oxide.

[0012] The anode includes a negative electrode material, which may be a carbon-based or non-carbon-based negative electrode material.

[0013] As can be seen from the above description, the present invention proposes to combine two or more metal ions with different reduction potentials / nucleation potentials in the same electrochemical device, and to control the reaction window by using the one with the lowest reduction potential / nucleation potential, thereby realizing a novel battery technology with dual or even multiple ion participation.

[0014] This invention introduces the electrochemical design of bimetallic or multimetallic ion systems, no longer limited to the redox reaction of a single metal ion, thus breaking through the material limitations of traditional lithium-ion batteries. By selecting metal ions with different reduction / nucleation potentials (such as lithium and calcium, lithium and sodium), existing cathode materials (such as LFP, LiVPO4F) and inert anode substrates (such as copper or aluminum) can be flexibly combined, avoiding the high cost of developing new materials. Since the behavior of each metal ion in the electrolyte and electrode materials can be controlled separately, this architecture has good compatibility and tunability, enabling the system to be modularly replaced and optimized according to different application requirements, providing a wider range of material selection space and design freedom.

[0015] Lithium is currently the core material of mainstream battery systems, but its abundance in the Earth's crust is limited and concentrated in a few regions, leading to volatile prices and high supply chain risks. In contrast, metals such as sodium, calcium, magnesium, and aluminum are abundant in the Earth's crust, have low extraction costs, and are widely available, which helps to establish a sustainable and regionally autonomous material system. This invention introduces these alternative metal ions and performs anodic deposition and dissolution reactions under operating voltage, effectively replacing the core functions of traditional lithium-based designs. This addresses the urgent need for low-cost, high-supply-stability materials during the energy transition period and promotes greater geographical diversity and economic resilience in the battery industry.

[0016] Design potential for enhanced battery capacity and diversified reaction mechanisms: The operation of bimetallic or multimetallic ion systems allows multiple redox reactions to occur simultaneously or in stages. For example, in a calcium-lithium system, lithium undergoes insertion / deintercalation at the cathode, while calcium undergoes metallization and demetallization at the anode, forming a bipolar energy storage mode. This mechanism not only improves the overall battery capacity density and reaction efficiency but also expands the reaction window, reduces polarization and energy loss, and enhances battery cycle stability. Furthermore, this design has the potential to introduce three or more ion participants, developing novel multi-potential platform energy storage systems to achieve intelligent tiered energy supply or segmented energy management, expanding its development potential in high-power energy storage, electric vehicles, renewable energy integration, and other advanced application areas.

Implementation Method

[0018] The present invention will be described and illustrated in detail below with reference to several preferred embodiments. The accompanying drawings are merely some exemplary representations or embodiments of the present invention. For those skilled in the art, the present invention can be applied to other similar situations without any progressive effort.

[0019] The terms “system,” “apparatus,” “unit,” and / or “module” used in this invention are for distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other words can achieve the same purpose, they may be replaced by other expressions. As shown in this invention, unless the context clearly indicates otherwise, words such as “a,” “an,” “an,” and / or “the” do not specifically refer to the singular and may also include the plural. Generally speaking, the terms “comprising” and “including” only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0020] Flowcharts are used in this invention to illustrate the operations performed by the system according to embodiments of the invention. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0021] Please refer to Figure 1, which is a schematic diagram of a preferred embodiment of the electrochemical energy storage device 10 of the present invention, comprising: a cathode 11, which can generate a first metal ion 111 that substantially participates in the electrochemical reaction during the electrochemical reaction process; an electrolyte 12, which can generate at least one second metal ion 121 that substantially participates in the electrochemical reaction during the electrochemical reaction process, the second metal ion 121 being different from the first metal ion 111, and the reduction potential / nucleation potential of the second metal ion 121 being higher than the reduction potential / nucleation potential of the first metal ion 111; and an anode 13, which includes at least one electrode foil for embedding and embedding the second metal ion 121 into and out of the anode 13 when substantially participating in the electrochemical reaction.

[0022] Wherein, the first metal ion 111 or the second metal ion 121 comprises lithium (Li), sodium (Na), calcium (Ca), potassium (K), magnesium (Mg), barium (Ba), strontium (Sr), aluminum (Al), zinc (Zn), nickel (Ni) or iron (Fe).

[0023] Preferably, in addition to the second metal ion 121, the electrolyte 12 may further contain one or more metal ions, such as a third metal ion, a fourth metal ion, a fifth or sixth metal ion, etc., as long as the reduction potential / nucleation potential of the metal ion that can substantially participate in the electrochemical reaction in the electrolyte is higher than the reduction potential / nucleation potential of the first metal ion 111 in the cathode 11, it falls within the scope claimed by the present invention. On the other hand, in other preferred embodiments of the present invention, the electrolyte 12 can also simultaneously generate the first metal ion 111 that substantially participates in the electrochemical reaction during the electrochemical reaction.

[0024] The electrode foils of the cathode 11 and anode 13 comprise copper foil, aluminum foil, or stainless steel foil. Preferably, the cathode 11 and anode 13 in this invention may or may not contain positive or negative electrode materials depending on the type of electrochemical device. Some preferred embodiments are anode-free batteries when no negative electrode material is included. The positive electrode materials applicable to this invention include, but are not limited to, ternary materials such as lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt oxide, and lithium cobalt oxide, as well as all commercially available positive electrode materials; the negative electrode materials include, but are not limited to, all commercially available carbon-based or non-carbon-based negative electrode materials.

[0025] The electrochemical energy storage device 10 provided by the present invention controls the charge / discharge voltage / potential range to ensure that the reaction occurs in the range below the reduction potential of the first metal ion 111 and above the reduction potential of the second metal ion 121, so that the electrochemical system is mainly the electrochemical reaction and performance of the second metal ion 121; in other preferred embodiments of the present invention, the electrochemical energy storage device 10 controls the charge / discharge voltage / potential range to ensure that the reaction occurs at a value equal to the reduction potential of the first metal ion 111, so that the electrochemical energy storage device 10 exhibits the electrochemical reaction and performance of the first metal ion 111 and the second metal ion 121 together.

[0026] Please refer to Table 1 below for the reaction equations and reduction / nucleation potentials of the first metal ion 111 or the second metal ion 121 that substantially participate in the electrochemical reaction. It should be noted that the reduction / nucleation potentials below are expressed as negative values; therefore, the larger the negative value, the lower the reduction / nucleation potential. For example, a reduction / nucleation potential of -2.71V is higher than a reduction / nucleation potential of -3.04V. Metal types Substantively participates in electrochemical reactions Reduction potential / Nucleation potential (E) o ) Lithium (Li) Li + +e⁻ ⇌ Li(s) -3.04V Sodium(Na) Na + +e⁻ ⇌Na(s) -2.71V Calcium (Ca) Ca 2+ + 2e⁻⇌ Ca (s) -2.87V Potassium (K) K + +e⁻ ⇌ K(s) -2.92V Magnesium (Mg) Mg 2+ +e⁻⇌ Mg(s) -2.93V Barium (Ba) Ba 2+ +2e⁻⇌ Ba(s) -2.912V Strontium (Sr) Sr 2+ +2e⁻⇌ Sr(s) -2.912V Aluminum (Al) Al 3+ +3e⁻⇌ Al(s) -1.66V Zinc (Zn) Al 3+ +3e⁻⇌ Al(s) -0.7618V Nickel (Ni) Ni 2+ +2e⁻⇌ Ni(s) -0.25V Iron (Fe) Fe 3+ +3e⁻⇌ Fe(s) -0.04V

[0027] <Example 1>

[0028] Please refer to Figure 2. The first embodiment of the present invention is a calcium battery based on a lithium battery framework. Lithium iron phosphorus (LFP) is used as the cathode material, Ca(ClO4)2 is added to the electrolyte as a source of calcium ions, and the anode is a copper substrate.

[0029] Calcium ions are introduced as a second metal ion 121, which has a higher reduction potential / nucleation potential than lithium ions. In this embodiment, calcium ions are added to the system as an electrolyte. By using the reduction potential / nucleation potential operating system of calcium ions, the present invention successfully provides a calcium battery in the presence of lithium ions. In this embodiment, based on a lithium anodeless battery using lithium iron phosphate (LFP) as the cathode material, this embodiment is charged and discharged as a calcium-based battery by simply introducing a calcium-based electrolyte. Calcium ions are provided by calcium salts in the electrolyte. Lithium ions can be provided by lithium salts or lithium cathode materials.

[0030] In this embodiment, the reduction potential / nucleation potential of lithium ions is -3.04V, while the reduction potential / nucleation potential of calcium ions is higher at -2.87V. Simultaneously, lithium ions also play a role in maintaining the overall system's electrical neutrality. After operating the electrochemical device at the calcium ion reduction potential / nucleation potential, during the charging process, calcium ions deposit at the negative electrode, forming a calcium metal battery. Specifically, by applying -2.87V to the system, Ca2+ ions will initiate an electrochemical reaction on the negative electrode side, transforming the original lithium-ion system into a calcium-ion system. During discharge, the calcium metal in the negative electrode dissolves into calcium ions, while lithium ions return to the positive electrode material, forming a battery with a lithium battery framework but achieving heterogeneous ion electrochemical performance, possessing a bimetallic ion (calcium-lithium) system.

[0031] Please refer to Figure 3. The second preferred embodiment of the present invention is a calcium battery based on a lithium battery frame. The battery type is a button cell, using LiVPO4F as the positive electrode material, aluminum foil as the anode current collector, C2325 separator, and electrolyte: 1M NaPF6 in EC (1:1) to assemble the battery. During charging, sodium ions will be reduced to sodium metal on the aluminum foil, and lithium at the positive electrode will be deintercalated into lithium ions in the electrolyte, and may also be deposited on the sodium.

[0032] The positive electrode of Example 2 was preferably prepared using LiVPO4F: Super P: PVDF in an 8:1:1 ratio with NMP as the solvent. Its theoretical capacity is 156 mAh / g. The electrode thickness is 65 μm, the active material is 2.8 mg, and the voltage range is 3.2~4.5 V. Lithium electrolyte was used to confirm the positive electrode performance, followed by sodium electrolyte. The capacity calculation for sodium electrolyte: after complete dissociation, its theoretical capacity is 159 mAh / g. 60µL = 0.007g, electrolyte capacity = 1.113 mAh. Electrode capacity = 156 * 0.00288 = 0.4449 mAh.

[0033] Please refer to Figure 4, which is a schematic diagram of an existing non-anode lithium battery for comparison.

[0034] Please refer to Figure 5, which shows the X-ray photoelectron spectroscopy (XPS) analysis of the first preferred embodiment of the present invention. The first preferred embodiment of the present invention shows calcium ion deposition on the negative electrode side, indicating that the device of the present invention successfully transforms the lithium-ion battery into a calcium-based battery.

[0035] Figures 6A and 6B show a comparison of the electrochemical performance of the comparative example and the first preferred embodiment of the present invention. The embodiment of the present invention exhibits a higher specific capacity during discharge, confirming the deposition of calcium ions, and the entire electrochemical system is a calcium system with higher capacitance characteristics.

[0036] Figure 7 shows a scanning electron microscope (SEM) analysis of the first preferred embodiment of the present invention. The results show that calcium metal deposition occurs on the negative electrode, confirming that the present invention successfully provides a calcium battery based on a lithium battery framework.

[0037] Figures 8A and 8B show the energy dispersive X-ray spectroscopy (EDS) analysis of the current collector after the first charge in the second embodiment of the present invention. The results confirmed the presence of sodium deposition and Na element signals on the surface of the current collector. This embodiment is a bimetallic ion system that effectively combines the electrochemical advantages of lithium and sodium, making it suitable for energy storage applications requiring high capacity and high power density.

[0038] Flowcharts are used in this invention to illustrate the operations performed by the system according to embodiments of the invention. It should be understood that the preceding or following operations are not necessarily performed precisely in sequence. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0039] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples by the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical fields and parameters used to confirm their breadth of range in some embodiments of the invention are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0040] Finally, it should be understood that the embodiments described in this invention are merely illustrative of the principles of the invention. Other modifications may also fall within the scope of this invention. Therefore, alternative configurations of the embodiments of this invention are considered as examples and not limitations, and are regarded as consistent with the teachings of this invention. Accordingly, the embodiments of this invention are not limited to those explicitly described and illustrated herein. [Simplified Explanation of the Diagram]

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are merely some examples or embodiments of the present invention and are not intended to limit the technical scope of the present invention. Unless obvious from the context or otherwise stated, the same reference numerals in the figures represent the same structures or operations. Wherein: Figure 1 is a schematic diagram of the electrochemical energy storage device of the present invention. Figure 2 is a schematic diagram of the first preferred embodiment of the electrochemical energy storage device of the present invention. Figure 3 is a schematic diagram of the second preferred embodiment of the electrochemical energy storage device of the present invention. Figure 4 is a schematic diagram of a conventional anode-free lithium battery of a comparative example. Figure 5 is an X-ray photoelectron spectroscopy (XPS) analysis of the first preferred embodiment of the present invention. Figures 6A and 6B are a comparison of the electrochemical performance of the comparative example and the first preferred embodiment of the present invention. Figure 7 is a scanning electron microscope (SEM) analysis of the first preferred embodiment of the present invention. Figures 8A and 8B are energy-dispersive X-ray spectroscopy (EDS) analysis of the second embodiment of the present invention.

Claims

1. An electrochemical energy storage device comprising: a cathode capable of generating a first metal ion substantially participating in the electrochemical reaction during an electrochemical reaction; an electrolyte capable of generating at least one second metal ion substantially participating in the electrochemical reaction during an electrochemical reaction, the second metal ion being different from the first metal ion, and the reduction potential / nucleation potential of the second metal ion being higher than the reduction potential / nucleation potential of the first metal ion; and an anode comprising at least one electrode foil.

2. The electrochemical energy storage device as claimed in claim 1, wherein: During the electrochemical reaction, the electrolyte also generates the first metal ion, which can substantially participate in the electrochemical reaction.

3. The electrochemical energy storage device as claimed in claim 1, wherein: The first metal ion or the second metal ion contains lithium (Li), sodium (Na), calcium (Ca), potassium (K), magnesium (Mg), barium (Ba), strontium (Sr), aluminum (Al), zinc (Zn), nickel (Ni) or iron (Fe).

4. The electrochemical energy storage device as described in claim 1 or 2, wherein: In addition to the second metal ion, the electrolyte further contains one or more foreign metal ions, and the reduction potential / nucleation potential of these foreign metal ions is higher than that of the first metal ion.

5. The electrochemical energy storage device as claimed in claim 1 or 2, wherein the electrode foil of the anode comprises copper foil, aluminum foil or stainless steel foil.

6. The electrochemical energy storage device as claimed in claim 1 or 2, wherein: The charging / discharging voltage / potential of the electrochemical energy storage device is controlled to be lower than the first metal ion reduction potential and higher than the second metal ion reduction potential; or equal to the first metal ion reduction potential.

7. The electrochemical energy storage device as claimed in claim 1 or 2, wherein: The cathode contains a cathode material, which includes ternary materials such as lithium manganese oxide, lithium iron phosphate, lithium nickel cobalt oxide, and lithium cobalt oxide.

8. The electrochemical energy storage device as claimed in claim 1 or 2, wherein: The anode comprises an anode material, which may be a carbon-based or non-carbon-based anode material.

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