Method for increasing safety of metal ion electrochemical device

Abstract

A method for increasing the safety of a metal ion electrochemical device comprises the following steps: providing the metal ion electrochemical device at least comprising a positive electrode, a negative electrode and an isolating membrane arranged between the positive electrode and the negative electrode; the negative electrode comprises a negative electrode current collector and a negative electrode active material covered on the negative electrode current collector, and a hydrophilic metal ion layer is arranged between the negative electrode current collector and the negative electrode active material; charging and discharging the metal ion electrochemical device to induce metal ions to be deposited between the negative electrode active material and the negative electrode current collector; by introducing the hydrophilic metal ion layer between the negative electrode current collector and the negative electrode active material, the device can limit lithium dendrites from being deposited between the negative electrode current collector and the negative electrode active material under overcharge circulation or rapid charge and discharge, and the situation that the metal dendrites directly pierce an isolating membrane to cause short circuit of the battery is greatly reduced.

Description

Technical Field

[0001] The present invention relates to a method for increasing the safety of an electrochemical device, and in particular to a method for increasing the safety of a metal ion electrochemical device. Background Art

[0002] When lithium-ion batteries are charged and discharged, Figure 4A and Figure 4B As shown in Figure 2, lithium dendrites will be deposited between the separator and the negative electrode material, as shown in Figure 2. Figure 4B The pointed dendrite layer formed in the middle position, this lithium dendrite structure is in direct contact with the isolation membrane. After several charge and discharge cycles, it will gradually puncture the isolation membrane and cause the lithium-ion battery to short-circuit. Summary of the Invention

[0003] In order to improve the problem that lithium dendrites are deposited between the separator and the negative electrode material during the charge and discharge cycle of existing lithium-ion batteries, and the sharp structure of the lithium dendrites may pierce the separator and cause the battery to short-circuit, the present invention provides a method for increasing the safety of metal ion electrochemical devices, which comprises the following steps:

[0004] Step 1: Providing a metal ion electrochemical device comprising at least a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode;

[0005] The negative electrode comprises a negative electrode current collector covered with a negative electrode active material, and a metal ion affinity layer is provided between the negative electrode current collector and the negative electrode active material;

[0006] Step 2: charging and discharging the metal ion electrochemical device; and

[0007] Step 3: A metal ion dendrite layer is deposited between the negative electrode active material and the metal ion-philic layer.

[0008] The metal ion electrochemical device comprises a lithium ion battery, a sodium ion battery, a potassium ion battery or a dual ion or multi-ion battery of any of the aforementioned metals.

[0009] The negative electrode active material includes carbon compounds, silicon or its compounds or oxides, aluminum or its compounds or oxides, germanium or its compounds or oxides, lithium titanium compounds or oxides, niobium titanium compounds or oxides, or a combination of the foregoing materials.

[0010] Preferably, the carbon-containing compound comprises graphite or soft carbon; and the lithium-titanium compound comprises lithium titanate.

[0011] The negative electrode current collector includes copper foil, aluminum foil, nickel foil, stainless steel foil, indium foil or a combination thereof.

[0012] The metal ion-philic layer includes elements from Groups 2A to 6A and Groups 1B to 6B and 8B, such as strontium (Sr), gallium (Ga), antimony (Sb), magnesium (Mg), calcium (Ca), barium (Ba), scandium (Sc), yttrium (Y), aluminum (Al), indium (In), thallium (Tl), germanium (Ge), tin (Sn), lead (Pb), bismuth (Bi), selenium (Se), tellurium (Te), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), titanium (Ti), molybdenum (Mo), niobium (Nb), mercury (Hg), compounds of the aforementioned elements, or combinations thereof.

[0013] Preferably, in step 2, the metal ion electrochemical device is charged and discharged at a normal or overcharge voltage and current.

[0014] From the above description, it can be seen that the present invention introduces a metal ion-philic layer between the negative electrode current collector and the negative electrode active material, so that the lithium-ion battery device can induce the deposition of lithium dendrites between the negative electrode current collector and the negative electrode active material (or under the anode active material) under normal cycle conditions or even under overcharge cycle conditions, thereby avoiding the problem of lithium dendrites directly piercing the isolation membrane and causing the lithium-ion battery to short-circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of the present invention and are not intended to limit the technical scope of the present invention. Unless otherwise apparent from the context or otherwise specified, the same reference numerals in the figures represent the same structure or operation. Among them:

[0016] Figure 1 Schematic diagram of the steps of a preferred embodiment of the present invention.

[0017] Figure 2 Schematic diagram of the metal ion dendrite layer deposited between the negative electrode active material and the metal ion-philic layer of the present invention.

[0018] Figure 3A 、 Figure 3B Electron microscope images of a preferred embodiment of the present invention before and after charging and discharging.

[0019] Figure 4A 、 Figure 4B This is an electron microscope image of the previous technology before and after charging and discharging.

[0020] Explanation of symbols:

[0021] 10Metal ion electrochemical device

[0022] 11 positive electrode

[0023] 111 positive electrode current collector

[0024] 112 positive electrode active materials

[0025] 12 negative electrode

[0026] 121 Negative electrode current collector

[0027] 122 Negative electrode active materials

[0028] 123 Metal ion-loving layer

[0029] 13 Isolation film

[0030] 14 Metal ion dendrite layer

[0031] Steps S1-S3 DETAILED DESCRIPTION

[0032] The present invention will be technically illustrated and described in detail below with several preferred embodiments. The accompanying drawings are merely some exemplary representations or embodiments of the present invention. For those skilled in the art to which the present invention belongs, the present invention can also be applied to other similar situations based on these drawings without making any further effort.

[0033] The terms "system", "device", "unit" and / or "module" used in the present invention below are a method for distinguishing different components, elements, parts, parts or assemblies at different levels. However, if other words can achieve the same purpose, the words can be replaced by other expressions. As shown in the present invention, unless the context clearly indicates an exception, the words "a", "an", "a" and / or "the" do not specifically refer to the singular, but may also include the plural. Generally speaking, the terms "comprise" and "include" only indicate the inclusion of clearly identified steps and elements, and these steps and elements do not constitute an exclusive list, and the method or device may also include other steps or elements.

[0034] Flowcharts are used in this disclosure to illustrate the operations performed by systems according to embodiments of the present invention. It should be understood that the preceding and following operations do not necessarily need to be performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0035] Please refer to Figure 1 and Figure 2 , which is a method of increasing the safety of a metal ion electrochemical device according to the present invention, comprising the steps of:

[0036] Step 1: Provide a metal ion electrochemical device 10, which at least includes a positive electrode 11, a negative electrode 12, and a separator 13 disposed between the positive electrode 11 and the negative electrode 12;

[0037] The negative electrode 12 includes a negative current collector 121 covered with a negative active material 122 , and a metal ion affinity layer 123 is provided between the negative current collector 121 and the negative active material 122 ;

[0038] Step 2: charging and discharging the metal ion electrochemical device 10; and

[0039] Step 3: A metal ion dendrite layer 14 is deposited between the negative electrode active material 122 and the metal ion affinity layer 123 .

[0040] Preferably, the metal ion electrochemical device 10 of the present invention comprises a lithium ion battery, a sodium ion battery, a potassium ion battery, or a dual ion or multi-ion battery of any of the aforementioned metals.

[0041] The positive electrode 11 is not limited in the present invention and may preferably include a positive electrode current collector 111 and / or a positive electrode active material 112. Any positive electrode current collector 111 and / or positive electrode active material 111 that is currently applicable to different metal ion electrochemical devices is within the scope of use and claim of the present invention.

[0042] The negative electrode active material 122 includes a carbon-containing compound, silicon or its compounds or oxides, aluminum or its compounds or oxides, germanium or its compounds or oxides, a lithium-titanium compound or oxide, a niobium-titanium compound or oxide, or a combination thereof. Preferably, the carbon-containing compound comprises graphite or soft carbon, and the lithium-titanium compound comprises lithium titanate. The negative electrode current collector 121 includes copper foil, aluminum foil, nickel foil, stainless steel foil, indium foil, or a combination thereof.

[0043] Furthermore, in a preferred embodiment of the present invention, an electrolyte and an electrolyte therein (not shown) are contained between the positive electrode 11 and the negative electrode 12 in the metal ion electrochemical device 10. The types of electrolyte and electrolyte therein are also not limited in the present invention. Any electrolyte and electrolyte therein that are currently applicable to different metal ion electrochemical devices in the existing technology are within the scope of use and claim of the present invention.

[0044] The metal ion-philic layer 123 refers to the affinity or wettability of the material surface with metal ions when deposited as metal. Its thickness is preferably between 1 and 100 nm, more preferably between 1 and 50 nm. Taking lithium as an example, lithiophilicity refers to the ability of a material with high lithiophilicity to induce uniform deposition of lithium ions on its surface, preventing the formation of lithium dendrites between the negative electrode active material 112 and the separator 13, thereby improving the performance and safety of the electrochemical device. The metal ion-philic layer 123 of the present invention includes elements from Groups 2A to 6A and Groups 1B to 6B and 8B, such as strontium (Sr), gallium (Ga), antimony (Sb), magnesium (Mg), calcium (Ca), barium (Ba), scandium (Sc), yttrium (Y), aluminum (Al), indium (In), thallium (Tl), germanium (Ge), tin (Sn), lead (Pb), bismuth (Bi), selenium (Se), tellurium (Te), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), titanium (Ti), molybdenum (Mo), niobium (Nb), mercury (Hg), compounds of the above elements, or combinations thereof.

[0045] On the other hand, in the aforementioned step 2, in addition to charging and discharging the metal ion electrochemical device 10 with the normal charging and discharging voltage and current of the metal ion electrochemical device 10, the present invention can also avoid the metal ion dendrite layer 14 being deposited between the negative electrode active material 122 and the metal ion affinity layer 123 under overcharging voltage and current conditions, thereby preventing it from puncturing or damaging the isolation membrane 13.

[0046] <Validity Test>

[0047] Please refer to Figure 3A 、 Figure 3B In the present invention, a lithium-ion battery is used as an example. The negative electrode current collector 121 of the negative electrode 12 is a copper current collector (Cu Current Collector), the negative electrode active material 122 is graphite, and the metal ion affinity layer 123 includes tin (Sn).

[0048] Figure 3A This is a cross-sectional electron microscope image (SEM) of a preferred embodiment of the present invention before charging and discharging. Figure 3B After charging and discharging, the metal ion dendrites 14 (lithium dendrites) can be clearly seen deposited between the negative electrode active material 122 and the metal ion affinity layer 123. This can prevent the lithium dendrites from piercing or damaging the separator 13 during charging and discharging, thereby increasing the safety of the metal ion electrochemical device 10.

[0049] Figure 4A 、 Figure 4B is a comparative example not including the metal ion affinity layer 123, Figure 4A This is a cross-sectional electron microscope image (SEM) of the comparative example before charge and discharge. Figure 4B The pointed dendrite layer formed in the middle position can be seen after charging and discharging. This lithium dendrite structure is in direct contact with the isolation membrane. After several charge and discharge cycles, it will gradually puncture the isolation membrane and cause the lithium-ion battery to short-circuit.

[0050] Furthermore, in addition to the preferred embodiments described above, other negative electrode active materials 122 or metal ion-philic layers 123 listed in the present invention have been proven to be effective, as shown in Table 1 below.

[0051] Table 1.

[0052]

[0053]

[0054] Flowcharts are used in this disclosure to illustrate the operations performed by systems according to embodiments of the present invention. It should be understood that the preceding and following operations do not necessarily need to be performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0055] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate 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 change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present invention are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0056] Finally, it should be understood that the embodiments described herein are intended only to illustrate the principles of the present invention. Other variations are also possible and fall within the scope of the present invention. Therefore, by way of example and not limitation, alternative configurations of the embodiments of the present invention may be considered consistent with the teachings of the present invention. Accordingly, the embodiments of the present invention are not limited to the embodiments explicitly described and illustrated herein.

Claims

1. A method for increasing the safety of a metal ion electrochemical device, characterized in that: The steps include: Step 1: Providing a metal ion electrochemical device comprising at least a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; The negative electrode comprises a negative electrode current collector covered with a negative electrode active material, and a metal ion affinity layer is provided between the negative electrode current collector and the negative electrode active material; Step 2: charging and discharging the metal ion electrochemical device; and Step 3: A metal ion dendrite layer is deposited between the negative electrode active material and the metal ion-philic layer.

2. The method for increasing the safety of a metal ion electrochemical device according to claim 1, wherein: The metal ion electrochemical device comprises a lithium ion battery, a sodium ion battery, a potassium ion battery or a dual ion or multi-ion battery of any of the aforementioned metals.

3. The method for increasing the safety of a metal ion electrochemical device according to claim 1, wherein: The negative electrode active material includes carbon compounds, silicon or its compounds or oxides, aluminum or its compounds or oxides, germanium or its compounds or oxides, lithium titanium compounds or oxides, niobium titanium compounds or oxides, or a combination of the above materials.

4. The method for increasing the safety of a metal ion electrochemical device according to claim 3, wherein: The carbon-containing compound includes graphite or soft carbon; and the lithium-titanium compound includes lithium titanate.

5. The method for increasing the safety of a metal ion electrochemical device according to claim 1 or 2, wherein: The negative electrode current collector includes copper foil, aluminum foil, nickel foil, stainless steel foil, indium foil or a combination thereof.

6. The method for increasing the safety of a metal ion electrochemical device according to claim 1 or 2, wherein: The metal ion-philic layer includes elements from groups 2A to 6A and elements from groups 1B to 6B and 8B.

7. The method for increasing the safety of a metal ion electrochemical device according to claim 1 or 2, wherein: The metal ion affinity layer comprises strontium (Sr), gallium (Ga), antimony (Sb), magnesium (Mg), calcium (Ca), barium (Ba), scandium (Sc), yttrium (Y), aluminum (Al), indium (In), thallium (Tl), germanium (Ge), tin (Sn), lead (Pb), bismuth (Bi), selenium (Se), tellurium (Te), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), titanium (Ti), molybdenum (Mo), niobium (Nb), mercury (Hg), compounds of the foregoing elements, or combinations thereof.

8. The method for increasing the safety of a metal ion electrochemical device according to claim 1 or 2, wherein: In step 2, the metal ion electrochemical device is charged and discharged at a normal or overcharge voltage and current.

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